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diff --git a/doc/geometry b/doc/geometry new file mode 100644 index 00000000..d4fcdb79 --- /dev/null +++ b/doc/geometry @@ -0,0 +1,52 @@ +CrystFEL detector geometry files +-------------------------------- + +The detector geometry is taken from a text file rather than hardcoded into the +program. Programs which care about the geometry (indexamajig, pattern_sim and +powder_plot) take an argument "--geometry=<file>" (or "-g <file>"), where <file> +contains the geometry. CrystFEL's representation of a detector is broken down +into one or more "panels", each of which has its own location for the centre of +the panel (i.e. the location of the central beam), its own camera length, +resolution and so on. Each panel fits into the overall image taken from the +HDF5 file, defined by minimum and maximum coordinates in x and y. The +coordinates are specified inclusively, meaning that a minimum of 0 and a maximum +of 9 results in ten items. Counting begins from zero. All pixels in the image +must be assigned to a panel. + +See "A note on data orientation" in the top level README file for important +information about how CrystFEL defines the axes. All coordinates (including the +centre coordinates for each panel) are measured according to these axes: there +is no coordinate system local to a panel. + +The syntax for a simple geometry might be as follows: + +; The number of panels +n_panels = 1 + +; "0/" specifies the first (and only) panel. If we had more panels, there would +; be a copy of the following lines but prefixes with "1/", "2/" and so on. + +; The region of the image which belongs to this panel: +0/min_x = 0 +0/max_x = 1023 +0/min_y = 512 +0/max_y = 1023 + +; The coordinates of the central beam which should be +; used for pixels in this panel: +0/cx = 491.9 +0/cy = 440.7 + +; The camera length (in metres) for this panel +0/clen = 67.8e-3 + +; The resolution (in pixels per metre) for this panel +0/res = 13333.3 ; 75 micron pixel size + +; The readout direction (x or y). If more than three peaks are found in +; the same readout region, they are all discarded. This helps to avoid +; problems due to streaks appearing along the readout direction. +0/badrow_direction = y + + +See the "examples" folder for some examples. |