Photoshop heightmap chunks not lining up

Hopefully I'm just stupid and can't find the right words to search to find an answer to this, if so please just send me a link... otherwise... omgwtf plz help.

I have a height map that's 2049x2049 (2x +1 format) in photoshop raw... 16 bit B/W and all that

It wont load correctly... it does this

I can cut it up into pieces and import them in at 512x512 but the heights seem to differ slightly at the edges, presumably because the height resolution on the terrain chunk im importing the height map to is fixed... while the actual relative height data of each heightmap is absolute (or should be) in relation to the overall heights of the entire city.

So when i import the height map of a chunk that (in reality) has heights between 0(water level) and 100meters, i can import it and use 100 as the height resolution. But the next piece might have slightly different actual heights. So is there a way to find height resolution data in each chunk to import them correctly (somewhere in PS) or... what do i do to make them all match up?

These are the settings I used for everything in PS

the chunks missing are where i started cutting it up... the full image was used for the original import that got all screwy