Lightmaps from HDR Probes Bernhard Spanlang VECG Group University College London...
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Transcript of Lightmaps from HDR Probes Bernhard Spanlang VECG Group University College London...
![Page 2: Lightmaps from HDR Probes Bernhard Spanlang VECG Group University College London b.spanlang@cs.ucl.ac.ukb.spanlang@cs.ucl.ac.uk.](https://reader035.fdocuments.in/reader035/viewer/2022062321/56649e565503460f94b4d927/html5/thumbnails/2.jpg)
Overview What are Lightmaps Related Work Motivation for using Radiance Capturing HDR Probes Creating Lightmaps Results Conclusion
![Page 3: Lightmaps from HDR Probes Bernhard Spanlang VECG Group University College London b.spanlang@cs.ucl.ac.ukb.spanlang@cs.ucl.ac.uk.](https://reader035.fdocuments.in/reader035/viewer/2022062321/56649e565503460f94b4d927/html5/thumbnails/3.jpg)
What are Lightmaps Precomputed illumination for
interactive walkthroughs stored in texture memory
Only view independent surfaces (Lambertian)
Not vertex colour (usually Radiosity) Can be stored in low-res texture for
blending original texture if MultiTexture hardware
![Page 4: Lightmaps from HDR Probes Bernhard Spanlang VECG Group University College London b.spanlang@cs.ucl.ac.ukb.spanlang@cs.ucl.ac.uk.](https://reader035.fdocuments.in/reader035/viewer/2022062321/56649e565503460f94b4d927/html5/thumbnails/4.jpg)
Related Work Radiosity solution
(LightScape, stored in vertex colour, adaptive mesh subdivision)
Games Engines (eg. Quakes qrad) Texture bakers in Lightwave and
3D Studio Max5, Brazil, FinalRender, etc.
![Page 5: Lightmaps from HDR Probes Bernhard Spanlang VECG Group University College London b.spanlang@cs.ucl.ac.ukb.spanlang@cs.ucl.ac.uk.](https://reader035.fdocuments.in/reader035/viewer/2022062321/56649e565503460f94b4d927/html5/thumbnails/5.jpg)
Motivation for using Radiance Physically accurate rendering Natural lighting with HDR Postprocessing using
Radiance tools(exposure, falsecolor, etc.)
Daylight simulationwith real surroundings
![Page 6: Lightmaps from HDR Probes Bernhard Spanlang VECG Group University College London b.spanlang@cs.ucl.ac.ukb.spanlang@cs.ucl.ac.uk.](https://reader035.fdocuments.in/reader035/viewer/2022062321/56649e565503460f94b4d927/html5/thumbnails/6.jpg)
Capturing HDR Probes Camera response Merging multiple exposures For image alignment use a remotly
controlled camera Reflective sphere
(Ball bearing) Cubic mapping
HDRShop Removing Camera???
void glow mat_glow004 1 1 1 0
![Page 7: Lightmaps from HDR Probes Bernhard Spanlang VECG Group University College London b.spanlang@cs.ucl.ac.ukb.spanlang@cs.ucl.ac.uk.](https://reader035.fdocuments.in/reader035/viewer/2022062321/56649e565503460f94b4d927/html5/thumbnails/7.jpg)
Lightmap Flow ChartLightinginformation inRadiance format, orHDR panoramicimage
geometryincluding TextureMaterialIn Inventor or VRMLformat, lighting canbe extracted
texture resolutionand packinginformation (howmany triangles perrow)
Lightmapgeneration tool(LMT)
Radiance scene andmaterial description
Radiance RenderingSystem
Lightmapcomposition script
Inventor file withnew UV coordinatesfor lightmap pluslightmap-texturereferences
Radiance viewparameters forrendering sublightmaps
rendered image foreach viewparameter
Lightmaps forinteractiverenderingreferenced ininventor file
![Page 8: Lightmaps from HDR Probes Bernhard Spanlang VECG Group University College London b.spanlang@cs.ucl.ac.ukb.spanlang@cs.ucl.ac.uk.](https://reader035.fdocuments.in/reader035/viewer/2022062321/56649e565503460f94b4d927/html5/thumbnails/8.jpg)
Placing Radiance Cameras In front of each
triangle Centre of
surroundingrectangle
An orthographiccamera (-vtl)
![Page 9: Lightmaps from HDR Probes Bernhard Spanlang VECG Group University College London b.spanlang@cs.ucl.ac.ukb.spanlang@cs.ucl.ac.uk.](https://reader035.fdocuments.in/reader035/viewer/2022062321/56649e565503460f94b4d927/html5/thumbnails/9.jpg)
Rendering the Surfaces Using Radiances’ view file (normally
used for walkthrough animations) Exploiting the ambient cache (-af
file) Allows parallel execution Unfortunately there is no way to set
the resolution in the view file. Bug in Desktop Radiance –pa option
ignored.
