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Clarify rank and units issues for NXmx and NXtransformations
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For Nxmx, clarify the possibility of 2- or 3-dimensional images by
adding a dataRank variable.

For NXtransformations, as suggested by Andreas Foerster clarify the
handling of units for different transformation types.
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@yayahjb
yayahjb committed Jan 23, 2017
1 parent 85a6952 commit 7bcfb8a
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38 changes: 24 additions & 14 deletions applications/NXmx.nxdl.xml
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Expand Up @@ -38,6 +38,9 @@
two-dimensional images. Some will produce three-dimensional
images, using one of the indices to select a detector element.
</doc>
<symbol name="dataRank">
<doc>rank of the ``data`` field</doc>
</symbol>
<symbol name="np">
<doc>number of scan points</doc>
</symbol>
Expand Down Expand Up @@ -91,10 +94,10 @@
in the field group_index, and the level in the hierarchy
given in the group_parent field. For example if an x-ray
detector, DET, consists of four elements in a rectangular array::
DTL DTR
DLL DLR
DTL DTR
DLL DLR
We could have::

group_names: ["DET", "DTL", "DTR", "DLL", "DLR"]
Expand Down Expand Up @@ -138,7 +141,7 @@
</group>
<group type="NXdetector">
<doc>
Normally the detector group will usually have the name detector
Normally the detector group will have the name ``detector``.
However, in the case of multiple detector elements, each element
needs a uniquely named NXdetector group.
</doc>
Expand All @@ -161,13 +164,16 @@

<field name="data" type="NX_NUMBER">
<doc>
This is the example for a dimension-2 detector. For a
a dimension-3 detector, a rank-4 data field is needed.
For a dimension-2 detector, the rank of the data array will be 3.
For a dimension-3 detector, the rank of the data array will be 4.
This allows for the introduction of the frame number as the
first index.
</doc>
<dimensions rank="3">
<dimensions rank="dataRank">
<dim index="1" value="np" />
<dim index="2" value="i" />
<dim index="3" value="j" />
<dim index="4" value="k" minOccurs="0"/>
</dimensions>
</field>

Expand Down Expand Up @@ -326,9 +332,10 @@

<field name="angular_calibration" type="NX_FLOAT" minOccurs="0">
<doc>Angular calibration data.</doc>
<dimensions rank="2">
<dimensions rank="dataRank">
<dim index="1" value="i" />
<dim index="2" value="j" />
<dim index="3" value="k" minOccurs="0"/>
</dimensions>
</field>

Expand All @@ -341,17 +348,19 @@

<field name="flatfield" type="NX_FLOAT" minOccurs="0">
<doc>Flat field correction data.</doc>
<dimensions rank="2">
<dimensions rank="dataRank">
<dim index="1" value="i" />
<dim index="2" value="j" />
<dim index="3" value="k" minOccurs="0"/>
</dimensions>
</field>

<field name="flatfield_error" type="NX_FLOAT" minOccurs="0">
<doc>Errors of the flat field correction data.</doc>
<dimensions rank="2">
<dimensions rank="dataRank">
<dim index="1" value="i" />
<dim index="2" value="j" />
<dim index="3" value="k" minOccurs="0"/>
</dimensions>
</field>

Expand Down Expand Up @@ -396,9 +405,10 @@
If the full bit depths is not required, providing a
mask with fewer bits is permissible.
</doc>
<dimensions rank="2">
<dimensions rank="dataRank">
<dim index="1" value="i" />
<dim index="2" value="j" />
<dim index="3" value="k" minOccurs="0"/>
</dimensions>
</field>

Expand Down Expand Up @@ -551,10 +561,10 @@

<field name="incident_beam_size" type="NX_FLOAT" units="NX_LENGTH" minOccurs="0">
<doc>
Two-dimensional array of FWHM (if Gaussian or Airy function) or
Two-element array of FWHM (if Gaussian or Airy function) or
diameters (if top hat) of beam in the order x, y
</doc>
<dimensions rank="1" />
<dimensions rank="1" value="2" />
</field>

