Other Possible Height Map Tools
There are even some editors for other (non-fps) games that can be used to manipulate a surface in 3D and then output a .bmp format file. It is worth noting that we found it particularly challenging to use them … possibly more challenging than the benefits of working in 3D.
SC3K Map Editor
The first of these programs was a terrain editor for SimCity3000 called the SC3K Map Editor from Tenermerx. It is a free download available here: sc3maped
The other editor we tried was the “Loathing” terrain editor that comes with Bungie’s Myth II game. If you’ve a copy of Myth II, this is something you could play around with. Both of these programs could output a .bmp format file. If you’ve used it to make some Myth II maps you may have some idea of how it works already. It is my opinion that if you use an editor for either of these two games to create your height map, you may still want to or need to manipulate it in an art program. If you can visualize the relationship between shades of gray and relative heights and slopes, the art program is probably the easier way to go.
Pencils, paintbrushes and a scanner
You can also make your heightmap by painting it by traditional methods and then scanning in the file and saving it as a .bmp. Though at some point you’ll probably want to switch over to digital manipulation.