Aligning Road Graphs to Terrain, Part 2

First of all, I have just upgraded to CItyEngine 2017 and I like it. The interface is less complicated and it takes fewer moves to do work. At least that’s my initial reaction.

Getting DEM raster data into your CityEngine model? No problem: File > Import > CityEngine Layers > Terrain Import, then select your raster as your Heightmap and either the same file or a georeferenced photo or map as your tTexture file. I’m using the grayscale raster for now.

Imagine my surprise when I imported a 2m Digital Elevation Map (DEM) from LiDAR and saw the monstrosity in the figure below. What the heck is that ?  Look at the Minimum and Maximum elevations in the blue circle: 27375 to 38902 meters? That’s an elevation range of 89813 to 127631 feet, which would make an SR-71 Blackbird go “…damn”. Using the raster calculator in ArcMap and multiplying by 0.01 fixed the issue. 273.75 to 389.02 meters or 898 to 1276 feet. Yeah. That’s better. Now I could cleanly import the elevation data and my roadway centerline shapefile (File > Import > CityEngine Layers > Shapefile Import).

The results of using the “Align Graph to Terrain” tool are at the top of the page. Using an offset of 1 meter, no segments of my roadways ended up below grade and I’ll worry about the “floating” appearance later.. I did have to clean up some geometry in the graph with the Cleanup Streets tool. My first modeling attempt on terrain has started off well.



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