Volume Viewer - memory usage

In some situations, Volume Viewer uses more memory than is necessary. This will be remedied when the program is optimized.

• For the DSN6, Delphi, and XPLOR formats, the whole file is read in order to extract a subregion; thus, specifying a subregion will speed up rendering and display but will not conserve memory. In contrast, only the specified subregions are read from MRC, NetCDF, and Priism files.
• When a data file is read with Step sizes greater than 1, every data value is read into memory; the needed values are placed in another matrix.
• Transparent Solid rendering uses four float values per voxel in RGBA mode and one 2-byte integer per voxel in colormap mode.
• Rendering a transparent Solid with 3D texture mapping makes an RGBA8 OpenGL texture (4 bytes per voxel). With 2D texture mapping, three such RGBA8 arrays are used.