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pasha_shknai

Issue with Site Model from an Imported DWG

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Hey everyone! I am a new member of Vectorworks.

I watched the lesson on

(from your channel) and wanted to repeat, but it was not easy.

I prepared a flat drawing of the site in AutoCad in scale 1:1000, after imported to Vectorworks 2016, chosed "2D" and my scale. When I tried to do "Survey Input" - "2D Polys to 3D Contours" I received a message "No 2D polygons found in this layer. Be sure 2D polygons are present and try again. (I want to notices that I try with 4 different drawing: with closed and open counter, in 2D and 3D (made by Autocad). All the time was the same message, but with 3d drawing of the place I received :"There was no valid 3D data selected to user for the Site Model source data. ...."

Please, could you convert my drawing to 3d relief and explain it how to do. I have no idea.

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Your drawings from Autocad appear to be PolyLINES not PolyGONS.

There is a major difference in VW.

As curvy as the contours are, I hesitate to recommend the Convert to Polygons command. While it will probably work, I think it will give you very complicated polygons and likely be very slow.

At this point I have to back off and let someone more familiar that I suggest how best to proceed.

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I imported #2 and #3 in vwx2016. With import option as all 3d:

#2 came in as polylines. Many of them are in several segments. Select All and Compose if this flattened version is needed.

#3 imported as NURBS curves with z values. This is the one to use for site model creation. Again, several contours were in segments, so Select All, then Modify>Compose. I do not know original units so no advice there. Suggest import as 1:1.

Anyway, after Compose (see above), create the Site Model as follows:

Select All (= 55 NURBS curves with various z values).

•Modify>Convert>Convert to 3d Polygons Edit: (=191 3d Polygons with various z values)

•Turns out the conversion segmented some of these 3d polys.

•They need Modify>Compose (=55 3d polys)

•Keep everything selected, then AEC>Terrain>Create Site Model. Accept the defaults.

Use OIP Site Model Settings to adjust the contour spacing etc.

Makes a nicely contoured terrain.

-B

Edited by Benson Shaw

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Benson,

Don't know that I have ever gotten a NURBS drawing in ACAD. Is that common? Most of mine come in as 2D polygons or 3D polygons.

Whether polygons or nurbs, can you select all and compose, or do you have to select each individual contour?

No one above mentioned the "Simplify 3D polygon" tool which is great for reducing the number of vertices.

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Rossford, anyone, did you import those dwg files? Did the #3 dwg import as NURBS contours?

I was surprised by the NURBS, too, when importing the #3 dwg. I thought it very unusual. Maybe something in my import settings? All 3d? Anyway, I welcomed that they had z values.

I selected a few single contours and noticed that some were segmented. So, yes, select all and compose. All the segmented contours joined in one go. The unsegmented contours were not affected. Composing dropped the object count from 191 to 55.

The site model seemed responsive in Wire Frame and Open GL so I didn't look at vertex count. But yes Simplify Poly is definitely a good way to cut down the number of points.

-B

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Your drawings from Autocad appear to be PolyLINES not PolyGONS.

There is a major difference in VW.

As curvy as the contours are, I hesitate to recommend the Convert to Polygons command. While it will probably work, I think it will give you very complicated polygons and likely be very slow.

At this point I have to back off and let someone more familiar that I suggest how best to proceed.

Actually, the lines are not polylines but Splines, which are similar to bezier curves. (polyines in AutoCAD are created by using the pline command, they can be smoothed afterwards and then become splines. Splines are created by using the spline command)

Because these splines are also 3D they are imported as NURBS.

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Benson,

Don't know that I have ever gotten a NURBS drawing in ACAD. Is that common? Most of mine come in as 2D polygons or 3D polygons.

Whether polygons or nurbs, can you select all and compose, or do you have to select each individual contour?

No one above mentioned the "Simplify 3D polygon" tool which is great for reducing the number of vertices.

It depends, in AutoCAD you have two 2D polyline commands

- pline; which generates 2d polylines that can consist of straight line segments and/or arcs. These can be converted into splines afterwards if needed.

- spline (smooth polyline); the equivalvent of bezier curve polylines in VW.

Then there is the 3Dpoly for 3d polylines/polygons.

3D splines are basically similar to NURBS in Vectorworks, but 3D in AutoCAD is either solid or mesh, I'm not sure if there is such a thing as a NURBS surface in AutoCAD, though I do most of my 3D in Vectorworks now so I'm not 100% sure about NURBS in AutoCAD without looking up.

