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Cannot create site model from 3D polylines

Daisy Z


Hi there, 


I've been really struggling with creating a site model on VW Architect 2020 from some contour lines that I received in dwg format. They came in 3D, and I have also tried flattening them and creating a site model from 2D (AEC>Terrain>Site Model from Source Data). Neither works - the product is a red square with a cross in it, nothing is generated. I've tried playing around with the parameters of the Site Model Settings, checked that there's no conflicts in the lines and also tried doing the same thing in VW 2018 - same result. If anyone is able to give me some suggestions that would be much appreciated!! I've linked the file here





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Sometimes you get good 3d data from a survey. Sometimes you even get a Site Model. But not usually. In that case, see below... 


There are a few steps in this process. To ensure success I have learned the hard way to:

1) Start with 2d Polygons. Make sure to verify that each (2d) contour is a continuous Polygon. Data from surveys is notoriously bad at this. I generally go through and visually/manually check each and every contour. I make sure that any unconnected segments are exactly coincident at their respective ends and use the Compose command to merge/join them. Also important that there are no "loops" or overlapping double backs. This will mess up a Site Model. I sometimes find it faster to trace over (in a new Design Layer) the contours on a survey (realizing that EXACT tracing is not actually possible, I accept that this introduces small errors, which in general do not amount to more than 3 or 4" which is within my tolerable limit; can be solved at the site IRL). Sometimes you need to trace anyway, if for example all you have is a PDF... 

2) Select all of the (verified!) 2d Polygons and Copy. Create a new Design Layer and Paste In Place, thereby preserving the original data, and aligning the new copies with it.

3) In the new Layer, select all the 2d Polygons and run command "Modify>Convert to 3d Polygons".

4) Select one 3d polygon at a time and assign a Z value to it (note there is a somewhat automated way to do this, but unless your original polygons were created in the EXACT order - lower to higher or visa versa- this procedure can get royally cocked up - See command "AEC>2d Polys to 3d Source Data")

5) Double check step 4. No really!

6) Optional, but highly advised: Select the 3d Polygons and run "AEC>Terrain>Simplify 3d Polys". Use a reasonable number, eg: 24". This command will result in a Group of 3d Polygons. You can and should visually compare these to their unsimplified parents. If they are not too divergent they should be fine. Again, this does introduce a bit of slop. But in lowering the vertex count in each polygon your Site Model will behave astoundingly better later on. (You can also compare the vertex count in any of the parent/offspring polys. This is telling!)

7) Usually on another new Design Layer, Paste In Place the group of simplified 3d Polygons. Ungroup them.

😎Select all the simplified 3d Polygons and run command "AEC>Terrain>Site Model from Source Data"


Depending on the size and complexity of the site this process can be time consuming. But in my opinion it's worth every minute (or hour!) in the long run.


Now you have a Site Model. Perhaps later I'll write another how-to on all the awesome things you can do with it.

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