Haplo, thought I'd share one method I use on Linux to edit terrain heightmaps, as it's pretty neat. I use ImageMagick on the command line to edit a png heightmap while it's on my opensim VPS server, in my opensim/bin directory.
I was looking at Linda Kellie's terrains at http://www.lindakellie.com/terrain.htm
and my favorite was Intertwined, 5th one down. So I grabbed it directly from her site to my opensim/bin directory with
Then I got experimental and thought this would look cool expanded as a group of regions. 3 x 3 seemed like a good one to try so with a simple command, I blew the image up to 768 x 768. People will gasp in horror at the thought, it's not something I would do with any image ordinarily, but hey, I was just messing around
Of course, make sure ImageMagick is installed. In Ubuntu, just type
sudo apt-get install imagemagick
Now, with your command line location in the directory where the 256 x 256 terrain image is, type this ImageMagick command to enlarge the image:
convert -resize 768x768 terrain-intertwined.png terrain-intertwined-big.png
You might think it wise to do a gaussian blur on the image to depixelize it after being enlarged--but I didn't bother and it turned out ok in the end. I had used this command in the past and it worked but this time I am getting syntax errors after trying several combinations so I gave up. Maybe someone can figure it out, or just don't bother - anyway, here is what I thought would work:
convert -gaussian-blur radius 3 terrain-intertwined-big.png terrain-intertwined-big.png
Moving on, you next need to slice up the image into 9 256 square images. This is where ImageMagick earns it's name! Here's the command:
convert -crop 256x256 terrain-intertwined-big.png -depth 8 intertwined.png
Note, this is where the color depth is set for 8-bit. You could have done this above in the resize operation also, not sure if it makes any diff.
The ending file name is the destination file name of all your sliced images, with a number appended to the end of each one starting with zero. Magic, eh?
Do the ls (list) command and see:
intertwined-0.png intertwined-1.png intertwined-2.png
intertwined-3.png intertwined-4.png intertwined-5.png
intertwined-6.png intertwined-7.png intertwined-8.png terrain-intertwined.png terrain-intertwined-big.png
Now you have 9 tiled images, so go ahead and create 9 regions and load the images for each one. I started with a fresh instance of Opensim to create the first region, then shut down and created the Regions.ini file manually for the remaining 8 regions. You can see them inworld by searching for Intertwined but that sim will likely not be online after June 31 so here's a pic from the map:
intertwined_map.png [ 252.13 KiB | Viewed 479 times ]
and here's a pic inworld, right at the corner junction where 4 regions meet, where a cube sits - the borders are pretty much undetectable:
intertwined_inworld.png [ 368.97 KiB | Viewed 479 times ]
You can go see for yourself while it's still up:https://login.osgrid.org/region/Intertwined-NE/2/2/23