Autodesk LIGHTSCAPE User Manual
/LJKWVFDSH
Œ
$SULO#4<<<
31#93<36034333308355
Copyright © 1993-1999 Autodesk, Inc.
All Rights Reserved
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LIMITED TO ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR
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Discreet is a division of Autodesk, Inc. Autodesk, AutoCAD, 3D Studio MAX, 3D Studio VIZ, DXF, and 3D Studio
are registered trademarks, and Lightscape, LSnet, and Discreet are trademarks of Autodesk, Inc. in the USA and/
or other countries.
Third-Party Trademarks:
OpenGL, Open Inventor and Silicon Graphics are trademarks or registered trademarks of Silicon Graphics, Inc.
Microsoft, Windows and Windows NT are registered trademarks of Microsoft Corporation. LightWave 3D is a
registered trademark of NewTek. ArchiCAD and Graphisoft are registered trademarks of Graphisoft R&D
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GOVERNMENT USE
Use, duplication, or disclosure by the U.S. Government is subject to restrictions as set forth in FAR 1 2.212
(Commercial Computer Software-Restricted Rights) and DFAR 227.7202 (Rights in Technical Data and Computer
Software), as applicable.
Third Party Software Program Credits
The software program contains content files licensed by 3Name3D, Santa Monica, CA; Artbeats Software, Inc.,
Myrtle Creek, OR; Modern Medium, Inc. Eugene, OR; ImageCELs® (Texture Files) Copyright © 1987-1999
IMAGETECTS™ in addition to the manufacturers listed in the Acknowledgements at the end of this manual. Please
note that the manufacturers reserve the right to discontinue or change any lighting or other products represented
in the software, and the copyrights to these content files are the property of their respective owners.
Printed in the United States.
Title:
Item No.:
Publication ID:
Date:
Lightscape User’s Guide
LIUG3.2-01
1.0
April, 1999
Table of Contents
toc
1 Introduction 1
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
About Lightscape . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Computer Graphics Rendering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Photometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
About Lightscape Documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2 Installation 11
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
System Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Installing Lightscape for the First Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Upgrading from a Previous Version of Lightscape. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3 Workflow 13
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Preparing the Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Processing the Radiosity Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4 The Interface 17
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Starting Lightscape. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Overview of the Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Interface Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Using Toolbars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Using File Controls. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Viewing the Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
Controlling the Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Selecting Objects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
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Transforming Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Setting Document Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Setting System Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
5 Importing Geometry 53
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Common Import Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Importing DXF Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Importing DWG Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Importing .3DS files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65
Importing a LightWave Scene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Exporting from 3D Studio MAX or 3D Studio VIZ to Lightscape. . . . . . . . . . . . . . . . 72
6 Refining Geometry 81
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
About Refining Geometry. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Working with Layers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Working with Blocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Modifying Block Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
Working with Block Instances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
Working with Surfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
7 Using Materials 103
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
About Material Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Using the Materials Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Workflow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Adding Materials to a Scene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
Editing Material Properties. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
Assigning Materials to Surfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
Aligning Textures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
8 Artificial Lighting 129
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
About Luminaires. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .129
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Using the Luminaires Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
Adding Luminaires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
Setting Photometric Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
Placing Luminaires in a Model. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
Editing Luminaires. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .139
Setting Luminaire Surface Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
Luminaire Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
9 Photometrics 149
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
Using Photometric Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
Creating and Editing Photometric Webs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
Customized Photometric Web Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
IES Standard File Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
Using LID Conversion Utilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
10 Daylight 159
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
About Sunlight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
About Skylight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
Using Daylight in Exterior Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
Interior Model Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
Illuminating Your Model with Daylight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
Enabling Daylight in Radiosity Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
❚❘❘
11 Radiosity Processing 169
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
About Radiosity Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
Processing Workflow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
Setting the Processing Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172
Setting the Surface Processing Parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179
Initiating the Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
Processing the Radiosity Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
Changing Materials and Luminaires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184
Meshing Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .184
Reducing Meshing Artifacts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187
Testing for Artifacts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
Modeling Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192
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12 Lighting Analysis 195
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
About Lighting Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
Displaying Light Distribution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
Analyzing Lighting Statistics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198
Controlling Analysis Grids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199
Using Workplanes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .200
13 Mesh to Texture 203
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
About Mesh to Texture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
Using Mesh to Texture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204
Mesh to Texture Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210
14 Rendering 213
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213
About Rendering in Lightscape . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213
Creating Images . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214
Rendering Multiple Views . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
Ray Tracing an Area. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .219
Rendering Large Jobs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220
Rendering Across a Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220
15 Animation 221
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221
About Animation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .221
Defining the Camera Path. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222
Setting Camera Orientation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227
Varying the Camera Speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231
Saving Animation Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236
Playing Back Animations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237
Using Animation Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
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16 Exporting 241
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
Exporting Panoramic Images . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
Exporting VRML Files. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245
Importing Solution Files into Modeling Packages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248
A Light and Color 249
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249
Light: The Physical World. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249
Color: The Perceived World. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
Constraints of Output Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253
B Batch Processing Utilities 255
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255
Processing Radiosity Solutions Using LSRAD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255
Ray Tracing Solution Files Using LSRAY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258
Rendering Files Using LSRENDER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263
Converting Radiosity Meshes to Textures Using LSM2T . . . . . . . . . . . . . . . . . . . . . . . 267
Converting Solution Files to VRML Files Using LS2VRML . . . . . . . . . . . . . . . . . . . . . 271
Merging Lightscape Files Using LSMERGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273
Converting DXF Files to Preparation Files Using DXF2LP. . . . . . . . . . . . . . . . . . . . . . 274
Converting 3DS Files to Preparation Files Using 3DS2LP. . . . . . . . . . . . . . . . . . . . . . . 276
Raytracing Solution Files Using LSRAYF. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277
Deleting Unused Layers and Materials Using LSPURGE . . . . . . . . . . . . . . . . . . . . . . . 281
About Batch Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282
Creating Batch Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282
❚❘❘
C LSnet 287
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287
About LSnet. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287
Using LSnet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 288
D Reflection Models 301
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301
Light and Materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301
Reflection Model for Radiosity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305
v
toc
Table of Contents
Reflection Model for OpenGL Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305
Ray Tracing Reflection Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305
E IES Standard File Format 309
F File Types 311
G Common Lamp Values 313
H Viewing Utilities 317
Viewing Utilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317
Using LSViewer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317
Using LVu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 320
I References 325
Glossary
327
Index 335
vi
Lightscape
An introduction to Lightscape
Lightscape™ is an advanced visualization system for generating accurate
lighting simulations of three-dimensional models.
