How to render both side of a mesh?

[Galaxeaaa]

Hi, I'm new to Mitsuba and I know this is a stupid question, but I really haven't found a convenient way to render the mesh on either side of it. The back is always black. In this render, for example, the floor's normal points downward.

Thank you!

[ziyi-zhang]

Hi @Galaxeaaa,

That can be achieved using a double sided BSDF. The doc is here.
Best

[Galaxeaaa]

Hi @merlinND,

Since I'm using a dataset providing xml files, I'll need to convert xml to Python dict first in this case. I wonder if there's a built-in function to do this? I only found mitsuba.xml_to_props here.

Thanks!

[ziyi-zhang]

No we do not provide such a conversion. Two alternative solutions:

• you can (ask chatgpt to) write a small python script to generate the double-sided version of xml
• or load the scene, and traverse the parameters using "mi.traverse(scene)" to replace the bsdfs with their double sided version.
  Best

[Galaxeaaa]

I've written a script to generate new xml already, but I feel the second one is even better. Thank you so much for your suggestion!

[ziyi-zhang]

Hi @Galaxeaaa
As reminded by merlinND, this actually requires changing the type of BSDF, which is not exposed in the traversal -- the traversal only exposes parameters of the current BSDF, not the BSDF itself.
Please ignore the second suggestion. Sorry for any inconvenience.

[Galaxeaaa]

I see. Thanks!