topic Hi Sven, in Intel® Embree Ray Tracing Kernels

rendering engine - material configuration

Cyril_D_ — Sun, 30 Jun 2013 18:21:42 GMT

Hi,

First, thanks so much for releasing such a powerfull library with such an easy to use API.

I have no experience at all with raytracers and despite all the warnings, so far I've found the rendering engine to be complete enough to achieve amazing results really fast. I made a little OpenFrameworks addon that allows to render OF geometries with the interactive renderer : https://github.com/kikko/ofxEmbree

However, I'm now trying to implement more defaults material, and I'm a bit struggling to find documentation on the different parameters for the materials. Looking at the provided examples I've managed to extract some information but I would like to know if these refer to any raytracing standards and if I can find documentation online about them. I haven't managed to google my way though that :(

So if anyone is able to share some information / link on any of these params, that would be of great help! Thanks!

//glass && Dielectric
float3 transmission;
float etaOutside;
float etaInside;

float3 transmissionOutside;

// MetallicPaint
float eta;
float3 shadeColor;
float3 glitterColor;
float glitterSpread;

// Metal
float3 k;
float roughness;

// MatteTextured
string Kd;
float2 s0;
float2 ds;

// Matte
float3 reflectance;

// Velvet
float backScattering;
float3 horizonScatteringColor;
float horizonScatteringFallOff;

Apologies, I just found out

Cyril_D_ — Sun, 30 Jun 2013 19:04:22 GMT

Apologies, I just found out the header of each material describes its parameters.

Thanks again and sorry :)

Here some description of the

SvenW_Intel — Wed, 03 Jul 2013 05:20:20 GMT

Here some description of the parameters. But best play around with them to get a feeling of what they do.

//glass && Dielectric
float3 transmission is a color you can assign to the glass material
float etaOutside and etaInside is the refraction index of the glass (inside) and the material around the glass (typically 1 for air)

float3 transmissionOutside;

// MetallicPaint
float eta is the refraction index of the clear coat layer
float3 shadeColor is the color of the diffuse layer below the clear coat
float3 glitterColor is not implemented
float glitterSpread is not implemented

// Metal
float3 eta, k is the real and imaginary part of the complex refraction index of a metal. The real part acts similar as for glass, whereas the imaginary part is some absoption coefficient.

float roughness determines how diffuse (1) or specular (0) the metal is

// MatteTextured
texture Kd is the diffuse texture
float2 s0 and ds is the texture coordinate transformation (look in the code how this is applied)

// Matte
float3 reflectance is the color of the diffuse material

Hi Sven,

Cyril_D_ — Thu, 04 Jul 2013 07:53:32 GMT

Hi Sven,

Thanks a lot for your feedback and explanations.
Makes more sense now.

Cheers,
Cyril