When doing a render, what would be the correct way to save the Z information to a file so i can restore it later? I would like to do a render of a scene and separally with lower settings a render of a smoke simulation and then load both images & their respective Z values and in the compositor unite them with Zcombine.
Connect z depth output to a File / Output node to save as an image in the format you specify, or send to Output node and save from the render window. OpenEXR file will save image depth data in the file or use MultilayerEXR to save all layers and passes in a single file
You can use File Input node to load external images/movies