It appears that, at the end of the images, is a black line that is causing that bug. Maybe is because of the image editor you are using? Try using another editor. By the way, you can also use the built-in terrain creator of the SDK if you want.
“I’m working on piecing together a height map” - That tells us close to nothing. Putting the images together, or using TerrainGrid, or using your own “chunk”-objects, or trying to place TerrainQuads in the SDK editor, or…?
I gave 2 images 16,26 & 15,26. Those are just 2 chunks from a 16x26 map. I’ve done this before just importing the pictures above. By piecing together I mean I took my original map (13312x8192) & split it into 1024x1024 chunks to use on a 1024x1024 map using the sdks create terrain. I’ve done it before with large worlds in the past but for some reason it’s not linking this height map? & I’ve tried opening the images on another system using various image editing software’s & there is no black line that appears.
Remember, the ‘texels’ of the height map are defining the corners of the terrain quads. So you get a quad between 0 and 1, between 1 and 2, and so on… all the way up to between 1022 and 1023 where it stops. (1024x1024 means 0 to 1023)
…so what do you suppose happens between 1023 and the 0 of the next tile?