3-Dimensional object reconstruction from projections
Applications in medical imaging
3D Microscopy in Dentistry
In this document, we present a method for 3D modeling, reconstruction and projection of
histological image data. Specifically, the data that is used, consists of series of cross
sections, taken from human teeth. Sectioning is being made with the use of a microtome in
order to produce slices that are usually 1mm of thickness. Subsequently, the slices are
being photographed and the photographs are digitized with a scanner. The procedure of
processing of digital images, construction of the 3D-model and
photorealistic rendering, is described below.
The Three Dimensional Model that we used for visualization, is based only on
information extracted from the boundaries of the objects of interest and is known as
Surface Representation Model. According to this model, external or even internal surfaces
are being reconstructed, skipping all the grayscale information that the grayscale images
include. The result, is a set of curved closed surfaces that define the shape and
topological characteristics of the teeth that are reconstructed. The use of pseudocoloring
and shading, is bound to give sometimes impressive results.
- At first, boundaries of slices have to be extracted, as the sole feature used in the
3D-model. This is usually done manually, since such accurate segmentation cannot be
accomplished with fully automatic methods. It is essential for the construction procedure,
that the boundary images do not contain any discontinuities.
- The second step, is to produce the main 3D wireframe model. It
is constructed by linking the boundary images to eachother, in terms of small triangular
objects, used for approximation of curved surfaces.
- Finally, assigning material texture to the approximated surfaces and using
pseudocoloring, we are able to visualize information that could not be otherwise
presented, such as 3D objects that are situated inside other 3D objects. The application
has proved to be extremely useful in cases where such information is essential to be
visualized. Especially in teeth reconstructions, it introduces
a unique way of presenting the external tooth in combination with the pulp chamber.