Currently, the volumetracing_accessor.ts is pretty large. Moreover, I would have expected quite a few times now already to find mapping-related accessor function in a file kinda like mapping_accessor.ts or editable_mapping_accessor.ts or so. Therefore, moving these accessors into their own file might be worth refactoring.
The most difficult part would be to decide which accessor should be moved and which should stay, as volumetracings and editable mappings are still very entangled.