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Notes

Vous pouvez trouver ici les notes plus ou moins en vrac que j'ai prise lors de l'étude de ce projet. C'était la première fois que je touchais a un GIS. Si c'est également votre cas, il y a potentiellement des réponses a vos futures questions ici.

Load Spatialite

  1. Have libspatialite in your LD_LIBRARY_PATH.
  2. Run select load_extension("mod_spatialite"); at SQLite startup.

How to Create a point

Example in this tutorial: https://gist.github.com/sixman9/805823

How to Test Points

Use the spatial index table.

/!\ DO NOT USE CONTAINS to filter out data. It's not as performant as the spatial index.

See https://www.gaia-gis.it/gaia-sins/spatialite-cookbook/html/rtree.html for what's happening under the hood.

Spatialite Getting Started

Petit test pour voir comment ça marche.

spatialite> CREATE TABLE points (id INTEGER PRIMARY KEY NOT NULL);
spatialite> SELECT AddGeometryColumn('points','dummypoints',3857,'POINT');
1
spatialite> INSERT INTO points (dummypoints) VALUES(Transform(MakePoint(384998.246399999,6366249.435399996366249.43539999,4964),3857));
spatialite> select * from points;
1|
spatialite> select AsText(dummypoints) from points;

SRID, quezako?

En pratique, on spécifie le SRID a spatialite en utiliant le code EPSG

  • Projection règlementaire en France: RGF93, EPSG:2154
  • Mercator (OSM/Google Maps): WGS84, EPSG:4326

D'après https://geodesie.ign.fr/index.php?page=rgf93, le RGF93 est compatible avec Mercator.

DSPs to Ingest

ADTH AISN BEFO BTHD CTYF EURE FI44 NATH NIVE NPDC SART SHSN SIEL SPTH VAUC

Requête sur l'Index Spatial

SELECT * FROM ipe
WHERE ROWID = (
    SELECT ROWID FROM SpatialIndex
    WHERE f_table_name = 'ipe'
    AND search_frame = BuildMBR(
      -1.405456066131592,
      43.53722495535158,
      -1.3643002510070803,
      43.54475322429539,
      4326)
);