Section a 3D wireframe (landscape contours)

OK - I have a 3D site survey that I suspect has come from an application specific piece of software (Map or something).

It's mainly comprised of 3D polylines and blocks, with a few lines, arcs etc thrown in.

I need to be able to draw out 2D ground level sections. How in the name of all that's holy can I section a wireframe? In reality what I want is really to end up with a series of points/nodes that retain generic properties (layer, colour etc) so I can draw the lines between them.

I know I can mesh it up but that will take a lot of time I don't have, plus the drawing will need a bit of touch up work before I can easily mesh.

I attach the dwg in question so please have a look for yourself - there is a UCS saved for the section origin and a solid box drawn where I basically want the section. I would be happy enough if I could get the pointer to snap to where the lines intersect the solid box surface.

Anyone?

(ah well, back to the drawing board...)

...ahem...

I've only just realised the 250kb limit so I've had to trim the drawing right down to very basics but you still be able to see what I mean.

Doove - 3D Wireframe Site Survey.dwg

This Lisp was on the Forum some time ago. You need to draw a polyline where you want the section profile.

QuickProfile.LSP

have you tried the section command? i dont know if it work on anything but solids but its worth a try.

This Lisp was on the Forum some time ago. You need to draw a polyline where you want the section profile.

Been away from this for a while just drawing the sections in by hand.

I tried the quickprofile.lsp but I'm having trouble getting it to work, I've drawn a polyline but it returns a message saying error; numberp = nil.

Does the polyline need to intersect the contours? If it does there really is no point to using the lisp as I'll have the ground level in section from the polyline I just drew? - in reality I don't know what the lisp is trying to do, I don't know lisp or programming very well. (any advice on a good book on autolisp would be appreciated as well!).

cheers

have you tried the section command? i dont know if it work on anything but solids but its worth a try.

sorry shift meant to mention that no, the section commands don't work on wireframes.

Worse - the flatten command doesn't work on 3D polylines and when I tried to convert them to other objects I started losing geometry. Bit of ****** really.

I tried the quickprofile.lsp but I'm having trouble getting it to work, I've drawn a polyline but it returns a message saying error; numberp = nil.

Just had another look at your drawing and it doesn't seem to be drawn in a conventional manner, that is with the plan in the X-Y plane and the elevations in the Z plane. Perhaps the lisp is getting its x, y, z in a tangle, and doesn't know which way is up. The alignment polyline does have to intersect contours in the x, y plane, then it seeks out the z value of the intersection. So it would seem that your layout has defeated the Lisp

The drawing is drawn with the plan in the x-y plane when the UCS is set to World. I've just tried drawing a polyline at z=0 along the section I'd want (parallel to the solid object) then running the lisp again; I'm assuming from your post that the lisp will return the x,y,z coords of the x,y intersection points of the polyline and contours.

Didn't work though. Do you think it could be because the countours are drawn as 3D Polylines?

I'll have a go after converting them to something else.

Thanks for your help though, really appreciated.

I was just confused with the multi-coloured UCS icon - I am not used to seeing that

However, I managed to get the drawing with the ucs icon in the more conventional aspect, loaded up QuickProfile, followed the prompts and this was produced. I did not bother to put all your contours on one layer, so the section was produced only using layer S_CONN.

Perhaps it doesn't work for your version of AutoCAD. It also has a nasty habit of leaving the system variable EDGEMODE as 1 instead of the usual 0.

Just about to get back to you, SUCCESS!

You were spot on, I set my UCS to plan parallel with the section I wanted and drew a z=0 polyline.

Then I returned the UCS to world and ran quickprofile and it worked purrrfectly.

Ah... the joy of conquest:twisted: ...

can't thank you enough for that, I hope you win the lottery.

cheers

Doove.