With 10x Visum HD : How to map the barcode id to the barcode sequence ?

Question

[sacha]

Hi,

I m trying to understand how 10x Visium HD for spatial transcriptomics works. Reading the protocol I understood that Read R1 harbors the UMI and the spatial barcode.

After downloading a public dataset , I succeed to get barcodes information using this command :

h5dump -d /barcodes Visium_HD_Human_Colon_Cancer_P1_molecule_info.h5

But I only get a barcodes identifiers like this one:

s_002um_00000_00056

I guess it means "spatial with 2 micro meter at coordinate x y ".

But now, I would like to get the DNA motif of the spatial barcode. I didn't find any mapping between spatial barcode ID and barcode sequence. How it works ?

I think the UMI should have a size of 16 bp and the barcode must have a size of 27 bp, because the total UMI+BC is 43 pb as the documentation said. How can I find this mapping ?