We have progressed on our Iray implementation of environment material.
We can now make a good projection of the environment on the geometries of the decor.
Open GL Rendering Iray Rendering
However, there are still some limitations to use this feature :
1. The scene may be rendered darker than with opengl
2. An environment map should be specified to get the appearance of Matte material and Iray Ground material, so if the decor is a closed scene, like an hemisphere, Matte and Ground materials will be black.
It is recommended to build opened decors, or in the case of hemisphere, to disable this feature to prefer built-in hemisphere of Iray (behavior of Patchwork 3D 2020.2)
3. In the case of using Alternative Background Maps in the environment, it should be an option to use it or not in Iray.
Be careful to use the same color space and tone mapping for the HDR and the Alternative map : Environment material will use Alternative map, but Matte and Ground materials will still reflect HDR colors. In case of color difference, it will be visible.
It is recommended to use high definition HDR for Iray usage, in place of low definition HDR + high definition alternative map.
Despite these limitations, we think that this feature has some added value, when respecting some pre-conditions.
This is why we decided to push this feature in the next 2021.1 version of Patchwork 3D.
However this feature stays Experimental, and is not activated by default.
To enable it you can check this checkbox in Iray Settings.
We are still working on this topic, with Iray development team, to reduce these limitations.