# Voxel id in annotation file

**URL:** <https://community.brain-map.org/t/voxel-id-in-annotation-file/1670>\
**Category:** How To\
**Tags:** reference-coordinates, allensdk\
**Created:** [June 15, 2022, 5:47pm UTC](https://community.brain-map.org/t/voxel-id-in-annotation-file/1670 "2022-06-15T17:47:07Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![bonniezyao](https://yyz1.discourse-cdn.com/flex027/user_avatar/community.brain-map.org/bonniezyao/32/642_2.png) [@bonniezyao](https://community.brain-map.org/u/bonniezyao)\
**Post date:** [June 15, 2022, 5:47pm UTC](https://community.brain-map.org/t/voxel-id-in-annotation-file/1670/1 "2022-06-15T17:47:07Z")

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Hi,  
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](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!

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<div class="post-metadata">

**Author:** ![bonniezyao](https://yyz1.discourse-cdn.com/flex027/user_avatar/community.brain-map.org/bonniezyao/32/642_2.png) [@bonniezyao](https://community.brain-map.org/u/bonniezyao)\
**Post date:** [June 16, 2022, 7:27pm UTC](https://community.brain-map.org/t/voxel-id-in-annotation-file/1670/2 "2022-06-16T19:27:16Z")

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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.