User:Boesecke: Difference between revisions
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The discussion in what format small angle scattering data should be saved is already going on for many years: XML, HDF5, NEXUS etc. I am convinced that this is not the most important question that must be answered. If somebody would decide: "It is BXHN" (just a name) I would not feel better because the most important part would still be missing: What data must be saved, what data are needed for analysis? As beamline scientist and local contact at X-ray scattering beamlines I have always tried to save as much useful metadata as possible together with the (2D) scattering data. I have always tried to make sure that the used geometrical parameters are not contradictory, i.e. well-defined. Many of these metadata are not needed very often, e.g. the proposal number, but some are practically always needed, e.g. the wavelength. The standard geometry is a small angle scattering experiment where the (1D, 2D) detector is perpendicular to the primary beam (required metadata: pixel sizes, wavelength, distance, beam center). I want to be able to analyze in a similar way standard geometry data and data from more complicated geometries, e.g. inclined detectors. I add parameters that default to the standard case when not given. An inclined detector is described by additional rotation angles that are zero when not defined. It can also be necessary to look to the data in a different way, e.g. to construct a physical detector mask, where distances in mm are much more adequate than in 1/nm. | The discussion in what format small angle scattering data should be saved is already going on for many years: XML, HDF5, NEXUS etc. I am convinced that this is not the most important question that must be answered. If somebody would decide: "It is BXHN" (just a name) I would not feel better because the most important part would still be missing: What data must be saved, what data are needed for analysis? As beamline scientist and local contact at X-ray scattering beamlines I have always tried to save as much useful metadata as possible together with the (2D) scattering data. I have always tried to make sure that the used geometrical parameters are not contradictory, i.e. well-defined. Many of these metadata are not needed very often, e.g. the proposal number, but some are practically always needed, e.g. the wavelength. The standard geometry is a small angle scattering experiment where the (1D, 2D) detector is perpendicular to the primary beam (required metadata: pixel sizes, wavelength, distance, beam center). I want to be able to analyze in a similar way standard geometry data and data from more complicated geometries, e.g. inclined detectors. I add parameters that default to the standard case when not given. An inclined detector is described by additional rotation angles that are zero when not defined. It can also be necessary to look to the data in a different way, e.g. to construct a physical detector mask, where distances in mm are much more adequate than in 1/nm. | ||
A description of my parametrization it is shown [[SX parametrization-ref-short 20120217.pdf | here]]. | A description of my parametrization it is shown [[media:SX parametrization-ref-short 20120217.pdf | here]]. | ||
It must be possible to extract the described parameters from a standard SAS file (what are the corresponding NEXUS parameters?). How could/must I save them after refinement in the standard SAS file? I surely do not want to overwrite any raw data, e.g. the monochromator rotation. For me it would be sufficient to write all my own parameters. But I would prefer a common way. | It must be possible to extract the described parameters from a standard SAS file (what are the corresponding NEXUS parameters?). How could/must I save them after refinement in the standard SAS file? I surely do not want to overwrite any raw data, e.g. the monochromator rotation. For me it would be sufficient to write all my own parameters. But I would prefer a common way. | ||
For statistical error propagation calculations I propose the optional use of a variance array that contains the variance of each pixel. | For statistical error propagation calculations I propose the optional use of a variance array that contains the variance of each pixel. | ||
Revision as of 17:03, 18 July 2012
from Peter Boesecke (ESRF, Grenoble)
The discussion in what format small angle scattering data should be saved is already going on for many years: XML, HDF5, NEXUS etc. I am convinced that this is not the most important question that must be answered. If somebody would decide: "It is BXHN" (just a name) I would not feel better because the most important part would still be missing: What data must be saved, what data are needed for analysis? As beamline scientist and local contact at X-ray scattering beamlines I have always tried to save as much useful metadata as possible together with the (2D) scattering data. I have always tried to make sure that the used geometrical parameters are not contradictory, i.e. well-defined. Many of these metadata are not needed very often, e.g. the proposal number, but some are practically always needed, e.g. the wavelength. The standard geometry is a small angle scattering experiment where the (1D, 2D) detector is perpendicular to the primary beam (required metadata: pixel sizes, wavelength, distance, beam center). I want to be able to analyze in a similar way standard geometry data and data from more complicated geometries, e.g. inclined detectors. I add parameters that default to the standard case when not given. An inclined detector is described by additional rotation angles that are zero when not defined. It can also be necessary to look to the data in a different way, e.g. to construct a physical detector mask, where distances in mm are much more adequate than in 1/nm.
A description of my parametrization it is shown here.
It must be possible to extract the described parameters from a standard SAS file (what are the corresponding NEXUS parameters?). How could/must I save them after refinement in the standard SAS file? I surely do not want to overwrite any raw data, e.g. the monochromator rotation. For me it would be sufficient to write all my own parameters. But I would prefer a common way.
For statistical error propagation calculations I propose the optional use of a variance array that contains the variance of each pixel.
