Voxel id in annotation file

I have annotation (2017, 10um) nrrd file visualized for registering to my dataset so I can match regions between the atlas and my whole-brain imaging. I assumed that each structure in the annotation file has a unique voxel id and that would match to a structure id. Where is this information stored?

I have looked at the ontology structure tree, but it’s not clear which id would match to the voxel value in the annotation file (http://api.brain-map.org/api/v2/structure_graph_download/1.json)
Existing structure mask would not help me since I have to register the atlas/annotation to my dataset dimensions.
Thank you for any help!

I have solved this issue and found out I compressed the file without intending to and changed the values attached to the file. That is why my ids weren’t matching up.