Thanks again for the reply yesterday, Ryan. I’ve been trying to understand better how all this works, and so today I made a test map and tried a few things as sort of control experiments. I used L3DT to create a 2048 x 2048 height map and then added a few features to it with known heights using a resolution of 1m, but leaving the majority of it flat. I exported the map as .r16 resizing it to 2017 x 2017 in the process, and then imported this heightmap into a new project in UE4 using the default component setup and leaving the coordinate scale at the default of 100 for all three axes.
First, as a quick side note, I explored your statements about the world size, and was able to position actors at +/- 1000000 uu with no problems. I found that interesting as I have read various figures. Some of that is probably based on older versions. However at the moment I am interested in terrain and the landscape system, and specifically how it treats vertical scale, so I did not explore this any further.
In this image I am displaying the imported landscape in wireframe mode. The highlighted box brush (1m cube) has been positioned centered on the base landscape level and then scaled x 2016 in the x direction. It exactly matches the dimension of the landscape, which pegs it at 2016 meters, which is what I would expect. However the base landscape level, which was set at 0m in L3DT, has been imported at z = -21834 in UE4.
The feature you can see in this image was created with 1m layers in L3DT. The highlighted box brush is a 1m cube that has been scaled in the z direction until it more or less matched the height of the first terrace. As you can see that resulted in a z scale factor of 45 for the brush. So the height of terrain features when the landscape actor has a z scale of 100 appears to be 45x the scale of the same features in L3DT. I placed another 1m cube next to the scaled up brush for reference to show what the height of the feature should be if the same scale was in use in both programs.
Lastly, as another test I set the z scale factor of the landscape actor to 0. At this scale factor the landscape base level is located at roughly z = -218, which makes a sort of mathematical sense in that it is 1/100 of the location at z scale = 100 (-21834 as mentioned above). In the image I have a brush that is 10m in the z direction located inside a feature that should be 10 meters in the L3DT scale, but with the landscape actor z scale factor set to 0 it now appears to be approximately 5m in height. This is also near enough to 1/100 the value at z scale factor == 100.
So I guess I have two main questions:
In the editor, for landscape actors, how is the z coordinate scaling factor applied to a height map on import? Is the height map value multiplied by the scaling factor (and assuming my setting it to 0 defaulted it to 1 internally)?
When a height map is imported what is the uu value of a unit increment in a height value? In L3DT for example I am working with a scale of 1 unit of height == 1m. I know in UE4 one uu == 1 cm. However it doesn’t appear to be that simple with landscape height.
Thanks again for your help.