No you cannot.
Photoshop being 15+1 bit instead of 16bit you are only going to irreparably damage your files.
Use a native 16bit program of any kind - or better and you probably have to for the size you are interested in; a GIS program.
If you use the old word partition you can, but you’ll have to batch import tile sets of about 12 (2km) tiles or so to prevent the engine crashing/running out of VRAM.
If you want to use the newer systems you are probably SOL anyway, so start assuming you need to batch tiles in.
Heres some pedestrian math for you anyway:
32x32 = 1024.
If each landscape tile is 1km^2 - and you get all the way to making impostors for it, youll have a maximum of 1020 drawcalls wasted on the landacape impostors.
That’s on top of at least 4 levels you are around/on which aren’t going to be impostors and will cost dpending on your inital setup (1x1 vs 2x2 and number of components).
Same area, with levels of a decent size 4km each would end up being
32/4 = 8 so 8x8 = 64 so that’s 60 drawcalls, which is rather managable by prettymuch anything.
On top of around 255*4 drawcalls for each landscape thats not an impostor.
You can go a step further and force 8km tiles but they don’t really play nicely with older systems or your graphics card.
32/8 = 4 whoch means youd only need to contend with 4 tiles, assuming you could handle them at all.
You wouldn’t get or need any impostors in this case which is slightly less work.
The drawcall count however is massive just for the landscapes themselves.
This somewhat limits (or used to? You know cuz of nanite i guess) how many things you can add into the level before performance is just bad.
Personally, I’d go with the nearest reccomended size to 2km^2.
32km^2 is a rather insignificant area to cover. Particularly after having put together and imported areas of approximately 256km^2
The 2km tile maps gives you a decent balance on good looking impostor textures (at 2k), to cost of rendering and memory load.
On top of half the drawcalls of the first math used on impostors.
Either way, I’d stick to the older system if i was into using landscapes at all.
Since im not… I’d just bring it into any DCC and make a mesh of the overall size I need optimized for tris count based on angular limits.
I’d then pick a size to cut it up into tiles (probably using the same reccomended sizes as the unreal terrain).
And pop the meshes into the level without even instancing them (unless there is a point instancing them, which depends on how you want to work their material).
At the end, I’d just have however many drawcalls per material per mesh of landacape to contend with.
And since meshes do fine irregardless of size they’d probably be just 4 at 8km^2 in this case.
Should you decide to drop the unreal landscape BS and need extra help, feel free to open a dedicated topic on it.
If you are sticking to the landacape now you more or less know what’s possible.
And for the record, the 256km^2 landscape runs Ok (4k 60fps) on a 1080ti. So it isn’t horrible inspite of the excessive amount of impostors/terrain drawcalls).