Edge Conditions: Heightmaps

When you closely look at a page that display several tiles such as Terrain Viewer R5, you will notice a slight gap between the tiles.

It would be fairly easy to simply extend the maps just a few pixels further om each side and obliterate the error. In the other hand, the gap is a constant reminder that that there is a bug somewhere and the underlying cause of this discrepancy should be ascertained

In principle each mesh is built of a grid of 256 x 256 vertices and they are laid out so that the edge vertices of adjacent meshes should match perfectly. But as you can see they don't.

So where is the error?

Is it in the way the meshes are laid out? Is it in te way that the dat is turned into a mercator projection and transformed into a PNG file? Does the error have to do with tuning the binary data into the intermediate TIFF file? Or is there something we don't yet understand about Jonathan de Farrant's data.

We don;t know. But the gaps are a constant reminder that there's something we need to investigate further.