#Acad 3DPline to 3DS
13 messages in this thread
Help! I have Autocad files with rectangles made out of 3D polylines that I
want to export to 3ds for shading etc. However, a polygon made out of a 3D
polyline (even if its joined) does not shade. Anyone have any ideas?
Thanks in advance, Doug.
two replies for the price of one: just try it, they should translate with no
difficulty. even a closed 2d polygon will translate. I could send you a file on
this if you'd like…let me know if so,
regards, gary
Ok ok I get the message (twice!) (g). Thanks Gary – I must be doing something
wrong, because mine don't come in as 3d objects. If you do have something you
can send (you said that you had a file on this?), that would be really
appreciated. Doug.
No problem. I don't know why yours don't come in properly. If you could e-mail
me the acad.dwg I could give it a try myself. I'm sending you the file I
mentioned, ACAD-3DS.doc. It's a windows Word file. If you can't load it let me
know and I'll convert it into a word processing format of your choice. I just
sent the file to Multi-CAD magazine for their publication, so I'd appreciate
your use of it for personal only. I tried all of the entities mentioned in the
article re: proper translation, so as not to put my foot in my mouth, so I'm
pretty sure of my words on this matter.
let me know how it goes….gary
Got you're article a couple of minutes ago – thanks! Looks pretty
comprehensive, and its definitely appreciated. Also, it will _not_ get faxed
immediately around the world… I made quite a discovery last night – I _can_
import 3Dpolylines into 3DS – just not the one generated by my terrain
modeller. After a lot of fooling around I've realized that these are perfect
polygons, but the last vertice is not closed. Which is something that I can
fix with an edit command, but a bit tedious after editing polygon #143,325…
So you will probably see a new message up on the acad forum, looking for
someone that knows of a program (or will write a lisp routine under contract)
which will close all my polygons at one time.
Thanks again for the help Gary.
Doug.
Glad to be of help. I'm curious though, in what way are these polylines 3D? Is
each line planar in itself but in a different plane than the other polylines,
or does the line wander through the 3 axis' like a motion path? There's
probably a routine around for closing a bunch of polylines at once, but you
might not want to if they have endpoints in separated locations. Also, are you
trying to "fill" the inside of these polylines when closed? If not, you could
just extrude them all a bit globally, which would get them into 3DS like tape
lines…
If you'd like some more help, jsut send me more bytes…
Good luck, gary
In answer to your question – they wander. Dramatically. They're from a 3d
terrain model – picture a mesh covering a landscape. So its important to close
them rather than just extrude them (good idea though) so that they can be
subsequently filled in during shading (i.e., to simulate grass). Someone over
on the acad forum just wrote me a lisp routine on the spot (yes I'm jumping!)
to do this, so I'll be trying it out tonight. Will keep you posted. Doug.
You've gotta love this forum. For 3D terrains, which I usually have to do
accurately for architectural projects, is (if starting from scratch): digitize
the contour lines from a survey if we don't get it on CAD, as polylines; move
each polyline up in space to its proper elevation; hang surfaces between each
pair of contour lines using the ruled surface command in ACAD, after selecting
a Surftab setting that will give me the number of faces I need for accuracy and
minimum mesh count; explode the surfaces into separate faces, and then in plan
view stretch the vertices (if necessary) to align properly with features such
as foundations (get under them), roads (slope to be at right angles to road
surface generally); and so on. An accurate terrain can be modelled quickly
using this method, and it produces good results.
Anyway, glad you're on your way, and past surface #176,948.
regards, gary
"an accurate terrain can be modelled quickly this way" You must be pretty
impressive at this – holy smokes that sounds like a big job. I'm using a
terrain modeller that takes ASCII data as xyz points, along with polyline (or
ASCII) surface features like roads, rivers etc. (or contours) and creates a
triangulated mesh over them. It then allows you to cut in pads, roads or other
features (draw the road, specify depth to cut and width) as well as doing cross
sections, volume calcs, etc. When the model is done, I drop a rectangular grid
on it – with small enough grid spacing, I can get a fairly smooth appearing
surface. Of course, there's the root of my problem; each grid square is a
3dpolyline which is (as yet) unclosed. Tried digitizing contours once (no ascii
data available) but it was a 3 day affair, and the accuracy is still
questionable. But maybe our files are somewhat larger. Sounds like you've got
a pretty neat method figured out.
Shucks. I guess it's what you mean by 'accurate'. My 3d terrain files
only end up as visualization tools, we don't do volume takeoffs or sections,
for example. It's just a fast way to get the general terrain in quickly. If and
when more detail is required, or revisions are made, I manually edit the faces,
and add things like curbs, cuts, and so on. As usual, part of the trick is to
know how much detail is needed, and only work it up where it's required.
Anyway, the level of accuracy is relative to the data I start with. These days,
if we comission a survey, we require that we get the data as a 3D AutoCAD file,
which puts much of the work on someone else's plate, and it usually arrives
quite accurate. To carry this accuracy forward if required is a function of the
Surftab variables that I set when hanging faces between the contour lines.
Anyway, sounds like you have more precise needs in the terrain field than I do.
I reserve my accuracy for the buildings we do, since that's our meat &
potatoes.
Anyway, talk to ya' later,
Gary
Hello; PMJI, but I read about the technique you use to create terain
meshes and I am wondering what software you are useing that allows
you to lay a mesh over a data set of 3d points and also takes into
acount roads, rivers… I am familiar with 3DSurf trom Schriber
Inst. ButI think that only layes a simple mesh over points but does
not allow more compicated tasks.
What I am really interested in know, is if this package you are using
costs $100 or is it more in the $3,000+ range?
Thanks for any info.
Also, what programs (if any) are capable of importing meshes as such
exported from VistaPro, I guess as Ascii-Z?
Sorry about the delay in replying – I've been away for a few days. I use a
system from a company called GWN in Calgary, Alberta (Canada) that is pretty
comprehensive – does cuts & fill, calculates volumes, x-sections, draws
profiles, calculates slopes, will cut out a road according to a x-sectional
profile and a path given (whether in 3d or just given in plan). Great program,
being used world wide for huge jobs (new Tokyo airport – or is it Hong Kong?),
and incredibly expensive! About $4,000 (CDN – thats about $3k US) plus
$400/year in maitenance fees. But it works great. Fast, and takes an unlimited
number of data points. If you want their address, let me know. Doug.