About format of spatially-varying lighting!

[UdonDa]

Hi, @lzqsd

I'd like to ask about the format of spatially-varying lighting.

In this Figure (f), you show the spatially-varying lighting.
However, I've never seen this representation such as a grid cell.

I have three questions.

1. Can this HDR render the lighting without converting a format in Blender?
2. How did you create this ground truth HDR?
3. Additionally, If you know references about this format, please let me introduce it.

Best regards,