photos are measured with automatic pointing. With at least 3 points,
which have to be pointed by the operator (the third point always with
approximate pointing), a resection of the photos can be computed and
with this the photo coordinates of the ground points, which are used
for the pointing. It is not necessary, to have a preparation of this
step. After the first 2 manual pointings, the operator is led through
the measurements and discrepancies can be seen immediately. The power
of the test is much better, than in the case of a direct measurement
of strips with 60 % sidelap and the preparation of the measurements is
reduced against this.
For a second photo flight for inspection of subsidences in coal mining
areas, a first triangulation with a minimum of points will be done.
This delivers the photo orientations. With the photo orientations and
the old ground coordinates, photo coordinates can be computed by program
APROX. These photo coordinates can be used for automatic pointing. So
it is not necessary to search for the old points in the new photos.
This method excludes the mixup of points. The power of the test during
measurement of a second photo flight is limited by the motion of the
points on the ground.
It has been shown, that raised overlaps to 60 % sidelap plus crossed
strips with also 60 % sidelap, has extended the time for measurement,
with the explanined method, only by 75 % of the time which is necessary
for a single block, even the number of photos was 4 times. In comparison
to measurements of a single block with comparators, it was faster to
measure the fourfold number of photographs computer supported with ana-
lytical plotters. The on-line data check on the base of known object
coordinates has reduced the number of blunders to a minimum. It was not
necessary to remeasure photos because the high number of photos per
point allows the exclusion of some photo coordinates without any problems.
The same measurement procedure can be used also for close range appli-
cations with a claim for high precision. Even for blocks with high end-
lap it can be useful. Tests have been made for block adjustment with
space photographs. The manual point identification was very difficult
and time consuming. So in a first step, control and check points have
been measured, each only in one model. Based on a preadjustment the
final measurements have been done very fast, so that the temperature
influence to the plate coordinate was reduced.
CONCLUSION
The optimisation of the working method of computer supported data aqui-
sition with analytical plotters yields to a strong increase of the cost
effectiveness of block adjustments. The possibilities of blunder detec-
tion during measurement in a sequential method - one strip after the
other - is limited. In the case of 60 % sidelap, or more, it is better to
measure at fist a subblock with 20 % sidelap. Based on the computed
ground coordinates the remaining strips can be measured computer sup-
ported fast and with improved power of the test.
The automatic pointing allows block configurations and raised number of
photos per point which have before not economic. The improved object
point accuracy and reliability allows new applications of the bundle block
adjustment.
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