Hi,

I need help because I want to render in mantra with a background and my problem is that I do not know which format pic option has to be my pic for perfect view here ?

tool: Lights > environment light > environment map.

Flat images can be any supported format, and are assumed to be equirectangular (lat-long). Cube maps must be multilayer format such as houdini rat, pic, or exr with layers named front back left right top bottom. The preferred format would be the native rat format as it supports high dynamic range and mip map textures. Other formats are converted to rat at rendertime, starting with rat eliminates this step and frees the memory that would be used to store the converted texture.

I'm looking for converter page or software to .rat on Google but I can not find anything.
can you help and suggest me one ?

“Convert an image using MPlay”
“Choose Render ▸ MPlay ▸ Load disk files”…

I understood this ,but it left in low quality my pic in rat format, it's strange, what resolution do you recommend converting my pic to use it as a background ?

I don't recommend lowering the resolution excessively when converting unless you only have diffuse materials, even then there will be energy loss when down sampling. The bundled command line utility icp/iconvert can be used to convert images to rat format. The composite suite within houdini can also be used to read in a supported image and write out a RAT format using a Composite render operator. Or simply load in mplay and save out as RAT. Note: the resolution will be limited if you do not have a commercial/Indie license.

https://www.sidefx.com/filmtv/compare/ [www.sidefx.com]