Spring RTS Engine

Trying to make a first map (seems overly complicated), not getting very far, please help:

1) Using GIMP I made a grayscale .bmp of what I want, but I am confused if it's supposed to be an 8-bit or 24-bit image (one tutorial mentions 8-bit), I saved it as a 24-bit grayscale, is this correct?

2) I like large maps, so it's 32 x 24, which translates to a 192 MB .bmp at 16,384 x 12,228 (x 512) pixels. When I try to scale it down to 1/8 size +1 to make the metal map etc, 16,384 = 2048 pixels +1 = 2049.....but 12,228 = 1528.5, do I round up or down here - for a final number of 1529, or should it be 1530 with the +1 pixel?

3) Also, GIMP doesn't want to scale it to exactly 1/8 the size of the original, no matter which method of interpolation (or none) I use, one dimension or the other always seems to end up off by few pixels, how can I get it to the correct size, or does it matter?

4) Question 3 aside, to make the metal map, I saved it as a 24-bit RGB image, trying to make it a red-channel only image seems difficult, does it have to be red-channel only? (GIMP doesn't seem to want to delete the Green and Blue channels, is that necessary?) I can select areas of the map, but can't seem to change them to red (I want to make all terrain metal, max metal underwater (like a metal map) and a lower amount around map edges at ground level, and a higher amount of metal (but not metal map max) near the center of the map. Is this possible, and how to do it?

I know, you're proably laughing, but any help would be appreciated. TYIA.

its 12288 not 12228

sorry thats all i can help at the moment, should solve the biggest issue

imo the easiest to get correct resolution+colordepth is to use the export function of springmapeditor.
http://springrts.com/phpbb/viewtopic.php?f=56&t=16341

1) you want 8-bit instead of 24- for the heightmap.... 16-bit is optimal, but you can't do it with gimp (save that for next map)

2) already solved :)

3) if you want scaling in gimp... go to image->scale image, make sure to unlink the aspect (the chain icon) and then put the exact size you'd like... doing it manually gets super messy

4) ye, as knorke says, easiest if you're having trouble with exports is to save a blank metal map with springmapedit that is the perfect size for your heightmap, edit with gimp, then re-save with the same settings (same for all of the source images you'll need really)

Thanks very much for all the quick replies!!!

I realized after looking at it again my image was the correct size of 16,384 x 12,288 (by luck, I think), (thanks to BaNa for pointing it out!, I wasn't getting it, doh!) I was fat fingering it trying to figure the 1/8 dimension and wrote the wrong size I quoted on a scrap paper I later referred to, (doh!) and thanks to KaiserJ ! (I should have looked at the help in GIMP, it's there too) I discovered the little chain icon was the reduction size issue

So I now have a 2049 x 1537 grayscale image. GIMP doesn't say if it's 8-bit, just Color Space: grayscale, but the properties of the file say it's 8-bit

And thanks to knorke and Kaiser J for suggesting springmapeditor I'll make my next map with it from scratch I guess

I've imported it into springmapeditor as a height map, I see some mistakes than need fixing, so it's a work in progress - I should save this as a RAW 16-bit image, is that the preferred choice of the 4 possible for a heightmap? Or just leave it 8-bit?

thanks for all your help, I'm sure I'll have more questions later

8-bit can only have 256 "levels" of height, wheras 16-bit can have thousands. on the other hand, 8-bit can be mucked with easily in any image editor, so its more convenient to work with (gimpable)

for many of my early maps, loading an 8-bit heightmap into springmapedit, hitting the "s" key (smooths the whole map) and then touching up details manually (further smoothing for nice ramps etc) gave pretty nice results... im guessing at least 90% of spring maps use a similar method (smoothed 8-bit) and they worked out great

i really like springmapedit for the visualization aspect; even if i dont make a single change to anything within the editor, its priceless to me for being able to fly around the map and examine things without having to compile first

with spring maps, beyond basics like "will it run", there isn't one "right" way to do everything; its more like english class than math class. create, experiment, enjoy yourself... and most importantly, make something fun for us to play

Thanks again KaiserJ, very helpful!

I ended up scrapping the first try and starting over with springmapeditor as my first attempt was too messy

so it's coming along slowly, got the 2nd attempt heightmap half-done now