mipmap blur/flickering at grazing angle, help plz!!

Development Rendering
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Hi, I have a painful issue about mipmap texture, for Oculus Quest 2 development.
blur/flickering at grazing angle is causing big problem. Would like to seek help from the wisdom of the folks here.

A bit context:

I’m using projected photos for simple background evnironment(in following images). The problem is, mipmap gets too low res on grazing angle grounds. If I force mipmap to increase resolution, then other areas get too much resolution and start to fliker when viewed. especially worse viewed in the headset.

compare copy
compare copy1920×751 182 KB

maya
maya1920×846 245 KB

Trying to understand the mechanism behind it, here are the question:

1 How does UE4 determine mipmap resolution?

A. Is it per triangle based?

B. Does stretching polygon along one axis affect the same way as proportional scaling?

C. If I turn off or use bias to increase resolution of mipmap, some nearby areas get too high texture density and start to flicker. In this case, other than separating geo manually with differently-scaled texture segments, is there a better solution?

D. Is there a way to manipulate the density threshold of the mipmaping?

2 How to visualize the texture density effectively?
I know there is “Required texture resolution” to help visualize the density, but when switch into this mode, even select the texture , it’s all black. Any one had the same issue?

output (1)
output (1)1286×1458 50.5 KB

Many thanks to any light shining into the confused soul!
Best regards

1 Like
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any one had similar issue?

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Afaik mipmaps are selected based on the rate of change of the texture coordinates between pixels, a higher rate of change means a higher mipmap (higher mipmap level = lower resolution) is selected. At grazing angles, the rate of change is very high and so a higher mipmap is chosen.

Probably not.

Texture samplers allow you to compute the mip level yourself, but you would have to figure out how to do it only for this particular part of the mesh and it just seems like a waste of time when it’s trivial to just split them up.

4

Thanks for the input, Arkiras.

How about the other question:
When selecting “required texture resolution”, everything is black even the texture is selected.

Did I miss any settings to see the colorized texture density display?