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3. SQL schema, SQLite and gama-local

The input data for a local geodetic network adjustment (program gama-local) can be strored in SQLite 3 database file. The general information about SQLite can be found at

http://www.sqlite.org/

Input data (points, observations and other related information) are stored in SQLite database file. Native SQLite C/C++ API is used for reading SQLite database file. It is described at

http://www.sqlite.org/c3ref/intro.html

Please note if you compile GNU Gama as described in Install and SQLite library is not installed on your system, GNU Gama would be compiled without SQLite support.

SQL schema (CREATE statements) is in gama-local-schema.sql file which is part of GNU Gama distribution and is in the xml directory.

All tables for gama-local are prefixed with gnu_gama_local_. In the documentation table names are referred without this prefix. For example table gnu_gama_local_points is referred as points.

Database scheme used for SQLite database is also valid in other SQL database systems. Almost every column has some constraint to ensure correctness.

You can convert existing XML input file to SQL commands with program gama-local-xml2sql, for example

 
$ gama-local-xml2sql geodet-pc geodet-pc-123.gkf geodet-pc.sql

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3.1 Working with SQLite database

First of all you have to create tables for GNU Gama in SQLite database file (here with db extension, but you can choose your own, e.g. sqlite).

 
$ sqlite3 gama.db < gama-local-schema.sql

You can check created tables by following commands (fist in command line, second in SQLite command line).

 
$ sqlite3 gama.db
sqlite> .tables

Output should look like this:

 
gnu_gama_local_clusters        gnu_gama_local_descriptions
gnu_gama_local_configurations  gnu_gama_local_obs
gnu_gama_local_coordinates     gnu_gama_local_points
gnu_gama_local_covmat          gnu_gama_local_vectors

When you have created tables you can import data. One way is to process file with SQL statements.

 
$ sqlite3 gama.db < geodet-pc.sql

Another way can be filing database file in another program.

For using sqlite3 command you need a command line interface for SQLite 3 installed on your system (e.g. sqlite3 package).


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3.2 Units in SQL tables

In the gama-local SQLite database, distances are given in meters and their standard deviations (rms errors) in millimeters. Angular values are given in radians as well as their standard deviations.

Conversions between radians, gons and degrees:

 
    rad = gon * pi / 200
    rad = deg * pi / 180
    gon = rad * 200 / pi
    deg = rad * 180 / pi

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3.3 Network SQL definition

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.

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.

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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3.4 Table points

Example (table contents):

 
conf_id|id |x       |y      |z|txy     |tz
------------------------------------------
1      |201|78594.91|9498.26| |fixed   |
1      |205|78907.88|7206.65| |fixed   |
1      |206|76701.57|6633.27| |fixed   |
1      |207|        |       | |adjusted|

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3.5 Table clusters

The cluster is a group of observations with the common covariance matrix. The covariance matrix allows to express any combination of correlations among observations in cluster (including uncorrelated observations, where covariance matrix is diagonal). For explanation see Observation data and points.

In the database observations are stored in three tables: obs, coordinates and vectors. Cluster’s covariance matrix is stored in table covmat. Every observation, vector or coordinate in database has to be in some cluster.

Observations, vectors and coordinates are identified by configuration id (conf_id), cluster id ccluster and theirs index (indx). Observation index (indx) has to be unique within observations of one cluster (which belongs to one configuration). The same applies for vectors and coordinates.

See also Set of observations.

Example (table contents):

 
conf_id|ccluster|dim|band|tag
-----------------------------
1      |1       |3  |0   |obs
1      |4       |4  |0   |obs

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3.6 Table covmat

Values of cluster covariance matrix are stored in covmat table. Attributes conf_id, ccluster identifies covariance matrix. Value position in matrix is specified by rind and cind fields.

Values rind and cind have to respect dim and band specified in table clusters. If value in covariance matrix is not specified (record is missing), it is considered to be zero.

Example (table contents):

 
conf_id|ccluster|rind|cind|val
--------------------------------
1      |1       |1   |1   |400.0
1      |1       |2   |2   |400.0
1      |1       |3   |3   |400.0
1      |4       |1   |1   |400.0
1      |4       |2   |2   |400.0
1      |4       |3   |3   |400.0
1      |4       |4   |4   |400.0

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3.7 Table obs

Table obs contains simple observations like direction or distance.

Example (table contents without empty columns):

 
conf_id|ccluster|indx|tag      |from_id|to_id|val           |rejected
---------------------------------------------------------------------
1      |1       |1   |direction|201    |202  |0.0           |0
1      |1       |2   |direction|201    |207  |0.817750284544|0
1      |1       |3   |direction|201    |205  |2.020073921388|0

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3.8 Table coordinates

Table coordinates contains control (known) coordinates.

See also Control coordinates.


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3.9 Table vectors

Table vectors contains coordinate differences (vectors).

See also Coordinate differences (vectors).


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3.10 Example of local geodetic network in SQL

Providing complete example would be reasonable because of its extent. However, you can obtain example by following these instructions:

Create a file with XML representation of network by copy and paste example from Example of local geodetic network to a new file. Note that file should start with <?xml version="1.0" ?> (no whitespace). Alternatively you can use existing XML file from collection of sample networks (see Download). Then you can convert your XML file (here example_network.xml) to SQL statements by program gama-local-xml2sql (the path depends on your Gama installation).

 
$ gama-local-xml2sql example_net example_network.xml example_network.sql

Now you have example network (configuration example_net) in the form of SQL INSERT statements in the file example_network.sql.

Another representations you can create and fill SQLite database (for details see Working with SQLite database):

 
$ sqlite3 examples.db < gama-local-schema.sql
$ sqlite3 examples.db < example_network.sql
$ sqlite3 examples.db

Once you have SQLite database, you can work with it from SQLite command line. You can get nice output by executing following commands.

 
sqlite> .mode column
sqlite> .nullvalue NULL
sqlite> SELECT * FROM gnu_gama_local_configurations;
sqlite> SELECT * FROM gnu_gama_local_points;
sqlite> SELECT * FROM gnu_gama_local_clusters;
sqlite> SELECT * FROM gnu_gama_local_covmat;
sqlite> SELECT * FROM gnu_gama_local_obs;

Or you can get database dump (CREATE and INSERT statements) by

 
sqlite> .dump

If it is not enough for you, you can try one of GUI tools for SQLite.


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This document was generated by Ales Cepek on March 25, 2014 using texi2html 1.82.