Is it possible to render/output a single frame out of the game engine to edit in photoshop?
If it is possible can it do channels?
You can use the screenshot & highresshot commands to capture the current frame. It won’t pause rendering though.
If you want to output certain channels, you would need create a some custom code to export what you need or apply some post processing to filter out the channels you don’t want.
You can export the buffer visualization targets. The new blueprint render-to-texture tools in 4.3 make use of this, although in this case it sounds like you just want the buffer outputs.
You must enable the ability to export buffer visualization targets in the editor. That can be found by clicking the upper-left Down-Arrow button in the perspective viewport and selecting “High Resolution Screenshot”
That will bring up a small window of the same name. You must check the box named “Include Buffer Visualization Targets”
You must actually leave this window up. It is ok to just click anywhere on the editor again, this window will move behind the editor and should not interfere. If you accidentally close the window, the buffer images will not render.
Now you need to play your game, pause it to whatever point you want the screenshot, and enter in the following custom command:
r.BufferVisualizationOverviewTargets BaseColor, DecalMask, Worldnormal
In this case, you would be telling the editor to export the Basecolor, Decal Mask and WorldNormal buffers when you render a highresshot.
To render the highresshot just type:
highresshot 2
where 2 is the multiplier of the current resolution. You should also get the specified buffers. You can include any of the buffers that you see under the buffer visualization menu.