United States
of America
1
- 69.
Ground Control Points.
Ad 5.21
rules proposed are in the "Propos
for a new Swedish Surveying Ordin
co",
Four points of known vertical ani
horizontal positions are required
in each photopair. In large scale|
mapping projects, 1:25 000 or lar
ger, the vertical positions of i
points in each model are usually |
established by field surveys. The
horizontal positions of the four
points would be established by
aerotriangulation procedures base
on approximately one field establi
ed position for esch 5 models. |
At scales of 1:50 000, the horizg Union
tal and vertical passpoints would soc. .
be established by aerotriangulatio
Basic ground control requirements
for these map scales will vary wii
each project. On the average, bani
of horizontal and vertical control
which are laid out perpendicular |
to the flight lines at about 15 |
model spacing are used. Airborne l|
rizontal control established by
HIRAN and vertical control by Ter
Profile Recordings (radar) signifi
cantly reduce ground surveyed cont!
requirements. |
Basic ground control is establishe
by ground survey techniques, and |
airborne trilateration techniques
(HIRAN line crossings). All horiszd
tal control is positioned in the |
: R Al
Universal Transverse Mercator Grid
|
I