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| Name | Type | Caption | Length | Value range |
|---|---|---|---|---|
| FILE * | String | Input file name | 1 - 192 | |
| FILM | String | Master file name | 0 - 192 | |
| DBGC * | Integer | Input Ground Control Point segment | 1 - 1 | |
| ORDER | Integer | Order of Polynomial Equation | 0 - 1 | 1, 2, 3, 4, 5 Default: |
| REPORT | String | Report mode | 0 - 192 | Quick links |
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FILE
Specifies name of the PCIDSK file containing the Ground Control Point (GCP) segment from which to generate the report.
FILM
Specifies the path and file name of the PCIDSK file that contains the master (reference) image to which the GCPs are tied. If this parameter is specified, the georeferencing is used to convert the GCPs to FILM pixel and line coordinates. If unspecified, no conversion of the GCPs is performed.
DBGC
Specifies the input GCP segment or layer for which to generate a report.
ORDER
Specifies the order of the polynomial equation used for the regression model that is used to fit the corrected-to-uncorrected GCP coordinates. If this parameter is not specified, the GCPs are printed with elevation values, but without the regression model.
The value used for ORDER is typically produced when collecting GCPs. If there are not enough GCPs for the specified order, a warning is displayed and the highest order allowable is used.
6 2nd 10 3rd 15 4th 21 5th
To obtain good results, it is best to have 2 or 3 times the minimum number of GCPs for a particular order; for example, 12 to 18 GCPs for 2nd ORDER. The GCPs should also be evenly distributed over the entire uncorrected image.
REPORT
Specifies where to direct the generated report.
Available options are:
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GCPREP writes the contents of a ground control point segment held in a PCIDSK database to a report device. If ORDER is not specified, only the GCP coordinates and elevation values are printed. If ORDER is specified, GCP coordinates (without elevation) are printed along with information on the generated regression model and residuals for each GCP.
If GCP coordinates are stored in LONG/LAT units, then coordinate values are reported as degrees, minutes, seconds and hemisphere.
A report device (REPORT) must be selected. If the report device is "OFF", GCPREP will force its output to the user's terminal.
GCP report
GCPREP can generate two types of reports
If ORDER is not specified, GCPREP prints a dump of the segment. This is divided into two sections:
If ORDER is specified, GCPREP generates a regression model that maps the input GCP set to the output GCP set, the list of GCP coordinate pairs, and a residual report. This is divided into four sections:
Each of these sections is described in greater detail below.
General information
The general information section gives the file name and data on the segment including:
Regression model
The regression model used to map the input set of GCPs to the output set of GCPs has the following form:
k k-j \
X' = FX(X,Y) = SUM SUM BX(i,j) X**i Y**j |
j=0 i=0 |
> k = specified order
k k-j | (1,2,3,4, or 5)
Y' = FY(X,Y) = SUM SUM BY(i,j) X**i Y**j |
j=0 i=0 /
where:
GCP list
If ORDER is not specified, each GCP coordinate pair are listed with elevation values, but without any extra information.
If ORDER is specified, the GCP coordinate pairs are listed along with information about how well they fit the regression model.
For each GCP, the residual is calculated as follows:
From this is subtracted the actual Set 1 value (U,V)
The calculation is expressed as follows:
residual X = FX(X,Y) - U = X' - U
residual Y = FY(X,Y) - V = Y' - V
The distance measure gives a single value for the error in a GCP pair, given the current regression model.
The calculation is expressed as follows:
distance = sqrt ((residual X)**2 + (residual Y)**2)
Residual report
The residual report provides a graphical representation of the distribution of error. Each GCP point is plotted with respect to its residual error in the X and Y axis. Points with high error are further away from the center. The right-most digit represents the location for a GCP's residual. For example, for GCP 12, the GCP residual would be where the 2 lies.