Lighting
Summary
In this chapter, you learn about:
Lightscape™
•
Computer graphics rendering
•
Photometry
•
Lightscape documentation
•
About Lightscape
Lightscape™ is an advanced lighting and visualization application used to create accurate images of
how a 3D model of a space, or object, would appear
if physically built. Lightscape uses both radiosity
and ray tracing technology as well as a physically
based interface for defining lights and materials.
Lightscape has many unique advantages over other
rendering technologies, including:
Realism
•
•
Interactivity
•
Progressive refinement.
•
Realism
Because Lightscape accurately calculates how light
propagates within an environment, you can obtain
subtle but significant lighting effects and produce
images of natural realism not attainable with other
rendering techniques. These effects include indirect
illumination, soft shadowing, and color bleeding
between surfaces.
Physically Based Lighting
Because the technology in Lightscape works with
actual photometric (light energy) values, you can
intuitively set up lights as they would be in the real
world. You can create lighting fixtures with any
distribution and color characteristics or import
Introduction
and lighting technology.
1
1
1
Introduction
specific photometric files directly from lighting
manufacturers. You can also specify natural daylight
simply by indicating the location, date, and time of
day.
Interactivity
The result of a radiosity solution is not just a single
image but a full 3D representation of the light distribution in an environment. Because the lighting is
precalculated, Lightscape can display specific views
of a fully rendered model much faster than with
traditional computer graphics techniques. With
faster hardware, it is often possible to move interactively through rendered environments. High-quality
walkthrough animations for film or video can be
generated in a fraction of the time required with
other professional animation systems.
Progressive Refinement
Unlike other techniques, a Lightscape solution
provides instant visual feedback, which continues to
improve in quality over time. At any stage in the
process, you can alter a surface material or lighting
parameter and the system will compensate and
display the results without starting the process over.
The progressive refinement radiosity algorithms
implemented in Lightscape give you precise control
over the quality of visualization required to perform
any given design or production task.
A 3D model contains geometric data defined in relationship to a 3D Cartesian coordinate system. This
system is sometimes referred to as
model may also contain other information about the
material of each object and the lighting. The image
on a computer monit or is made up of a large number
of illuminated dots called
a computer graphics image of a geometric model is
to determine the color for each pixel on the screen
(screen space)
specific viewpoint.
The color of any specific point on a surface in a
model is a function of the physical material properties of that surface and the light that illuminates it.
Two ge ne ral
and global illumination—are used to describe how
surfaces reflect and transmit light.
based on the model information and a
shading algorithms
pixels
world space
. The task in creating
—local illumination
. The
Local Illumination
Local illumination algorithms
vidual surfaces reflect or transmit light. Given a
description of light arriving at a surface, these mathematical algorithms predict the intensity, spectral
character (color), and distribution of the light
leaving that surface. The next task is to determine
where the light arriving at the surface originates. A
simple rendering algorithm considers only the light
coming directly from the light sources themselves in
the shading.
describe how indi-
Computer Graphics Rendering
This section provides an overview of computer
graphics rendering and a conceptual understanding
of the techniques available with Lightscape. This
information will help you decide which technique is
most suitable for the visualization task you want to
perform.
2
Global Illumination
In considering more accurate images, however, it is
important to take into account not only the light
sources themselves, but also how all the surfaces and
objects in the environment interact with the light.
For example, some surfaces block light, casting
shadows on other surfaces; some surfaces are shiny,
in which case we see in them the reflections of other
surfaces; some surfaces are transparent, in which
Lightscape
Computer Graphics Rendering
❚❘❘
case we see other surfaces through them; and some
surfaces reflect light onto others.
algorithms
are rendering algorithms that take into
Global illumination
account the ways in which light is transferred
between the surfaces in the model.
Lightscape uses two global illumination algorithms:
ray tracing
and
radiosity
. Before explaining how
these techniques work, it is useful to have a basic
understanding of how, in the physical world, light is
distributed in an environment. Consider, for
example, the simple room illustrated as follows.
Global illumination in a room
This room has one light source. One theory of light
considers light in terms of discrete particles called
, which travel out from the light source until
photons
they encounter some surface in the room.
