4.2 Numbering the photos

RELAX, BINGO and several BINGO tools recognise the structure of an aerial photograph block due to the sequence of the photo numbers and partially also additionally due to the orientations of the photos. Thus appropriate numbering of the photos is important.

Within a flight line the photos should be numbered in ascending or descending order. Between first and the last photo numbers of a flight line there should be no photo numbers from another flight line. If e.g. all photo numbers are preceded by the related number of the flight line, care must be taken to ensure that all photos in the line have the same number of digits.

Example of inappropriate numbering:

…..    1_5    1_6    1_7    1_8    1_9    1_10    1_11    1_12    1_13    1_14    1_15 …..

…..    2_5    2_6    2_7    2_8    2_9    2_10    2_11    2_12    2_13    2_14    2_15 …..

…..    3_5    3_6    3_7    3_8    3_9    3_10    3_11    3_12    3_13    3_14    3_15 …..

Resulting sorted list:

    1_5    1_6    1_7    1_8    1_9    2_5    2_6    2_7    2_8    2_9    3_5

    3_6    3_7    3_8    3_9    1_10    1_11    1_12    1_13    1_14    1_15    2_10

    2_11    2_12    2_13    2_14    2_15    3_10    3_11    3_12    3_13    3_14    3_15

The photo number list shown above will be sorted internally in all BINGO programs and tools according to ascending numbers. Since the photos of a flight line are now no longer one after the other in the list, the line structure cannot be recognised correctly.

With improved numbering, the sorted list contains all photos of a flight line in sequence:

    1_05    1_06    1_07    1_08    1_09    1_10    1_11    1_12    1_13    1_14    1_15

    2_05    2_06    2_07    2_08    2_09    2_10    2_11    2_12    2_13    2_14    2_15

    3_05    3_06    3_07    3_08    3_09    3_10    3_11    3_12    3_13    3_14    3_15

Correct numbering plays an important role in RELAX when the option “Standard aerial triangulation” is selected (default). With inappropriate numbering the flight line cannot be recognised correctly. The approximate value determination function may either not work or not work properly.

In BINGO points with only two photo rays can be eliminated automatically. Those points in a photo which occur at the end of a flight line, however, will not be deleted. The same is true for points in a photo which occur before or after a gap in the flight line. With inappropriate numbering this option cannot function perfectly.

Also BINGO can no longer determine correctly whether a photo only appears in one flight line or in several, and thus contributes to connecting the flight lines. The programs REPLO and 3dView can no longer display the structures in the correct colours.

Fig. 4.2-1 The flight lines are not recognised correctly with inappropriately numbered points.

Fig. 4.2-2 Points with only two photo rays at the end of the flight lines
and a gap in the middle of the flight line (correct numbering)