The RMS error (root of mean square) and distance provide an estimate of the overall error for the entire collection of GCPs (where N is the number of GCPs and K is the number of terms for the specified order):
RMS for X = sqrt ( sum( (residual X)**2 ) / (N - K) )
RMS for Y = sqrt ( sum( (residual Y)**2 ) / (N - K) )
RMS Distance = sqrt ( (RMS for X)**2 + (RMS for Y)**2 )
where: - K is 3 degrees of freedom for a 1st "ORDER" model.
6 2nd
10 3rd
15 4th
21 5th
If there are as many or fewer GCPs than K, the RMS error is reported as N/A (Not Applicable).
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The file irvine.pix has 22 GCP points stored on segment 27. A report on these GCPs is generated:
EASI> FILE = "irvine.pix" EASI> FILM = EASI> DBGC = 27 EASI> ORDER = EASI> REPORT = "TERM" EASI> R GCPREP
irvine.pix [S 11PIC 512P 512L] 14-Aug-90 27:GCPIRV Type:214 [Ground Control Points] Last Update:30-Apr-97 Contents: 22 GCP's to REG Irvine to Eltoro Set 2 Units:UTM 11 S E000 Set 1 Units:PIXEL Number GCPs:22 GCP SET 2 GCP's ELEV. SET 1 GCP's ELEV. Id -(UTM 11 S E000)-- (METER) -------(PIXEL)------- (METRE) 1 ( 430915.00, 3731875.00, 0.0)( 76.50, 90.50, 0.0) 2 ( 432995.00, 3730885.00, 0.0)( 140.50, 117.50, 0.0) 3 ( 440175.00, 3730845.00, 0.0)( 380.50, 118.50, 0.0) 4 ( 438175.00, 3730915.00, 0.0)( 312.50, 116.50, 0.0) 5 ( 431695.00, 3728745.00, 0.0)( 99.50, 187.50, 0.0) 6 ( 433145.00, 3728595.00, 0.0)( 147.50, 193.50, 0.0) 7 ( 436175.00, 3728205.00, 0.0)( 247.50, 206.50, 0.0) 8 ( 439075.00, 3727805.00, 0.0)( 344.50, 217.50, 0.0) 9 ( 440555.00, 3729145.00, 0.0)( 393.50, 175.50, 0.0) 10 ( 431535.00, 3725885.00, 0.0)( 94.50, 281.50, 0.0) 11 ( 433385.00, 3725775.00, 0.0)( 155.50, 284.50, 0.0) 12 ( 438465.00, 3725915.00, 0.0)( 323.50, 280.50, 0.0) 13 ( 432645.00, 3724785.00, 0.0)( 131.50, 318.50, 0.0) 14 ( 431185.00, 3725045.00, 0.0)( 82.50, 311.50, 0.0) 15 ( 438135.00, 3724665.00, 0.0)( 312.50, 320.50, 0.0) 16 ( 440525.00, 3724495.00, 0.0)( 391.50, 325.50, 0.0) 17 ( 431815.00, 3722865.00, 0.0)( 102.50, 383.50, 0.0) 18 ( 433965.00, 3722615.00, 0.0)( 173.50, 389.50, 0.0) 19 ( 436435.00, 3723025.00, 0.0)( 255.50, 375.50, 0.0) 20 ( 440275.00, 3722335.00, 0.0)( 382.50, 396.50, 0.0) 21 ( 436155.00, 3725045.00, 0.0)( 246.50, 309.50, 0.0) 22 ( 432635.00, 3725865.00, 0.0)( 130.50, 283.50, 0.0)
The file > has 22 GCP points stored on segment 27. A report on these GCPs along with a residual report for a 2nd order regression model is generated:
EASI> FILE = "irvine.pix" EASI> FILM = EASI> DBGC = 27 EASI> ORDER = 2 EASI> REPORT = "TERM" EASI> R GCPREP
