Bump Vs Shadows

Mon Jan 06, 2014 9:25 am

Hi Octane Team

Here is my question : Is this a normal behaviour ?
The result is the same with Bump and Normal maps.

I still wish you a great year.

Mon Jan 06, 2014 12:25 pm

yes, this bump behaviour should be solved, it has been limiting the intensity of bump and normal maps on Octane renders for far too long!

merid888 · Mon Jan 06, 2014 1:31 pm

you cannot compare octanerender with vray, they are to different softwares

Mon Jan 06, 2014 1:58 pm

you can compare "limitations" on the softwares, and this is clearly a limitation.

Mon Jan 06, 2014 3:02 pm

i've already encountered this with blender cycle and Brecht, the developper, explained to me that it was 'normal' for an unbiased renderer like (cycles ) octane: a side effect of the terminator one, possible...

Mon Jan 06, 2014 4:12 pm

vipvip wrote:i've already encountered this with blender cycle and Brecht, the developper, explained to me that it was 'normal' for an unbiased renderer like (cycles ) octane: a side effect of the terminator one, possible...

I don't think so, terminator artifact is due to lowpoly mesh, this sphere is very high poly.

Mon Jan 06, 2014 6:08 pm

yes, but try to render a 'very high' poly-bumped moon... that's what i did before with cycles and the result was almost the same...
didn't try with octane but it would be interesting to see the result.
after all, i agree with you, it is perhaps not the same problem than terminator but it was ( there is ? ) a problem around that and i'm afraid i couldn't be seolved with this kind of renderers...
i've read with a lot of interest your topic about IOR<1 and refraction studies: it seems to be great results with the newer 1.24 version : waht is you opinion about that ?

Mon Jan 06, 2014 6:11 pm

Here the difference between bump and disp

Tue Jan 07, 2014 1:54 am

The problem with the bump mapping is the same problem as with low polygon meshes, in both cases you get what are called shadow terminator artifacts. Near the edge of the shadow there are spots where the object should be lit by the light source according to the shading normals, but where the triangle is facing away from the light source. This may occur either because of bump mapping or because of normal interpolation. The result is that the lighting on these triangles goes missing.

This is a hard problem to solve without introducing other problems such as light leaks. So for now I can't really offer any workaround. If you have a curved surface with a bump map you can try if you can increase the size of the light source, this will make the shadow edge a bit smoother.

--
Roeland

Tue Jan 07, 2014 2:08 am

roeland wrote:The problem with the bump mapping is the same problem as with low polygon meshes, in both cases you get what are called shadow terminator artifacts. Near the edge of the shadow there are spots where the object should be lit by the light source according to the shading normals, but where the triangle is facing away from the light source. This may occur either because of bump mapping or because of normal interpolation. The result is that the lighting on these triangles goes missing.

This is a hard problem to solve without introducing other problems such as light leaks. So for now I can't really offer any workaround. If you have a curved surface with a bump map you can try if you can increase the size of the light source, this will make the shadow edge a bit smoother.

--
Roeland

Hello Roeland

Would it be possible to make the bumpmap intensity change from 100% in normal to 0% in grazing for each ray that hits the surface?