Odd bug with Virtual Heightfield Mesh - flickers out only at specific camera angles

I have a very strange bug when using the VHFM. It flickers out of view (disappears) but only at two very specific camera angles, ~45 looking down and when straight-down. Doesn’t happen if the camera is under the mesh… In the editor, if I move the camera a certain distance above the landscape/heightfield-mesh the effect stops.

I can leave the camera at one of the two angles and rotate and the landscape is still not visible, but as soon as I move the camera up/down it comes back… Tried a rebuild of all as well as a reboot of the editor.

Not using displacement, but I updated the Neg/Pos Z-bounds on the source landscape, and using the bounds-view I can confirm I’m still inside the bubble for that landscape secion.

Issue persists in the standalone playtest.

Unsure what I did to make this happen, cannot seem to undo it…

EDIT: …aaaand it just seemed to resolve itself… I moved and reset the locations all the things involved with the landscape, rvt volumes, height-mesh, etc and it seems to no longer present.

Leaving this here in case someone else runs into the same issue.

Sounds like your run-of-the-mill occlusion culling issue.

I’d look at what the vhfm is actually using for bounds evaluations.
Also, freeze rendering if it works with it. While the bug is active, and try to determine if there’s a reason you aren’t seeing by showing all bounds/collisions.

I want to say I’ve seen a comment here or there about resetting the location of the RVT volume and/or the target seeming to help people. That appears to be what it was here.

I did check the show-bounds and all the landscape component bubbles came up but I was always well inside them.

Hasn’t presented since but I think the general takeaway is when in doubt, reset locations, reset bounds, regen textures, just to be safe.

BTW, since I have you, what do you think? The holy-trinity achieved!  Landscape is a go-go! - Album on Imgur

Not sure what to think.
Using meshes is still probably a lot safer for performance overall.

But if you get 80fps at native 4k with nothing but the landscape it would stand to reason you have enough wiggle room to actually add foliage and other things.

After all, meshes and landscape grass don’t go together.


Of course when it was all green-colored in the shader-view, FPS was a bit higher, but the lighting cost is still killer. BUT, as you said, enough FPS to burn a few.

Feature-wise, surprised I could make it all work, particularly the depth-blending and the mesh-displacement/heightmesh… Off to critters…

Being a blender guy, wouldja be able to point a fella in the right direction? Particularly the UI/control-scheme is all bonkers to me. I come from UE/Max; don’t get blender… Best I could make was a set of flat-sheets at various levels of tessellation for some other things…

Unfortunately there’s no shortcut for experience when it comes to blender.
Ask @ClockworkOcean. He knows.

You are welcome to send a PM/add me on Discord if you need quick pointers.

Either way, it all depends on what you are trying to achieve.

If you wanted to make a scene like this one for instance. I would leverage the Houdini landscape tools for procedural generation.

If I wanted to make a few rock face meshes, I’d set up a plane with 1px per meter in Blender of the size I’d want, I’d move (import) it into Zbrush, and sculpt there with as many subdivisions as I think works.
Then simply bake the result down in zbrush.

You could do the same in Blender, and u
I usually do, but the bake process is much more time consuming. When you hand sculpt anyway.

Blender is great for doing precise work

And with some set up baking down unrelated parts into a trim sheet.

Zbrush is best for humanoid/organics. Also with a steep learning curve and a billion crashes (nothing new right, we use unreal so what’s a billion crashes all things considered?)

Houdini can do it all, probably, but its a 3rd thing to learn. Which is OK if you get into it I suppose.
However I would say to stick to what it does best.
A friend of mine is the one actually coding the landscape algorithms, so I’m biased on it.
At the same time, farcry 4 wasn’t bad at all, cliff face wise. That was made with Houdini SFX. Or was it 5?
I lost track because the games have been absolutely horrible since after 3…

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Thanks for the reply.

For what I wanted I have been able to accomplish here. The big 4 for me on a landscape were the accurate triplanar mapping w.o distorted normals + blending over pixel-depth + blending ‘stuff’ with the landscape + displacement. Albeit a ‘tad’ more expensive than I wanted (material-wise) but some respectable FPS still.

As always thanks for your input and advice.

I’ll second @MostHost_LA 's comments about Blender. I think it’s because it’s had such a tortuous history, they somehow managed to leave crucial segments out of the interface. There’s something on a genetic level that doesn’t make sense.

Having said that, I am slowly getting better at it.