Measurements of labels

Measurements of labels set system of coordinates of a photo. It is necessary to measure labels so that the coordinates system of a photo was correctly constructed. Coordinates system of a photo should be constructed so that the direction of an axis of abscissas coincided with a direction of flight. Also it is important for slot-hole and panoramic photos that the axis of abscissas passed by an axis of the main points of a photo. The beginning of  coordinates system of the central photo should coincide with the center of a photo.

At measurement of labels the direction from the first label to the second label (and unimportantly 2 or 4 labels are measured) determines a direction of an abscissas axis of coordinates systems of a photo. The axis of ordinates is built perpendicularly axes of abscissas and forms the right rectangular system of coordinates. The beginning of coordinates system is defined by measurement of the central cross, and at its absence, by the crossing of directions between the first - the third label and the second - the fourth label (for a case of 4 labels) or by a segment midpoint between the first and second labels. If displacement is set, the center of coordinates system of a photo is shifted from position determined by labels and the central cross onto size of displacement by along axis of abscissas.

In the central photo and on the aero-photograph the labels are usually designated. In this case it is necessary to use a mode of measurement of 2 labels and to measure two opposite labels. If in a photo the central cross is designated it is necessary to measure and it. If labels are not designated, it is necessary to use a mode of measurement of 4 labels and to measure 4 corners of the source raster.

In a slot photo the labels are not designated, therefore it is necessary to use a mode of measurement of 4 labels and to measure 4 corners of a raster. Thus the direction from the first label to the second label should coincide with a direction of flight of the flying device.

In a panoramic photo the number of the measured labels depends on the size of a panoramic photo. If the source raster contains a source analog photo so, that the line of the main points of a photo gos along the middle of the source raster it is necessary to measure 4 corners of a raster. If the source raster is contained a part of the source analog photo and a line of the main points gos not on the middle of a raster it is necessary to use a mode of measurement of 2 labels with the central cross, and a direction from the first to the second labels should coincide with a direction of flight. As the central cross it is necessary to measure the first label. Thus, displacement should be set. The size of displacement should be equaled to half of size of a photo on a direction conterminous with a direction of flight.