Depending on the material of the surface, some of
these photons, traveling with particular wavelengths, are absorbed, while others are scattered
back out into the environment. The fact that photons
traveling at a particular wavelength are absorbed
while others are not is what determines the color
(also referred to as the
spectral reflectance
) of the
surface.
The way a surface reflects photons depends primarily on its smoothness. Surfaces that are rough tend
to reflect photons in all directions. These are known
as
diffuse surfaces,
and this type of reflection is
known as
diffuse reflection
. A wall painted with flat
paint is a good example of a diffuse surface.
Diffuse reflection
Specular reflection
Very smooth surfaces reflect the photons in one
direction, at an angle equal to the angle at which they
arrive at the surface
surfaces are known as
(angle of incidence)
specular surfaces,
type of reflection is known as
specular reflec tion
. These
and this
. A
mirror is an example of a perfectly specular surface.
Of course, many materials display some degree of
both specular and diffuse reflection.
The final illumination of the room is determined by
the interaction between the surfaces and the billions
of photons that are emitted from the light source. At
any given point on a surface, it is possible that
photons have arrived directly from the light source
(direct illumination)
more bounces off some other surfaces
illumination)
or el se in dir ec tl y t hro ug h o ne or
(indirect
.
If you were standing in the room, a very small
number of the total photons in the room would enter
your eye and stimulate the rods and cones of your
retina. This stimulation would, in effect, form an
image that is perceived by your brain. Computers
replace the rods and cones of a retina with the pixels
of the computer screen. One goal of a global illumination algorithm is to recreate, as accurately as
possible, what you would see if you were standing in
a real environment. A second goal is to accomplish
this task as quickly as possible, ideally in
real time
(30 images per second). There is currently no single
global illumination algorithm that can accomplish
both of these goals.
3
1
Introduction
Ray Tracing
One of the first global illumination algorithms to be
develope d is known as
ray tracing
recognized that while there may be billions of
photons traveling about the room, the photons you
primarily care about are the ones that enter the eye.
The algorithm works by tracing rays
each pixel on the screen into the 3D model. In this
way, it computes only the information needed to
construct the image. To create an image using ray
tracing, do the following procedure for each pixel on
the computer screen:
Trace a ray back from the eye position, through
1.
the pixel on the monitor, until it intersects with a
surface.
The model provides the reflectivity of the sur-
2.
face, but not the amount of light reaching that surface. To determine the total illumination, trace a ray
from the point of intersection to each light source in
the environment
(shadow ray)
source is not blocked by another object, use the light
contribution from that source to calculate the color
of the surface.
The intersected surface may be shiny or trans-
3.
parent. The algorithm must determine either what is
seen in or through the surface being processed. Repeat steps 1 and 2 in the reflected (and, in the case of
transparency, transmitted) direction until another
surface is encountered. The color at the subsequent
intersection point is calculated and factored into the
original point.
If the second surface is yet again a reflective or
4.
transparent surface, repeat the ray tracing process
. In ray tracing, it is
backward,
from
. If the ray to a light
until a maximum number of iterations is reached or
until no more surfaces are intersected.
Ray tracing
Ray tracing is a very versatile algorithm because of
the large range of lighting effects it can model. It can
accurately account for the global illumination characteristics of direct illumination, shadows, specular
reflections (for example, mirrors), and refraction
through transparent materials. The main disadvantage of ray tracing is that the process can be slow and
computationally expens ive for environments of even
moderate complexity.
Another significant disadvantage of ray tracing is
that it does not account for one very important characteristic of global illumination—diffuse
interreflections.
Traditional ray tracing techniques accurately
account for only the light arriving directly from the
light sources themselves. But, as shown in the room
example, light does not only arrive at a surface from
the light sources (direct lighting), it also arrives from
other surfaces (indirect lighting). If you ray trace an
image of the table (as shown in the example), the
area under the table appears black because it receives
no direct light from the light source. You know from
experience, however, that this area would not really
be completely dark because of the light it would
receive from the surrounding walls and floor.
4
Lightscape
Computer Graphics Rendering
❚❘❘
Traditional ray tracing techniques often refer to this
indirect illumination as
ambient light.
With this
technique, an arbitrary value that has no correlation
to the physical phenomena of indirect illumination
and that is constant throughout space is simply
added. This often causes ray traced images to appear
very flat. This is particularly true for architectural
environments, which typically contain mostly
diffuse surfaces.
Radiosity
To address some of the shortcomings of the ray
tracing algorithm, researchers began investigating
alternative techniques for calculating global
illumination.
In the early 1960s, thermal engineers developed
methods for simulating the radiative heat transfer
between surfaces. Their goal was to determine how
their designs would perform in various applications
such as furnaces and engines. In the mid-1980s,
computer graphics researchers began investigating
the application of these techniques for simulating
light propagation.
Radiosity
graphics world, differs fundamentally from ray
tracing. Rather than determining the color for each
pixel on a screen, radiosity calculates the intensity
for discrete points in the environment.
Radiosity accomplishes this by first dividing the
original surfaces into a mesh of smaller surfaces
known as
the amount of light distributed from each mesh
element to every other mesh element. It then stores
the final radiosity values for each element of the
mesh.
When this light distribution has been calculated,
specific views of the environment can be rapidly
displayed on the screen (often in real time) using
, as this technique is called in the computer
elements
. The radiosity process calculates
simple hardware-assisted scan-line techniques. This
property is often referred to as
view independence,
because the light distribution is precalculated for the
whole environment and does not have to be recalculated for each specific view. Ray tracing, on the other
hand, is known as a
view-dependent
algorithm,
because the lighting has to be recalculated for each
view.
