Hello, I have height data on a two
dimensional equidistant latitude longitude grid and my ultimate goal is
to calculate the curvature of the contours. Here is an illustration of
what I want to do - http://www.indiana.edu/%_______________________________________________ SciPy-User mailing list [hidden email] https://mail.python.org/mailman/listinfo/scipy-user |
It may help you 2017-10-16 15:31 GMT+02:00 ashwin .D <[hidden email]>:
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Yes I looked at that. The thing is my data is in raster coordinates(latitude and longitude - equidistant grid). When I pull out the coordinates from collections are these polygons (vectors) or is the raster entity still retained ? On Mon, Oct 16, 2017 at 7:50 PM, Nicolas Cellier <[hidden email]> wrote:
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If you fear that, you can easily map the raster coordinates to the real ones and convert this after extracting the contour. It's an extra step but should not be a real difficulty.
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Le 16 oct. 2017, à 16:25, "ashwin .D" <[hidden email]> a écrit:
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In reply to this post by Nicolas Cellier
Ashwin, I have found that the scikit image routine find_contours is easier to work with than extracting the data from the ContourSet object as in the cited stackoverflow example. If you do something like from skimage.measure import find_contours cs = find_contours(array, values) (where values are the levels you want for your contours and array is the grid of values) then you get back a list of contour lines. For each contour you have a Nx2 array of effective indices into the array. You can convert to your lat-long grid by multiplying by the appropriate scales. skimage also has a nice routine called grid_points_in_poly which will return a boolean array that is True for all points of the input array that are inside the polygon to which you can use one of the contours as an input. Regards, Jon On Mon, Oct 16, 2017 at 10:31 AM, <[hidden email]> wrote: --
________________________________________________________ Jonathan D. Slavin Harvard-Smithsonian CfA [hidden email] 60 Garden Street, MS 83 phone: (617) 496-7981 Cambridge, MA 02138-1516 cell: (781) 363-0035 USA ________________________________________________________ _______________________________________________ SciPy-User mailing list [hidden email] https://mail.python.org/mailman/listinfo/scipy-user |
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