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Network definitions are stored in the configurations table.
This table contains all parameters for each network such as value of a
priori reference standard deviation or orientation of the xy
orthogonal coordinate system axes.
It is obvious that in one database file can be stored more networks (configurations).
Configuration descriptions (annotation or comments) are stored separately
in table descriptions.
The description is split to many records because of compatibility with various
databases (not all databases implements type TEXT).
Field (attribute) conf_id identifies a configuration in the database.
Field conf_name is used to identify configuration outside the database
(e.g. parameter in command-line when reading data from database
to gama-local).
Table configurations contains all parameters specified in
tag <parameters /> (see section Network parameters) and also
gama-local command line parameters (see section Program gama-local).
The list of all table attributes (parameters) follows.
sigma_apr value of a priori reference standard deviation—square
root of reference variance (default value 10)
conf_pr confidence probability used in statistical tests
(dafault value 0.95)
tol_abs tolerance for identification of gross
absolute terms in project equations (default value 1000 mm)
sigma_act actual type of reference standard deviation
use in statistical tests (aposteriori | apriori); default value
is aposteriori
update_cc enables user to control
if coordinates of constrained points are updated in iterative
adjustment. If test on linerarization fails (see section Test on linearization),
Gama tries to improve approximate coordinates of adjusted points and
repeats the whole adjustment. Coordinates of constrained points are
implicitly not changed during iterations.
Acceptable values are yes, no, default value
is yes.
axes_xy
orientation of axes x and y; value
ne implies that axis x is oriented north and axis y
is oriented east. Acceptable values are ne, sw,
es, wn for left-handed coordinate systems and en,
nw, se, ws for right-handed coordinate systems
(default value is ne).
angles right-handed defines counterclockwise observed angles
and/or directions, value left-handed defines clockwise observed
angles and/or directions (default value is left-handed).
epoch
is measurement epoch.
It is floating point number
(default value is 0.0).
algorithm
specifies numerical method used for solution of the adjustment.
For Singular Value Decomposition set value to svd.
Value gso stands for block matrix algorithm GSO by Frantisek Charamza
based on Gram-Schmidt orthogonalization,
value cholesky for Cholesky decomposition of semidefinite matrix
of normal equations
and value envelope for a Cholesky decomposition with
envelope reduction of the sparse matrix.
Default value is svd.
ang_units
Angular units of angles in gama-local output.
Value 400 stands for gons and value 360 for degrees
(default value is 400).
Note that this doesn’t effect units of angles in database.
For further information about angular units see Angular units.
latitude
is mean latitude in network area.
Default value is 50 (gons).
ellipsoid
is name of ellipsoid (see section Supported ellipsoids).
All fields are mandatory except ellipsoid field.
For additional information about handling geodetic systems in gama-local
see Tags <gama-local> and <network>.
Example (configuration table contents):
conf_id|conf_name|sigma_apr|conf_pr|tol_abs|sigma_act |update_cc|... --------------------------------------------------------------------- 1 |geodet-pc|10.0 |0.95 |1000.0 |aposteriori|no |... ... axes_xy|angles |epoch|algorithm|ang_units|latitude|ellipsoid --------------------------------------------------------------------- ... ne |left-handed|0.0 |svd |400 |50.0 | |
The list of description table attributes follows.
conf_id
is id of configuration which description (text) belongs to.
id
identifies text in a database.
text
is part of configuration description.
Its SQL type is VARCHAR(1000).
There can be more than one text for one configuration. All texts related to one configuration are concatenated to one description.
Example (description table contents):
conf_id|indx|text ----------------------------------------------- 1 |1 |Frantisek Charamza: GEODET/PC, ... |
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