pbrt-v4
pbrt-v4 copied to clipboard
image differences with MIS compensation and approximate BSDF PDFs
With
Sampler "halton"
"integer pixelsamples" 8
Film "rgb" "float iso" 200
"integer yresolution" [ 800 ]
"integer xresolution" [ 1200 ]
Scale -1 1 1
LookAt 3.69558 -3.46243 3
3.04072 -2.85176 2.55
-0.317366 0.312466 0.895346
Camera "perspective"
"float fov" [ 38 ]
Integrator "volpath" "integer maxdepth" 1
WorldBegin
AttributeBegin
LightSource "infinite"
AttributeEnd
AttributeBegin
Material "coateddiffuse" "float roughness" .1
"rgb reflectance" [ .2 .2 .2 ]
Shape "bilinearmesh"
"point3 P" [ -100 -100 0 100 -100 0 -100 100 0 100 100 0 ]
AttributeEnd
if UniformInfiniteLight
is modified to ignore the allowIncompletePDF
flag, then the image converges to a different result. (And worse, using the SimplePathIntegrator
with light sampling only also seems to give something different!)
Everything matches if "coateddiffuse" is replaced with a "diffuse" material.
@mmp are there any updates on this topic?
I am facing the same problem when using coateddiffuse
and trying to combine BSDF sampling with other sampling techniques.
I realized that explicitly using the outcomes of f()
and PDF()
for a sampled direction leads to a different result than using the outcome of Sample()
directly.
No updates, unfortunately--I haven't had time to look at this in more depth. (Fixes welcome. :-) )