Geography Reference
In-Depth Information
; - the angular differences of latitude, between the target and,
respectively, the two positions of the lab vehicle.
Between two circular arcs on latitude,
and
;
1,2
2
1
2,
TT
2
, which are delimited by two meridian
circles and which are situated, the first at the latitude 0, and the other at the latitude
, the
following relation exists:
cos
(9)
T
T
Also on the basis of the scheme from the figure 20 which presents the positioning mode of a
target on an equivalent sphere of the terrestrial globe, the linear distances can be calculated
on the basis of angular coordinate differences by means of an equation set, with the
following form:
min.
(10)
a meters
2
r meters
for the distances on the longitude
direction;
360
60
min.
(11)
b meters
2
R meters
for the distances on the latitude
direction;
360
60
where:
rR
cos
.
For the establishment, on this basis, of the computing relations for the geographic position
absolute coordinates of the target T, it resorts to the positioning scheme presented in figure
21, taking account of the fact that due to the relative reduced dimensions of the sighting
field, its spherical curved surface is approximated by in plan projection of this field.
By this, in plane projection of the sighting field, the circle arcs are replaced by linear
segments, as follows:
1,
T
1,
T
a
2
R
cos
2
R
cos
;
(12)
1
T
2
2,
T
360
60
360 60
x
1,2
1,2
a
2
R
cos
2
R
cos
;
(13)
2
T
2
2,
T
360
60
360
60
1,2
b
2;
R
(14)
1
360
60
2,
T
(15)
b
2;
R
2
360
60
These result in the following expressions for the azimuth angles:
bb
a
1,2
2,
T
1
2
tan
;
(16)
T
cos
1
1
1,
T
2
2,
T
