Thanks for suggestions (and for providing cg*).
Removing /KEEP_ASPECT_RATIO and Position don't make a big difference (http://postimg.org/image/7gthbxqfh/).
Adding
cgMap_Continents, /ADDCMD, MAP_STRUCTURE=mapCoord, Color='red', /hires, LINESTYLE=3, THICK=2, /COUNTRIES, /COASTS
show that my own shape file line up with the vectors drawn by cgMap_Continents but the image is still geometrically off.
The datum of the image use is from MODIS (a sphere with radius = 6371007.181) and can perhaps be the source of the
error? Don't know if this is a standard supported datum or if there are any IDL-ENVI differences in handling geometry?
Regards
/Jonas
Code used:
pro mapmap
compile_opt idl2
e = ENVI(/HEADLESS)
file1 = 'D:\forskning\2015\MOD09A1\XPP\Senegal\MEAN_NPP_SENEGAL.img'
raster1 = e.OpenRaster(file1)
meannpp = raster1.GetData()
cgWindow
shapefile = 'D:\forskning\2015\MBOW_etal\Brandt\data\Senegal_long_rot.sh p'
mapCoord = Obj_New('cgMap', 'SINUSOIDAL', LIMIT=[11, -18, 18, -11], $
CENTER_LATITUDE=0, CENTER_LONGITUDE=0, $
FALSE_EASTING=0, FALSE_NORTHING = 0, SPHERE_RADIUS=6371007.181 )
mapCoord -> AddCmd
cgloadct,53, /Window, /Addcmd
cgImage, meannpp, /ORDER, /WINDOW,MINVALUE=1,maxvalue=2000, MapCoord=mapCoord, /addcmd
cgDrawShapes, shapefile, Colors='black', MapCoord=mapCoord, /projected_XY, /AddCmd
cgMap_Continents, /ADDCMD, MAP_STRUCTURE=mapCoord, Color='red', /hires, LINESTYLE=3, THICK=2, /COUNTRIES, /COASTS
cgMap_Grid, LatDel = 1.0, LonDel = 1.0, /Box_Axes, Color='blue', $
Map_Structure=mapCoord, /AddCmd
END
On 02/10/2015 23:47, David Fanning wrote:
> Jonas Ardo writes:
>
>> I have shape file (covering Senegal) in Sinusoidal projection I like to overlay on an image with the same projection.
>> Plotting the shape file only using cgDrawShapes works fine (http://postimg.org/image/8ax6pgm3x/) but when first using
>> cgImage to draw an image with the shape file on top, the data sets don't line up correctly and there is a geometric
>> mismatch ( http://postimg.org/image/s796ijbjj/).
>> The image and the shape file fit perfectly when displayed using ENVI.
>>
>> What have I missed in order to get a good geometric match between the shape file and the image?
>
> A couple of things, I think. First, it doesn't look to me like your
> image and your map have the same aspect ratio. So, because you keep the
> aspect ratio of your image, it doesn't fit properly into the map
> projection. Second (and possibly related to the first), you use the
> POSITION keyword on your map, but neglect to use it for your image. I
> would remove the KEEP_ASPECT keyword and use the POSITION keyword
> itself. Or, more likely, I would create a window with the aspect ratio
> of the image, since you say it has been created with a map projection.
>
> Also, don't do this:
>
> Color=cgColor('blue')
>
> on Coyote Graphics commands. Just do this:
>
> Color='blue'
>
> Only use cgColor if you are trying to get "normal" IDL commands to
> behave properly. This will avoid problems for people who are still using
> the indexed color model.
>
> Cheers,
>
> David
>
>
--
Jonas Ardö
Lund University, Sweden
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