Overburning Bug With Texture "fresnel" "sopra"

[Meelis]

Hi

LuxRender 0.9dev 27-02-2012 (64bit no OpenCL)
Blender 2.61 r43210

I have layered glossytranslucent material with homogeneous volume inside.
After i switched the volume ior to sopra format, i get the mesh overburning (gets brighter and brigther, all other objects get underexposed as i lower the light gain)

Sopra ior:

Code: Select all

2   0.38   0.72   17
1.68795      0
1.68283      0
1.6785      0
1.67482      0
1.67164      0
1.66887      0
1.66645      0
1.66431      0
1.66241      0
1.66071      0
1.65918      0
1.6578      0
1.65654      0
1.65539      0
1.65434      0
1.65337      0
1.65246      0
1.65163      0

Code: Select all

Texture "Sopra" "fresnel" "sopra"
   "string filename" [".................../Marble O-Ray IOR.nk"]

MakeNamedVolume "Red Marble" "homogeneous"
   "texture fresnel" ["Sopra"]
   "color g" [0.00000000 0.00000000 0.00000000]
   "color sigma_a" [50.00000000 50.00000000 50.00000000]
   "color sigma_s" [200.00000000 200.00000000 200.00000000]

I was able to export the scene from blender, but after i reopen blender and that blend with the sopra ior, then LuxBlend wont export and gives error:

float division by zero

Anyways, i don't need dispersion but i was wondering if Sopra ior has some other advantages.
What would it do when there is no dispersion in homogeneous volume?

Render settings:

Code: Select all

Renderer "sampler"

Sampler "metropolis"
   "float largemutationprob" [0.150000000000000]
   "bool usevariance" ["true"]
   "integer maxconsecrejects" [16384]

Accelerator "qbvh"

SurfaceIntegrator "bidirectional"
   "integer eyedepth" [128]
   "integer lightdepth" [128]
   "string strategy" ["one"]
   "float eyerrthreshold" [0.99]
   "float lightrrthreshold" [0.99]

VolumeIntegrator "multi"
   "float stepsize" [0.010000000000000]

PixelFilter "gaussian"
   "float xwidth" [2.000000000000000]
   "float ywidth" [2.000000000000000]
   "float alpha" [2.000000000000000]


[rendermagic]

Anyways, i don't need dispersion but i was wondering if Sopra ior has some other advantages.
What would it do when there is no dispersion in homogeneous volume?

Can't answer your other questions, but I can comment on this one. One of the primary advantages of using SOPRA is that if you are dealing with a material that should have dispersion, the SOPRA description does a better job describing that dispersion across multiple wave lengths. This is one of those features that makes Lux a 'full spectral' renderder. As far as I know, SOPRA used in Lux is primarily for dispersion accuracy. It also allows you to describe the material accurately by essentially defining the different IORs of that material across multiple wavelengths.

[Meelis]

Hi

Thank you rendermagic.

I should have posted the scene with problem but it's too big.
I will post the material just in case but i'm allready sure the warning "float division by zero" was there with a good reason.
Maybe in LuxBlend there should be not possible to select Sopra texture for the volume that doesn't support it.