Parent Topic: FLIGHT
PARAMETERS
FLIGHT is controlled by the following global parameters:
Name Prompt Count Type
FILE Database File Name 1-64 Char
FILM Database Master File Name 0-64 Char
DBGC Database Ground Control Segment 1 Int
DBEC Database Elevation Channel List 0-1 Int
INPXSZ Input Spacing (range, azimuth) 2 Real
ESCALE Elevation Scale and Offset 0-2 Real
MAPTOL Map Error Tolerance 0-1 Real
DELAY Time Delay to First Input Pixel 1 Real
ALTI Altitude Above Sea Level (m) 1 Real
HEAD Heading Angle in Degrees 1 Real
POINT Point on Flight Path (E, N) 2 Real
ORDER Order of Polynomial Equation 0-1 Int
RANGETYP Range Data Type: SLANT/GROUND 1-6 Char
HEIGHT Height Above Ground (m) 0-1 Real
REPORT Report mode: TERM/OFF/filename 0-64 Char
The following parameters receive output:
OALTI Altitude Above Sea Level (m) 1 Real
OHEAD Heading Angle in Degrees 1 Real
OPOINT Point on Flight Path (E, N) 2 Real
OCOEFF Coefficients for Line Function 2-9 Real
FILE
Specifies the name of the PCIDSK database file containing the SAR
slant or ground range input image and ground control point segment
(DBGC).
EASI>FILE="filespec"
FILM
Specifies the name of the master PCIDSK database file containing the
elevation image (DBEC). FILM will contain the corrected SAR image
output by STG. If FILM is not specified, then it defaults to FILE.
EASI>FILM="filespec" | FILE and FILM are different
EASI>FILM= | FILE and FILM are the same
DBGC
Specifies the database ground control point segment which contains
the GCPs which map the input SAR image on the uncorrected file
(FILE) to the elevation image (DBEC) on the master file (FILM). The
GCP segment must be on the uncorrected file (FILE). Coordinates must
be in either PIXEL units or the georeferencing units of the master
image. If DBEC is not specified, then the elevation for each GCP is
taken from the GCP segment.
EASI>DBGC=segment | existing GCP segment number
There must be at least ORDER+2 GCPs on the GCP segment. If ORDER=1
(default value), then 4 to 6 GCPs are required for accurate results.
If DBEC is specified and there are GCPs whose coordinates are not
within the master image, then an error message is printed and the
program terminates.
DBEC
Specifies the image channel containing the elevation data on the
master file. The elevation image must be geometrically corrected and
registered. If DBEC is not specified, then the elevation for each
GCP is taken from the ground control point segment (DBGC).
EASI>DBEC=i | elevation channel on master image
EASI>DBEC= | elevation is taken from GCP segment
INPXSZ
Specifies the pixel spacing of the input slant or ground range SAR
image in metres, for both horizontal (range) and vertical (azimuth)
directions.
EASI>INPXSZ=Xsize,Ysize | two real values
ESCALE
Optionally specifies the scale and offset to apply to the elevation
values in the elevation channel (DBEC) to convert values to metres.
If not specified, scale defaults to 1, and offset defaults to 0.
EASI>ESCALE= | no scaling
EASI>ESCALE=scale | scale (no offset)
EASI>ESCALE=scale,offset | scale and offset
The equation for the conversion is:
elevation in metres = scale * (value + offset)
For example, to convert elevation values from feet to metres, where
a value of 0 represents 1000 feet:
EASI>ESCALE=0.3048,1000 | metres = 0.3048 * (value + 1000)
MAPTOL
Specifies map error tolerance in metres, used to determine when the
estimates for the output flight path parameters (OALTI, OHEAD, and
OPOINT) have reached a desired level of accuracy. If MAPTOL is not
specified, it defaults to the horizontal pixel size of the elevation
data defined by FILM's georeferencing segment.
EASI>MAPTOL= | defaults to elevation pixel size
EASI>MAPTOL=error | positive real value
DELAY
Specifies the radar time delay (in microseconds) to the first input
SAR pixel.
