High stuttering with the Oculus Rift only with models exported from blender

Development Asset Creation
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Hi all,
I’m trying to make architectural visualisations. The editor I use to create the 3D Models is blender. I export the models as .fbx with all the specifications the unreal engine needs. When imported I get no error reports at all and everything seems to be fine. When I start a viewport preview I get framerates of 120 and more and the game runs buttery smooth. When I start a VR Preview with the rift the framerate is still good but I get a very high stuttering and extreme spikes in the latency of the rift. When I control the player with mous and keyboard everything is fine. The stuttering is only present with the physical movement of the head.

I tried the “sun temple” and the “RealisticRendering” examples from the store and with them I don’t get this behaviour and everything is fine with the rift (no high latency and no stuttering).
After that i imported a model exported from blender in the sun temple and droped them in the scene. When I start the VR Prieview now everything is fine as long as the blender model ist not seen by the player. When the blender model comes in the view the stuttering ist back again and gets worse when the blender model gets more space on the screen. So its definetly something about these models but I don’t know what it is.
When the lightling mode is changed to unlit or wireframe in the VR Preview the stuttering is also gone. It only appears in lit mode.

I attached one of the models that is causing this behaviour.

This specific model gives a tangent bases error at import but it also happens with error free models.

The engine used is 4.83 with Oculus Runtime 0.7.0.0 the DK2 and a GTX 780 3GB.

Screenshot from the Latency Timing in unlit mode.

58983-latency_reading_unlit_mode.jpg
58983-latency_reading_unlit_mode.jpg1297×774 352 KB

Screenshot from the Latency Timing in lit mode with high spikes.

58984-latency_reading_lit_mode.jpg
58984-latency_reading_lit_mode.jpg1291×768 254 KB

I would really like to know what is causing this because blender is my main 3D creation suite.

Thanks in advance,

2

Just a blind shot in the dark:

  • Open the console and enter ‘stat scenerendering’
  • How many draw calls does the scene have, when you look at the model? (More than about 1500 are a serious problem without high-end CPUs)
  • To reduce draw calls, limit the material slots of the model (as few as possible, not more than about 5). AFAIK that’s even a problem if the very same material is applied to different slots
  • How many polygons has the model? Budget for whole scene should be under ca. 1.500.000 as a rule of thumb for VR
  • Do you use a very complicated shader to render the materials of the model?
  • Also try to deactivate screen space reflections (r.ssrQuality 0) in VR and limit postprocessing (sg.postProcessing 2), shadows (sg.shadowQuality 2) and general effects (sg.effectsQuality 1). It can also help to deactivate the hierachical Z-Buffer for small scenes (r.HZBOcclusion 0) and slightly reduce the pixel density (hmd pd 0.9).

Did you try to invoke the GPU profiler (CTRL+SHIFT+;)?