METHODS FOR RECONSTRUCTION OF 3-DIMENSIONAL STRUCTURES

The aim of the contribution is to provide the reader with an account o f methods for creating computer reconstructions of medical data acquir ed in the form of planar cross sectional slices. This kind of data is frequently obtained from Various medical scanners like computed tomogr aphy and magnetic resonance imaging. The models of data are created by small volume elements in the shape of cube, called voxels. The voxels arranged in a regular space grid envoy information about the relevant volume of modeled object. Relating individual voxels to different par ts of modeled modeled objects we define space structures (classificati on). The structures can be also chosen with thresholding. To visualize data we can chose two different approaches: volume or surface renderi ng. In the case of volume rendering the whole data set is visualized r egardless to the classification and threshold. We described several me thods: summed, averaged and maximum intensity projection. These method s are suitable for visualization of contrast structures. The second ap proach, surface methods, requires as the first step to define object - visualized structure either by thresholding (definition of voxels wit h intensity in given interval) or by the classification (definition of voxels with given volumetric properties). We described two simple alg orithms (Voxel value shading, Depth shading) and several more complex shading ones (Z-buffer gradient shading, Voxel gradient shading and Gr ay level gradient shading). The setting of color and transparency to p articular structures enables to visualize hidden or inner objects. The best quality of visualization is reached by Gray level gradient shadi ng, when small surface details are Visible well.