The calibrated fiducial and reseau coordinates are used for automatical
positioning of the floating mark. The orientation of the photo on photo
carrier is defined by the location of the photo side information and
for not centered photos by the approximate location of the principal
point on the plate. So it is simple to use also the outer part of the
Large Format Camera photos. The program takes care about the photo part
which is located on the plate, that means, in the case of the Large
Format Camera all fiducial and reseau marks located on the plate can be
measured, even if a fiducial or reseau mark is visible only in one photo.
In any case the fiducial and reseau marks are measured before the photo
points and in reverse sequence after finishing the measurement of photo
points. Usually the photo points are measured twice, after the first
measurement a second measurement will follow in reverse sequence, but
this is an option. The back measurement is very fast because the pointing
can be done accurately by the instrument, but usual an offset of 50 um
is used for the second measurement so that the operator has to make an
independent pointing, which leads to the information of the pointing
accuracy.
There are different possibilities of approximate or exactly automatic
pointing of photo points.
After transformation to the fiducial marks, the photo coordinates can be
corrected by earth curvature and refraction influence and radial symme-
tric distortion. A reseau correction can be done off-line by program
BLPRE.
2. COMPUTER SUPPORTED POINTING
Photo points can be pointed approximately by program B159 with known photo
coordinates of both or one of the photos, based on known object coordina-
tes (ground coordinates) and based on measurements in the neighboured
strip.
Known photo coordinates we can get from preliminary measurements, approxi-
mate from digitizer or with known object coordinates and photo orienta-
tions from program APROX. Object coordinates we can get from an adjust-
ment of a premeasurement, the first results of a deformation analysis,
digitized maps or other sources. B159 computes during data aquisation
strip coordinates. If at least 2 points are measured in the overlapping
area of strips, a computer supported pointing can be done with trans-
formed coordinates of the neighboured strips.
3. ON-LINE BLUNDER DETECTION
The term "on-line" has to be specified more in detail. A realy on-line
blunder detection implies a check immediately after registration of a
photo point. Usually this is not necessary. It is sufficient, to have
a check after finishing the registrations in a photo model when the
photos are still on the carrier and remeasurements can be done at once.
Also the second type of check is named as on-line.
If any prevalue of the point location is available, the program B159 com-
pares it with the registration on a chosen accuracy level. Blunders are
instantly notified. After terminating the measurements of a photo model,
«3376. =