Re: 3D Reconstructions and more

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Malcolm (and anyone who's interested):

Dick Jefferies and I were heavily into making models of calcichordates from 
serial sections. We did this work many years ago, the techniques of it were 
described in the following reference:

Jefferies, R. P. S. & Lewis, D. N. 1978 "The English Silurian fossil <<
Placocystites forbesianus>> and the ancestry of the vertebrates" Phil. 
Trans. roy. Soc. London ser. B 282 : 205-323.

We did not use computers in any of our work, partly because of the 
primitive nature of computers in those days, partly because of the 
phenomenal amount of memory required, and partly because the methods 
available just were not accurate enough. Point plotting of sections gave a 
stepped appearance to the picture which our method did not, and for the 
kind of detail we wanted was not appropriate.

Our section intervals were 70-100 microns, depending on the magnification 
of the final medel. This meant some 250 peels were made for each model! But 
there is no alternative for the details required.

Our method of aligning sections was the crude one of pushing a fine pin 
into the mounting medium such that it was visible for several sections, and 
could easily be repeated before the marks disappeared. The marks were also 
modelled and alignment made.

Of course, to produce such models is very time consuming, but the results 
are well worth the effort!

Try it out.

Dave.

On Tue, 6 Jun 1995 9:20:36 +0100 ,
  Malcolm Herbert writes:

>
>Hello all...
>
>I am a new subscriber to Paleonet, so first a little background
>
>I am primarily a computer scientest, but have spent the last 3-4 years 
>working computer-based 3D reconstructions from serial sections in 
>palaeontology. This work has been mainly with Brachiopods, in conjunction
>with Mike Basset at the National Museum of Wales, Cardiff. 
>
>Some reconstructions and further details can be found at my web page
>
>http : //www.acs.lamp.ac.uk/~malc/
>
>On the 3D reconstruction issue a number of points
>
>1. Most serial sections do not contain fiduciary marks and therefore
>cannot be aligned accurately in 3D
>
>2. The sections are usually undersampled and the rate of change in shape
>is usually dramatic making reconstruction difficult
>
>3. Section drawings can sometimes by
>
>
>e difficult to convert into digital data
>
>
>this tends to make most current data and drawings unsuitable for 
>reconstruction and the results can sometimes be dissappointing
>
>If you want any more information please di hestitate to contact me
>
>Malcolm Herbert
>University of Wales, Lampeter
>Dyfed SA48 7ED
>01570 424727
>email : malc@lampeter.ac.uk
>URL   : http: //www.acs.lamp.ac.uk/~malc

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                    \\/// Live long and prosper \\\//

 David N. Lewis, Collections Manager, Fossil Invertebrates and Plants,
 Department of Palaeontology, The Natural History Museum, Cromwell Road,
 London, SW7 5BD, England. Tel. +44 (0)171 938 8833; Fax +44 (0)171 938 9277;
 e-mail: INTERNET  dnl@nhm.ac.uk  JANET  dnl@uk.ac.nhm

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