find_outer_region(im, r=None)[source]#

Find regions of the image that are outside of the solid matrix.

  • im (ndarray) – Image of the porous material with 1’s for void and 0’s for solid

  • r (scalar) – The radius of the rolling ball to use. If not specified then a value is calculated as twice maximum of the distance transform. The image size is padded by this amount in all directions, so the image can become quite large and unwieldy if too large a value is given.


image – A boolean mask the same shape as im, containing True in all voxels identified as outside the sample.

Return type:



This function uses the rolling ball method to define where the outer region ends and the void space begins.

This is particularly useful for samples that do not fill the entire rectangular image, such as cylindrical cores or samples with non- parallel faces.


Click here to view online example.