A bidirectional formulation for Walk on Spheres
(Interactive Image Comparison)

Below you can find interactive versions of the image comparisons in Figures 8 and 9 of the paper "A bidirectional formulation for Walk on Spheres".

Tip: Move the mouse over the images to compare the algorithms on specific parts of the scene.
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Sparse boundary values

We compare forward WoS (left) to reverse WoS (right) at equal time with few samples (top) and with 16× as many samples (bottom). Reverse WoS produces a smooth result even with few samples, converging more quickly than forward WoS.

Low-sample forward WoS [Sawhney and Crane 2020] Low-sample reverse WoS [Ours] High-sample forward WoS [Sawhney and Crane 2020] High-sample reverse WoS [Ours]

Sparse sources

Here we perform an equal-time comparison of forward vs. our reverse WoS on a scene with three sparse sources and zero boundary conditions. Compared to the converged reference, our approach with only 4e4 sampled paths produces visually better results than forward WoS with 3.24e6 total paths.

Forward WoS [Sawhney and Crane 2020] Reverse WoS [Ours] Converged reference Source terms