Height Maps
As my environment is a city, I wanted to use a city height map and have buildings and skyscrapers surrounding the environment. I searched for a city height map and found this image (above) of a real city. However, when I tried to use this height map, it ended up very spike-y as all the white / light grey areas turned into huge spikes. As there is a lot of detail in this image, the peaks and troughs were very varied in close proximity to each other and looked messy. It would have taken a lot of sculpting to make that into a usable landscape.
I then tried to use a simpler city height map, so I used this image (above)
This (above) was the result. It worked a lot better than my first height map attempt, but still didn't look right, they didn't look too much like buildings and would have taken a lot of time sculpting, deleting, re-arranging and scaling to look right.
After trying a couple of city height maps, I tried a mountain terrain height map, made from mixing a few images together in photoshop and making the image greyscale so it could be used as a height map. The image below was the result in Unreal. I think this looks much better than the attempts with the city heightmaps - after sculpting and painting this it would look like a believable mountain range.
For my environment, I think I am not going to have a height map, as I am happy how it looks without one, and I don't want the surrounding area to be mountains.