irvine.pix [S 11PIC 512P 512L] 14-Aug-90 27:GCPIRV Type:214 [Ground Control Points] Last Update:30-Apr-97 Contents: 22 GCP's to REG Irvine to Eltoro Set 2 Units:UTM 11 S E000 Set 1 Units:PIXEL Number GCPs:22 Model Parameters FX FY 1 CONS -.515408046498260E+06 0.103816404717361E+07 2 X 0.409770039935630E-01 -.939822785479323E-01 3 Y 0.267968956042250E+00 -.513255793267947E+00 4 X * Y -.152523277662878E-07 0.180093763456064E-07 5 X**2 0.561412397840845E-07 0.304930209797344E-07 6 Y**2 -.350472150304014E-07 0.634172878188551E-07 GCP's are ordered from worst to best residuals. GCP Set 2 GCP's Set 1 GCP's Residual Distance No. -(UTM 11 S E000)- ---(PIXEL)---- -------(PIXEL)------- 1( 430915.0, 3731875.0)( 76.5, 90.5)( 1.88, 2.20) 2.90 2( 432995.0, 3730885.0)( 140.5, 117.5)( -2.02, -1.77) 2.69 5( 431695.0, 3728745.0)( 99.5, 187.5)( -0.73, -1.69) 1.84 : : : : : : : 6( 433145.0, 3728595.0)( 147.5, 193.5)( -0.09, 0.10) 0.13
Residual Plot (PIXEL): RMS=( 0.87, 1.21) 1.49 +-------------------+-------------------+ | | 1 | | | | | | | | |7 | | | 9 | | |12 | | 1417 | | | 22| | | | 19 | +------------------6+-15--13------------+ | |18 8 | | 16 | | | 4 | | | 20 | 11 | | | | | 10| | | 2 5 | | | | | | | | +-------------------+-------------------+
The file irvine.pix has 22 GCP points stored on segment 27. A report on these GCPs along with a residual report for a 2nd order regression model is generated. The GCPs are scaled according to the georeference information read from eltoro.pix:
EASI> FILE = "irvine.pix" EASI> FILM = "eltoro.pix" EASI> DBGC = 27 EASI> ORDER = 2 EASI> REPORT = "TERM" EASI> R GCPREP
irvine.pix [S 11PIC 512P 512L] 14-Aug-90 27:GCPIRV Type:214 [Ground Control Points] Last Update:30-Apr-97 Contents: 22 GCP's to REG Irvine to Eltoro Set 2 Units:UTM 11 S E000 Set 1 Units:PIXEL Number GCPs:22 Model Parameters FX FY 1 CONS 4.248559735234818e+05 1.112639580071419e+06 2 X -4.622317506994889e+00 -1.347636184887232e+00 3 Y 2.101431063347210e-01 -4.452972525942169e-01 4 X * Y 1.536511648182455e-07 -1.800426295263713e-07 5 X**2 5.640856900238640e-06 3.066117394856329e-06 6 Y**2 -3.497643161233199e-08 6.331545267690559e-08 GCP's are ordered from worst to best residuals. GCP Set 2 GCP's Set 1 GCP's Residual Distance No. -(UTM 11 S E000)- ---(PIXEL)---- -------(PIXEL)------- 1( 430915.0, 3731875.0)( 76.5, 90.5)( 1.88, 2.20) 2.89 2( 432995.0, 3730885.0)( 140.5, 117.5)( -2.02, -1.77) 2.69 5( 431695.0, 3728745.0)( 99.5, 187.5)( -0.74, -1.69) 1.84 : : : : : : : 6( 433145.0, 3728595.0)( 147.5, 193.5)( -0.09, 0.10) 0.13 Residual Plot (PIXEL): RMS=( 0.87, 1.21) 1.49 +-------------------+-------------------+ | | 1 | | | | | | | | | 7 | | | 9 | | |12 | | 1417 | | | 22| | | | 19 | +------------------6+-15--13------------+ | |18 8 | | 16 | | | 4 | | | 20 | 11 | | | | | 10| | | 2 5 | | | | | | | | +-------------------+-------------------+
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