Getting percent overlap between a mask and parcels

Hi all,
I need some help sort of getting started with a project I am working on. So I have ROI masks for subjects in MNI-1mm space (so equal to 1.0 where the ROI is, and 0 everywhere else) and I have an atlas with 333 parcels (Gordan atlas) where I have the surface area and the centroid in MNI. I am trying to figure out the overlap of those ROI masks with each parcel. Any tips to get started?

“whereami -omask” in AFNI can compute the overlap of each ROI mask with atlases,but you will have to configure the Gordon atlas for AFNI.

https://afni.nimh.nih.gov/pub/dist/doc/htmldoc/template_atlas/howto.html

I tried that out and I think I am getting the correct output… question for you though, For example (pasted below) why would whereami output some overlaps that have ‘0.0%’? Like there are 333 parcels in the Gordon atlas, so I would expect 333 overlap outputs- or any % overlap that is greater than 0% but in the example pasted below I got 5 ‘0%’ overlaps

++ Input coordinates orientation set by default rules to RAI
++ In ordered mode …
++ Have 2 unique values of:
0 1
++ Skipping unique value of 0
++ ========================================================================
++ Processing unique value of 1
++ 55511 voxels in ROI
++ 55511 voxels in atlas-resampled mask
Intersection of ROI (valued 1) with atlas Gordontest_full (sb0):
10.1 % overlap with Visual3, code 15
3.7 % overlap with Visual14, code 137
3.4 % overlap with Visual2, code 8
3.0 % overlap with RetrosplenialTemporal3, code 130
2.8 % overlap with Visual18, code 141
2.5 % overlap with Visual11, code 131
2.5 % overlap with DorsalAttn14, code 100
2.2 % overlap with Visual13, code 136
1.4 % overlap with RetrosplenialTemporal4, code 143
1.3 % overlap with Visual12, code 132
1.1 % overlap with Visual16, code 139
1.0 % overlap with Visual15, code 138
0.9 % overlap with Visual6, code 20
0.9 % overlap with None20, code 144
0.8 % overlap with Visual17, code 140
0.6 % overlap with None2, code 18
0.6 % overlap with RetrosplenialTemporal2, code 14
0.5 % overlap with Visual8, code 97
0.4 % overlap with Visual5, code 17
0.4 % overlap with None19, code 142
0.3 % overlap with Visual, code 5
0.3 % overlap with None3, code 19
0.3 % overlap with Visual21, code 175
0.3 % overlap with RetrosplenialTemporal, code 13
0.2 % overlap with None18, code 135
0.2 % overlap with None, code 11
0.2 % overlap with Visual9, code 98
0.2 % overlap with Visual4, code 16
0.1 % overlap with CinguloOperc9, code 72
0.1 % overlap with Salience2, code 83
0.1 % overlap with Auditory8, code 70
0.1 % overlap with Visual7, code 90
0.0 % overlap with CinguloOperc8, code 71
0.0 % overlap with None17, code 134
0.0 % overlap with CinguloOperc12, code 82
0.0 % overlap with Visual10, code 99
0.0 % overlap with None4, code 73
----- 42.6 % of cluster accounted for.

MANAGED BY INCF