For a given material in a structure, a distance transform computes the distance to the boundary of the material for every point (voxel) in the structure. This is useful when characterizing the structure’s pore morphology.

After selecting Euclidean Distance Transform (EDT) from the pull-down menu, the settings for the calculations can be modified through the Edit… button. At the top of the Euclidean Distance Transform dialog, choose the Result File Name.

Decide which Domain Boundary Conditions should be used during the calculations.

Domain Boundary Conditions

The Distance Mode defines the Material IDs that are considered. From any point (voxel) inside these Material IDs the distance to the nearest boundary to all other Material IDs is calculated. The default is to analyze the pore space, so that the distance of any pore voxel to the next solid material is computed. However, if switching the Distance Mode to GivenID, all Material IDs present in the structure can be selected.

If Component Distance is checked, for each point of the domain the distance to the next boundary is computed. In this case all boundaries between the materials are considered, including the pore space. When Component Distance is checked, the selection of Distance Mode is disabled, as the EDT is computed for all structure components at once. Also, High Resolution will be applied for the computation in this case.

If Signed Distance is checked, a modified version of the EDT is used. In the pore space or background materials, the signed EDT will be the same as in the original version, but the signed EDT will also compute a negative distance inside of the solid or foreground material.

To run the calculations with High Resolution might be useful when the pore space is expected to be especially narrow. The standard algorithm computes distances directly on the voxel grid, i.e. when determining a pore size, only the distances from the center of a pore voxel to the center of a solid voxel are taken into account. High Resolution also takes the voxel surfaces and edges into account, so the computed distances correspond to the distance to the next surface or edge. The disadvantage of the High Resolution mode is that the calculation runtime and memory usage may increase by a factor of eight.