[NeXus-definitions-tickets] [NeXusDefinitions] #267: timestamps for detector image frames

[NeXus Base Classes and Instrument Definitions]

#267: timestamps for detector image frames
----------------------------+------------------------
 Reporter:  Tobias Richter  |      Owner:  Unassigned
     Type:  enhancement     |     Status:  new
 Priority:  major           |  Milestone:
Component:  general         |   Keywords:
----------------------------+------------------------
 NXdetector has the following commented out:

 {{{
     <!-- TODO missing fields: timestamps for start and stop exposure -->

     <!-- TODO Are start and stop times needed for each pixel? -->

     <!--<field name="start_time" type="NX_DATE_TIME" units="NX_TIME">
                         <doc><!-\- TODO -\->need some documentation
 here</doc>
                         <dimensions rank="3">
                                 <dim index="1" value="i"/>
                                 <dim index="2" value="j"/>
                                 <dim index="3" value="k"/>
                         </dimensions>
                 </field>
                 <field name="stop_time" type="NX_DATE_TIME"
 units="NX_TIME">
                         <doc><!-\- TODO -\->need some documentation
 here</doc>
                         <dimensions rank="3">
                                 <dim index="1" value="i"/>
                                 <dim index="2" value="j"/>
                                 <dim index="3" value="k"/>
                         </dimensions>
                 </field>-->
 }}}

 That information would be very valuable (not per pixel though). And I do
 not like strings for time. NX_DATE_TIME with NX_TIME units makes no sense
 anyway.

 So something like NXlog does would be good:

 {{{

 <field name="start_time" type="NX_FLOAT" units="NX_TIME">
   <doc>number of time units the frame acquisition started after the
 absolute point in time recorded in the start attribute</doc>
   <dimensions rank="1">
      <dim index="1" value="np"/>
   </dimensions>
   <attribute name="start" type="NX_DATE_TIME" />
 </field>
 <field name="stop_time" type="NX_FLOAT" units="NX_TIME">
   <doc>number of time units the frame acquisition stopped after the
 absolute point in time recorded in the start attribute</doc>
   <dimensions rank="1">
     <dim index="1" value="np"/>
   </dimensions>
   <attribute name="start" type="NX_DATE_TIME" />
 </field>
 }}}

 In order not to provide too much redundant information one of the fields
 might be enough, because we have count_time and real_time etc. as well.

-- 
Ticket URL: <http://trac.nexusformat.org/definitions/ticket/267>
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NeXus Base Classes and Instrument Definitions