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Use the Hydrate static function method to create the object from its dehydrated form. The dehydrated form consists of a hash containing the object’s properties and values. The Hydrate and Dehydrate methods let you store the object state in memory and restore it later.

Representing an object as a hash is necessary for running ENVI analytics with the ENVI Task Engine and the ENVI Services Engine.

See the ENVIHydrate function if you are creating a general IDL routine that will restore multiple object types.

For additional information, see "What are Hydrate and Dehydrate routines used for?" in the ENVI API Programming Guide.


; Start the application
; Define the spatial reference object data
rpcLineDenCoeff = [8.2062290D+008, 146530.90D, 2350871.0D, $
  -465666.30D, 1709.5350D, -1829.8090D, -1122.8140D, -109.65130D, $
  -236.17350D, -113.09640D, -1.0511430D, -0.59464460D, 0.28530330D, $
  0.36169420D, -0.14511410D, 0.12011280D, -0.037436850D, -1.3185750D, $
  -0.32494720D, 0.030033410D]
rpcLineNumCoeff = [1.5322480d+008, 4206503.0D, -9.9999990d+008, $
  -577846.10D, -164510.60D, -492.93490D, 657289.40D, -558932.00D, $
  -2868272.0D, 303.33970D, 2065.4790D, -97.933320D, -2082.4690D, $
  28.393320D, -1707.6330D, 281.19970D, 76.317960D, -2031.7740D, $
  1607.2070D, -0.048244400D]
rpcOffsets = [2536.0000D, 3003.0000D, 32.833100D, -117.23340D, 33.000000D]
rpcSampDenCoeff = [5.1351520d+008, 91693.590D, 1471087.0D, -291396.60D, $
  1069.7630D, -1145.0260D, -702.61510D, -68.615710D, -147.78860D, $
  -70.771530D, -0.65776600D, -0.37210640D, 0.17853220D, 0.22633480D, $
  -0.090807010D, 0.075162100D, -0.023426580D, -0.82511530D, $
  -0.20333980D, 0.018793790D]
rpcSampNumCoeff = [2.8127720d+008, 9.9999990d+008, 1970968.0D, $
  -6127672.0D, 2552674.0D, -211183.60D, -70378.780D, 177598.70D, $
  3700.5000D, 1395.2010D, -263.22950D, -51.521790D, -1299.7060D, $
  -214.88460D, 2026.6580D, 0.93249080D, 19.797070D, -1993.1030D, $
  -141.81680D, 1.3218580D]
rpcScales = [2537.0000D, 3004.0000D, 0.027900000D, 0.062500000D, 220.00000D]
; Create a custom spatial reference object
spatialRef1 = ENVIRPCRasterSpatialRef( $
  RPC_LINE_DEN_COEFF = rpcLineDenCoeff, $
  RPC_LINE_NUM_COEFF = rpcLineNumCoeff, RPC_OFFSETS = rpcOffsets, $
  RPC_SAMP_DEN_COEFF = rpcSampDenCoeff, $
  RPC_SAMP_NUM_COEFF = rpcSampNumCoeff, RPC_SCALES = rpcScales)
; Retrieve the dehydrated hash
dehydratedForm = spatialRef1.Dehydrate()
; Restore the object
newSpatialRef = ENVIRPCRasterSpatialRef.Hydrate(dehydratedForm)
Print, newSpatialRef, /IMPLIED_PRINT


Result = ENVIRPCRasterSpatialRef.Hydrate(DehydratedForm, ERROR=value)

Return Value

The result is a reference to a new object instance of the spatial reference.






Required. A string value of RPCRasterSpatialRef indicating what object type the hash represents.


Required. A five-element, double-precision array that specifies the Line_Offset, Sample_Offset, Latitude_Offset, Longitude_Offset, and Height_Offset values. Example:

"rpc_offsets" : [2536.0000, 3003.0000, 32.833100, -117.23340, 33.000000]


Required. A five-element, double-precision array that specifies the Line_Scale, Sample_Scale, Latitude_Scale, Longitude_Scale, and Height_Scale values. Example:

"rpc_scales" : [2537.0000, 3004.0000, 0.027900000, 0.062500000, 220.00000]


Required. A 20-element, double-precision array of RPC line numerator coefficients. Example:

"rpc_line_num_coeff" : [1.5322480d+008, 
4206503.0D, -9.9999990d+008, -577846.10D,
-164510.60D, -492.93490D, 657289.40D,
-558932.00D, -2868272.0D, 303.33970D,
2065.4790D, -97.933320D, -2082.4690D,
28.393320D, -1707.6330D, 281.19970D,
76.317960D, -2031.7740D, 1607.2070D,


Required. A 20-element, double-precision array of RPC line denominator coefficients. Example:

"rpc_line_den_coeff" : [8.2062290D+008, 
146530.90D, 2350871.0D, -465666.30D,
1709.5350D, -1829.8090D, -1122.8140D,
-109.65130D, -236.17350D, -113.09640D,
-1.0511430D, -0.59464460D, 0.28530330D,
0.36169420D, -0.14511410D, 0.12011280D,
-0.037436850D, -1.3185750D, -0.32494720D,


Required. A 20-element, double-precision array of RPC sample numerator coefficients. Example:

"rpc_samp_num_coeff" : [2.8127720d+008, 
9.9999990d+008, 1970968.0D, -6127672.0D,
2552674.0D, -211183.60D, -70378.780D, 177598.70D,
3700.5000D, 1395.2010D, -263.22950D, -51.521790D,
-1299.7060D, -214.88460D, 2026.6580D, 0.93249080D,
19.797070D, -1993.1030D, -141.81680D, 1.3218580D]


Required. A 20-element, double-precision array of RPC sample denominator coefficients. Example:

"rpc_samp_den_coeff" : [5.1351520d+008, 
91693.590D, 1471087.0D, -291396.60D,
1069.7630D, -1145.0260D, -702.61510D,
-68.615710D, -147.78860D, -70.771530D,
-0.65776600D, -0.37210640D, 0.17853220D,
0.22633480D, -0.090807010D, 0.075162100D,
-0.023426580D, -0.82511530D, -0.20333980D,



Set this keyword to a named variable that will contain any error message issued during execution of this routine. If no error occurs, the ERROR variable will be set to a null string (''). If an error occurs and the routine is a function, then the function result will be undefined.

When this keyword is not set and an error occurs, ENVI returns to the caller and execution halts. In this case, the error message is contained within !ERROR_STATE and can be caught using IDL's CATCH routine. See IDL Help for more information on !ERROR_STATE and CATCH.

See Manage Errors for more information on error handling in ENVI programming.

Version History

ENVI 5.4


API Version


See Also

ENVIRPCRasterSpatialRef, ENVIRPCRasterSpatialRef::Dehydrate, ENVIHydratable, ENVIHydrate

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