![Page 10: Lightmaps from HDR Probes Bernhard Spanlang VECG Group University College London b.spanlang@cs.ucl.ac.ukb.spanlang@cs.ucl.ac.uk.](https://reader035.fdocuments.in/reader035/viewer/2022062321/56649e565503460f94b4d927/html5/thumbnails/10.jpg)
Lightmap Composing Aim is to merge all rendered surfaces to
a single texture for efficient hardware rendering
Simplest approach: use pcompos placing the images next to and above each other.
UV coordinates of resulting VRML file have to reflect this.
ra_ppm –e converts Radiance file to ppm file at a specified exposure.
![Page 11: Lightmaps from HDR Probes Bernhard Spanlang VECG Group University College London b.spanlang@cs.ucl.ac.ukb.spanlang@cs.ucl.ac.uk.](https://reader035.fdocuments.in/reader035/viewer/2022062321/56649e565503460f94b4d927/html5/thumbnails/11.jpg)
Results(1/4)
Composed LightmapsCameras on Geometry
![Page 12: Lightmaps from HDR Probes Bernhard Spanlang VECG Group University College London b.spanlang@cs.ucl.ac.ukb.spanlang@cs.ucl.ac.uk.](https://reader035.fdocuments.in/reader035/viewer/2022062321/56649e565503460f94b4d927/html5/thumbnails/12.jpg)
Results(2/4)
Radiance Interactive Lightmaps
![Page 13: Lightmaps from HDR Probes Bernhard Spanlang VECG Group University College London b.spanlang@cs.ucl.ac.ukb.spanlang@cs.ucl.ac.uk.](https://reader035.fdocuments.in/reader035/viewer/2022062321/56649e565503460f94b4d927/html5/thumbnails/13.jpg)
Results(3/4)
OpenGLRadiance Lightmaps
![Page 14: Lightmaps from HDR Probes Bernhard Spanlang VECG Group University College London b.spanlang@cs.ucl.ac.ukb.spanlang@cs.ucl.ac.uk.](https://reader035.fdocuments.in/reader035/viewer/2022062321/56649e565503460f94b4d927/html5/thumbnails/14.jpg)
Results(4/4)
LightmapRadiance
![Page 15: Lightmaps from HDR Probes Bernhard Spanlang VECG Group University College London b.spanlang@cs.ucl.ac.ukb.spanlang@cs.ucl.ac.uk.](https://reader035.fdocuments.in/reader035/viewer/2022062321/56649e565503460f94b4d927/html5/thumbnails/15.jpg)
Possible Improvements Maintain connectivity of 3D triangles
for 2D UV texture coordinates Where not possible add extra pixels
for interpolation (Sand pixels) Triangle areas reflected in texture
size Coplanar surfaces represented by
one lightmap element Packing lightmap elements
![Page 16: Lightmaps from HDR Probes Bernhard Spanlang VECG Group University College London b.spanlang@cs.ucl.ac.ukb.spanlang@cs.ucl.ac.uk.](https://reader035.fdocuments.in/reader035/viewer/2022062321/56649e565503460f94b4d927/html5/thumbnails/16.jpg)
Summary What are Lightmaps Related Work Motivation for using Radiance Capturing HDR Probes Creating Lightmaps Results Conclusion