Path-Space Differentiable Rendering of Participating Media

Supplemental Materials

Cheng Zhang^*, Zihan Yu^*, and Shuang Zhao University of California, Irvine      (* equal contribution)

In this supplemental material, we show animated versions of a few inverse-rendering optimizations. For each example, we visualize derivatives with respect to one of the parameters.

Scene	# Param.	# Iter.	Time (per iteration)
Branches (Fig 10)	1	100	39s
Bust (Fig 10)	1	120	3m 24s
Bumpy sphere (Fig 10)	2	125	22.77s
Point Light	2	125	34s
Bunny0	3	200	3m 47s
Spheres (Fig 11)	2	150	3m 15s
Bunny (Fig 11)	17	125	9m 35s
Pool (Fig 11)	100	300	5m 52s

Branches

• This example contains a few twisted pipes lit by a small area source. The space around the branches is filled with heterogeneous medium.
• We search for the rotation angle of the tree (around the vertical axis) by looking at its shadow.

Bust

• This example contains a marble bust, modeled by rough dielectric surface and medium of varying albedo inside.
• We search for the rotation angle of the bust (around the vertical axis).

Bumpy sphere

• This example contains a bumpy glass sphere lit by a small area source. The space around the sphere is filled with homogeneous medium.
• We search for the position of the emitter (expressed using 2 variables)

Point Light

• This example contains a bumpy glass sphere lit by a point source. The space around the sphere is filled with homogeneous medium.
• We search for the position of the emitter (expressed using 2 variables)

Bunny0

• This example contains a silver bunny in the Cornell Box filled with homogeneous medium
• We search for the position of the bunny.

Spheres

• This example contains a big bumpy glass sphere and two smooth glass spheres lit by a small area source. The space around the spheres is filled with homogeneous medium.
• We search for the position of the larger sphere (expressed using 2 variables).

Bunny

• This example contains a homogeneous translucent bunny that exhibits rough refraction on the surface and multiple scattering in the interior.
• We use a control cage with 16 vertices to deform the bunny in a non-rigid fashion.
• We search for the optical density of the medium, roughness of the surface and the positions of 5 visible cage vertices.

Pool

This example contains a swimming pool lit by a small area light above.

The interface between water and air (beyond field of view) is bumpy and parameterized with 100 parameters.

We search for the control parameters of the interface by only looking at the casted caustics underwater.