Messages from Usenet group comp.lang.idl-pvwave, compiled by Paulo Penteado
difference between icontour and contour?
hello, I have a problem with strange artifacts when i use icontour and a map projection. The problem occurs only when i use icontour, not when i use contour. I would like to make a contour plot with the north pole as center of the map. The data and coordinates are stored in three fields, f_data(i,j), f_longitude(i,j), f_latitude(i,j). First I set the projection via map_set, /stereographic, 90, 0, /isotropic, limit = [0, -180, 90, 180], /grid, /continents, latdel=20, londel=20 followed by the contour-plot contour, f_data, f_longitude, f_latitude, /fill, /over The result is correct, as expected. The field is displayed, including the pole. Then I try the same using icontour instead of contour. I choose the 'polar stereographic'-projection and import the fields f_data, f_longitude, f_latitude. Via Insert->Visualization and setting Grid units to 'Degree' and Fill contours to 'True' my f_data is layed over the pole, but there are strange artefacts around the pole. I tried to isolate the problem and used different f_data. Some f_data that are displayed proper and some are not - but in contour they are all displayed correctly. So i think that contour and icontour handle the input fields in a different way. What can I do to get rid of the artefacts? Thanks PS: i use IDL 6.3 for Windows