I can’t seem to get a transparent background in Composer. There is a thread here where the OP tries a new scene and says that solved it. I can’t start a new scene, it’s too complex.
What settings do I need to use to get the black background I see in my scene to go away and give me an alpha? I have use Alpha checked for my file types. The scene has 4 rect lights and no other lighting.
No matter what I do, delete or configure, I can’t get a transparent background like what you “do” get when I start a new scene. If I do that and put a cube in it and remove the ground, I get a perfect PNG with alpha. But I can’t get it on a scene that has already been worked on.
Ok thanks for the question. This should work “out of the box” as long as you render a PNG with “alpha” turned on in the settings for Movie Capture. I cannot tell from your post if you are talking about getting some kind of transparent background to show up directly in the RTX viewport or after you create a render with Movie Capture. There is no way to “preview” a transparent background directly in the RTX viewport. This will only show up once you load the PNG into Photoshop or After Effects.
Yea, like I mentioned, I’ve already enabled the switch you mention. I don’t care about seeing the transparency in the viewport, I just can’t get a PNG or TGA to render with the Alpha intact.
If I start a new file, it works perfectly. But I have a file in which I deleted the default environment and added lights to. Some setting is preventing the Alpha channel from being created. I just have a black background in the viewport and I can’t it to be invisible or to stop being rendered.
Well can you send me the USD file “Collected” using “File > Collect” so I can take a look ? If you have added an environment or dome light, and you can see the hdri background, then that could block the alpha channel. But as a rule, if you can see only black in the viewport, the alpha channel should work. Try deleting your lights and start fresh and see if that solves the issue.
I’m collecting it. I spent a LOT of time setting up the lights. So my reason for posting was to see if there was some simple setting I was overlooking. I tried deleting the lights and just adding one quickly to see what happened and still no Alpha. It’s something I don’t know about having to do with the default background in the scene.
I’m just learning Composer for about 4 months, so I’m not an expert and I’m sure this is user error but I’ve spent literally 15 hours trying to solve it. Yes, I could have started over and maybe solved it, but I want to learn and “know” what causes this for future events like it. Plus, I’m a 3ds Max Expert Elite over at Autodesk, and like you, I educate and help users solve problems. So for me, “solving” this is more important so that I learn.
Are you using USD Composer 2023.2.5 or the current Kit App Template from GitHub ?
Two bugs:
Enabling “motion blur” when in the Real Time mode, will block the alpha channel. Just to be clear there really isn’t motion blur in realtime. The option to turn it on does a kind of real time version of it, but it is not great. So if you are rendering in real time mode, turn it off in the Post Processing menu.
I see you are trying to output to TGA file format. It seems there is a bug here, where the TGA file format does not produce the alpha channel, even though it should. When I switch to EXR or PNG, the alpha channel works great.
So in conclusion, do not use tga, use png or exr, and do not engage motion blur for realtime.
