Hello All,
Thanks for the suggestions. I have an array of latitude, longitude coordinates from GPS measurements from various stations with corresponding variability (i.e., standard deviation) over a period of operation. I am trying to plot the errorbars of latitude and longitude on a latitude-longitude axes. I am first obtaining the latitude-longitude axes and then projecting the lat-lon points. Next, I wanted to plot the errorbars corresponding to lat and lon values by using the commands as suggested in the example of Coyote graphics. While I see the figures and the points on the lat-lon axes nicely, I don't see the error bars and x-y labels. Can you suggest where I am going wrong? Below is my IDL code for your reference...
; ---------------------------------------------
PRO test_errorPlot
xlon = longitude
ylat = latitude
xstd = lon_err & ystd = lat_err
x_higherr=(xlon + xstd) & x_lowerr=(xlon - xstd)
y_higherr=(ylat + ystd) & y_lowerr=(ylat - ystd)
; Set up variables for the plot
xtitle='Longitude'
ytitle='Latitude'
title='Errorbar Plot'
position = [0.125, 0.125, 0.9, 0.925]
thick = (!D.Name EQ 'PS') ? 3 : 1
; Data Projection to Map coordinates
Lats=[50.84D,50.96D] ; deg.N
Lons=[6.36D,6.50D] ; deg E
centerLat=(Max(Lats) + Min(Lats)) / 2.0
centerLon=(Max(Lons) + Min(Lons)) / 2.0
zoom=12
scale = cgGoogle_MetersPerPixel(zoom)
xsize = 600 < 640 ; Max size of Google image with this Google API
ysize = 600 < 640 ; Max size of Google image with this Google API
resolution = STRTRIM(xsize,2) + 'x' + STRTRIM(ysize,2)
map = Obj_New('cgMap', 'Mercator', ELLIPSOID='WGS 84')
uv = map -> Forward(centerLon, centerLat)
uv_xcenter = uv[0,0]
uv_ycenter = uv[1,0]
xrange = [uv_xcenter - (xsize/2.0D*scale), uv_xcenter + (xsize/2.0D*scale)]
yrange = [uv_ycenter - (ysize/2.0D*scale), uv_ycenter + (ysize/2.0D*scale)]
map -> SetProperty, XRANGE=xrange, YRANGE=yrange
cgDisplay, 600, 500, Title=title
cgMap_Grid, MAP=map, /BOX_AXES, /cgGRID, FORMAT='(F0.2)'
cgPlotS, xlon, ylat, PSYM=16, SYMSIZE=1.2, MAP=map, COLOR='red'
; Draw the error bars in the signal Y
cgErrPlot, xlon, y_lowerr, y_higherr, COLOR='blu5',Thick=thick
; Draw the error bars in the signal X
cgErrPlot, ylat, x_lowerr, x_higherr, COLOR='blu5',Thick=thick, /Horizontal
END
; Display the plot in a graphics window.
cgDisplay, 600, 500
test_errorPlot
; Create a PostScript file.
cgPS_Open, Filename='test_errorPlot.ps'
test_errorPlot
cgPS_Close
; Create a PNG file with a width of 600 pixels.
cgPS2Raster, 'test_errorPlot.ps', /PNG
END
;-------------------------------------
Thanks in advance
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