3D point cloud data (fwd)

[Wookey]

I got this message from some guys in the BCRA Cave radio and Electronics
group, asking about skinning point clouds, now that they have a dataset.

I know that the Wakulla II project did some software for dealing with point
clouds, but I haven't seen any skinning done and I've been told that the
'skinning' problem is mathematically extremely difficult, although I note
an example from someone at '3d pipeline corp' in a recent Compass and Tape
that seemed to work pretty well but no timings or software was provided. I
also recall Sellers and Chamberlain using autocad to skin a model produced
by ultrasonic cross-section scanning - maybe it could do point clouds too?

Obviously displaying the point cloud is trivial, but the skinning part is
rather harder. Does anyone know of any existing, available solutions? Or
have any suggestions as to how it might be done?

Wookey
-- 
Aleph One Ltd, Bottisham, CAMBRIDGE, CB5 9BA, UK  Tel +44 (0) 1223 811679
work: http://www.aleph1.co.uk/     play: http://www.chaos.org.uk/~wookey/
---------- Forwarded message ----------
Date: Thu, 17 Apr 2003 21:12:01 +0100
From: Richard Rushton <Richard@yabon.demon.co.uk>
To: Brian Pease <bpease@99main.com>, wookey@aleph1.co.uk, 
    Mike Bedford <BEDFORDMD@AOL.COM>, Richard Rushton <r.rushton@fcl.com>
Subject: 3D point cloud data

Hi Wookey, Brian,

Recently we had a go with a 3D laser scanner in Yordas cave - it was
being demo'd by a company called Measurement Devices Ltd.
It has produced a couple of massive point cloud files and we have a
program that lets us view this data (as a point cloud). The data seems
fairly simple - four numbers per measurement - I assume some sort of 3D
co-ord plus a magnitude. Example of the data format:

-0.200 -1.044 -0.896 155
-0.198 -1.033 -0.878 162
-0.201 -1.049 -0.890 166
-0.210 -1.095 -0.927 164
-0.205 -1.074 -0.906 164
-0.204 -1.068 -0.898 163
-0.209 -1.091 -0.916 165

The scanner was mounted on a tripod and scanned vertically for a near
180 degrees (measurements directly above and below the scanner are not
taken). The scan head then rotates a small amount and then takes another
vertical slice. In this way a full 360 spherical scan is compiled.
The software for viewing the data seems to rely on the point density to
give its surface definition. This is not too bad for areas close to the
scanner, but as the cave wall gets further away the points get further
apart (spherical surface expansion).
I was wondering if you had any experience in dealing with point clouds?
Do you have any software that can handle point clouds and convert them
to some sort of rendered skin?.

Best Regards
-- 
Richard Rushton