Re: [CAD_CAM_EDM_DRO] ASCII point cloud file

Hi Marcus,

That's all true, as I have discovered in my earlier efforts with points
and scanned lines. I was merely trying to give Peter some possible ways
to get points into CAD. I didn't inquire how many points he had to work
with. I have painfully (as you've noted) selected points in a
"waterline" and drawn lines using Vector's Poly line (spline) with
limited success.

If the points from imported from digitizing can be used in sequential
fashion, then a poly line can be reconstructed. If several sets of
lines are import this way, than some suggestion of a surface MIGHT be
obtained. A long way from truely being able to use a real point cloud.
Vector's conversion program(s) would be more of a help here.

Alan KM6VV


Marcus & Eva wrote:

>
> Hi Alan:
> My understanding is that a point cloud, even if imported successfully,
> is not of any great use in developing useable CAD data without a lot of
> manipulation.
> Imagine a digitized coke bottle, from which you're trying to build a surface
> model so you can tell a cutter to traverse the surface.
> You need to triangulate all the points to provide a patchwork quilt of tiny
> surfaces and then stitch them together.
> If you've got millions of points, this could be a daunting exercise.
> Suppose instead, you've got a simple shape...well then you need relatively
> few points to define it, and may as well just have measured and drawn it up
> in CAD by conventional means (even if you used a CMM or other digitizer to
> get the relevant points of reference.)
> If your shape is something like an outline of a teardrop for example, you
> would run a spline through all the points on any one level,and loft the
> splines together to develop your shape from that.
> These are workarounds...I've used some myself, but it's painfully tedious to
> do it that way.
> What I am pretty sure of, is that there are no CAM programs out there that
> can cut just from a point cloud without further manipulation of the data.
> The automation of that manipulation process is what Copycad and others do.
> So if the purpose is to do reverse engineering with any hope of accuracy or
> efficiency, the point cloud data by itself is almost useless.
> Cheers
>
> Marcus
>
> ----- Original Message -----
> From: "Alan Marconett KM6VV" <KM6VV@...>
> To: <CAD_CAM_EDM_DRO@yahoogroups.com>
> Sent: Sunday, March 09, 2003 7:20 PM
> Subject: Re: [CAD_CAM_EDM_DRO] ASCII point cloud file
>
> > Hi Peter, Marcus,
> >
> > Just a thought, it might be possible to use Vector CAD/CAM's PCL (point,
> > circle, line) import function. You'd have to edit the point cloud to
> > fit PCL format, but it could probably be done with BASIC, or perhaps in
> > a spread sheet. OR convert the point cloud to Gcode moves, and then
> > import (backplot) that.
> >
> > I think Vector also has an STL translate program that could do the job.
> >
> > Alan KM6VV
> >
> >
> > Marcus & Eva wrote:
> > >
> > > Hi Peter:
> > > One doesn't!
> > > Unfortunately, getting point cloud data into a format useable by a CAD
> > > program is a bit more involved than just dumping it in.
> > > There are VERY few CAD programs that recognize point cloud data.
> > > The best way I'm aware of, is to spend a pile of money for Delcam's
> Copycad.
> > > This is reverse engineering software that is designed to create
> surfaces
> > > from point clouds and outputs STL and IGES which most 3D CAD programs
> can
> > > read.
> > > Once you have the surfaces in your CAD program, you can begin to
> manipulate
> > > them.
> > > Cheers
> > >
> > > Marcus
> > >
> > > ----- Original Message -----
> > > From: "forumtvm" <forumtvm@...>
> > > To: <CAD_CAM_EDM_DRO@yahoogroups.com>
> > > Sent: Sunday, March 09, 2003 5:03 PM
> > > Subject: [CAD_CAM_EDM_DRO] ASCII point cloud file
> > >
> > > > Hi,
> > > >
> > > > I am new to reverse engineering and will like to find out how one can
> > > > utilise an ASCII point cloud file.
> > > >
> > > > How does one insert/import such a file into AutoCAD?
> > > >
> > > > Thanks
> > > >
> > > > Peter
> >