janine liu

Building off the CUDA-based pathtracer I developed, I implemented the paper Edge-Avoiding À-Trous Wavelet Transform for fast Global Illumination Filtering. This describes an algorithm for denoising the image by applying a blur to the surfaces without disrupting the edges in the scene. These edges are defined by differences in the positions, normals, and colors of the raytraced information in the scene.

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The denoiser derives its name from "À-Trous wavelet transform," which is a way to approximate a Gaussian blur without taking as much time to compute it. This involves taking the original coordinates of the Gaussian kernel and spreading them out over a larger area, sampling parts of the image to approximate a bigger blur, as shown below.