Hi, thank you!
The thing is that this is for a single tuple of irc coordinates cast to a 3-element array and then flipped to cri.
In general, flipping would be the transformation between irc and cri, but if you had a batch, it would be more likely in the last dimension. (This is - in an abstract way - similar to BGR->RGB, but ignore this if it adds more confusion than it helps.)
If I had a tensor that was in IRC “data layout” and wanted to convert it to CRI data layout (similar to channel-first CHW vs. channel-last HWC layout for images), then I would need to use .permute(2, 1, 0), but this is not the case here because we are talking about indices into tensors.
Best regards
Thomas