Extract roof form tool creating triangle buildings?

Adam_Jones

So I'm attempting to use the extract roof form tool to create a 3d model of a small city.  When I run this tool, my buildings look like triangles as shown (the extruded buildings are light gray and the original footprints are lavender).  I'm following the exact steps in the Portland tutorial.  Also, if it's relevant, all buildings are returning with a flat roof in this analysis.  Thanks so much!

LeeBrinton

Hi Jill,

Are you using the Local Government 3D Basemap tools? If so, I think the first issue is that your XY unit might be in meters, and the tool set assumes foot. If this is the case you will need to set any of the parameters that are based on area or cell size to reflect that. For example, one of the tools for calculating roof form asks for a "Minimum Flat Roof Area" this is 250 by default. If your XY units are in meters then you want this value to be closer to 23. The same can be said for the other parameters in this step for i.e. "Min Slope Roof Area". Also watch out for the vertical units, if your Z units are meters or feet you might need to do a similar conversion. 

The second possible issue you could be seeing, and I am only speculating. Are you extruding the footprints to a Z value before you run the "3D Enable Buildings" step? If so then I think you would run into a weird issue where the rule package that's assigned could be confused because it assumes a flat polygon as the input. 

All of this is based on my assumption that you're using the Local Gov 3D Basemap solution. If you're using another toolset just let me know. 

LB