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Recent Developments with Simpleplot

A new set of IsoSurface routines have been implemented in preparation for the release of 2-15 later this year. To test the new SIMPLEPLOT IsoSurface module we obtained and viewed the Visible Human dataset. This is a set of transverse CT, MRI and cryosection images of a male cadaver. The data is from the National Library of Medicine in the USA. The data chosen for viewing was the fresh CT data. This was supplied in nine sections with different resolution and positions for each section.

The data was initially read in slice by slice for each section as a 512 x 512 array of 16 bit values. These represent the density at each point. The slices were first drawn using a simple contouring routine and the range of data levels was calculated.

The offsets and scales for each slice were extracted from the scan header in order to align the slices. The scaling of the slices was accomplished using the new interpolation routine to regrid a 2-D array.

The first three sections of the data have slices at 1mm intervals, the fourth section has 3mm slice intervals. The new interpolation routine was used to generate two extra slices between the fourth section slices to give a 1mm separation.

A subregion of the slices that enclosed the head were then saved as a separate file containing 222 slices each of 200 x 250 data points.

The new (42Mb) file was then loaded into a separate program, this called the SIMPLEPLOT IsoSurface function passing the array, NX, NY, NZ and the data level to draw. From this raw data a level of 890 gave the head with flesh and 1390 gave the base skull.

The new software was prototyped on an Indy and implemented on a 486 PC. Testing is being carried out on Alpha, Unix, Windows NT and Windows 3.1 systems. To see other interesting bits of the body data, visit the BUSS WWW site at

Geethani Piyasena