I am experiencing a weird phenomenon.
I have implemented large scale terrain that is divided into chunks of various resolutions/LOD. When two different LOD chunks are near each other, I do stitching once on the CPU to fix the seam. The way I do it is it take two points from the higher resolution chunk that align up to the lower one and compute their average height. Then I set the middle vertex height to that average and apparently this fixes all discontinuities between chunks.
But something is amiss. It seams hat my simple average is not up on par with the way the hardware rasterizer triangles and sometimes a single pixel wide hole appears. These come and go as you move the camera around, often staying only for one frame.
In the above image I was lucky enough to capture two of the fleeting seams near each other. The red line is the LOD discontinuity. The two seams are circled in red. As I move around the camera, white pixel come and go, all found on the discontinuity line. Otherwise, when the pixels don't show up, there are no seams.
Any idea how to fix this? My far plane is pretty far away, may have something to do with it.
The only idea I have is to add extra triangles in that "seam".