NXoff_geometry.nxdl.xml

<?xml version="1.0" encoding="UTF-8"?>
<?xml-stylesheet type="text/xsl" href="nxdlformat.xsl" ?>
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<definition xmlns="http://definition.nexusformat.org/nxdl/3.1" category="base"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://definition.nexusformat.org/nxdl/3.1 ../nxdl.xsd"
  name="NXoff_geometry"
  type="group" extends="NXobject">

  <symbols>
    <doc>These symbols will be used below.</doc>
    <symbol name="i"><doc>number of vertices in the shape</doc></symbol>
    <symbol name="k"><doc>number of faces in the shape</doc></symbol>
    <symbol name="l">
      <doc>
        number faces which are detecting surfaces or form the boundary of
        detecting volumes
      </doc>
    </symbol>
  </symbols>

  <doc>
    Geometry (shape) description.
    The format closely matches the Object File Format (OFF) which can be output
    by most CAD software.
    It can be used to describe the shape of any beamline component, including detectors.
    In the case of detectors it can be used to define the shape of a single pixel, or,
    if the pixel shapes are non-uniform, to describe the shape of the whole detector.
  </doc>

  <field name="vertices" type="NX_NUMBER" units="NX_LENGTH">

    <doc>
      List of x,y,z coordinates for vertices.
      The origin of the coordinates is the position of the parent component, for
      example the NXdetector which the geometry describes.
      If the shape describes a single pixel for a detector with uniform pixel
      shape then the origin is the position of each pixel as described by the
      ``x/y/z_pixel_offset`` datasets in ``NXdetector``.
    </doc>

    <dimensions rank="2">
      <dim index="1" value="i" />
      <dim index="2" value="3" />
    </dimensions>

  </field>

  <field name="winding_order" type="NX_INT">

    <doc>
      List of indices of vertices in the ``vertices`` dataset to form each face,
      right-hand rule for face normal.
    </doc>

    <dimensions rank="1">
      <dim index="1" value="j" />
    </dimensions>

  </field>

  <field name="faces" type="NX_INT">

    <doc>The start index in ``winding_order`` for each face.</doc>

    <dimensions rank="1">
      <dim index="1" value="k" />
    </dimensions>

  </field>

  <field name="detector_faces" type="NX_INT">

    <doc>
      List of pairs of index in the "faces" dataset and detector id. Face IDs in
      the first column, and corresponding detector IDs in the second column.
      This dataset should only be used only if the ``NXoff_geometry`` group is
      describing a detector.
      Note, the face indices must be in ascending order but need not be
      consecutive as not every face in faces need be a detecting surface or
      boundary of detecting volume.
      Can use multiple entries with the same detector id to define detector volumes.
    </doc>

    <dimensions rank="2">
      <dim index="1" value="l" />
      <dim index="2" value="2" />
    </dimensions>

  </field>
    <attribute name="default">
        <doc>
            .. index:: plotting
            
            Declares which child group contains a path leading 
            to a :ref:`NXdata` group.
            
            It is recommended (as of NIAC2014) to use this attribute
            to help define the path to the default dataset to be plotted.
            See https://www.nexusformat.org/2014_How_to_find_default_data.html
            for a summary of the discussion.
        </doc>
    </attribute>

</definition>