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Site Model Issues


benboggs

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Hello - We have a survey of a large high school site. The site is very long and skinny, lots of topo change. I have been trying to compose a site model for the site. However the model does not clip to the site boundary that I have drawn. What it does is it connects contour lines and generates its own boundary. The blue lines are the existing topo lines to my generated grade limits. However the green lines are the automatic connected topo lines. I do not want the site model to automatically connect lines.

What I have done is take the survey CAD poly lines and generated a site model from those.

Also - when I go to change the site model crop - the crop moves/manipulates the original survey contour lines. You can see as the contour labels from the survey are not in line with the VW generated survey contours. Why would a site model crop move the survey contour lines?

I have watched many tutorials - but most are of square sites and not large complex sites.

Thanks

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  • 4 weeks later...

I wanted to give an update (thanks Robert for your time yesterday on the phone). My experience so far has seen that when just using the autocad polylines to make a site model - VWs will take some liberties and truncate some of the swales, ridges etc. Roberts suggested I use the DTM file from the surveyor. It worked and the contours are almost (very few minor/insignificant differences) identical to that of the survey.

however I am still curious as to why the VWs generated site model - when using jsut CAD 3d polylines - will not mimic the CAD contours perfectly?

Thanks for all of the help from everyone who has commented.

Ben

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Another technique for problem contours:

Use Duplicate Along Path to create a bunch of evenly spaced 3d loci along each contour. Choose a repetition about equal to the minor contour separation. Then create the site model from the loci.

If starting with 2d contour polylines, adjust the z of the loci to the value of the contour elevation. If starting with 3d contours at correct z, then the new loci will be created at correct z.

It's probably best to place the loci on their own separate layer.

Select all the loci (but not the contour polys) and create the site model.

-B

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