Distance maps (also called distance transforms) are powerful tools for a number of image processing techniques, such as computing Watersheds and scalar values. The values in a distance map are the minimal distances to labeled voxels in the source region of interest and are created in the floating point data type. You should note that image data is not considered when computing distance maps.
When you create either a distance map or signed distance map, such as the one shown below that describes the distances within pore space, each voxel outside the region of interest is replaced with a gray value equal to that voxel’s distance from the nearest voxel in the ROI.
Distance map in XY, XZ, and YZ planes
The distance map is created and added automatically to the Data Properties and Settings panel (see Image Properties and Settings).