List of Routines By Functionality | MISR Toolkit: Main Page
-Abstract
MTK_SNAP_TO_GRID snaps a region of interest to a MISR grid given a path, resolution and a region
structure. It is not typically called directly, instead it is used by Mtk_ReadData and Mtk_ReadRaw
to adjust the region defined by the SetRegion routines to the grid of the MISR product file to read.
The Mtk_ReadData and Mtk_ReadRaw routines always return data on a MISR grid approximated by the region,
no spatial interpolation is performed (only block assembly). This routines does the snap from region to
grid. It may be useful to perform region to map to coordinate computations without actually reading data.
-Copyright
Copyright (2005), California Institute of Technology.
U.S. Government sponsorship acknowledged.
-I/O
Given:
path MISR path number
resolution resolution
region region structure
the call:
status = MTK_SNAP_TO_GRID( path, resolution, region, mapinfo )
returns:
status 0 on success; otherwise failure
mapinfo map info structure
-Examples
;;
;; Set up input parameters
;;
path = 37
resolution = 275
lat = 66.0
lon = -89.0
lat_extent = 1.5
lon_extent = 1.0
status = MTK_SETREGION_BY_LATLON_EXTENT( lat, lon, lat_extent, lon_extent, "degrees", region )
status = MTK_SNAP_TO_GRID( path, resolution, region, mapinfo )
;;
;; Output...
;;
print, 'path : ', path
print, 'resolution : ', resolution
help, /struct, region
print, '================================================='
help, /struct, mapinfo
IDL outputs:
path : 37
resolution : 275
** Structure <5353c0>, 4 tags, length=32, data length=32, refs=1:
GEO_CTR_LAT DOUBLE 66.000000
GEO_CTR_LON DOUBLE -89.000000
HEXTENT_XLAT DOUBLE 83489.657
HEXTENT_YLON DOUBLE 55659.772
=================================================
** Structure <2866210>, 37 tags, length=1064, data length=1064, refs=1:
PATH LONG 37
START_BLOCK LONG 36
END_BLOCK LONG 37
RESOLUTION LONG 275
RESFACTOR LONG 1
NLINE LONG 640
NSAMPLE LONG 448
PIXEL_CENTER LONG 1
SOM_PATH LONG 37
SOM_ULC_X DOUBLE 12394112.
SOM_ULC_Y DOUBLE 1065762.5
SOM_CTR_X DOUBLE 12481975.
SOM_CTR_Y DOUBLE 1127225.0
SOM_LRC_X DOUBLE 12569838.
SOM_LRC_Y DOUBLE 1188687.5
GEO_ULC_LAT DOUBLE 66.950041
GEO_ULC_LON DOUBLE -89.380321
GEO_URC_LAT DOUBLE 66.451144
GEO_URC_LON DOUBLE -86.901382
GEO_CTR_LAT DOUBLE 66.001338
GEO_CTR_LON DOUBLE -89.003794
GEO_LRC_LAT DOUBLE 65.052256
GEO_LRC_LON DOUBLE -88.652965
GEO_LLC_LAT DOUBLE 65.523048
GEO_LLC_LON DOUBLE -91.031282
PP_PATH LONG 37
PP_PROJCODE LONG 22
PP_ZONECODE LONG -1
PP_SPHERECODE LONG 12
PP_PROJPARAM DOUBLE Array[15]
PP_ULC_BLOCK1 DOUBLE Array[2]
PP_LRC_BLOCK1 DOUBLE Array[2]
PP_NBLOCK LONG 180
PP_NLINE LONG 512
PP_NSAMPLE LONG 2048
PP_RELOFFSET FLOAT Array[179]
PP_RESOLUTION LONG 275
-Particulars
None.
-Required Reading
For important details concerning this module's function, please refer to
the MTK routine MtkSnapToGrid.c.
-Version
-IDL-MTK Version 1.2.0