In GeoDict, the GAD objects are converted into a voxel geometry. The details of this conversion are defined by the Domain. The domain determines the resolution, the size and position of the bounding box, the background materials, and the overlap behavior of objects. Whenever a structure is created or loaded in GeoDict, the corresponding domain parameters are stored. They can be accessed and changed through the Edit Domain command which is additionally available from the GAD Objects context menu. In a GAD file, those parameters are defined in the Domain section.

GeoDict knows and uses three different ways to specify the domain size, defined by the value after the key DomainMode:

• DomainMode VoxelNumber: The voxel length, specified by the value after the key VoxelLength, and the number of voxels in the three spatial directions, specified by the values after NX, NY and NZ, are given.
• DomainMode Length: The voxel length specified by the value after the key VoxelLength, and the lengths of the domain in the three spatial directions, specified by the values after the keys LengthX, LengthY and LengthZ, are given. The number of voxels (NX, NY and NZ) is calculated automatically.
• DomainMode VoxelNumberAndLength: This mode is similar to DomainMode VoxelNumber, but additionally the physical lengths of the domain are specified by the values after the keys LengthX, LengthY and LengthZ. This mode is used when wanting to save a difference of the physical lengths (LengthX, LengthY, and LengthZ) to the lengths given by the voxel length and the number of voxels (VoxelLength, NX, NY, and NZ).

Additional to the size of the domain, the origin of the geometry is specified. A shift of the origin from (0.0, 0.0, 0.0) is given by the values after the keys OriginX, OriginY, and OriginZ.

The domain of the voxel geometry may be periodic in one or more of the three spatial dimensions. This is specified by the values after the keys PeriodicX, PeriodicY and PeriodicZ, which may be False or True. If the domain is periodic in the X-directions, this means that an object leaving the domain through one of the two domain boundaries in X-direction reenters the domain from the other boundary in X-direction. Periodicity in Y- and Z-direction is defined accordingly.

With Edit Domain, the position and resolution of the domain can be changed. Changing the domain leaves the absolute size and position of the objects themselves unchanged, but it might change which part of an object is shown inside of the voxel grid, and how well it is resolved. Basically, Edit Domain allows to do the following tasks:

Change resolution

Shift the field of view

Distinguish between background and hollow parts

Redefine overlap behavior