I imported the EXR file into Nuke and used a READ node to display it (make sure there are no # in the file’s name).
To check that the EXR file actually contains all the passes you need, connect it to the viewer node and in the top left of the viewer window change through the “rgba” channel options (remember to put it back!) to see all the passes the file possesses.
This is the Node tree from Alec’s composite that I based my Node tree around:
Previous research into Nuke.
Splitting up the EXR File into Passes
I found this website super handy. Use Shuffle nodes to split up the passes (make sure the viewer is connected to the one you are working on).
The Refraction and Refraction Opacity (which I needed and thankfully rendered anyway) passes were proving hard to merge.
When importing another file (foreground or background) make sure it has the same format. My background was larger than my objects so it took my years to figure out how to fix it – change the actual image settings outside of Nuke.
My image was also coming out transparent because I needed to bring in my alpha again as it was incorrectly separated from the rest of the passes.
Alec helped me fix this and after a few more correction I was done! Here is my final image and it’s breakdown video (made using after effects):