Gen, from one New Hampshire guy to another, i'm gonna try to help you out here. Please try to heed my advice...
Okay, ur trying to make an OTA Remake, thats an awesome idea. But you have a serious problem with your textures. Everyone else has been rather brutally honest, not to hurt you feelings or anything, but to rather explain to you that you are going in the wrong direction.
Now then, if you want to create a spring map based off of OTA textures the first thing you need to do have a copy of OTA. From there you need TAE, (installable from the TA:CC cd).
Next you need Kinboat's
Annihilator 1.6, and then a copy of
HPI Viewer.
Alright, first off, i'm going to assume you have OTA and that you have installed OTA in the typical manner including all of the expansions along with all of the patches and the NOCD crack.
Now, first off, you will need to start up HPI Viewer...

Neat huh?
Next you will need to open the file that contains the original map...
You will note that the above image has "Open HPI File" highlighted, now, while that is the option we will be using, the file we will be opening will not actually be an HPI file, it will instead be a .ccx file. See below:
With the ccmaps.ccx archive opened we see that it contains all of the Multiplayer Cavedog maps from the Core Contingency Expansion. Below you will see the map we want in the archive viewer.
The next thing to do is select both "Metal Isles.ota" and "Metal Isles.tnt"
The .ota file contains all of the schema date (start positions, wind, metal). The .tnt file contains the texture data and height data, which is what we want.
Save both of the files in the OTA maps directory in "c:\cavedog\totala\maps\"
Make sure both files are saved, especially the .tnt file!
Alright, we are done with HPI Viewer, now you need to bring up Annihilator by Kinboat. The program fucking rocks, not just because of its ease of use and low system load, but also because of its shear power. You can do so much more with this program that what I am going to mention.
Alright, first you are going to select Open Map from the file menu...
From there you need to go to c:\cavedog\totala\maps and open the "Metal Isles.tnt" from that directory.
Behold! Its our map! Okay, now that its open, you need to bring the cursor to the "Map" menu. You will notice two options...

"Export Heightmap" ^

"Export Map as BMP..." ^
The first thing you need to do is export the Map as BMP, this is your entire texturemap, it is at the proper resolution for the map size and will be completely compatible with Mother's Mapconv.
And then of course you need to Export the Heightmap...
ZOMG! Its not at the right resolution!

Yes, thats right,
the OTA heightmap is not at a Mapconv compatible resolution, actually its
1/16th of the OTA texturemap. With that said all you need to do is
double the resolution and add one pixel. Of course i don't recommend doing this with anything but Photoshop, I suppose GIMP or PSP will be just as good, but Photoshop has stood by me for a long time now and i can't imagine using anything else.
Things to keep in mind:
Doubling the OTA Heightmap will cause some distortion, its recommended you correct that as you see fit. Also;
The OTA Texturemap and Heightmap will not line up perfectly when ported over to spring, why? Because the
OTA texturemaps use a forced perspective to give the illusion of 3D, this was not laziness on cavedog's part as some have said. Cavedog did not design their textures with spring in mind, as a matter of fact I doubt they would have predicted an engine like spring would ever be created by the fanbase.
So with that in mind, how do we correct it? Well, the simplest way is to actually move the OTA Heightmap up or down a few pixels, some trial and error will be required for this. For metal maps it is also important to understand that the south faceing walls of the Metal world are longer than the north ones, what you can do there is squish those parts of the texture with a resizing tool and replacing the missing peices of floor texture with other flat parts of the map.
Oh and since you are not doing a straight port, I highly recommend that you add your extra isles within the Annihilator editor instead of drawing them out form scratch, it will look better and be easier.
That concludes my super awesome OTA Remake tutorial. I hope this helps more than just Genblood! ^_^
-[NR]Quanto
"I'm in ur base killin ur dudes!"