Save all render passes to EXR image?

Question

I am having an issue with EXR file export that I did not encounter in previous versions of Blender. I used to be able to render a render layer with all its passes and get all the passes included with the render layer with the EXR export; the problem I am finding now is that I am not able to "pack" the passes with the EXR file (see graphic below). I am working with "standard" EXR, as I understand that the EXR multilayer is for multiple file handling (packing all the image files into a single container), but I may be wrong.

In the screenshot, the graphic is an EXR saved from the rendered layer; you can see in the screenshot how the "extra" passes from the render layer has been ignored by the graphic and only shows the standard image, z and alpha passes. I found this issue for the first time with Blender 2.71; and maybe with Cycles; in the past I have never had an issue with EXR export.

Am I missing something? I hope EXRs still work with Blender, I wouldn't know how to composite without such invaluable aid. Sorry if this question has already been answered somewhere; I have really searched the site for information on EXR but I could not find an answer to my issue.

Answer 1

Single EXRs or Multilayer?

First you have to decide what type of OpenEXR you want to render:

• OpenEXR to get single files of your passes or channels/layers
• EXR Multilayer to get a multi-channel file with all your passes or channels/layers included

This decision really depends on your further workfow. For e.g. Blender or Nuke it's much more useful to have one multi-channel EXR, but in Photoshop, After Effects or Fusion it's easier to use single EXRs.

In the context of the Layer Management the EXR Multilayer term is quite confusing. For this reason and also to consider the OpenEXR concept it should be named EXR Multichannel.

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Passes/AOV's

Then you have to decide which passes are key for compositing. In the view Layer tab->Passes section of the properties editor select the passes you need:

For 2.79 and earlier: In Scene Tab you can enable all standard passes of the render engine and create individual render layers.

You are ready to render if Multilayer EXR fits your needs. Blender automatically writes all enabled passes and layers as single channels to the EXR as expected.

If you choose OpenEXR, Blender only saves the beauty pass (final render) although other passes are selected. To save all your passes or channels/layers separately is only possible with the help of the image compositor. In this case you have to create a file output node and add new input slots in the properties of the node:

Still the same for Blender 2.8x:

The file output node makes it possible, whether OpenEXR or EXR Multilayer, but especially in the multilayer case, that you can unleash the full power of the format and pack your custom channels e.g. mattes or backgrounds like this:

Note: If a 'Z pass' is required, check out these answers: How can I get a Depth of field render pass?

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Cycles light passes for reference

Further explanation in the manual: https://docs.blender.org/manual/en/latest/render/layers/passes.html

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Tlousky's production script

To speed up this process you can also use Tlousky's production script. It automatically creates a file output node based on your enabled passes and your output directory:

Note: It's not updated since blender 2.69 that's why some passes are currently not supported.

Answer 2

From the sounds of what you are explaining, You do want to select EXR Multipass.

the 'standard EXR' will only include RGBA, and an optional Z-depth, regardless of what other passes you have selected.

the OpenEXR Multi layer option will include each pass as a separate layer that you can then access from the image node inside blender.

The method Yauda had described will output a separate file for each pass. which will mean when you bring them back into blender, each layer will be have to be a separate image node.

Answer 3

Say goodbye to 'File Output'!

There is an obvious misleading on this thread. Every video and every post on forums says that you need to have 'File Output' node in the compositing, which is so tedious to have so many layers ,name them and connect one by one!

Just UNCHECK 'use nodes' on compositor. And choose the output format to 'openEXR multilayer'. All the passes you chose would automatically be saved in the exr file, with the pass default name.

Answer 4

I can't comment so I will ask it here: are you asking how to save the different passes to different files ?

If so, you can add a file output node that will export your passes in the desired format.

Here I apply some filter on my passes, but then I output the desired one into files. See the properties of my File Output Node. You can choose the format, codec, etc of the EXR files. You can even choose different format for different files if you prefer.

When you add the File Output Node, you will need to add as many input in the node as files you want.

I hope this helps.

Answer 5

In my experience (I use EEVEE) I never got things to work with EXR files so I just export all the passes to seperate files using the output file node for each passe. I am new to all of this so it's maybe not the right thing to do but at least it is working very well.

For example for a movie clip it works like for single images.

As you can see in the image, all passes are going to be saved in different folders

Then you only have to use the movie clip node or image node as input for each passes and then composite them with effects you want.

It looks like this:

For this example I only used the combined and the myst (depth) passe, but it is the same for all other passes.

If I am completely off I am sorry, but it works for me the way I want!

Good luck!