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I imported #2 and #3 in vwx2016. With import option as all 3d:

[...]

Use OIP Site Model Settings to adjust the contour spacing etc.

Makes a nicely contoured terrain.

-B

I got similar results, though I converted the 3D NURBS to 3D polygons first and then did a compose though the end result is most likely the same.

Except that I noticed that if you select to show 3D contours and have the site model displayed as a 3D mesh it shows some merged areas based on the shown contours. When you overlay the original contours than some loops were cut off based on those contours and some were merged so I would thoroughly check the site model for any of the critical areas to find out if that happened or not.

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I wonder if the NURBS result from something new in vwx2016, or from something in the source ACad file. It's fine with me either way.

I hope VWX engineers are solving that problem of clipped site model contours when the source contours are tightly curved. I workaround by adding to the source data a few interpolated 3d vertices or short 3d polys between the contours in the clipped areas.

@ArtV - In another thread you suggest acquiring source contours from GIS software. Does that eliminate or at least reduce the clipped contours? Or is that advantageous in other ways?

My GIS experience is limited and only with QGIS (but I sent them a donation!) plus a bit of Vectorworks georeferencing capabilities so these are newbie questions: Aren't GIS contours georeferenced and therefore distorted from the usual orthographic plan view in Vectorworks? Do the GIS contours need to be converted to a specific projection or reference system prior to use in the site model?

-B

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Regarding the NURBS result, I just did a quick test.

A DWG file with two splines, one having an elevation (Z-value) of 3 and one with no elevation assigned was imported into Vectorworks 2016 and 2015.

When imported with the 2D and 3D setting, both lines got imported as 2D polylines, when imported with the All 3D setting both lines got imported as NURBS. If there was something new to cause the NURBS it was already introduced in 2015.

Regarding using GIS software to create contours... most GIS software use polylines/polygons by default, especially when exporting to Shape files. Going this route may avoid clipping/jaggy contours from any conversion to polygons/3D polygons and the subsequent need to reduce the number of control points with again possible "overcompensation"/clipping of the contour.

In the other thread it was not clear how the original contours were generated, but GIS software can possibly do a better job in generating (more usable) contours than either Vectorworks or manual drafting.

Regarding projection, yes GIS contours are georeferenced. Unless I am mistaken Vectorworks files are basically georeferenced too using plate carree projection as default, so if you would use that as the projection in your GIS software and then export as shape file and also import a dwg with the same contours (and align the dwg import to the internal origin) then they should overlap. (Assuming you are using correct units for both)

In my case whenever I need a site model then the document I am using it for is georeferenced anyway so for me it is sort of a non-issue.

Edited by Art V

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I have been told that VW works faster if the origin of the drawing is 0-0, not thousands/millions of miles away. So, even when I have geo reference, I don't use it, at the moment.

Will use the next project I get with GIS to experiment a bit.

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Yes, in theory Vectorworks works faster if the drawing is close® to 0,0 (as internal origin.)

In reality you will not notice much of a slow down for Vectorworks itself if it is at georeferenced coordinates (e.g. in UTM coordinate system this is around 500km east of the origin and up to a few thousand kilometers north of the origin).

Only when you are having tons of objects or large 3D models at coordinates you may start to notice a slowdown.

The one slowdown you may notice is that you may end up on the page area and then have to move back to the actual drawing, so it would be a good idea to create a saved view for that.

Also, when working with georeferenced drawings, please leave all origins and the page area at the internal origin of the document. It will save you from headaches in the long run.

That being said, one advice that you should preferably stick to no matter what ... if you have to work at coordinates and they are georeferenced then by all means use that georeference and do not move the drawing to 0,0 as this may introduce all kinds of errors which you don't want if accuracy is important.

For example, the UTM zones are 6 degrees in longitude wide, with the central meridian in the middle of the zone. Because of the projection, the further away you get from the central meridian the more distortion there will be. Moving the drawing closer to the internal origin will get you in that distorted area and upon reprojection things may start to look different from what you intended.

So either don't use georeference at all or stick to it and work at proper coordinates.

If you need to do a transformation (conversion) from one projected coordinate system into another, consult a geodesist for the proper conversion if possible or have it checked by a geodesist just to be sure. (the best way would be to have the client supply the data in the proper format so that is is their responsibility to get it right). There is often more than one way to do a transformation and you definitely don't want to use the wrong one.

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