Radiosity
Early versions of the radiosity algorithm had to
completely calculate the distribution of the light
among all the mesh elements before displaying any
useful results on the screen. Even though the end
result was view independent, the preprocessing took
considerable time. In 1988, this preprocessing
portion of the radiosity algorithm was reformulated.
The new technique, referred to as
ment radiosity,
allows users to obtain immediate
progressive refine-
visual results, which progressively improve in accuracy and visual quality.
The progressive refinement radiosity algorithm
used in Lightscape works in the following way:
The surfaces are meshed into a set of relatively
1.
large elements. The initial elements can be subdivided automatically into smaller elements in areas
where a significant intensity difference is detected
5
1
Introduction
between adjacent mesh elements (for example,
across shadow boundaries).
Light is distributed from each luminaire to all
2.
surfaces in the environment. (A luminaire is a light
fixture, with one or more lamps and housing.) In
this calculation, surfaces can block other surfaces,
casting shadows.
Depending on the characteristics of the surface
3.
material, some of the energy reaching a particular
mesh element is absorbed, while the remaining energy is reflected into the environment. An important
assumption in radiosity is that all the surfaces are
ideal diffuse
(Lambertian)—that is, they reflect light
equally in all directions.
After distributing the energy from each direct
4.
light source (direct illumination), the progressive radiosity algorithm continues by checking all the surfaces and determining which surface has the most
energy to be reflected. This surface is then treated as
an area light source emitting the reflected energy to
all the other surfaces in the environment (indirect illumi nation ).
The process continues until most of the energy
5.
in the environment has been absorbed (energy equilibrium) and the simulation reaches a state of
.
gence
conver-
Each distribution of light from a luminaire or
surface, as just described, is called an
iteration
.
The number of iterations required for a simulation
to reach a state of convergence varies depending on
the complexity of the environment. Because the iterations are sorted to calculate the surfaces with the
greatest energy first, the rate of convergence for the
radiosity solution is much faster in the beginning.
Toward the end, the amount of energy remaining to
be distributed is so small that there is no perceptible
difference in the resulting images from one iteration
to the next. Therefore, while it may take many iterations for a solution to reach full convergence,
typically you can interrupt the process when an
acceptable solution has been obtained.
Radiosity and Ray Tracing Differences
Although the ray tracing and radiosity algorithms
are very different, they are in many ways
complementar y.
The ray tracing algorithm has the following advantages and disadvantages:
Advantages Accurately renders direct illumi-
nation, shadows, specular reflections, and transparency effects.
Memor y efficient.
Disadvantages Computationally expensive; the
time required to produce an image is greatly affected by the
number of light sources.
View dependent; the process
must be repeated for each view.
Does not account for diffuse interreflections.
The radiosity algorithm has the following advantages and disadvantages:
Advantages Ca lculates diffuse interreflec tions
between surfaces.
View independent for fast display
of arbitrary views.
Immediate visual results, which
progressively improve in accuracy and quality.
6
Lightscape
Photometry
❚❘❘
Disadvantages 3D mesh requires more memory
than the original surfaces.
Surface-sampling algorithm is
more susceptible to imaging artifacts than ray tracing.
Does not account for specular reflections or transparency effects.
Neither radiosity nor ray tracing offers a complete
solution for simulating all global illumination
effects. Radiosity excels at rendering diffuse-todiffuse interreflections and ray tracing excels at
rendering specular reflections.
By merging both techniques, Lightscape offers the
best of both. In Lightscape, it is possible to combine
a ray-tracing postprocess with a specific view of a
radiosity solution to add specular reflections and
transparency effects. In this situation, the radiosity
solution replaces the inaccurate ambient constant
used in many programs with accurate indirect illumination values. This leads to a much more realistic
image. In addition, because the direct lighting can
be calculated in the radiosity solution, the ray tracer
does not have to cast any shadow rays, only reflected
or transmitted rays. This greatly reduces the time
required to ray trace an image. By integrating both
techniques, Lightscape offers a full range of visualization possibilities, from fast, interactive lighting
studies to combination radiosity/ray traced images
of exceptional quality and realism.
Photometry
Lightscape is founded on a physically based simulation of the propagation of light through an
environment. The results are not only highly realistic renderings, but also accurate measurements of
the distribution of light within the scene. This
section briefly describes the quantities used to characterize these measurements.
You specify the brightness of a luminaire in Lightscape using the physically based quantities. You can
obtain these values directly from the manufacturers
of various lamps and luminaires. A table of some
common lamp types is provided in Appendix G,
“Common Lamp Values.”
There are several theories that describe the nature of
light. For this discussion,
capable of producing a visual sensation in a human
observer.
When designing a lighting system, you want to evaluate its performance in terms of the human visual
response. Thus
measure light, taking into account the psychophysical aspects of the human eye/brain system.
The lighting simulation system uses four photometric quantities:
Luminous flux
•
Illuminance
•
Luminance
•
Luminous intensity.
•
Luminous flux
time arriving, leaving, or going through a surface.
The unit of luminous flux is the
both the International System (SI) of units and in the
American System (AS) of units. If you think of light
as particles (photons) moving through space, then
the luminous flux of a light beam arriving at a
surface is proportional to the number of particles
hitting the surface during a time interval of 1 second.
