-------- Original Message --------
Subject: Volume Calculation
Date: Tue, 2 Sep 2008 04:07:09 -0700 (PDT)
From: Bill Sellers <[EMAIL PROTECTED]>
To: [email protected]
References: <[EMAIL PROTECTED]>
Dear Diego,
It depends on how your data is formatted. If you just have points then
you need to calculate the convex hull first (use the free Qhull
software - it's not trivial). If you already have a proper surface
then most CAD programs will calculate the volume for you. My preferred
option is FormZ which copes with non-convex polyhedra too and also
calculates the moments of inertia and principle axes which I find
useful (but I imagine Rhino will do this too). If you don't want to
spend any money volumes of convex polyhedra are fairly easy - you just
find a point inside and resolve the volume into a series of pyramids
with the apexes at that point. You can calculate the volumes of those
pyramids with standard formulae and then you just sum them. Non-convex
volumes are not trivial - you need to subdivide the volume into convex
components and then sum them and that's quite tricky.
Cheers
Bill
--
Dr. Bill Sellers Email:
[EMAIL PROTECTED]
Lecturer in Integrative Vertebrate Biology Skype: wisellers
Faculty of Life Sciences Tel. 0161 2751719
The University of Manchester Fax: 0161 2753938
Jackson's Mill, PO Box 88 Mob: 0785 7655786
Sackville Street, Manchester, M60 1QD, UK http://homepage.mac.com/wis/ASL/
On 2 Sep 2008, at 11:41, morphmet wrote:
-------- Original Message --------
Subject: Re: Mirror a .ply file?
Date: Wed, 27 Aug 2008 08:49:57 -0700 (PDT)
From: Diego Astua de Moraes <[EMAIL PROTECTED]>
To: [email protected]
References: <[EMAIL PROTECTED]>
Hi
I know this is not morphometrics sensu strictu, but since the topic of
3D software came up, I was wondering if anyone knows how to calculate
the volume of a convex polyhedron delimited by a series of polygons
that
came from a series of x,y,z points. It would be something like
calculating the area of the minimum convex polygon as used in home
range
studies, only in 3D. I found a way to do it in Rhino a few years ago,
but it was not straighforward, and haven´t looked at it since...
Feel free to contact me off list as this is beginning to get off
topic...
Thanks
Diego
Diego Astúa de Moraes, D.Sc.
Departamento de Zoologia - CCB
Universidade Federal de Pernambuco
Av. Professor Moraes Rego, s/n.
Cidade Universitária
50670-420 Recife, PE
Fone(fax): (81) 2126-8353
email: [EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]> -
[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>
On Wed, Aug 27, 2008 at 11:48 AM, morphmet
<[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>> wrote:
-------- Original Message --------
Subject: Re: Mirror a .ply file?
Date: Fri, 15 Aug 2008 00:17:18 -0600
From: [EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>
To: morphmet <[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>>
References: <[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>>
Any 3D modeling software, e.g. Rhino, 3DS, Maya, some free-ware,
will
do that in one click.
Martin Friess
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