Does any of you smart puppers out there know if it’s possible to bring back a previously rendered image into the compositor?
For instance:
I hit render
My render appears in the compositors render layers with all the passes I selected (AO, Depth, Alpha, Denoise etc)
I can add all the nodes I want to edit the image
I save the image and save the project file
I shut down/Blender crashes
I reopen blender
I have to re-render the image to get it back into the compositor!!!
It’s worth noting that i tried adding back in the previously saved image (png) and it does not retain all the meta/pass data the it had immediately after rendering.
Yeah so if i just add in a png that i have previously rendered, it doesn’t contain all the pass data. it only contains the alpha and the image itself. Does exr contain ALL pass/meta data?
Update: i just tried rendering as exr, saving, closing blender and reopening then adding back in the exr as an image and it only retains alpha, image, and depth. all other pass date is lossed (AO, denoising info, shadow, emission etc).
AFAK the EXR format can save this but most (all) other don’t. So i believe the workflow isn’t prepared for EXR saving thisautomatically. I’m not sure about this but if for example someone add a UV layer to the render output… where do you think this should go… Isn’t the File Output Node for this ? Of course you have to use an input node if it crashes (may be there should be a “file buffer node” ?) Or you do it in two turns? First save all your layers. Second composite them. You have to do it this way anyway if not using blenders compositor… (it’s just too nice to have it)
"Essentially you DON’T want to do the compositing in your 3D scene but rather render your 3D directly to “OpenEXR Multi Layer” format (in the output settings). If you’re not using Cryptomatte then you can set it to “Float (Half)”
Then you would do your compositing in another scene or blender file and bring your render in to the comp using Image nodes rather than the Render Layer nodes. The Image nodes will have all the same pass outputs as long as you render OpenEXR MultiLayer from your 3D scene"
Where does this come from? … i mean:
If setting ViewLayer → Passes → Data → UV it apears in the Image Editor and also when compoiting in the Render Layer node. The workflow doesn’t suggest any saving of the UVlayer to anywhere (and with what name?) and it doesn’t if for example of PNG is used. So EXRmultilayer could do this yes but is was inlcude in blender… when ?.. Even if using Output Properties → Cache Result (Tip: Save render cache to EXR file (usefull for heavy compositing)) this doesn’t seem to produce any EXRmultlauer in TMP (using png or EXR…) (tested with linux and 2.9x)
But on the other hand : using File Output Node:
"Essentially you DON’T want to do the compositing in your 3D scene but rather render your 3D directly to “OpenEXR Multi Layer”
Doesn’t make sence because there are no output settings at all to save UV without using Compositing → Use Nodes.
(Sadly it doesn’t seem to work for me. Even installed an EXR viewer … all black)
I don’t know that much but that is what I have seen mentioned… And I checked, with multilayer exr, in the compositor image input you get the option to choose in a dropdown the view layer which gives you the passes.
Nice work Okidoki. and thank you all. So in summary, basically you need to use a .exr multilayer if you want to edit individual elements/passes of a shot and a file output node node if you want to edit the shot in an image editing suite.
