Parent Topic: FLIGHT

EXAMPLE

We are given a left-looking 8-bit slant range radar image of the Gatineau Park area in Quebec, Canada. The image size is 4096 pixels by 6750 lines. It is stored in database file GATINEAU.PIX. The estimated flight path parameters for this radar image are as follows: 

   Heading                  : 110 Degrees (left-looking)
   Altitude                 : 6550 metres
   UTM of Point on Path     : 413908 E, 5037388 N
We are also given the following data regarding the slant range radar image: 

   Slant Range Pixel Size   : 4 metres (range) by 3.89 metres (azimuth)
   Time Delay to First Pixel: 43.1 microseconds
The user wishes to convert the slant range image to ground range, registered to 8-bit elevation data of Gatineau Park area. The size of the elevation image is 1024 pixels by 1024 lines. It is stored on database file GATDTM.PIX, and has the following characteristics: 

   UTM of Upper Left Corner : 422050 E, 5050800 N
   UTM of Lower Right Corner: 434850 E, 5038000 N
   Elevation Data Pixel Size: 12.5 by 12.5 metres
   Vertical Resolution      : 2 metres ASL per grey-level value
This information would be stored in GATDTM.PIX's georeferencing segment by running program GEOSET: 

 EASI>FILE="gatdtm.pix"
 EASI>UPLEFT =422050,5050800
 EASI>LORIGHT=434850,5038000
 EASI>MAPUNITS="UTM"
 EASI>RUN GEOSET
 EASI>RUN GEOREP
The first step is to collect at least six ground control points, mapping the slant range radar image on GATINEAU.PIX to UTM coordinates within the area covered by the elevation data on GATDTM.PIX. This is accomplished by obtaining a topographical map of the area and running the GCIT program. (See the Geometric Correction Manual).

Before running GCIT, an overview of the radar image must be transferred to the display, and enhanced. 

 EASI>FILE="gatineau.pix"
 EASI>DBIC=1
 EASI>VDOC=1
 EASI>DBIW=
 EASI>VDOW=
 EASI>RUN IVI
 EASI>RUN DCP "ID1 : LE1"
A new GCP segment is created by running the GCIT program. A report of the GCPs can be printed by running the GCPREP program. 

 EASI>FILE="gatineau.pix"
 EASI>DBIC=1
 EASI>DBIW=
 EASI>DBGC=
 EASI>DBSN="SLANTUTM"
 EASI>DBSD="GCP's mapping slant range image to UTM coordinates"
 EASI>SMPL=
 EASI>VDOB=1,2
 EASI>MAPUNITS="UTM"
 EASI>RUN GCIT
 EASI>RUN GCPREP
Now, we can run the FLIGHT program using the GCP segment created by GCIT. All GCPs must be located within the area covered by the elevation data, or the FLIGHT program will print an error message and stop. If any GCPs are outside GATDTM.PIX, GCIT must be run again to delete the invalid GCPs and to add new ones. Initial estimates of flight path parameters are specified. We assume that 8-bit elevation data are stored on the first channel of the file GATDTM.PIX, and that there is a second empty spare channel. MAPTOL defaults to the elevation pixel size as derived from the georeferencing segment (12.5 metres). 180 degrees must be added to the aircraft heading of 110 degrees, because the radar image is left-looking.

The parameters for the FLIGHT program are as follows: 

 EASI>FILE="gatineau.pix"
 EASI>FILM="gatdtm.pix"
 EASI>DBEC=1
 EASI>INPXSZ=4.0,3.89
 EASI>ESCALE=2,0
 EASI>MAPTOL=
 EASI>DELAY=43.1
 EASI>ALTI=6550
 EASI>HEAD=290
 EASI>POINT=413908,5037388
 EASI>ORDER=1
 EASI>RANGETYP="GROUND"
 EASI>HEIGHT=
 EASI>REPORT=
The following report is generated by FLIGHT program: 

  FLIGHT  Flight Path Estimation       V5.1 EASI/PACE  14:47 22-Jul-92

  GCP |       Pixel        Line      Easting     Northing    Elevation
      |                                                        (ASL m) 
 +--------------------------------------------------------------------+
    1 |     1780.50     2561.50    427450.00   5044750.00       184.00
    2 |     1680.50     3907.50    432200.00   5042450.00       208.00
    3 |     3153.50     3090.50    431500.00   5049650.00       114.00
    4 |     2259.50     1240.50    423400.00   5048700.00       170.00
    5 |      532.50     2330.50    424250.00   5039000.00       108.00
    6 |      795.50     3169.50    427900.00   5039300.00       132.00

 Height of aircraft above sea level           :      6898.73 metres
 Heading of aircraft clockwise from due north :       291.43 degrees
 Easting of point flown over by aircraft      :    413908.00
 Northing of point flown over by aircraft     :   5037412.12

 Specified map error tolerance                :        12.50 metres
 Actual residual error                        :        14.48 metres

 WARNING:  Residual error greater than specified map error tolerance.


 1st order equation relating distance from point on flight path (D)
 to line number on slant range radar image (L)

  L =   .339141E+02 + ( -.255050E+00 * D   )

 Standard deviation about regression equation :       12.97 lines
At this point, OALTI, OHEAD, OPOINT, and OCOEFF should contain the correct flight path parameters, which can be input into the STG program. To run STG, use the same parameter values that were used for the FLIGHT program. In this example, the output ground range radar image is transferred to the second channel on the file containing the elevation data. 

 EASI>FILI="gatineau.pix"
 EASI>FILO="gatdtm.pix"
 EASI>DBIC=1
 EASI>DBOC=2
 EASI>DBEC=1
 EASI>RUN STG
Parent Topic: FLIGHT
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