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From: Dominik K. <dom...@gm...> - 2015-11-15 17:14:28
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Dear xrayutilities-users, recently I implemented a new way of visualizing reciprocal space maps which might be useful for several of you so I decided to post a small explanation here. For the visualization of reciprocal space maps the irregularly spaced experimental data are often "gridded" onto a regular grid. Although this sometimes causes problems [1] its often simply necessary. Especially when any loss of resolution is to be avoided the grid density has to be chosen at limiting values which often cause artifacts in the data. Such artifacts are for example seen in the left most panel of the attached figure. To make this process more smooth I implemented something I call "fuzzy"-gridding. For the 1D case thats described in the appendix of an article about powder diffraction we published earlier this year [2]. The basic idea is to mimic better the experimental conditions in which every data point is actually not a mathematical point but has to be considered to have some extension due to the limited experimental resolution. Considering this resolution in the gridding process by distributing data points fractionally on multiple grid points on can avoid the girdding artifacts very easily (see middle panel of the attached figure). For comparison the figure also shows the visualization with a matplotlib function 'pcolormesh' which in certain cases allows to avoid gridding all-together. see its documentation for details [3]. The code and data to generate the attached image can be found in the example directory of xrayutilities (see GIT master [4]). Fuzzy gridding functions are now available for 1D, 2D and 3D gridders and will be inlcuded in the next release of xrayutilities. Any feedback is welcome! cheers dominik [1] https://sourceforge.net/p/xrayutilities/mailman/message/32836996/ [2] http://scripts.iucr.org/cgi-bin/paper?S1600576715003465 [3] http://matplotlib.org/api/pyplot_api.html#matplotlib.pyplot.pcolormesh [4] https://sourceforge.net/p/xrayutilities/code/ci/master/tree/examples/xrayutilities_fuzzygridding.py |
