HexGimp Terrain
Below is a legend for the terrain I am using in hexGimp.
Cold
This terrain occurs in high degrees of latitude (typical 55 ° North or South) or at high altitudes depending upon your latitude. This terrain can also occur via magic or terraforming.
Dead
This terrain occurs where the environment has been destroyed by extreme events: Magic, Radiation, Pollution.
Dry
This terrain usually occurs in several places on maps. Rain Shadow lands or terrain that occurs between 30° to 35° North and South . Certain species could also cause a desert to occur (in addition to or instead of dead terrain). My own additions are as follows:
Glass Sea Terrain: (inspired by the Desert of Desolation Glass Sea) - a land where the sand has all be heated at high temperatures forming jagged glass terrain
Purple Sands Terrain: When I was creating the Glass Sea Terrain I saw came across this color scheme which I though looked interesting. It could be radioactive sands, or Spice (from Dune) or something magical.
Forest
Forest terrain occurs where there is plenty of rainfall and the soils allows for good drainage. In my usage I prefer to use the forest types as appropriate to the forest type and not whether it is an evergreen or deciduous. My main turning point was seeing that in the Southern United States and along the Western Coast there are stands of majorly Conifer forests where I had thought there would primarily be only Decidious trees. I also renamed Jungle to be Tropical Forests as I cannot get a good definition of Jungle but there are a lot of definitions for Tropical Forest. I did not break out my terrain for Tropical Forest into Wet/Dry but I may create that distinction at a later date. At this point my main distinction between Regular Tropical Forest and Light Tropical Forest is how many canopy layers I believe the forest would have.
Grasslands
This terrain usually occurs where there is more rainfall than a desert but not enough to create a forest. In my maps I often use choice grazing land because I like the visual over grassland. Another difference for my maps is I have removed most of the Light Forest terrains in place of Savannah terrain. This is another instance where I like the visual better and the name fits the terrain better.
Hills
This terrain occurs where the ground has minor to decent changes in elevation. The terrain usually resembles the terrain next to it, though if the hills are drastic enough "Rugged Hills" may be a better option if Mountain terrain seems too extreme. In older BECMI there is only one kind of hill terrain ("Rugged") I like having different options for the hills now as it makes it easier to determine what the party will encounter/see as they adventure.
Terrace Farms is a work in progress. The art is a little rough on it and I want to try a few more options to see if I can make it look more appropriate.
Mountains
This terrain occurs where there is extreme changes in height. If several of these hexes are near one another it can cause the terrain to change climate. Broadleafs forests will thing out into Conifer Forests into snowy topped mountains. One oddity I did discover in the Southwest United states is that mountain terrain will become more covered in vegetation as one ascends to a certain point. The reason for this is water will condense better at the higher altitudes.
The background for snowy mountains being white or brown for me is determined by how long the landscape is snowy. If it's over seventy five percent of the year then I think a white background feels more appropriate.
Seas & Ocean
This terrain represent the ocean. For most of my maps I usually don't use these hexes as hexes. I use the colors then free draw the water to represent the coastlines in a more natural manner.
Underground
Field Moss
These terrain occur underground primarily. It might be possible for the Fungal Forests and Swamp to appear above the surface but the other terrain are best represented by surface terrains. When I map walls for the underground I almost never use the "Solid Rock Textured" option. I've experimented with making it a pattern and what not but have not had any luck in it's use.
Wetlands
This terrain occurs where there is too much water for the land to drain. It frequently occurs on the coast, at the end of rivers or between hills and mountains. I have hyperlinked the definition of the above to better explain each type of terrain but in a nutshell here is a quick breakdown:
Bogs and Fens are both mires. Both accumulate peat. One of the main differences is in the acidity of the soil. For my maps I distinguish the two by having Bogs supporting Forests and Fens supporting Grasslands. (I may change this as I do more research and just combine the two terrains into one).
Marshes for use in my maps represent wetlands that do not have a lot of trees, mainly grassy plants that thrive on water.
Swamps are used in my maps to represent areas that are forested but also very wet.
Mud Bogs came from a Mystara fan map. The only article on Wikipedia I see about mud bogs is something called mud bogging. At some point I'll review if I need this or can retire the terrain from my brushes.
Miscellaneous
The Blank hex is used by HexGimp to create the white background for starting hex maps. Lava is used in situations where lava pools form. I don't normally use this as a hex but as a color selector to represent lava pools.