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--- dac_experiments:geometry [2019/05/08 17:31] – [Example: How to find out my own O-matrix] matthias
+++ dac_experiments:geometry [2026/08/12 05:35] (current) – smerkel
@@ Line 12: / Line 12: @@
 More precise and detailed calculations are available in this file, extracted from the fable project: {{ :processing:fable_geometry_version_1.0.8.pdf |}}.
+===== Omega rotation direction =====
+Pay attention to the direction of the omega rotation. On many beamlines, the direction of omega is opposite to the drawing above. Simple take a picture of your sample, with a negative omega value, a positive omega value, and cross-check.
+In the [[fileformat:prm|Input file for ImageD11 (prm)]], the omega rotation direction is defined with the parameter **omegasign**.
+If you are performing a DAC experiment, the shadows from the DAC opening can help to figure out whether your omega rotation axis is positive (as in the drawing above) or negative.
 ===== Detector orientation =====
@@ Line 19: / Line 27: @@
 Here is an example, taken from an old Fable manual (Note: one of the example is wrong, I did see that some times ago, seb)
-{{ :processing:fableimageorientexample.jpg?nolink&400 |}}
+{{ :processing:fableimageorientexample.jpg?nolink&400 |Fig. 2: Example for the 8 possible orientations of a 2D image}}
 Fig. 2: Example for the 8 possible orientations of a 2D image.
@@ Line 33: / Line 41: @@
 Let's do it for the image at ω1 = -20°
-{{ :dac_experiments:orientations.png?600 |}}
+Images, such as the one below, can be generated with the [[software:timeless_viewer|TIMEleSS Viewer]].
+{{ :dac_experiments:orientations.png?600 |Fig. 3: Example for different orientations of the same image}}
-Fig. 3: Example for different orientations of the same image.
+Fig. 3: Example for different orientations of the same image. Those were generated in Fabian, but you can now get the same in the more modern implementation of the [[software:timeless_viewer|TIMEleSS Viewer]].
 === Step 1 ===