8.1 Working with the ITERA file
The ITERA file is used:
- For transfer of approximate values of the photo orientations from the program RELAX.
- For output of adjusted photo orientations and the adjusted coordinates of points. The results may be read in for the next computation. Thus good approximate values are available for the unknowns of photos and points, and the number of necessary iterations will be reduced.
- For transfer of adjusted results to post processing programs (e.g. BINGO tools).
* * FAIRFIELD SUISUN SEWER DISTRICT * Example data for GPS application using CPAS solution method * * <___Photo_Name_><___Easting__><__Northing__><__Height_><___Phi__><__Omega_><__Kappa_><__Camera_> ORIA 1001 10578097.789 4240801.181 1469.232 1.0949 0.6476 0.1900 2 ORIA 1002 10578860.883 4240803.028 1466.670 0.1122 1.1385 -1.2756 2 ORIA 1003 10579625.365 4240800.466 1462.862 0.0495 0.4329 0.7661 2 ORIA 1004 10580385.658 4240808.710 1467.625 0.2418 0.0549 0.7736 2 : : : : : : : : : * <___Point_Name_><___Easting__><__Northing__><__Height_><_S_X_><_S_Y_><_S_Z_><Ray> CORD 306 10578240.324 4237534.996 34.433 0.066 0.063 0.111 +4 CORD 307 10578131.921 4238767.918 40.850 0.054 0.053 0.064 +4 CORD 309 10579781.150 4241479.932 83.851 0.084 0.103 0.206 3 CORD 311 10585735.234 4241520.319 79.885 0.101 0.131 0.263 3 CORD 312 10588575.199 4241381.424 247.114 0.100 0.122 0.256 2 : : : : : : : : : * <__Camera_Name_><____c___><___xH___><___yH___><___s_c__><__s_xH__><__s_yH__> CAPA 2 153.9230 0.0261 0.0112 0.0128 0.0154 * <__Camera_Name_><____ex__><____ey__><____ez__><__d_phi_><__d_ome_><__d_kap_> ECCA 2 -4.1341 0.5449 2.1525 0.0000 0.0000 0.0000 * <__Camera_Name_><_Par.No_><__Parameter_Value_><___Format_Factor__><__Sensor_Type_> APAV 2 7 0.283159E-01 0.100000E+01 RMK APAV 2 8 -0.164961E-01 0.100000E+01 RMK : : : : : END |
Example for an ITERA file |
The ITERA file is ASCII-coded and has the same format as the GEO INPUT file. The camera name is appended to the ORIA respectively ORIT statement. As it is established by the program, the number of checks and error messages is considerably reduced compared to those for the GEO INPUT file. It is not recommended to produce this file manually, and editing should not be done at all, or else with the greatest care.
Parameter ITIO in the PARA statement in the GEO INPUT file controls whether data are read from the ITERA file and/or are again written to this file. The orientation parameters of the photos (ORIA and ORIT statements) are written, and also the coordinates (CORD statements) and adjusted camera unknowns (CAPA, APAV and ECCA statements, see GEO INPUT file).
If the standard deviations of the unknowns were calculated, these are also output for the point coordinates in the CORD statement. In addition the number of photos in which the point had been measured is indicated at the end of each line. A plus-sign is preceded, if the point had been measured in more than one strip. For terrestrial photos this option is switched off automatically. The output on the ITERA file is effected sorted by ascending photo and point names. When re-reading the file the standard deviations are not considered.
If further photos are orientated in addition to an already existing ITERA file, the ITERA file will be completed with the new data by RELAX.
Before BINGO overwrites the data saved in the ITERA file after adjustment (optional), a backup copy of the ITERA file is first created with the name old-itera.dat. In the case of divergence – standard deviation s0 and the addition to the unknowns will increase from iteration to iteration – the ITERA file will usually become unusable, when the parameters to be written to the ITERA file were set. One can then go back to the old file.
C | comments |
ORIA, ORIT | photo orientations |
CORD | coordinates of points |
CAPA | camera constant and principal-point position |
ECCA | eccentricity vector e' |
APAV | values of additional parameters |
END | end of data |
Statements in the ITERA file | |
BINGO uses the values contained in a CAPA or ECCA statement in the ITERA file as approximate values only. Therefore the CAPA statement is significant only when camera constant and/or principal-point position are carried as unknowns for this camera.
Input of CAPA statement from the GEO INPUT file is still necessary.
If photo orientations and/or coordinates (ORIA, ORIT and CORD statements) are read in (completely or in parts) from GEO INPUT file as well as from the ITERA file, the approximate values from the ITERA file will be used for the adjustment. The resulting practical consequences are:
- If the ITERA file has been established during a divergent adjustment then these data must not be read again.
- Some error corrections have to be carried out not only in GEO INPUT file but also in the ITERA file (for example, if an image appeared upside down, i.e. κ was wrong by 200 gon).
Use of the ITERA file is obligatory if additional parameters are to be adopted. Before applying additional parameters, good approximations for the photo orientations must be available. Otherwise the selection process of additional parameters may be disturbed (compare ADPA statement in GEO INPUT file).