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High "quality" CAD model, Low FPS (9m poly)


I currently have a high quality/poly CAD model. The poly count is around 9 million polygons (yes I'm aware of that's a lot :)).. However.. the thing is that without shadows and with baked light we manage to run this in VR with a FPS of around 100FPS in Unity3D using a 1080GTX card (even higher when we run it using a TitanX card).. But I really cant get this to run smoothly in UE4.

Since I would prefer to convince my colleagues of using UE4 instead of Unity, since I really like the visual fidelity of UE4 and the editor itself a lot more, I started by setting up a very simple level with only the model and disabled shadows and baked all lights and set them to be static.. however.. the FPS is still quite poor.. I have also tried to just use plain simple basic materials.. but that doesn't change anything really.. The thing is that the clients we work with usually don't have game ready and low(er)-poly models ready.. but they do have "photo realistic" models.

So.. are there any tricks that you guys are aware of to get a higher FPS, but without the need of re-modeling the model? I'm aware of normal maps and such.. but what I'm really looking for is if there is something that I can do in the engine/editor itself to make it possible to render smooth 90FPS+ using a very high-poly model that I haven't already mentioned..

FYI, I have also tried to reduce the polycount to 3 million polygons.. and the FPS went up, but its still to poor for any VR experience.

And should mention that we are using the HTC Vive.. just in case that this might have something to do with what at least appears to be poor FPS

Thanks in advance!

Br, Inx

Product Version: UE 4.15
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asked Mar 07 '17 at 11:52 AM in VR

Inx51 gravatar image

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2 answers: sort voted first

As it turns out.. Unreal Engines default rendering setting is to use deferred rendering, which isnt used in unity3d as default (they use forward rendering).... So.. by switching from deferreed to forwards I managed to gain a solid 90FPS+ using a 9M poly CAD model.. For anyone else that might experienced this problem and hasnt switched to forward rendering.. here is some additional instructions: https://docs.unrealengine.com/latest/INT/Engine/Performance/ForwardRenderer/#performanceandfeatures

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answered Apr 21 '17 at 08:51 AM

Inx51 gravatar image

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I've been dealing with a very similar situation, I was given a model with 13m+ polygons from archicad to use in VR with HTC Vive while using both a setup with 2x980Ti and now I'm working with a single GTX1080 (In case you're wondering, I had an increase in performance with the single card, even though I was making use of SLI for VR, which also gave me an increase in performance from a single 980Ti - one of the UE4 updates included build in support for SLI).

I had no other choice than reduce the polycount and "be smart" about what pieces I was importing, I exlcuded this and that part because it wouldn't be visible, I divided the geometry in smaller components depending on the importance given the context (floors, walls, outdoor, indoor, far away, close to the user/camera, etc.) and remodeled the most important parts.

Right now I consider it very poorly optimized, roughly with 3m polygons, but I'm running it at a steady 90fps in Vive with r.screenpercentage 200 (with more tweaking I'm sure I could go up to 220 or more), I have exposure and bloom effects on, very basic translucent shaders (this is what kill my performance), no SSR and no AO, everything is baked light.

All of this with deferred rendering in a short time schedule, eventually I'll give deferred rendering a try, but here's my 2 cents.

Cheers - John

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answered Apr 21 '17 at 11:48 AM

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