Portal-Masked Environment Map Sampling
(Dining Room Image Comparison)

Below you can find interactive versions of the result comparisons for the Dining Room scene from Figure 4 and Table 1 of the paper "Portal-Masked Environment Map Sampling". We compare our new importance sampling technique to three baseline techniques: sampling only the environment map, sampling only the solid angle of the portal, or multiple importance sampling (MIS) of these two previous methods. All images (except for reference) use 8 samples per pixel, but the sampling techniques result in different variance and render times. To quantify the relative performance of each technique in a single representative number, we report the time-to-unit-variance (TTUV)—computed as the MSE × render time—in parentheses.

Tip: Move the mouse over the images to compare the algorithms on specific parts of the scene.
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Ambient environment map

Envmap Sampling<br />(TTUV: 18.14) Portal S.Angle Sampling<br />(TTUV: <strong>3.17</strong>) Envmap/S.Angle MIS<br />(TTUV: 5.47) Ours (portal visible energy selection)<br />(TTUV: 3.60)
Reference Envmap/S.Angle MIS<br />(TTUV: 5.47) Ours (portal visible energy selection)<br />(TTUV: <strong>3.60</strong>)

Factory environment map

Envmap Sampling<br />(TTUV: 18.60) Portal S.Angle Sampling<br />(TTUV: 19.68) Envmap/S.Angle MIS<br />(TTUV: 10.94) Ours (portal visible energy selection)<br />(TTUV: <strong>2.25</strong>)
Reference Envmap/S.Angle MIS<br />(TTUV: 10.94) Ours (portal visible energy selection)<br />(TTUV: <strong>2.25</strong>)

Sunny environment map

Envmap Sampling<br />(TTUV: 22.99) Portal S.Angle Sampling<br />(TTUV: 17329.34) Envmap/S.Angle MIS<br />(TTUV: 29.98) Ours (portal visible energy selection)<br />(TTUV: <strong>11.66</strong>)
Reference Envmap/S.Angle MIS<br />(TTUV: 29.98) Ours (portal visible energy selection)<br />(TTUV: <strong>11.66</strong>)