Illuminanc e
surface of unit area. This quantity is useful for
describing the level of illumination incident on a
surface without making the measurement dependent on the size of the surface itself. The SI unit of
illuminance is the
photometry
is the quantity of light energy per unit
is the luminous flux incident on a
(lx), equal to 1 lumen per
lux
is radiant energy
light
was developed to
(lm), used in
lumen
7
1
Introduction
square meter. The corresponding AS unit is the footcandle (fc), equivalent to 1 lumen per square foot.
Part of the light incident on a surface is reflected
back into the environment.
reflected off a surface in a particular direction and is
the quantity converted to display colors to generate a
realistic rendering of the scene. Luminance is
measured in candelas per square meter or per square
inch. The
nous intensity emitted by a single wax candle.
Finally,
luminous intensity
time emitted by a point source in a particular direction. The unit of measure of luminous intensity is the
. Luminous intensity is used to describe the
candela
directional distribution of a light source—that is, to
specify how the luminous intensity of a light source
varies as a function of the outgoing direction.
was originally defined as the lumi-
candela
Luminance
is the light energy per unit
is the light
About Lightscape
Documentation
The Lightscape manuals are comprehensive documents that contain all the information you need to
learn and use Lightscape efficiently and effectively.
The documentation for your Lightscape software
includes:
• Lightscape 3.2 User’s Guide
line file
• Learning Lightscape 3.2
file
printed manual and on-
printed manual and online
The
Lightscape 3.2 User’s Guide
tions of the techniques and concepts required to set
up, process, and render a Lightscape solution.
Learning Lightscape
of the procedures discussed in this manual.
The Lightscape Online Help system provides topicbased information as well as reference information
about the main interface elements.
provides step-by-step examples
provides explana-
Using This Guide
This guide is designed to provide information both
by topic and in the order of a typical workflow. More
experienced users can use the guide for reference,
turning directly to sections of specific interest.
The following typographical conventions are used
in this manual:
Convention:
Courier
Bold
Italic
▲
| Used to indicate that you are to
Description:
Used for program commands,
such as
lid2cibse
lid2ies
Used for emphasis and when a
new term is introduced.
Used to indicate a warning.
choose an item from a menu or
submenu. For example,
File | Parameters | Load tells you
to choose Load from the Parameters submenu of the File menu.
.
or
Online Help
•
• Installing LSnet
• README.TXT
scape home directory).
8
online file
(an online text file in your Light-
Lightscape
Getting More Help
If you need more information, contact Discreet™
Customer Support at one of the following telephone
numbers. You can also send queries by e-mail.
Discreet Customer Support
North
America: (877) DISCREET
Elsewhere: (514) 954-7550
Fax: (514) 954-7254
E-mail: discreet.techsupport@autodesk.com
WWW: http://www.discreet.com
Reader’s Comments
We would like to hear from you. Your comments can
help us improve the quality of our documentation.
Mail, fax, or e-mail your comments to:
Discreet Documentation Department
10 Duke Street
Montreal, Quebec, Canada
H3C 2L7
About Lightscape Documentation
❚❘❘
Fax:
E-mail:
(514) 954-7495
docs@discreet.com
9
NOTES
10
This chapter describes how to install your Lightscape system.
Installation
How to install Lightscape and its
components.
2
Summary
In this chapter, you learn about:
System requirements
•
Installing Lightscape for the first time
•
Upgrading Lightscape from a previous version.
•
System Requirements
The following table describes the minimum and the
recommended system requirements for running
Lightscape.
Minimum
Requirements:
Intel Pentium or
Pentium Pro at 200
MHz
Recommended
Requirements:
Intel Pentium II
(350MHz + processor)
Minimum
Requirements:
Windows NT 4.0
(with Service Pack 4),
Windows 95
(with Service Pack 1),
or Windows 98
64 MB RAM 128 MB of 100 MHz
PCI Graphic card
supporting 16-bit
colour depth
1 GB hard disk 4 GB or higher free hard
CD-ROM drive Motherboard with Intel
Monitor 19 to 21 inch monitor
Recommended
Requirements:
Windows NT 4.0 with
Service Pack 4
RAM (consider 256 MB
or more for power users)
A hardware accelerated
OpenGL video card with
at least 8 MB of RAM
drive space
BX chipset
11
2
Installation
Minimum
Requirements:
Windows NT or
Windows 95-complaint
point device
Recommended
Requirements:
All standard equipment
(mouse, CD-ROM drive,
cabling for TCP/IP-compliant network)
Installing Lightscape for the First
Time
Version 3.2 of Lightscape is designed to work with
the following: Windows 95 (with Service Pack 1),
Windows NT 4.0 (with Service Pack 4), and
Windows 98.
You must authorize Lightscape before you
Note:
install. See the authorization request form
included with the software.
If the installer prompts you to restart your com-
4.
puter, do so before starting Lightscape.
Upgrading from a Previous
Version of
To upgrade from a previous version of Lightscape,
simply install the new version as if you were
installing the software for the first time. You will be
prompted to uninstall the existing version. If you
choose not to uninstall, the existing version is
overwritten.
If you do not want to overwrite previous versions of
Lightscape, install the versions in different
directories.
Lightscape 3.2 can read files from any previous
version .
Lightscape
To install Lightscape:
Place the Lightscape CD-ROM in the CD-ROM
1.
drive.
If you are installing Lightscape on Windows
Note:
NT, you should have administrator privileges.
Choose Run from the Windows Start menu.
2.
