I've tried the methods proposed by John at LightroomSolutions, but it seems to only work well for RAW shooters (I have a mix).
There's two issues exporting from Aperture:
- In some (maybe all?) cases when applying IPTC data to a JPEG master (either in the library or on export), Aperture will reset the Orientation field (so portrait shots get rotated back to landscape).
- The only way Aperture natively exports GPS data (if it was applied from within Aperture, i.e. isn't already in the master) is via the XMP sidecar
Unfortunately Lightroom doesn't even look at the XMP sidecars for JPEG photos, so your options are:
- Include some IPTC data embedded in the JPEG (excluding GPS) and potentially lose the orientation data
- Lose all your IPTC metadata (keywords, face names, ratings, ...) but keep the orientation
- Write a complex script to "post process" your exported files (e.g. copying EXIF data from XMP sidecar into the JPEGs)
Ideally Adobe could resolve this by either
- Providing a way to import from an Aperture library directly (including all metadata that can be converted)
- Allowing the import process to read XMP sidecars for JPEG images (even if the sidecar is then forgotten about after import, as I realise major changes to allow JPEG + XMP side-by-side would be tough)
- Providing a tool to do the "post processing" mentioned above for copying EXIF data from XMP sidecars into JPEGs for a directory hierarchy of exported Aperture projects
(i don't know if Adobe read these forums? not sure where to submit such feedback if they don't, as I've really only just started using Lightroom now that Aperture is on the way out)