Major vessels of human circulatory system
This example shows a geometric model of the main vessels of the human circulatory system. Anatomical sections of a male specimen (visible human data) published by the USA National Library of Medicine under the visible human project were used to extract the data points(nodes) of the main vessels.There are 1871 anatomical sections available at 1.0 mm intervals in this database. These are full colour images of 2048 X 1216 pixels with a resolution of 0.33 mm/pixels in both directions. This gives a physical size of an image to be 675.84 x 401.28 mm.
The images have been linearly transformed using the three reference "markers", as the outline of the body of the specimen did not align properly when images were staked in the x-y plane along the z axis going through the centre of each image. Digitising data points on an image is described in example as (Digitising a pig torso: building a mesh over a CT image). To develop this geometric model, the above mentioned images at 5 - 25 mm intervals were used. Here only a few images are shown for illustrative purposes. While digitising the images, information of radii of various vessel groups was also gathered and included in the exnode and exelem files as a separate field. Also digitised were the heart, liver, kidneys and the brain. Initially, a network consisting of linear elements was created. Then both the exnode and exelem files were modified to accommodate for the derivative information. Further, "smoothing" command was used to update the nodal derivatives. This command computes the derivative by taking the average slope from nodes on either sides of a given node.