1.3 Coordinate Calculation
1.3.1 Coordinate calculation processing in 1999
Regarding the survey results in 1999, the
results of the coordinates (latitude, longitude, ellipsoidal height) of GRS80
coordinate system have been first gained. Next, the results of the other five
types of coordinate have been gained by calculation processing of coordinate
conversion in the order of 2) > 3) > 4) > 5) > 6) on the basis
of these coordinate results.
1) Calculation of the latitude, longitude
and ellipsoidal height of GRS80 coordinate system
The latitude, longitude and ellipsoidal height of GRS80 coordinate system of
all points in the network are obtained through a three dimensional network
adjustment in which the total station observations (range, horizontal angle and
vertical angle), leveling observations are used as fixed point of height
components, and the coordinates and orientaion at the station datum determined
by GPS survey are used as the known.
2) Coordinate conversion from GRS80
coordinate system to ITRF94 coordinate system
The latitude, longitude and ellipsoidal height of GRS80 coordinate system have
been converted to X,Y and Z of ITRF94 coordinate system according to the
following formula:
X
= (N+h) cos(phi) cos(lambda)
Y
= (N+h) cos(phi) sin(lambda)
Z
= {N (1e^{2}) +h} sin(lambda)
Where,
phi:latitude, lambda: longitude, h : ellipsoidal height, N : radius of
eastwest curvature, e : first eccentricity.
3) Conversion from ITRF94 coordinate
system to local coordinate system (without geoid correction)
X,Y and Z of ITRF94 coordinate system have been converted respectively to X_{local},
Y_{local }and Z_{local }of local coordinate system according to
the following formula:
X_{local }= XX_{0}
Y_{local }= YY_{0}
Z_{local }= ZZ_{0}
Where, X_{0},
Y_{0}, and Z_{0} are the coordinate values of the ITRF94
coordinate system of the station datum at each observation station.
4) Conversion from local coordinate
system (without geoid correction) to horizontal coordinate system (without
geoid correction)
X_{local}, Y_{local }and Z_{local }of local coordinate
system have been converted to N, E and U of horizontal coordinate system
according to the following formula:
_{}
Where, phi :
latitude, lambda : longitude.
5) Conversion from horizontal coordinate
system (without geoid correction) to horizontal coordinate system (with geoid
correction)
Geoid
correction of horizontal coordinates has been executed according to the
following formula by using the angle of inclination of the primary inclination
constituent of geoid inclination (constituent xi for northsouth direction and
constituent eta for eastwest direction). (Refer to 1.4 for the details
regarding the primary inclination constituent of geoid.)
_{}
6) Conversion from horizontal coordinate
system (with geoid correction) to local
coordinate system (with geoid correction)
Horizontal
coordinate system (with geoid correction) has been converted to local
coordinate system (with geoid correction) by rotating the geoid correction (N_{geoid
correction}, E_{geoid correction }and U_{geoid correction})
of horizontal coordinate system to reverse direction according to the formula
described in 4. The deviation that has been found with this rotation is only
limited to the vertical deviation of the coordinate axis and had almost no
effect at all to the conversion since the angle difference was very small.
_{ }
_{}
Where, phi :
latitude, lambda : longitude.
1.3.2 Coordinate calculation processing in 1996  1998
1) The same procedure for coordinate
calculation processing in gaining the survey results in 1999 is applied to data
obtained once every year between 1996  1998.
2) However, as for the coordinates
(latitude, longitude and ellipsoidal height) and the azimuth angle (station
datum > azimuth reference point) of the station datum (as shown in Table 6)
which were necessary in the threedimensional network adjustment for
determining the latitude, longitude and ellipsoidal height of GRS80 coordinate
system, the values gained in 1999 have been used.
Table 6 Station datum and Azimuth reference
point

Koganei station 
Kashima station 
Miura station 
Tateyama station 
Station datum 
S3 
S3 
S3 
L2 
Azimuth reference point 
S1 
S1 
L2 
L1 