polylines and 3D

Hello everyone I'm new here. I have questions all the time and I figured this would be the best place to get answers.

Ok I'm trying to do a ground survey in 3D and of course when the survey comes in autocad it already has 3D values. The only way I can figure to draw it is to use a polyline and connect a few dots, extrude them and then shade. My problem is when I draw the polyline, say triangle, all three points stay at the elevation of the first point. What am I doing wrong? Or how should I be doing it? Thank you.

Normal Polylines can only be drawn at one elevation.

Try using a 3DPolyline. If you want to make a closed polyline, be sure to use the close option instead of drawing the final leg.

depending on how the points are laid out you can do a spline between a bunch of points on the same elevation, and make a surface or loft between them.

Thing that sucks about 3DPoly's is that you can't have any fillets on them.

Fast Learner

Try the PFACE command. Altrough it is for creating surfaces using applications, it can be used manually.

Thank you all very much! I guess I would have found it if I picked my buttons but since I type in all the quick text I was lost at what to do. But thanks again Its coming together nicely now.

here is another thing that may help. make multiple viewports so you can see your drawing from different angles. i just used the 3dpoly command and during your line creation you can select different viewports, just remember your tracking settings.

Ok my next step? Ok if I drew a grid using all the survey points and just the line comand. Is there a way to convert all those lines into 3d polylines? How would I go about that? Now that I know how to get the job done I want to know a fast way to do it. I'm not very good at writing a lisp yet so I need another way.

im not sure if there is a way to do this. If you use a SPLINE it will be a single entity through all your points. If you are using survey lines shouldnt you have measurements with the same elevation? if so or if all your lines are planar you can use the pedit command to join them, but they have to all be in the xy plane.

Perhaps my PEDIT3D.lsp (see http://www.black-cad.de) can help...

Good luck

Jochen

There are a few ways that you can do this in autocad - none of them particularly good. If you have the architecture version of the software you can use the DRAPE tool - This creates a terrain model as an AEC object from any lined object or point with a z-axis. It smoothes everything out and can create very detailed and complex survey models. The drawback on this method is that it doesn't always work accurately and that you cannot delete chunks out the object of it once its created - or if anyone knows how, please tell me!

Another option is 3DFACE which creates a 3d surface anywhere in 3d space with either 3 or 4 sides.

If you have already joined your survey points using the 3DPOLY command you may then only need EDGESURF.

3DMESH also works but its not the most user friendly way of creating a mesh and it often doesn't import into 3ds max properly!