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Concepts: |
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Approximate Predetermined Lighting Function With
Spherical Harmonics |
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Lighting Function Is an HDR Image, with other
Area Lights |
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Use a Paul Debevec HDR Image as the
Predetermined Light function |
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Create a Spherical Harmonic lighting/shading
plug-in for Maya using the Maya API in C++ |
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Additional lights will be added to illuminate
the scene |
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Models (i.e., boxes, spheres, cones, etc) |
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In Scope: |
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Diffuse Unshadowed Transfer |
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HDRI Lighting |
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Out Of Scope: |
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Diffuse Shadowed Transfer |
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Diffuse Inter-reflected Transfer |
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Done: |
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Generated HDR Image to use a texture map for
lighting sphere |
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Mel Script for Generating additional Area Lights |
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Complex Models: Happy Buddha, Stanford Rabbit,
Armadillo, etc. |
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Projecting Light functions to SH Space |
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Generated Coefficients for lighting
approximation |
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Method For Sampling Light Sphere |
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TBD: |
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Verify Projection of HDR Images w/ Matlab |
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Preprocessing Import Tools for Maya to Calculate
SH approximation for BRDF |
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Generated HDR Image to use a texture map for
lighting sphere: |
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Manipulated an HDR image, converting it from HDR
format to an Angle Map format. |
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Converted the angle map into a diffuse/specular
map. |
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Wrote a Maya C++ plug-in for Lambertian surfaces. |
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Configured Maya to use the plug-in for specified
surfaces. |
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Projecting Light functions to SH Space: |
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Wrote classes/function to convert a HDR/Angle
Map file to a approximated lighting function |
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Tools produce a set of coefficients for
approximating the light function. |
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Acquired more complex models for proposed scene: |
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Converted models from the Stanford repository
(.ply models) to a format that was compatible with Maya (.obj models). |
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Wrote a Mel script generate scene: |
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Mel script was needed to create and configure
lights, models, and connect certain Maya and Spherical Harmonic nodes to
these models. |
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Apply certain attributes to light and models. |
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Additional Import Tools Needed for Maya Plug-in: |
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To approximate the BRDF for a surface in SH
space we need all geometry information for the surface. |
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Maya’s Architecture allows for sampling a single
point per pass only (in plug-ins). But we can render use the ray tracinf
utilities in Maya to cast rays for our own shadows. |
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Maya’s Architecture (Two APIs to Learn): |
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Mel scripting – Nice scripting API but very
extensive. Maya is built exclusively with Mel so it need a lot of features. |
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Development API(C/C++) – Necessary for creating
new internal nodes and data types. Very restrictive, data flow
non-intuitive, type-less data and data blocks. |
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Maya’s ray tracing/plug-in architecture give
access to a single sampling of environment instead of all environment. |
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Maya’s Architecture: |
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Too Many features to learn in a very limited
time. |
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Development Books and API documentation is
geared for Artists and novice developers. Lacked advanced level
documentation. |
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Use a Nurb Sphere as a lighting function with a
texture that represents light color, intensity, etc. |
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Conclusion: Bad Idea! This type of method
doesn’t work well with Maya’s Architecture. |
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Notes
