Messages from Usenet group comp.lang.idl-pvwave, compiled by Paulo Penteado
Hello~ I want to overlap contour lines on a map. However, I think it doesn't match exactly (I checked the gridlines).. especially, as it goes to the edge.. Could someone know how to fix it? Here is an example... ;------------------------------- lon = FINDGEN(91) lat = FINDGEN(115) x = 17.0 + lon*(1/6.0) y = 23.0 + lat*(1/6.0) seed=1L temp = sin(x)^2 * cos(x) z = DIST(91,115) LOADCT, 39 WINDOW,1,TITLE='WORLD MAP',xsize=800,ysize=900 CONTOUR, z, x, y, /Follow, position=[0.1,0.1,0.9,0.9] $ , NLevels=20, XStyle=1, YStyle=1, /NoErase, /FILL ;$ MAP_SET, /CYLINDRICAL, LIMIT=[23.0,17.0,42.0,32.0], /CONTINENTS $ , /HIRES, Mlinethick=1., position=[0.1,0.1,0.9,0.9] $ , /Noerase;, /ISOTROPIC MAP_CONTINENTS, /HIRES,color=255, /FILL_CONTINENTS, /CYLINDRICAL ; /mercator MAP_CONTINENTS, /COAST, color=0, /HIRES, /CYLINDRICAL ; /mercator MAP_GRID, charsize=1.25, color=100 ,latdel=2, londel=2 $ , /BOX_axes, GLineStyle=2 ;------------------------------- Thank you. Sincerely. Son
Thanks a lot! Now, it works very well. When you have a time, please explain why 'contour' line should be after 'map_set' when you have a time? Son
Son writes: > When you have a time, please explain why 'contour' line should be > after 'map_set' when you have a time? This is primarily because the "IDL way" is to fit data to map projections, not to fit map projections to data. In any case, it is the MAP_SET call that sets up all the data to device coordinate conversion factors, etc. that are needed for overplotting data on the map. This is similar to what happens when you issue a PLOT command. Cheers, David -- David W. Fanning, Ph.D. Fanning Software Consulting, Inc. Phone: 970-221-0438, E-mail: david@dfanning.com Coyote's Guide to IDL Programming: http://www.dfanning.com/ Toll-Free IDL Book Orders: 1-888-461-0155
In article <62cdb6eb.0309031011.6e9ce978@posting.google.com>, "Son" <shson@darkstar.sr.unh.edu> wrote: > Thanks a lot! > Now, it works very well. > When you have a time, please explain why 'contour' line should be after > 'map_set' when you have a time? Son Try setting the map projection to anything other than mercator (try /goodes) and remove the limit. Plotting the contour before using map_set causes a map to be drawn over the unprojected contour. Contur (ing) after the map_set (with the /over keyword) tells IDL to use the graphics projection that you have already set up.