[NeXus-committee] DECTRIS example summary

[V. Armando Sole]

Hi Eugene,

That still does not make transparent the link mechanism (different 
paths) and does not solve the problem that in fact we are segmenting 
what in other case would be a single dataset as Ben pointed out.

Following that approach, the main thing to be made to the supplied file 
is:

- Make sure all the links are in the same NXdata group in the master 
file.
- Add a *new* attribute to that NXdata group in order to let us know 
the "signal" inside is build up of a set of links.

Anybody is free to come with other suggestion. This one has the 
advantage that DECTRIS has almost nothing to do (make sure the links 
-not the targets- are inside an NXdata group) and everything can be 
solved at the master file level (adding attributes to the NXdata group 
in line with the new approach of defining the plots).

Armando

On 14.01.2013 21:24, Wintersberger, Eugen wrote:
> Hi all
>   Ok - if I got the entire discussion right the problem is to access
> metadata for the different blocks as links are entirely transparent 
> in
> HDF5. In order to increase confusion let me make another proposal
> (though I am not sure if someone has already made a suggestion like 
> this
> - I somehow lost track)
>
> master file:
> -----------
> entry:NXentry/instrument:NXinstrument/detector_1
> ....
> entry:NXentry/instrument:NXinstrument/detector_n
> entry:NXentry/data:NXdata/data_1 (link to data in detector_1)
> ...
> entry:NXentry/data:NXdata/data_n (link to data in detector_n)
>
> detector_i is a link to the detector group in the file for the i-th
> image block
>
> image block file:
> ----------------
> entry:NXentry/instrument:NXinstrument/detector:NXdetector/data
>                                                           
> first_image_nr
>                                                           
> last_image_nr
> entry:NXentry/data:NXdata/data (link to data in detector group)
>
> To my opinion this approach has several advantages:
> 1.) because the detector group is linked to the master file all the
>     detector related metadata can be accessed easily
> 2.) as the entire detector group is available the different image
>     blocks can be of different pixels size, geometry, or what ever
> 3.) I have it when detector data is not stored in an NXdetector group
>     along with the metadata.
>
> best regards
>   Eugen
>
> On Mon, 2013-01-14 at 14:38 +0100, Mark Koennecke wrote:
>> Hi,
>>
>> from your feedback and my own study I find that there are the 
>> following
>> problems
>> with the example file as is:
>>
>> - Structure is wrong regarding linked data sets. Should be either:
>>
>>    * entry:NXentry/data_00001:NXdata/data (Preferred ....)
>>    * entry:NXData/data:NXdata/data_0001
>>
>> - On data, signal=1 attribute is missing
>> - On external link, NeXus attribute
>> NAPIMOUNT=nxfile://th02c_ps02_1_data_000001.h5#data
>>    missing
>> - In detector, flatfield, efficiency data is missing. This is not 
>> critical,
>>    I just wonder.
>>
>> Am I right? Is this what I tell DECTRIS tomorrow? Or do I miss 
>> something?
>>
>> Also, what is the opinion, do we need another Telco on this one?
>>
>> Regards,
>>
>>               Mark
>>
>>
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