Indigo Renderer Forum

I am trying to render a transparent volume. The shape is transparent but seems really dark. I have turned off the absorption layer in the material and have set the absorption coefficient in the medium to 0. I'm not sure where else to look. What other factors affect volume transparency?

I am using Indigo 3.6.26.

Transparent materials rendering black are often due to non-closed volumes, or normal orientation issues.

Check that:
- The transparent material volume is made of a closed geometry
- The material is applied to the whole closed geometry
- Normals point outwards

Etienne

Is there a good way to test for open geometry or bad normals? I am using some geometry I generated in code, as well as some geometry that I imported from blender and both look the same. Is it safe to assume that the blender geometry is correct?

Playing around with this some more it looks like my transparent geometry might also be casting shadows in the scene. is this normal behavior? Can I disable it?

Which software are you using? share your file and someone might have a look.

it's not safe to assume that a procedural geometry will result clean unless if the generating algorithm has such dedicated routines.
You could try to merge vertices under a certain threshold distance, close holes and eventually conform normals.

OK, so I finally put together some test scenes that better illustrate my issue. I have two images here, a solid sphere encapsulated in a transparent sphere. In the first image the transparent sphere is small and creates a thin layer of glass around the solid sphere. In the second image the transparent sphere is much larger and creates a thick layer of glass. The apparent light loss, or color change, is the same in both cases. I would expect the color shift to be dependent on the thickness or radius of the transparent sphere but that doesn't seem to be the case. I'd like to create a smoother transition between the clear and solid surfaces if possible.

In the process of experimenting with this I noticed another strange anomaly. If I enable displacement mapping on the transparent surface the position of the specular highlights shifts slightly to the left, even if the displacement value is set to zero. Based on the equation in the manual I would expect to see no change.

For the transparency issue, try rendering using BiDir and glass acceleration turned on (or with the new beta release, use arch glass option on your transparent medium)
not sure about the displacement question you mentioned.

Glass acceleration doesn't seem to help much for curved glass. The new arch glass option helps the color, but removes all of the refraction caused by the transparent surface.

It has been asked before: What modeling software do you use ?

If you post scenes, then post them in the native format of your modeling software. Otherwise it is very difficult to determine what went wrong.

It could be scale. Here is the glass 200mm*200mm*4mm, scale 1 scale 1000, so the glass becomes four meters thick