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INTEGRATE: Difference between revisions
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→How does INTEGRATE work?
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* the program does ''not'' look around each reflection to detect an overlap situation, it just gathers the pixels for each reflection. | * the program does ''not'' look around each reflection to detect an overlap situation, it just gathers the pixels for each reflection. | ||
* if two reflections differ in phi, but have the same position on the detector, then, as a consequence of step 1 the pixels are assigned to that reflection whose phi-calc is closest to the phi of the frame considered. The relative intensities of these reflections are not taken into account because at this stage they are unknown! Thus, ''no deconvolution is attempted''. | * if two reflections differ in phi, but have the same position on the detector, then, as a consequence of step 1 the pixels are assigned to that reflection whose phi-calc is closest to the phi of the frame considered. The relative intensities of these reflections are not taken into account because at this stage they are unknown! Thus, ''no deconvolution is attempted''. | ||
* as a user, when your crystal-detector distance was chosen too low, or the reflections are very broad, or if the crystal has a high mosaicity (all of which result in many overlaps), you may try reducing MINPK down to some percentage between 75 and (say) 50. This will result in more completeness, ''but you should monitor the quality of the resulting data''. Conversely, if you raise MINPK above | * as a user, when your crystal-detector distance was chosen too low, or the reflections are very broad, or if the crystal has a high mosaicity (all of which result in many overlaps), you may try reducing MINPK down to some percentage between 75 (the default) and (say) 50. This will result in more completeness, ''but you should monitor the quality of the resulting data''. Conversely, if you raise MINPK above 75 you will discard more reflections, but the resulting dataset may be cleaner - again: ''check the statistics''. In particular, the latest version of [[XDSSTAT]] prints out R_meas as a function of PEAK and intensity. | ||
* this method degrades if the average profiles cannot be completey formed, as the scaling-up relies on their accuracy. This may happen if the reflections are too close in x,y and, at the same time, the mosaicity is high (such that no lunes exist, with edges that help constructing the average profiles). ''It is therefore useful to check the printed profiles in INTEGRATE.LP''. | * this method degrades if the average profiles cannot be completey formed, as the scaling-up relies on their accuracy. This may happen if the reflections are too close in x,y and, at the same time, the mosaicity is high (such that no lunes exist, with edges that help constructing the average profiles). ''It is therefore useful to check the printed profiles in INTEGRATE.LP''. | ||