RE: Point cloud data from rendering

From: Charles Overy (
Date: Wed Aug 22 2001 - 23:44:39 EEST


My perpetual search is for an end run around the "single water tight solid"
from solid modeling CAD that seems to be a real bottleneck for a number of
possible RP applications.
 The difficulty that we face daily is that there is no utility in
architecture (nor would I think in may applications) of generating a single
solid or of dealing with coincident faces or the like because in reality a
building does not consist of a single homogeneous material and there are
coincident faces all over the place (metal on a beam or two pieces of wood
up against each other). However, in toto, the exterior of a building does
represent a single watertight solid (or pretty close to it).

Prompted by demoing milling software, Visual Mill in particular, that uses
a virtual bit to sample the surface of a form and can then re-export the
"milled" data as a new stl it occurs to me that the same thing should be
able to be done either with a bit of arbitraily small diameter on a machine
of infinite versatility (no real world limitations) or just by the
rendering engine that is already doing ray tracing. Unfortuntely, I do not
understand in enough detail how a ray trace engine works so I cannot
conceptualize whether it is possible or practical to generate a point cloud
sampling with a renderer and if this point cloud would be managable by
applications such as yours. As we have discussed, in trying to solve this
problem just with Geomagic Wrap and RapidForm I am stopped by the fact that
the data set does not have regularly spaced points over the surfaces and
contains too many interior points. My musing is, if the vitrual scanner
engine is a way to create regular surface data from complex and not "well
formed" models that can then be reverse enginneered inot a buildable solid.

I have looked at Arius before although not at pointstream. It seems like
they are still processing real world data not virtual data. No? Do you
have a contact there?



-----Original Message-----
From: []On
Behalf Of Ping Fu
Sent: Wednesday, August 22, 2001 1:32 PM
Cc:; Walter Noot
Subject: RE: Point cloud data from rendering

Pointstream from Arius3D is already doing this.

Check it out at

What application are you thinking about? I am
sure the people at Arius3D would like to hear
from you.


-----Original Message-----
From: []On
Behalf Of Charles Overy
Sent: Wednesday, August 22, 2001 2:38 PM
Subject: Point cloud data from rendering

Hello all,

Does anyone know if it is possible to create point cloud data from a
rendering or renderable image. My thinking is to create a "virual scanner"
add in to a render engine, create good point cloud data of a surface form
and reverse engineer it using Geomagic, Rapidform or the like. It occurs to
me that a render engine must know where the "surface" of model is and as
rendering is more forgiving and more pervasive than solid modeling it would
be of tremendous benefit to be able to generate .stl from a render type of
application. The reverse enginnering applications have plently of utility
for stitching holes and filling the backside of objects that have not been
scanned and this utility could be turned to the patching of areas that were
not rendered.

Am I nuts (again!)


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