AT_2D Class Function Manual

ADJUST

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Purpose

To perform a block adjustment.  There are three type of adjustment model made available, namely "conformal", "affine" and "poly2nd". 

Each type ofadjustment requires a certain minimum number of tie point and ground control points.  For example "conformal" requires that there are at least 3 ground control points, and they are at least 3 tie-points in each single photographs. If this requirement is not fulfilled, then singularity occurs.

Minimum requirement for "conformal" is 2 points, for "affine" is 3 points, and for "poly2nd" is 6 points.

Please note that all observed points are treated as tie points, thus they form equations, no matter whether it is a single point or tie point.  However, single points will not get adjusted, hence no residual.

The input Ground control point file can contain points which are not measured in model and they will be automatically discard by the program.

The function requires a filename to store the adjustment result.  If file name extensions are omitted, the function will add default extensions to the files.  The default extension of the camera file is ".txt".  if a path name is not include in the specified file name, the function will store the file in the current data path, set by command "set path".

***** Important Note: sd_xpyp and sd_gcp which are used as default value for SD if it is omitted in the input measuring file, must be set BEFORE reading data (loadobs, and loadgcp).

Class

AT_2D

Usage

{Matrix} ret  =  object.ADJUST({String} argm1, {String} argm2)

argm1 = filename to store the adjustment result

argm2 = type of adjusment, must be "conformal", "affine", or "poly2nd"

        (default is "conformal")

Example:

->BLK = AT_2D()

->BLK.sd_gcp() = 2.50

->BLK.sd_xpyp() = 0.03

->BLK.loadobs("my_input_data")

->BLK.loadgcp("my_gcp")

->BLK.adjust("my_result","affine")

->

See also (class function)

loadobs, loadgcp

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LOADGCP

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Purpose

To load ground control point data from a file.  The file is an ASCII file and must consists of records having 3 or 4 fields, namely point number, x coordinate and y coordinate and SD.  If the last field is omitted, the default SD, set by function "sd_gcp", will be used.  The following shows an example of a ground control point file.  Please note the use of "/" symbol in the data file, which indicates that the particular line is not wanted to be read, could be a comment line, or a wrong piece of data.

If file name extensions are omitted, the function will add default extensions to the files.  The default extension is ".txt".

Unless the path name is given in the file names, the function will search for the files in the current working directory, defined by command "set path".

 

/ read from a 1/250,000 topographic map
/ unit = meter
/ Horizontal GCP
/        Pt no     X              Y             SD
/        1    -667047.376     217712.596     50.000
         2    -619366.596     242930.557     50.000
/        3    -695941.636     247336.830     50.000
         4    -658920.623     180101.449     50.000
         5    -818214.107     164667.097     50.000
         6    -828170.906     166537.475     50.000
         7    -778269.784      91986.820     50.000
         8    -786453.088      15842.096     50.000
/ more....
/ ........

 

 

Class

AT_2D

Usage

{void} object.LOADGCP({String} argm1)

argm1 = ground control point filename

Example:

->BLK = AT_2D()

->BLK.loadgcp("my_gcp")

->

See also (class function)

loadobs, adjust

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LOADOBS

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Purpose

To load observation data, 2D  x y coordiates, from a file.  The file is an ASCII file and must consists of blocks of records having 3 or 4 fields, namely point number, x coordinate and y coordinate and SD.  If the last field is omitted, the default SD, set by function "sd_xpyp", will be used.

Each block in the observation file must start with a number represent the photo number.  Then it is followed by all measurement in that photo.  Then it starts again with the second photo and so on.  Each photo measurement can come in any order.

The following shows an example of a observation data file.  Please note the use of "/" symbol in the data file, which indicates that the particular line is not wanted to be read, could be a comment line, or a wrong piece of data.

Please note that most points do not have SD, and the setting default value will be used.  Points that require a particular SD can be manually assigned, and the program will ignore the default SD and assign the specified SD to them, for example points 8340302, 8340305 in photo 83403 in the file below.

