In this Project a Path tracer is created by using the concept of GLobal Illumination. In thsi technique a bunch of rays are shooted into the scene and each ray is tracked until they hit the light, the color at every bounce is calculated and multiplied with the previous color. This process is repeated for every iteration ,and the color obtained at each iteration is averaged and added to the previous value.
All the basic requirements such as
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Full global illumination
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Properly accumulating emittance and colors to generate a final image
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Supersampled antialiasing Have been implemented
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Parallelization by ray instead of by pixel via stream compaction This was done using Thrust library and the function if_remove was used to compress the ray pool by removing the dead rays.
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Perfect specular reflection Was achieved by reflecting the rays when they hit the reflective surface
The extra features that were implemented are :
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Translational motion blur Here the object position was varied according to linear interpolated values of its start and end position during each iteration
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Snell-based Refraction, i.e. glass Here the basic Snells refraction was implemented using the Glm::refract function and a probability was assigned to get both reflections and refractions on the material
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OBJ Mesh loading and rendering with Bounding boxes The Obj loading was implemented earlier for ray tracer , but in this assignmnet the maximum and minimum co-ordinates of the mesh were calculated and sent to the GPU and hence a max min box intersection test was done
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Interactive camera A interactive mouse has been implemented by imagining a camera attched to the sphere and hence the new positions are calculated based on that. To do this feature CIS 563 cloth simulation assignmnet was referred, and it partially acted as a guide for path tracer interaction feature.
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Depth of field DOF was implemneted by selecting a depth plane away from the camera and jittering the camera position during each iteration.
Here is the first image with the basic diffuse applied on all the materials
With Reflections applied
With refractions applied
With Depth of Field
With Motion Blur
With OBJ loader and bounding boxes
Other renders
In this Performance evaluation, the speeds or the time elapsed for with and without stream campaction is compared. Here initially when the number of bounces are less, without stream campaction would work better because of thrust remove_if overhead calculations for smaller bounces. Whereas it can be easily seen how the performance improves when the number of threads are reduced when we have more number of bounces and hence more number of rays that can be removed from the raypool