EASI>DELAY=microseconds | positive real number
DELAY is used to determine the slant range distance in metres to the
first input pixel in the SAR image. This is calculated using the
following formula, where the speed of light is 299.793 m per
microsec.:
slant range distance = DELAY * speed of light / 2
ALTI
Specifies an estimate of the aircraft platform altitude in metres
above sea level. If there are no elevation data (DBEC is defaulted),
then ALTI specifies the estimated altitude above ground instead.
ALTI must be specified.
EASI>ALTI=x | positive real value
If RANGETYP="GROUND", then the HEIGHT parameter must also be
specified.
HEAD
Specifies an estimate of the aircraft heading in degrees clockwise
from due north. If radar image is left-looking, then 180 degrees
must be added or subtracted from the actual heading angle. If this
is not done, the resulting image from STG will be empty!
EASI>HEAD=angle | real value between 0.0 and 360.0
POINT
Specifies an estimate of the coordinates of any point on the flight
path. Coordinates must be specified using the georeferencing units
of the master image (usually UTM).
EASI>POINT=easting,northing | positive real values
POINT does not have to specify a coordinate within the area covered
by the elevation data on DBEC.
ORDER
Specifies the order of the polynomial equation which calculates the
line numbers in the input SAR image, given the distance along the
flight path in metres from the UTM coordinate, OPOINT. ORDER
defaults to 1, which means that FLIGHT assumes that the aircraft was
flying at a constant velocity. Specifying higher values for ORDER
allows for variations in the aircraft velocity. ORDER can range from
1 to 8, but is normally set to 1.
EASI>ORDER=i | Integer between 1 and 8
EASI>ORDER= | defaults to 1 = constant velocity
There must be at least ORDER+2 GCPs on GCP segment.
RANGETYP
Specifies the type of input SAR image which is to be corrected. Two
types of SAR data are supported: slant range and ground range.
EASI>RANGETYP="SLANT" | slant range data
EASI>RANGETYP="GROUND" | ground range data
HEIGHT
Specifies the assumed aircraft height in metres above ground, when
the input SAR data is ground range instead of slant range. HEIGHT
must be set to the aircraft height that was assumed when the ground
range image was created.
EASI>HEIGHT=x | positive real value
- If RANGETYP="GROUND", HEIGHT must be specified.
- If RANGETYP="SLANT", HEIGHT is ignored.
REPORT
Specifies the report device to which the generated report should be
appended. FLIGHT generates a report on the calculated flight path
parameters and the GCPs used to estimate them.
EASI>REPORT="filename"
EASI>REPORT= | defaults to terminal output
The following names have special meaning:
EASI>REPORT="TERM" | Output the report to the terminal
EASI>REPORT="DISK" | Append the report to file IMPRPT.LST
EASI>REPORT="OFF" | No report is produced
OALTI
FLIGHT calculates the aircraft altitude in metres above sea level,
and saves the result in the output parameter OALTI. The value of
OALTI must be used as input to STG.
OHEAD
FLIGHT calculates the aircraft heading in degrees clockwise from due
north, and saves the result in the output parameter OHEAD. The value
of OHEAD must be used as input to STG.
OPOINT
FLIGHT calculates the UTM coordinates of a point on the flight path,
and saves the result in the output parameter OPOINT. The value of
OPOINT must be used as input to STG.
OCOEFF
FLIGHT calculates the coefficients of the polynomial function used
to determine the line numbers in the input SAR image, given the
distance along the flight path in metres from OPOINT. The values of
OCOEFF must be used as input to STG.
The output coefficients a,b,c,d,e,f,g,h,i are assigned to OCOEFF in
an ascending order:
L = a + (b * D ) + (c * D**2) + (d * D**3) + (e * D**4)
+ (f * D**5) + (g * D**6) + (h * D**7) + (i * D**8)
D is the distance in metres from OPOINT, and L is the input SAR
image line number. D can be positive or negative, depending on
whether the input line number is ahead or behind the coordinate
specified by OPOINT.
Parent Topic: FLIGHT
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