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

Below you can find interactive versions of the result comparisons for the Living 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: 16.45) Portal S.Angle Sampling<br />(TTUV: <strong>2.90</strong>) Envmap/S.Angle MIS<br />(TTUV: 4.17) Ours (portal visible energy selection)<br />(TTUV: 3.16)
Reference Envmap/S.Angle MIS<br />(TTUV: 4.17) Ours (solid angle selection)<br />(TTUV: 3.16) Ours (portal visible energy selection)<br />(TTUV: <strong>3.16</strong>)

Factory environment map

Envmap Sampling<br />(TTUV: 84.56) Portal S.Angle Sampling<br />(TTUV: 44.36) Envmap/S.Angle MIS<br />(TTUV: 35.92) Ours (portal visible energy selection)<br />(TTUV: <strong>13.57</strong>)
Reference Envmap/S.Angle MIS<br />(TTUV: 35.92) Ours (solid angle selection)<br />(TTUV: 16.06) Ours (portal visible energy selection)<br />(TTUV: <strong>13.57</strong>)

Sunny environment map

Envmap Sampling<br />(TTUV: 4.84) Portal S.Angle Sampling<br />(TTUV: 428.82) Envmap/S.Angle MIS<br />(TTUV: 3.13) Ours (portal visible energy selection)<br />(TTUV: <strong>2.03</strong>)
Reference Envmap/S.Angle MIS<br />(TTUV: 3.13) Ours (solid angle selection)<br />(TTUV: 3.13) Ours (portal visible energy selection)<br />(TTUV: <strong>2.03</strong>)