Precomputed visibility cell question

Development Getting Started & Setup
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1

I applied precomputed visibility to my project.

Does precomputed visibility work when camera is in the precomputed visibility cell?

If camera is out of precomputed visibility cell, Doesn’t work precomputed visibility?

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2

Hey byelove,

That would be correct. You can use Stat Initviews to check the stat for Statically Occluded Primitives and Occluded Primitives to make sure that it is working. Occluded Primitives will be the dynamic occlusion queries and Statically Occluded Primitives are the primitives occluded by precomputed visibility.

I have some information on my personal site here converted and based on the older UE3 documentation which is still pretty relevant. http://timhobsonue4.snappages.com/culling-precomputed-visibility-volumes

There is UE4 documentation being worked on for this as well.

I hope this helps.

Tim

3

Thank you Tim.
If my camera in my project is so high.
Should I adjust PlayArearHeight in the BaseLightMass.ini?
My Project camera is so high. My project is third-person view.

4

And I have one more question.
I am developing VR project.
Someone tells me that precomputed visibility is only for mobile project,
It’s right?
Thank you

5

Adjust the PlayAreaHeight to fit your needs. If you have to set it to some really high value then you’ll probably not get the most out of Precomputed Visibility. You get better results when there is restricted movement for the player.

Precomputed Visibility will work with any platform. The fact that it gets more attention with mobile is due to the fact that there is no real dynamic occlusion on mobile devices. Dynamic occlusion queries are expensive and can be taxing on the GPU and with mobile’s limitations it’s more difficult. As phones get more powerful that will likely change though.

Precomputed visibility can work with anything. While it’s more often recommended to be used with mobile, platforms like VR can see the added benefit too since it reduces the number of hardware occlusion queries that need to be handled dynamically since the precomputed visibility is taking care of some of that!

Here’s the order to remember the expensiveness for visibility/occlusion culling:

  • Cull Distance Volumes
  • View Frustum Culling
  • Precomputed Visibility
  • Dynamic Occlusion (hardware occlusion queries)
6

It has been very helpful for me,
Thanky you.