Bug: Some Gatan DM3 metadata not standardized to OME

[crueden-x]

We have a sample Gatan DM3 dataset for which not all desired metadata is being successfully standardized to OME. Stage position coordinates and timestamps in particular, but a few other fields too.

The dataset in question can be found at gatan/nuno/Prefix_3VBSED_slice_0011.dm3 on the data server.

The following fields were specifically mentioned as desired for standardization:

xPos (m)    -540.422
yPos (m)    -449.049
^ I think there should be a 'micron' - lowercase Mu - character between
  the '(' and the 'm'

Indicated Magnification    6400.0

Pressure (Torr)    0.149491
^ this is a low vaccum measurement; for high vacuum, I remember noting
  that I could not read the value except in Gatan's Digital Micrograph.

Specimen position (um)    26.016023423936744
^ not so important, but I'd like to comment that this probably is, in
  microns, how much the stage was raised (z distance) since an
  arbitrary starting value.

Field of View (m)    21.122219446599484
^ probably also missing a Mu

Spot Size    4000.0

Voltage    1500.0

Sample Time = 3.0

There are also supposed to be variable-width timestamps contained in the file, but they may not even be present in the Original Metadata table right now, so I am not sure whether they are being parsed.

Lastly, some of the above fields may not have an appropriate place in the OME schema yet, so we would need to file separate tickets to cover those.

See the ​metadata from .dm3 files thread on fiji-devel for further details.

[crueden-x]

Another data file which may be useful for working on this ticket: gatan/nuno/Prefix_3VBSED_stack_30_slice_0290.dm3.

[mlinkert]

See #3677 for relevant model changes.

[mlinkert]

Bugs resolved with: ​https://github.com/openmicroscopy/bioformats/pull/408

Model changes are recorded in #3677.