[NeXus-committee] NXgeometry discussion

Peterson, Peter F. petersonpf at ornl.gov
Fri Mar 19 04:49:35 GMT 2004

This is to remind you that today (Friday) is the last day of discussion on NXgeometry and its children.
Currently the NXgeometry http://www.neutron.anl.gov.:8080/NeXus/70 contains NXtranslation, NXorientation, NXshape, and a field for sorting out the order the beam goes through components.
NXtranslation http://www.neutron.anl.gov.:8080/NeXus/71 contains a type to tell what coordinate system is being used (cartesian, cylindrical, or spherical), the coordinates, and (if relative position) a NXgeometry that the NXtranslation is relative to. In the long documentation of the coordinates are a full explanation of the origin and its orientation, and also how a relative position is calculated.
NXorientation http://www.neutron.anl.gov.:8080/NeXus/72 contains six of the direction cosines (the other three are easily calculated) and a NXgeometry that the orientation is relative to.
NXshape http://www.neutron.anl.gov.:8080/NeXus/79 currently has two values, a description of a shape, and the parameters for the shape. Things that really need to be discussed is what are "standard" shapes and what their parameters are; and how to describe an arbitrary shape (i.e. an engine block).
The discussion will be closed at 5:00PM CST so please comment early so people have time to respond.
Peter Peterson
Executive Secretary, NIAC

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