Hello Guys, I am relative a new IDL programer who would appreciate
some help in how to remap a sample data from satellite projection to
Lambert Conformal.
Here are the detail of What I have done so far:
;;INPUTS are 2D- arrays of : DATA, LAT & LON ;;; each 1600*600
inproj = 7 ;Satellite projection
indatum = 0 ; Clarke 1866
yy=WHERE(LAT GE -90.0 AND LAT LE 90.0)
zz=WHERE(LON GE -180.0 AND LON LE 180.0)
inclat=MEAN(lat(yy)) & inclon=MEAN(lon(zz)) ;;input central
lat,lon
inlimit=[MIN(LAT(yy)), MIN(LON(zz)), MAX(LAT(yy)), MAX(LON(zz))]
LAT1=REVERSE(LAT,2) & LON=REVERSE(LON, 2) & DATA=REVERSE(DATA,
2)
;;;Desired output 2D ARRAY of DATA, LAT & LON ;;each 1073* 689
;;; I want the LAT/LON values of the corners of the grid to be :
outproj=104 ; /GCTP lambert conformal conic
outdatum = 0 ; Clarke 1866
outlimit=[238.4459,20.1919, 229.8965,49.9396, 299.1145,50.1054,
290.7919, 20.3317]
outsp1 = 25.0 ; Out standard parallel 1
outsp2 = 25.0 ; Out standard parallel 2
outclat = 37.9 ; Out standard parallel 2
outclon = -97.0 ; Out standard parallel 2
;;Define the malp projections
mapin=MAP_PROJ_INIT(inproj, ELLIPSOID=indatum, CENTER_LATITUDE=inclat,
$
CENTER_LONGITUDE=inclon, limit=inlimit)
mapout= MAP_PROJ_INIT(outproj, /GCTP, ELLIPSOID=outdatum,
STANDARD_PAR1=outsp1,
STANDARD_PAR2=outsp2, CENTER_LATITUDE=outclat,
$
CENTER_LONGITUDE=outclon,
limit=outlimit)
;;;converting lat/lon to UV coord with some help from Mr. Fanning's
docs online
xx=MAP_PROJ_FORWARD(LON(*,0), LAT(*,0),
MAP_STRUCTURE=mapout)
yy=MAP_PROJ_FORWARD(LON(0,*), LAT(0,*),
MAP_STRUCTURE=mapout)
xvec=REFORM(xx[0,*]) & yvec=REFORM(yy[1,*])
xhalf=(xvec[1]-xvec[0])/2.0 & yhalf=(yvec[1]-yvec[0])/2.0
xrange=[xvec[0]-xhalf, xvec[N_ELEMENTS(xvec)-1] +xhalf]
yrange=[yvec[0]-yhalf, yvec[N_ELEMENTS(yvec)-1] +yhalf]
newrange=[xrange[0], yrange[0], xrange[1], yrange[1]]
;;Question: I actually wanted to use “outlimit” which is an 8
element not 4, how
;;can I use that instead?
;;; Remap the data
timgout=MAP_PROJ_IMAGE(data, MAP_STRUCTURE=mapin) ;,
UVRANGE=uvrange) ; inlimit, IMAGE_STRUCTURE=mapin,
imgout=MAP_PROJ_IMAGE(data, newrange, MAP_STRUCTURE=mapout,
UVRANGE=uvrange,
IMAGE_STRUCTURE=mapout)
When I plot this using on a window, the map projection looks right but
the data does not seem to be remapped correctly.
This is my first time using map_proj_init and map_pro_image. Please
help.
Thanks
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