Ty p e
3.
replace “d” with the letter that represents your CDROM drive.
The Lightscape Setup wizard guides you step-bystep through the installation process. You are greeted
with a welcoming message followed by a series of
dialogs. These dialogs let you choose the components of Lightscape to install and the directory in
which to install them.
In the dialogs that display the Back button, you can
go back to a previous step by clicking on this button.
You can also cancel the installation process by
clicking Cancel.
d:\setup
and press Enter. If required,
Any files saved with Lightscape 3.2 that
Note:
include material information cannot be read by
earlier versions of Lightscape. File formats that do
not include material properties information like
animation files (.la), layer state files (.lay), and
parameter files (.df) are portable from Lightscape
3.2 to Lightscape 3.1 or 3.1.1.
12
Lightscape
This chapter provides an overview of the process of creating a Lightscape
solution. Each step of this process is explained in detail in the chapters that
follow.
Workflow
How to use Lightscape.
3
Summary
The Lightscape process consists of two major
stages—the
In the Preparation stage, the model structure is
similar to that of many CAD and modeling
programs. In this stage, you can edit geometry,
materials, and lights. The Preparation model is
saved in a Lightscape Preparation file with a .lp file
extension.
P
REPARATION STAGE
Import
Geometry
Preparation stage
Define
Materials
Orient
Surfaces
Insert and
Move Lights
and the
Solution stage
Insert and
Move Blocks
Refine the
Model
In the Solution stage, Lightscape alters the model
structure to optimize it for radiosity processing. The
model is saved in a Lightscape Solution file with a .ls
.
file extension. In this stage, you process the radiosity
solution of your model. You can modify materials and
the photometric properties of lights, but you can no
longer manipulate the geometry or add lights to your
model. If you need to make changes to geometry, you
must return to the Lightscape Preparation file, make
the changes, and then generate a new Solution file.
S
OLUTION STAGE
Process Radiosity
Solution
Refine the
Solution
Output
13
3
Workflow
Preparing the Model
During the Preparation stage, you can import the
model, adjust surface orientation, define materials
and assign them to surfaces, define luminaires and
place them in the model, and add, delete, and reposition objects as required.
Importing Geometry
The first step in creating a lighting simulation is to
import a geometric model into Lightscape. You can
import models from a wide variety of CAD and
modeling applications as well as from block and
luminaire libraries.
For more information, see Chapter 5, “Importing
Geometry,” and Chapter 6, “Refining Geometry.”
Orienting Surfaces
After you import a model, you must ensure that all
surfaces are properly oriented.
Surface orientation determines which side of a
surface is considered when calculating the light
reflections. For example, to simulate the lighting in a
room, the wall surfaces should be oriented toward
the inside of the room.
For more information, see Chapter 6, “Refining
Geometry.”
procedural textures to enhance the appearance of
surfaces.
Lightscape also comes complete with libraries of
hundreds of ready-to-use materials.
For more information, see Chapter 7, “Using
Materials.”
Adding Light
You can add artificial light and/or daylight to your
model.
All artificial lighting in your model comes from
luminaires (light fixtures). You can use luminaires
from a library or create your own. Adjust the photometric properties of the luminaires, and then place
them in your model. You can also use IES files to
import real-world lighting parameters from lighting
manufacturers.
Lightscape also comes complete with libraries of
hundreds of ready-to-use luminaires.
Use daylight to add an extra element of realism to
your model. Daylight is provided by two sources: the
sun and the sky.
For more information, see Chapter 8, “Artificial
Lighting,” Chapter 9, “Photometrics,” and Chapter
10, “Daylight.”
Defining Materials
Use materials to determine how each surface interacts with light. Because Lightscape is based on
physically accurate simulation techniques, it is
important to provide accurate material specifications to obtain realistic results. Templates make it
easy to define properties for numerous materials
including metal, polished stone, flat paint, water,
and so on. You can also use textures maps and
14
Refining the Model
Lightscape provides a limited suite of tools to
modify the geometry of a model. You can add,
delete, move, or duplicate surfaces, blocks, and
luminaires. For example, you could add furniture,
move an interior wall, or rotate a spotlight before
processing the radiosity solution.
For more information, see Chapter 6, “Refining
Geometry.”
Lightscape
Processing the Radiosity Solution
❚❘❘
Processing the Radiosity
Solution
During the Solution stage, Lightscape uses radiosity
to accurately calculate how light propagates in the
model.
When you initiate the radiosity process, Lightscape
reduces the model to a set of surfaces that are optimized for this process. Once the model is initiated,
you can no longer manipulate the geometry or add
luminaires.
During the Solution stage, you run the radiosity
process, refine the solution, and resume radiosity
processing to obtain the final results. You can then
output the results as an animation or as individual
images, analyze the lighting results, and export the
solution to other programs.
Setting Processing Parameters
Use process parameters to control the quality of the
radiosity solution. Setting the process parameters is
a balancing act. Finer settings produce better qual ity
images, but they also require more processing time
and memory.
To improve the efficiency of the solution, you can
adjust global processing parameters, which apply to
the entire model, and local processing parameters,
which apply to specific surfaces.
For more information, see Chapter 11, “Radiosity
Processing.”
How radiosity works is described in detail in
Chapter 1, “Introduction.”
Refining the Solution
In the Solution stage, you cannot change the model
geometry, but you can change the characteristics of
a material and the photometric properties of a luminaire. Once you make your changes, you can update
the results of the radiosity solution by either
continuing the processing from where you left off or
by restarting the processing from the beginning.
