How can I preserve library structure (and ideally, edits) when migrating from Aperture to Darktable?

Question

I've got a fairly large (>150GB) photo collection, comprising loads of RAW photos, currently sitting between three or four Aperture libraries.

Given how much time and effort have been put into making this library, I'm seriously considering moving away from Aperture and towards the open-source (and cross-platform) Darktable app in the near future.

Having said that, I have two questions about migration from one platform to the other:

• Darktable stores its library in an SQLite database file. Are there any tools allowing me to (relatively easily) dump my Aperture library into Darktable's SQLite library?

• One of Aperture's selling points has been a non-destructive editing approach using a base photo and treating edits like layers over the original photo. Will Darktable support this kind of model?]

First and foremost, I'm interested in knowing if there's a way to preserve Aperture library structure (mainly, projects and folders) in Darktable. I assume EXIF data would be preserved, however if that's not a given, it's fairly crucial.

I can survive without preserving Aperture edits, although if there's a way to preserve those in Darktable's library it would definitely be a plus.

Answer 1

Partial answer on preserving Library structure, or at least recording it.

In Aperture for each folder or project give all photos in that container the name of the container.

E.g. if you have

folder - holidays
    folder - 1984
        Project Wreck Beach, BC
        Project Whistler, BC

Then you give the first project the keyword F_Holidays-P_1984-Wreck_Beach

Albums can work the same way. Give each album an A_ keyword. If you have folders of Albums,then they get keywords like F_Best-shots-A_West-Coast

My first thought was to do it in chunks: E.g. give everything in a folder F_Best-Shots, then label the abbum separately, but you would lose the hierarchy if you do this. Some you could deduce, but if you hundreds of containers....

After you have done this, write all keywords back to media, then, since you are going to lose your edits, select all images that have adjustments (Rule adjustments is applied)

If you think you may want to re-edit these export as a format that matches the bit-depth of the original. Avoid Jpeg for anything that you will re-edit. PNG, Tiff, PSD. If you have adjusted versions of JPEGS, I don't know how much you will lose on export.

Get your master file names in sync with your primary versions names. This will allow you later to get masters and derived pictures back together. You can do this with metadata batch change.