<field name="profile" type="NX_CHAR" minOccurs="0">
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37 changes: 24 additions & 13 deletions base_classes/NXtransformations.nxdl.xml
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Expand Up @@ -33,11 +33,12 @@
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://definition.nexusformat.org/nxdl/3.1 ../nxdl.xsd"
>
<!--
nxdl.xsd rules do not allow us to show this as a variable name
- we'll use AXISNAME in ALL CAPS for consistency with the
use in NXDATA.
-->
<!--
nxdl.xsd rules do not allow us to show this as a variable name
- we'll use AXISNAME in ALL CAPS for consistency with the
use in NXDATA. We'll use AXISUNITS for the units appropriate
to the type of axis.
-->

<doc>
Collection of axis-based translations and rotations to describe a geometry.
Expand All @@ -49,7 +50,10 @@
There will be one or more transformations (axes) defined by one or more fields
for each transformation. The all-caps name AXISNAME designates the
particular axis generating a transformation (e.g. a rotation axis or a translation
axis or a general axis).
axis or a general axis). The all-caps name AXISUNITS designates the
units appropriate to the transformation_type value, i.e. ``NX_LENGTH`` for
``translation``, ``NX_ANGLE`` for ``rotation``, and ``NX_UNITLESS`` for
``general``.

This class will usually contain all axes of a sample stage or goniometer or
a detector. The NeXus default McSTAS coordinate frame is assumed, but additional
Expand Down Expand Up @@ -93,7 +97,7 @@
This entire explanation is not clear.
-->

<field name="AXISNAME" nameType="any" type="NX_NUMBER" maxOccurs="unbounded">
<field name="AXISNAME" nameType="any" units="AXISUNITS" type="NX_NUMBER" maxOccurs="unbounded">
<doc>
Units need to be appropriate for translation or rotation

Expand All @@ -116,19 +120,26 @@
<item value="general" />
</enumeration>
</attribute>
<attribute name="vector" type="NX_NUMBER">
<attribute name="vector" units="NX_DIMENSIONLESS" type="NX_NUMBER">
<doc>
Three values that define the axis for this transformation
Three values that define the axis for this transformation.
The axis should be normalized to unit length, making it
dimensionless. For ``rotation`` axes, the direction should be
chosen for a right-handed rotation with increasing angle.
For ``translation`` axes the direction should be chosen for
increasing displacement.
</doc>
<dimensions rank="1" value="3" />
</attribute>
<attribute name="offset" type="NX_NUMBER">
<doc>
A fixed offset applied before the transformation (three vector components).
</doc>
<dimensions rank="1" value="3" />
</attribute>
<attribute name="offset_units" type="NX_CHAR">
<doc>
Units of the offset.
Units of the offset. Values should be consistent with NX_LENGTH.
</doc>
</attribute>
<attribute name="depends_on" type="NX_CHAR">
Expand All @@ -138,7 +149,7 @@
</doc>
</attribute>
</field>
<field name="AXISNAME_end" nameType="any" type="NX_NUMBER" minOccurs="0">
<field name="AXISNAME_end" units="AXISUNITS" nameType="any" type="NX_NUMBER" minOccurs="0">
<doc>
AXISNAME_end is a placeholder for a name constructed from the actual
name of an axis to which ``_end`` has been appended.
Expand All @@ -147,7 +158,7 @@
at the corresponding positions given in the AXISNAME field.
</doc>
</field>
<field name="AXISNAME_range" nameType="any" type="NX_NUMBER" minOccurs="0">
<field name="AXISNAME_range" units="AXISUNITS" nameType="any" type="NX_NUMBER" minOccurs="0">
<doc>
AXISNAME_range is a placeholder for a name constructed from the actual
name of an axis to which ``_range`` has been appended.
Expand All @@ -156,7 +167,7 @@
in the field AXISNAME_end and the field AXISNAME.
</doc>
</field>
<field name="AXISNAME_average_range" nameType="any" type="NX_NUMBER" minOccurs="0">
<field name="AXISNAME_average_range" units="AXISUNITS" nameType="any" type="NX_NUMBER" minOccurs="0">
<doc>
AXISNAME_average_range is a placeholder for a name constructed from the actual
name of an axis to which ``_average_range`` has been appended.
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