You save the results of the radiosity solution in a
Lightscape Solution (.ls) file.
Outputting your Work
During the output stage, you can render a Lightscape radiosity solution very quickly using
OpenGL® rendering or more accurately using the
Lightscape ray tracer. Ray tracing adds specular
reflections and transparency effects to the final
images. You can also use the ray tracer to create
higher quality shadows in the entire model or for
specific light sources. For more information, see
Chapter 11, “Radiosit y Processing,” and Chapter 14,
“Rendering.”
The options you choos e determine the im age quality
and the time it takes to generate an image. The
choice you make depends on your intended use. The
following uses are the most common:
Single images
•
Radiosity Processing
To process the radiosity solution, Lightscape calculates the diffuse light energy distribution in the
model, both direct and indirect. You can interrupt
the processing of the radiosity solution at any time to
alter or fine-tune the model’s appearance.
Walk-through animations
•
Vir tual reality
•
Lighting analysis.
•
Single Images
You can produce high-quality images of any resolution. You can quickly output the image from a
15
3
Workflow
Moving from Preparation Stage to Solution Stage
To compute a solution, you must first specify the light sources, materials, and texture maps associated
with the surfaces in the environment. You define this data for a model during the preparation stage.
Once you initiate the model for processing (convert it to a solution file) you can no longer create or
reposition any surfaces or light sources. All modifications of this nature must be performed during the
preparation stage.
During the solution stage, you can modify the characteristics of light sources and materials at any time;
the simulation compensates for the resulting changes in illumination. This feature promotes an interactive approach to design, so you can quickly evaluate and make refinements to obtain precisely the
look you want.
radiosity solution using OpenGL rendering. To
obtain a more accurate image, however, you can ray
trace the image. For more information, see
Chapter 14, “Rendering.”
Walk-through Animations
You can create camera paths for generating walkthrough animations of your radiosity solutions. You
can generate high-quality antialiased images very
quickly with OpenGL rendering. For more information, see Chapter 15, “Animation.”
If you want to add specular reflections and accurate
transparency effects, you can ray trace each frame.
For greater efficiency, you can use a batch program
or LSnet when rendering animations. For more
information, see Appendix B, “Batch Processing
Utilities.”
Virtual Reality
If your goal is to produce a virtual reality environment for interactive walk-throughs, you cannot use
ray tracing. You must strive for the highest quality
from the most compact and efficient model using
the radiosity process alone. Because the radiosity
solution results in a simple polygonal mesh with
specific radiosity values (converted to RGB colors)
stored at the vertices, results can be displayed very
rapidly using OpenGL rendering. To increase
display speed, use an OpenGL-compliant graphics
accelerator board.
You can use the Mesh to Texture tool to reduce
geometric complexity in the environment by
converting meshes and geometry into texture maps.
This is important when using Lightscape to create
environments for interactive games or web sites. For
more information, see Chapter 13, “Mesh to
Texture.”
A Lightscape radiosity solution can also be exported
into the VRML format. This data can then be used in
specialized display and virtual reality applications.
For more information, see Chapter 16, “Exporting.”
Lighting Analysis
If you are primarily interested in lighting analysis,
Lightscape provides a variety of tools for visualizing
the lighting data contained in the radiosity solution.
Generally, radiosity solutions for lighting analysis
can be created coarser (and faster) than those
required to produce realistic images. For more information, see Chapter 12, “Lighting Analysis.”
16
Lightscape
The Interface
An introduction to the Lightscape
tools and interface conventions.
4
The Lightscape user interface provides access to a suite of interactive tools, which
you use to prepare models for radiosity processing.
Summary
In this chapter, you learn about:
Starting Lightscape
•
The interface conventions
•
Using the toolbars
•
Using file controls
•
Viewing the model
•
Controlling the display
•
Selecting objects
•
Transforming objects
•
Setting document properties
•
Setting system options.
•
Starting Lightscape
To start Lightscape, double-click the Lightscape
application icon. By default, this icon is located in
the Lightscape program folder.
You can also start Lightscape by choosing it from the
Start menu.
Overview of the Interface
The Lightscape interface consists of five major
Lightscape model components. The largest and
most important is the Graphic window. It is located
on the left side and occupies the majority of the
screen, by default. The four other components, the
Layers, Materials, Blocks, and Luminaires tables, are
grouped together in a vertical bar of list windows on
17
4
The Interface
The Lightscape Interface Elements
Menu bar
Toolbars
Graphic
window
Status bar
the right side of the screen. You can reposition and
resize all of these windows as required.
The Lightscape menu bar occupies the upper
portion of the Graphic window. Directly below the
menu bar is the default location for the displayed
toolbars. A status bar at the bottom of the Graphic
window communicates information as required.
The title bar displays the name of the current file
loaded in the Graphic window.
You can perform editing operations in a variety of
ways: by using the pulldown menus on the Lightscape menu bar, by clicking the appropriate button
on a toolbar, or by using the secondary mouse
button to open a context menu.
Layers table
Materials
table
Blocks table
Luminaires
table
Graphic Window
You use the Graphic window to display and edit the
geometry of the current model. In the Graphic
window, you select objects by clicking them with the
left mouse button.
In the Graphic window, Lightscape supports several
orthogonal projection modes, as well as perspective
projection. You can also use the interactive view
tools to navigate through the model in each projection quickly.
