Re: [CAD_CAM_EDM_DRO] ASCII point cloud file

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
>
>
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