Shape of object changes when camera moves? So this problem is massively difficult to describe in words, making it very difficult to do any kind of search for; if it's a duplicate, please point me in the right direction.

Below is a gif of what's going on:



As the gif hopefully shows, the shape of the ground plane changes significantly as the camera moves.

I discovered this behavior when I noticed some odd rendering behavior in Freestyle, where some of the lines were disappearing for no readily apparent reason, which I eventually realized was the ground plane being in unexpected places in the render (I was only rendering the lines, not colors).

It should be noted that this ground plane is huge; it's around 2km x 1km in size. I don't know if that has any kind of affect, but if it does, I could probably cut it into smaller pieces.

The purpose of this is to be a large map that I can render from a variety of angles for illustration purposes, so I can't have the ground position/shape being so mutable. What's going on?
The problem that I was having was two separate problems:


The ground plane going bonkers in the camera preview
The ground plane appearing to be in the wrong place in renders


The solution to the first problem turned out to be increasing the near clipping distance on my camera from 1mm to 1cm, though I'm not entirely sure why the clipping distance has an affect on geometry in the preview; the shifting geometry also is preview only and is not reflected in the final render (thanks to Duarte in the comments for pointing this out).

The solution to the second problem only seemed to be related to the first, and turned out to be that I had at some point disabled the subsurf modifier on render, causing the rendered geometry to be completely wrong. Re-enabling it fixed the issue completely. Always check your modifiers!