There are several display modes that control the way
Lightscape displays the model. For example, the
model can be displayed in solid or wireframe mode.
For more information, see “Viewing the Model” on
page 29.
18
Lightscape
Overview of the Interface
❚❘❘
The Graphic window normally holds only a single
view of the model at any one time. However, during
animation editing, Lightscape breaks the Graphic
window into four concurrent views to aid in the
creation and editing of the motion path.
Layers Table
The
Layers table
defined in the current model and indicates their
state. A check mark to the left of the layer name
indicates that the layer is on (active) and that the
objects on that layer are currently being displayed in
the Graphic window. You can double-click a layer
name to toggle its state on and off.
contains a list of all the layers
Layers table
Current
layer
Context
menu
You can right-click the Layers table to display the
Layers context menu, which contains functions
appropriate to the layer selection set.
For information on using layers, see “Working with
Layers” on page 82.
Materials Table
The
Materials table
currently available in the model. You assign materials to surfaces in the model to define their
appearance and how light energy incident on the
surfaces behaves.
contains a list of all the materials
Material preview
A letter to the left of the layer name indicates it
is the current layer. Any new objects you add to the
model are added on the current layer.
Material with
an assigned
texture
A texture symbol next to the material name
indicates that the material contains a texture map. If
the symbol is colored, the texture is loaded and
displayed in the Graphic window. A green indicates that the texture file could not be found.
19
4
The Interface
The material preview displays the currently selected
material. For more information, see “Customizing
Material Previews” on page 20.
Right-click the Materials table to display a context
menu of functions for manipulating the materials in
the table. Double-click any material name to activate
the Material Properties dialog, which contains tools
for editing the characteristics of the selected
materials.
For more information on working with materials,
see Chapter 7, “Using Materials.”
Customizing Material Previews
The material preview displays the material currently
selected in the Materials table. You can resize the
preview and toggle it on or off.
Changing the Sample Sphere Diameter
You can change the diameter of the sample sphere to
make its size consistent with the objects in your
model to which you will apply the material. This
provides an accurate preview of materials that have
procedural textures applied or a fixed tile size. The
sphere diameter is measured in the units of your
model. For more information about setting the
model units, see “Setting Units Properties” on page
46.
To change the diameter of the sample sphere:
Right-click in the preview.
1.
Choose Diameter and select the number of units
2.
from the list.
Material preview with Fixed Size set to 1m x 1m.
Diameter of sample
sphere set to 1m.
Diameter of sample
sphere set to 10m.
Move the horizontal bar
to resize the preview
If more than one material is selected, the
Note:
preview is gray.
To toggle the
preview
on or off:
Right-click the Materials table and choose Preview
from the context menu.
20
Enabling Background and Reflection Images
You can enable the display of background and reflection images in the material preview.
To
toggle these options on and off:
Right-click in the preview and select the appropriate
opti on.
Lightscape
Overview of the Interface
❚❘❘
The Backgroundoption helps you view the effects of
transparency and index of refraction by adding a
multicolored image behind the preview sphere.
Background
disabled.
Background
enabled. The image
makes it easier to
see the transparent
“glass” sphere.
The Reflection option displays reflective highlights
by placing an image in front of the preview sphere
that is reflected in its surface.
Reflection disabled.
Blocks Table
The
Blocks table
able in the model. A
of objects (surfaces or other blocks) assigned a
common name and an insertion point. Once you
have defined a block, you can make repeated
instances of it and place them into the model at a
variety of locations, sizes, and orientations.
Blocks are available only during the Prepara-
Note:
tion stage.
contains a list of all the blocks avail-
in Lightscape is a grouping
block
Block preview
Reflection enabled.
Reflection
highlights are
visible in the center
of the sphere.
For information about setting the background and
reflection images, see “Setting Preview Control
Options” on page 50.
The block preview displays the currently selected
block. For more information, see “Customizing
Block and Luminaire Previews” on page 22.
You can double-click any block name to isolate the
block for display and editing in the Graphic window.
Right-click the Blocks table to display a context
menu of funct ions for manipulating the block s in the
table.
21
4
The Interface
For more information on blocks, see “Working with
Blocks” on page 85.
Luminaires Table
The
Luminaires table
naires available in the model. A
type of block used to represent light fixtures and
includes a definition of
that control how light energy is emitted from it. In
the Preparation stage, double-click a luminaire
name to isolate it for display and editing in the
Graphic window. Open the Luminaire Properties
dialog to edit photometric characteristics of the
luminaire.
contains a list of all the lumi-
luminaire
is a special
photometric characteristics
Luminaire preview
Right-click the Luminaires table to display a context
menu of functions for manipulating luminaires in
the table.
For more information on using luminaires, see
Chapter 8, “Artificial Lighting.”
Customizing Block and Luminaire
Previews
The block and luminaire previews display the
objects currently selected in the table. You can resize
the preview and toggle it on or off.
Move the horizontal bar
to resize the preview
The luminaire preview displays the currently
selected luminaire. For more information, see
“Customizing Block and Luminaire Previews” on
page 22.
22
To toggle the preview on or off:
Right-click the Block or Luminaires table and
choose Preview from the context menu.
Changing the View
Use the interactive view controls to change the view
of the block or luminaire in the preview. You can
select view controls from the toolbar, from the
preview context menu, or by using hot keys.
The following view controls are available in
Note:
the preview: Orbit, Rotate, Zoom, Pan, Dolly, and
Scroll.
Lightscape
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