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Upper extremity modelling with
Spatch and HamaPatch
 
| Spatch
is a free 3D surface modelling program for the PC which has special application
to anatomy drawing. The program is small (1 megabyte) and its .spt data
files are tiny compared to other 3D formats such as .dxf or .obj. It is
brilliant in its simplicity. Unfortunately, its author, Mike Clifton, and
its original home page have both disappeared from the internet. I have
posted a copy of the program
here.
An archive of hand .spt files is available
here
(work in progress).
The program works as follows: the user
constructs shapes from splines (lines connecting dots) as for the images
here: |
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| Complex mesh constructions can be made
and modified, then rendered as 3D smooth surfaces by the program:
These can be spun around in real time and
easily modified. The slick thing about this program compared to others
is that few actual control points are required to create complex shapes. |
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| There are a few electronic anatomy image
resources, such as Primal's Interactive Hand, but this supplies only static
images, such as the ones referenced on this
page. As such, they have limited usefulness.
Here, the distal end of the humerus has
been modelled in two (articular and nonarticular) 3 dimensional sections
which overlap: The articular surface is easily defined by 22 control points.
It doesn't take much time
playing with the program before it becomes obvious how very complex organic
shapes can be generated from very few points of information - just as living
shapes arise from a few genetic control points - just as all shapes are
created during embryonic through only two processes: extrusion and invagination
- the same effects that the control points have on the surfaces you
create! It is a transforming experience to construct anatomic models
with this realization in mind. Try it! |
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| The same model, rendered by the program.
This model was used for the diagrams in this
page. |
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| amapatch:
Hamakazu's Hamapatch
is the next generation of sPatch. It is also free, works with the spatch
file format, and has many great additional features, such as allowing you
to work with simultaneous wireframe and visible surface renderings in real
time, choosing different colors for different portions of the model, and
a number of other helpful featues. Hamapatch is available here.
The site is in Japanese, but the download file includes both English and
Japanese versions. If the site is down, I have posted a copy of the zipped
file here. The English version does not
yet have a working help file, but Jonathan Lee has compiled an excellent
help file, posted here.
Hamapatch is still under development, but is truly amazing in it present
form. Also amazing is that the entire (zipped) program is only 353 kb!
Small is beautiful. |
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| The file for that image, humerus.spt,
is 11 kb. In contrast, the dxf version of the same surface is 1837
kb, shown here in another program: |
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| I hope to develop a library of sPatch
based upper extremity models. Here, the proximal, middle and distal phalanges
of a finger, in wireframe, and rendered from the file phalanges.spt. |
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| These models can be exported to a variety
of formats, including DXF, POV-ray, Renderman, VRML and others. This allows
them to be painted or viewed from any angle or point of view as
was done here with Amorphium |
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| Or animated, as was done here using
Poser
4. (...hmmm, still needs some work...) |
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| Models:
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Other sPatch links:
Hamapatch links:
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| 3D VRML anatomy sources |
http://www.people.nnov.ru/fractal/VRML/Splines/Splines.htm
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If you are interested in collaborating
on anatomic sPatch / Hamapatch models, please contact
me.
Charles Eaton MD
Go to 
main page
 |
American
Society
for
Surgery
of the
Hand
assh.org
The Best
Resource
For Your
Hands,
Period.
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