If file name extensions are omitted, the function will add default extensions to the files.  The default extension is ".txt".

Unless the path name is given in the file names, the function will search for the files in the current working directory, defined by command "set path".

 

/ DISP images
/ Observed image rectangular coordinates of tie pts and GCPs, unit = mm
/ acc of image coord observation is 0.030 mm (30 micron)
/ Each block starts with Photo number, then followed by observed coord
/ Pt 1-39 are GCPs, others are tie points

/
83403
         1         -7.061        -14.684
         2         -7.923        -25.338
         3          1.490        -12.127
         4        -15.091        -11.434
         5         -0.513         19.742
         6          0.926         21.424
         7        -18.280         20.074
         8        -31.176         29.713
         9        -40.931         11.865
   8340301          1.691         21.589
   8340302         -8.398          8.378   0.1
   8340303         -8.119         -3.641
   8340304         -4.050        -28.741
   8340305        -11.928        -49.109   0.1
   8340306        -30.515         28.588
   8340307        -34.601         14.616
   8340308        -33.001          1.353
   8340309        -32.061        -12.196
   8440301        -48.182         37.053
   8440302        -49.018         31.561
   8440303        -50.464         19.331
84403
         1         36.679        -15.173
         2         35.217        -25.736
         3         44.914        -12.391
         4         28.095        -11.699
         5         43.508         19.729
         6         44.842         21.426
         7         25.459         20.270
         8         12.054         30.327
         9          1.491         12.210
        11         -8.043         21.699
        12        -34.293         14.372
        13        -43.722         23.487
   8340301         45.562         21.546
   8340302         35.401          8.321
   8340303         35.335         -3.817
   8340304         39.016        -29.154
   8340305         30.451        -49.834
   8340306         12.700         29.172
   8340307          8.450         14.931
   8340308          9.811          1.384
   8340309         10.647        -12.433
   8440301         -5.971         38.189
   8440302         -6.867         32.547
   8440303         -8.492         20.004
   8540301        -53.912         28.264
   8540302        -52.692         21.559
   8540303        -43.371         16.195
   8540304        -35.477         32.885
   8540305        -20.811         21.809
   8540306        -45.454         13.658
85403
/       11         36.060         21.588
        12          8.772         14.554
        13         -0.775         23.976
        14        -30.821          2.558
        15        -30.390         16.663
        16        -48.120         19.385
        17        -48.609          0.613
   8340306         56.640         28.792
   8340307         52.472         14.608
   8340308         53.528          1.008
   8340309         54.284        -12.815
   8440301         38.044         38.195
   8440302         37.157         32.540
   8440303         35.470         19.924
   8540301        -11.805         29.095
   8540302        -10.415         22.173
   8540303         -0.722         16.502
   8540304          7.611         33.466
   8540305         22.960         21.881
   8540306         -2.965         13.988
   8640301        -46.235         27.784
   8640302        -53.572          7.366
   8640303        -30.836          2.558
   8640304        -52.327         -8.425
/ more....
/ ........

 

 

Class

AT_2D

Usage

{void} object.LOADOBS({String} argm1)

argm1 = observation data filename

Example:

->BLK = AT_2D()

->BLK.loadobs("my_observed_data")

->

See also (class function)

loadgcp, adjust

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SD_GCP

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Purpose

To report the current setting of default value of standard deviation of ground control.  This value will be only used for those data that have no SD. 

Class

AT_2D

Usage

{double} ret  =  object.SD_GCP()

Example:

->sd1 = BLK.sd_gcp()

->

See also (class function)

sd_xpyp

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SD_XPYP

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Purpose

To report the current setting of default value of standard deviation of observation data.  This value will be only used for those data that have no SD. 

Class

AT_2D

Usage

{double} ret  =  object.SD_XPYP()

Example:

->sd2 = BLK.sd_xpyp()

->

See also (class function)

sd_gcp

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