Hi Aaron, I'm currently looking at the ME-DEM workflow and I'm attempting to work through the entire process of importing the base DEM and then replacing it in the modelling apps. Consequently I've had a few insights as to what would be useful specifically for ME-DEM, but I also think for a lot of other terrain modellers out there, looking to build large terrains that 'make sense'.
Among other thngs, the upcoming article will compare the relative speeds and terrains of L3DT, Wilbur and Leveller. GeoControl will also be thrown into the mix, though not as a complete solution yet.
I'm not going to be able to build the terrain in each app- (1 4K terrain is quite enough!) so I've opted to time-test the building of the mountain range only.
Apart from time considerations I'm not able to use L3DT or Leveller to illustrate base dem import and remodelling because I don't feel there are really the heightmap tools in place yet. It's possible to use these apps but there are currently other more efficient methods (as covered in the article).
The base DEM is extremely useful and I'm now very glad that we chose to go down that path. It basically avoids the problem that a lot of large hand-modelled terrains have: of an essentially flat landscape interspersed with hills and mountains. In ME-DEM's workflow, it's possible to make every pixel contribute to a coherent terrain over continent scale.
I've divided the terrain modelling into 3 parts based on scale: macro, meso, micro.
Macro is really where all the important stuff happens (for large terrains) and which most terrain apps are not really good at. The general flow of the land, governed mainly by the larger rivers. How to use the base DEM? I think the only way to work with it is to completely replace it during our phase 2.
There's only one real solution to this imo and that's contours and contour interpolation or the equivalents. If there was any way to introduce this into L3DT it would triple it’s usefulness at a stroke.
In L3DT we have the DM generated from the imported base DEM and contours in the heightmap generation or the heightmap prev. One immediate help would be to have those contours visible over the Design Map. With this it would be possible to quickly and accurately re-model large areas through the DM. Perhaps only the contour pixels too, rather than a complete overlay if you see what I mean.
Another way to achieve contours is simply by select area> set to height, but contour drawing- ie a pencil rather than arbitrary select, etc, are more intuitive imo. Perhaps a Heightmap pencil? or a DM pencil with sub-pixel res for drawing contours which snapped to the DM pixels on inflation to the heightmap?
You could introduce the abilty to cycle between the DM and heightmap within L3DT:import heightmap> generate DM> draw contours on heightmap> generate DM > alter the DM with the DM pencil > generate heightmap, etc. The abilty to define how the new info is incorporated into the existing info would also be handy; replace, add especially.
When altering large areas, if arbitrary selections are not possible, better visibilty for the pixels being altered by the DM pencil in the current pass: maybe set those red until another operation is preformed.
Coupled with the ability to draw/use contours is the real advantage of having a tool which can select from a heightmap by height range: ie select between 899-900m would give a selection on screen defining the 900m contour. With this selection still in place, it would be great to be able to draw a contour which developed this ‘proto-contour' to add more detail or make corrections, etc. For ME-DEM, this avoids the complication of having to import yet another layer: ie dem and contour info. Simply extract the contour info from the dem. The operation has to allow the simultaneous selection and contour or DM drawing though to be useful.
Imo, the two most useful things would be 3D prev and the contours (visibilty/draw/select by height). The pencil current edit visibilty is another must as well, try keeping track of a sea of DM pixels altered by 100m with an image overlay in place...ouch!
I realise you're busy so just some thoughts for the future thrown in. If I have any more I'll pipe up
Cheers,
monks