AutoCAD export of surfaces produces 2D data

[AussieHans]

When exporting to AutoCAD, surfaces set up to display contours and triangles by the surface style settings create polylines for the contours, and 3D faces for the triangles. Problem is all elevations are zero. Many of our clients use the 3D faces to recreate the surface in their software. Now a 3D face with zero elevation vertices is as useful as a bicycle is for a fish. Exploding the surface before exporting to AutoCAD creates proper 3D primitives, and exporting to AutoCAD then produces polylines and 3D faces with the proper elevations. I did my export, and then closed AutoCAD, stupidly saying yes to the “Do you want to save changes” prompt, and my own surface was history. So now I copy the drawing first, and load the copy before going in with the little red dynamite stick.

Just wondering about the logic behind this 2D resolving of the surface to polylines and 3D faces.

[apweng]

The export to AutoCAD function "explodes" CD objects to their native entities and does nothing to existing AutoCAD entities in the drawing.

If you orbit your C3D drawing to a 3D view (anything other than plan view), and then export the surface, you'll find that the resulting AutoCAD polylines have a Z elevation assigned.

The other challenge with this command is the destination layer assignments. Style configuration affects destination layers and you don't necessarily get what you'd expect.

This becomes difficult when trying to deliver drawings to clients who will not accept a CD drawing.

Andrew

[AussieHans]

Thanks, I'll try the 3D orbit thing.

Yes, we also have clients that won't accept out Civil3D 2007 drawings, they are running 2006, their headoffice has directed them to give 2007 a miss and wait for 2008. Anything I export directly to 2004 comes out ratshit, I export to 2007 and then save that file as 2004.
If a drawing has more than one layout/viewport, I'm often sorely tempted to issue an export for every layout to try to explain that they are in fact receiving "degraded" data compared to a Civil3D file.

[dana.probert]

if you make your view just slightly non-plan- do a 3d orbit or isometric, it does hold the 3d element on export to autocad.

could you also give them a landxml file along with the dwg? that way, they can recreate your suface literally?

[AussieHans]

I've considered that, I get the impression that Landxml exports only export the objects and none of the associated styles, so my presentation of contours, contour labelling etc all goes missing. Same as with parcels: The segment labels don't come through, spanned labels (for what they are worth), the parcels segments are constructed differently. Unless I’m doing something wrong. What I have done too is send pdf files along as well so the client could visualize the "real thing" at least.

Will Civil3D objects be portable between 2007 and 2008? This object incompatibility is a real headache, I can understand there needs to be progress, but we are in a somewhat wicked situation where nobody (clients) has any use for our 2007 Civil3D data, this is over 10 months after the release.

[Sinc]

I tried doing this - switching to FRONT view and doing the export - and the export retained the Z-value, but it flattened everything into the X-Z plane instead! This is utterly ridiculous.

So what's the deal, the view has to be set to something that isn't a "Top", "Front", "Back", etc., view? It has to be something skew?

Autodesk seems to have done a much better job this year as far as releasing software that doesn't crash so much. Last year's release was pretty pathetic in this regard. But it looks like the big issue now is going to be the complete lack of interoperability. It should not be this difficult to share data created in Civil-3D.