diff options
Diffstat (limited to 'doc/geometry.txt')
| -rw-r--r-- | doc/geometry.txt | 26 |
1 files changed, 22 insertions, 4 deletions
diff --git a/doc/geometry.txt b/doc/geometry.txt index 22e4ae3f..414ad634 100644 --- a/doc/geometry.txt +++ b/doc/geometry.txt @@ -13,10 +13,10 @@ 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. +See "A note on data orientation" below 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: @@ -54,3 +54,21 @@ n_panels = 1 See the "examples" folder for some examples. + + +A note on data orientation +-------------------------- + +In the image data extracted from the HDF5 file, CrystFEL defines "x" as the most +quickly varying coordinate in the data, and "y" as the second most quickly +varying coordinate in the data. It doesn't know what to do with any extra +dimensions in the HDF5 dataset beyond the second. + +The origin, which is considered the lower left corner of the image, is defined +by CrystFEL as the first element in the image data. Positive x points in a +direction to the right, and positive y points upwards. CrystFEL considers the +positive z direction to be the direction of the incident beam completing the +right-handed set of axes. + +The detector surface is currently always assumed to be perpendicular to the +incident beam. |