Hello,
I had a question regarding the algorithm used to determine the scatter plot for the Krumbein sphericity and the volume distribution.
With the scatter plot, I was curious if there were certain cutoffs used in the algorithm; it seems like maybe not all of our pores were analyzed. If there is a help section in the user guide that explains this could I receive guidance to it?
With regards to the volume distribution, analysis was made on our entire sample was well as 3 single pores. When the entire sample was analyzed, the histogram on the volume distribution matched the PoroDict analysis. However, when we analyzed only 3 (the largest pore and 2 other small ones), it did not match up at all. I was curious if there was a statistical explanation for why the analysis on the entire sample proved accurate but the analysis of just 3 pores was off. Thank you.
Respectfully,
Jack Davis
Dear Jack,
there are some parameters which may influence the results significantly, especially if you change them.
All parameters are explained in our User Guide, which you can find here: https://geodict-userguide.math2market.de/2025/porodict_identifypores.html (https://geodict-userguide.math2market.de/2025/porodict_identifypores.html)
First, you mentioned that you analyzed also only 3 pores of the whole sample. A crucial step is how you reduced the analysis to only those 3 pores. Can you tell how you did that (e.g. by cropping the structure, or flood-fill/reassign parts of the structure)?
Based on the observations you reported, I suppose there might be changes on the connectivity between the pores in the step of going from the whole sample to only 3 pores. There are two parameters, which might change the number of analyzed pores due to different connectivity.
One of the parameters is the Minimal Pore Diameter. Unconnected pores that are smaller than the given diameter are excluded from the analysis.
Another parameter is the Interface Threshold which defines whether two pores are merged and treated as one for the analysis or not.
Another possibility is that the volume histogram plots have different settings
In the Result Viewer you can change the Number of Bins in the volume histogram. Depending on that number the individual pores from the scatter plot might be plotted in different bins, i.e. different bars, in the volume histogram plot. Compare the results for 10 and 30 bins below.
VolumeHistogram_10Bins.pngVolumeHistogram_30Bins.png
To have a more detailed look what could cause the differences, I would need more information and maybe also the data you used.
Best regards
Anne