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site model

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I followed Peter Cipes' excelent description of how to create a site model in his answer to Edward Williams query. In the exercise he gave it worked perfectly. When I tried to apply the same procedure to a DWG file it did not work. The first indication I had it wasn't working was in step 5.

5) Run the menu command AEC/SURVEY INPUT/2d POLY'S to 3d CONTOURS. You will be given some choices in the dialog. Set the contour interval at 24" (2ft) then click NEXT at each highlighted Polygon. When finished you will be asked if you want to keep the originals. In this case (for demonstration) choose NO.

I set the contour interval in the dialog box and click next and it takes me back to the contour map with the contours deselected. The elevation never shows up in the Object Info pallet.

How do I fix this?

Thank you,

Ed

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Ed, DWG files are only as good as the person (and/or software) who did the original drafting. Often there may be either discontinuous, overlapping or otherwise 'unusable' polylines. Therefore I recommend that the contours be traced over, in order (from lowest to highest elevation) and then the new (traced) polylines/polygons be used.

Another option is to check and then copy and paste-in-place each polyline/polygon (again in order).

In either case you need to make sure you are dealing with clean and orderly data. Also, if the original contour lines are "polylines" they must first be selected and "Convert(ed) to Polygons" prior to running the "2d Poly's to 3d Contours" command.

Hope that helps...

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I have run into some issues with DWG contours that were exported from ACAD civil or LDD. I don't think Vectorworks translates the 3D polylines very well. Depending on how they were exported from ACAD the contours are sometimes a proxy object. When it is exploded the contours do some funky stuff. I usually check out the files I get from surveyors in AutoCAD to clean up any issues with contours before importing into VW.

As Peter said, tracing the contours is the best way to get a good result but on large areas it can be a pain. If you have Autocad you can try to convert the contours to 2D polylines or have the person who is sending you the files convert them. I found that Arch desktop handles the contours from Civil or LDD fairly well compared to vanilla ACAD or ACAD lite.

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In the survey dwg I receive there are 3 NS classes:

(after importing to VW)

NS - which are 3D loci,

NS_contours - which are 2D polys,

NS_triangles - which are 3D polys.

I select either the 3D loci or 3D polys and create a site model

without tracing anything works everytime.

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Mar, you have a very good surveyor ;-) You are lucky! Most drafts-people are, shall we say, not perfect...

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Thanks Peter,

I trace the contour lines with the Polyline tool. Convert to polygons. Choose AEC/SURVEY INPUT/2d POLY'S to 3d CONTOURS and then an Interval of 12" with Create 3D Polygons selected. Click OK. When the set elevation window comes up the only first contour line is supposed to be active and I have a choice to select Up or Down and then a choice of Done or Next. That should happen for each line.

At the point the set elevation window comes up I lose it. The survey map gets really big and all the lines are deselected. That is as far as I can get with my DWG file.

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I have always found this tracing a bit tedious so an other trick is

(I think it was Archoncads) instead of tracing, place a number of

3D loci (correct height of course) along 2D contours select & create site model.

I thought autocad people where quite rigid and standardized

meaning USA = AUS

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That's a good tip about 3d loci. And no, there is (at least in my experience) a whole lot of variation. All the way from very standard and consistent to very very sloppy...

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I have had a problem with the 3D Loci not translating well from some sources. When I import a survey dwg vectorWorks says that some objects will be deleted so try another option. Each option gives me a different warning that something will be deleted.

Sometimes I get the contours but no point data and I have to explode the contours and rejoin them. Sometimes I get the point data but have to fiddle with them to be able to use them.

I know it has to do with how the original survey DWG was saved and what program was used. The surveyors I deal with are usually using Civil 3D or LDD. Is there a preferred method of exporting those files for Vectorworks to import them cleanly?

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Try importing just the basic survey datum, and then use VW to generate the 'clean' DTM.

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Thank you for the hot tips. Tracing the contours with polylines and copying and pasting into a new document is working. You are all what makes this such a valuable forum.

Ed

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