Disable Auto Exposure on Skybox only?

How can I disable AutoExposure on a custom Skybox actor but nothing else? I tried creating an unbound Post Process Volume with priority 0 and a smaller Post Process Volume with priority 1 but the higher priority volume still effected the Skybox which was outside the volume.

Hello Jack,

I am not having trouble using the set up you described. Perhaps you forgot to uncheck the ‘Unbound’ on the other volume. Try following the set up I am using to test against your own and see if our settings differ. Keep in mind I am working within 4.8 preview 1 binary version so the drop down settings might look a bit different, but the outcome should be the same.

Unbound Global Post Process Volume

This is a screenshot of what the level looks like with the Unbound post process volume and Auto-Exposure Bias set to 0 and the Min and Max Brightness to 1.0. The volume shown in the screenshot is actually the ‘Bound’ volume with a higher priority and ‘Auto-Exposure’ enabled.

Bound Post Process Volume Exposure

Here I have set the ‘Priority’ to 1.0 and changed the Auto-Exposure settings as desired. Whenever walking into this volume in the scene, the auto-exposure settings take over. Let me know if you need further assistance or if you managed to get it set up properly.

Andrew Hurley,

Andrew Hurley

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Thanks!

Thanks for the response. It’s my understanding that when min and max brightness are both 1.0, Auto Exposure is disabled. If you set your min to 0.03 and max to 2.0 on the bound PPV, would your geo outside the bound PPV be uneffected by AutoExposure?

I’m thinking PPV isn’t what I’m needing to use to accomplish the request to make only the Skybox uneffected by AutoExposure.

Hey Jack,

If I go into the bound volume at the default settings, as you mentioned, with its priority set to 1.0, my entire scene will then adopt the auto-exposure as long as I remain in the volume. As soon as I step outside of the bound volume, the unbound volume then takes priority and my scenes auto-exposure is disabled.

I might be a little confused as to what you are trying to accomplish. From what I have gathered, you wish to enter a post process volume with a set amount of auto-exposure, and have your entire scene affected by the volume aside from the Skybox?

If this is not correct, then if you could better clarify your ultimate goal that would help me understand what you need to do? If this is what you are trying to achieve, I will look into how this could be done if possible. If it is not possible, I will look into entering a feature request for the option to be available.

Thank you,

Andrew Hurley

Hey Jack,

After some further investigation, I might have discovered a way to render your Skybox without it being affected by the ‘Auto-Exposure’ of your Post Process Volume. In theory it should work as long as you set it up properly, which might take a bit of trial and error as well.

So in order for you to be able to do this, you will essentially want to set up a blendable post process material to render in a custom pass as well as the main pass. Within the blendable material, you will want to add a multiply and a power node with scalar parameters. These parameters will essentially mask or cancel the auto-exposure of your post process volume for the Skybox. The multiply is your brightness, and the power is your contrast which you can use to even out the values of the auto-exposure.

You will also want to set up a way to get the sky distance so that you are able to contain the custom pass to the skybox alone and to help improve performance. Keep in mind, if you have anything else in the custom pass it will be affected as well. The scalar parameters are created so you can instance the blendable material, and use the value sliders to fine tune for the desired look and feel.

Post Process Materials

Both of these links should provide you with enough information to get started. If you have any other questions or need additional assistance, please let me know.

Regards,

Andrew Hurley

Thanks for the update. I’ll give that a shot and respond if I have any issues.

You are welcome. Yes, please let me know if you are able to get a functioning prototype of the approach mentioned, or if you need further assistance.

Note: I need the skybox to remain unaffected by AutoExposure at all times.

“From what I have gathered, you wish to enter a post process volume with a set amount of auto-exposure, and have your entire scene affected by the volume aside from the Skybox?”

That’s correct! Sorry I wasn’t clear earlier. The problem is very evident when looking at a nighttime sky covered in stars / Milky Way, etc.

Thanks again!

Sure - go ahead and share it.