Madhavan Bomidi writes:
> After running my program above by correcting size and
> window to 600 by 600, I find that the image from the above l
> ink of google statics is enlarged in area and covers more
> portion of above/below, side-ways in comparison to the above
> link image.
I don't understand what this means. When I make the same changes to my
code (from your program) the map coordinates *exactly* match the image,
which is exactly what they are suppose to do. If you would like to "zoom
into" your image, you will have to trim both the image and the xrange
and yrange limits of the map coordinate object appropriately
> Is there a way I can provide the limits of lat-lon axis that I
> want to overlay on the google statics map?
A vector of X and Y projected meter values associated with the image can
be constructed like this:
dims = Image_Dimensions(googleImage, XSIZE=xsize, YSIZE=ysize)
xvec = cgScaleVector(Dindgen(xsize) + 1, xrange[0], xrange[1])
yvec = cgScaleVector(Dindgen(ysize) + 1, yrange[0], yrange[1])
If you wanted to trim 50 pixels of the left of the image and 100 pixels
off the right of the image. You might do something like this:
googleImage = googleImage[*, 50:xsize-100, *]
You will have to re-define your xrange accordingly:
xrange = [xvec[50],xvec[xsize-100]]
Here is the code I'm using.
PRO Google_Map_Plot
; Set up variables for the plot. Normally, these values would be
; passed into the program as positional and keyword parameters.
centerLat= 51.525517D ; (Max(Lats) + Min(Lats)) / 2.0 deg. N
centerLon= 12.927633D ; (Max(Lons) + Min(Lons)) / 2.0 deg. E
zoom = 16
scale = cgGoogle_MetersPerPixel(zoom)
; Gather the Google Map using the Google Static Map API.
googleStr = "http://maps.googleapis.com/maps/api/staticmap?" + $
"center=" + StrTrim(centerLat,2) + ',' + StrTrim(centerLon,2) + $
"&zoom=" + StrTrim(zoom,2) + "&size=600x600" + $
"&maptype=satellite&sensor=false&format=png32"
netObject = Obj_New('IDLnetURL')
void = netObject -> Get(URL=googleStr, FILENAME="googleimg.png")
Obj_Destroy, netObject
googleImage = Read_Image('googleimg.png')
; Set up the map projection information to be able to draw on top
; of the Google map.
map = Obj_New('cgMap', 'Mercator', ELLIPSOID='WGS 84', /OnImage)
uv = map -> Forward(centerLon, centerLat)
uv_xcenter = uv[0,0]
uv_ycenter = uv[1,0]
xrange = [uv_xcenter - (300*scale), uv_xcenter + (300*scale)]
yrange = [uv_ycenter - (300*scale), uv_ycenter + (300*scale)]
; Trim the image and xrange 50 pixels on left and 100 on right.
dims = Image_Dimensions(googleImage, XSIZE=xsize, YSIZE=ysize)
xvec = cgScaleVector(Dindgen(xsize) + 1, xrange[0], xrange[1])
yvec = cgScaleVector(Dindgen(ysize) + 1, yrange[0], yrange[1])
googleImage = googleImage[*, 50:xsize-100, *]
xrange = [xvec[50],xvec[xsize-100]]
map -> SetProperty, XRANGE=xrange, YRANGE=yrange
; Open a window and display the Google Image with a map grid and
; location of Coyote's favorite prairie dog restaurant.
cgDisplay, 700, 700, Title='Google Image with Coyote Graphics'
cgImage, googleImage[0:2,*,*], /Keep_Aspect, $
Position=[50, 50, 650, 650] / 700., OPOS=opos
map -> SetProperty, POSITION=opos
cgMap_Grid, MAP=map, /BOX_AXES, /cgGRID
cgPlotS, -105.1, 40.6, PSYM='filledstar', SYMSIZE=3.0, $
MAP=map, COLOR='red'
; Overlay the points on the map
geo_lon=[ 12.928891,12.926434,12.925875,12.922277,12.913507,12.925407, $
12.927663,12.927191,12.928041,12.926399,12.925676,12.926233, $
12.942073,12.927199,12.927197,12.927209,12.941039,12.922861, $
12.925361,12.928772,12.937340,12.927910,12.926749,12.929081, $
12.930733,12.917927,12.937282,12.940540,12.931345,12.920242, $
12.927734,12.934965,12.913434,12.926365,12.925563,12.925388, $
12.926150,12.927432,12.928548,12.925627,12.928129,12.927163, $
12.928032,12.929043,12.919992,12.931943,12.927277,12.928178, $
12.916696,12.926318]
geo_lat=[51.525643,51.528963,51.529627,51.526104,51.526895, $
51.525046,51.525569,51.525998,51.529957,51.526427,51.525457, $
51.525176,51.527107,51.525662,51.525315,51.524935,51.520126, $
51.522013,51.525613,51.526004,51.525096,51.526548,51.525709, $
51.518588,51.522657,51.525658,51.519825,51.536149,51.526332, $
51.519956,51.535018,51.531251,51.518749,51.525994,51.525979, $
51.524687,51.525668,51.521689,51.526567,51.526391,51.525455, $
51.526486,51.525986,51.525204,51.528715,51.527705,51.522675, $
51.525066,51.534141,51.524814]
PRINT, MAX(geo_lon),MIN(geo_lon),MAX(geo_lat),MIN(geo_lat)
numColors = N_Elements(geo_lon)
cgLoadCT, 33, NColors=numColors
cgPlotS, geo_lon, geo_lat, COLOR=Bindgen(numColors), $
PSYM=16, SYMSIZE=1.2,MAP_OBJECT=map
END ;*********************************************************** ******
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
Sepore ma de ni thue. ("Perhaps thou speakest truth.")
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