To combine the two datastores into a single datastore, one option would be to use the combine function to create a CombinedDatastore:
cds = combine(volds, pxds);
Alternatively, if you wish to use the datastore for semantic segmentation, you might find a randomPatchExtractionDatastore to be the most useful:
patchSize = [50 50 50];
patchds = randomPatchExtractionDatastore(volds, pxds, patchSize);
This extracts corresponding randomly-positioned patches from the two datastores.
For a complete example showing how to perform semantic segmentation of 3-D volumes using deep learning, you can take a look at this example:
