Global Positioning System Reference
In-Depth Information
data. Although R-Tree enables multi-dimensional indexing, GeoCouch
implementation supports only two dimensions.
GeoCouch provides spatial views in CouchDB that enables CouchDB
to perform geospatial queries, using bounding boxes.
CouchDB documents are stored in the JSON format (GeoJSON for
documents with spatial data) and therefore allow representing Point,
LineString, Polygon, MultiPoint, MultiLineString and MultiPolygon
geometries.
GeoCouch has no internal utilities to import spatial data, but there are
external tools like shp2geocouch
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that creates GeoCouch databases from
ESRI Shapefi les.
GeoCouch only allows bounding boxes search and do not provide
different output formats beyond GeoJSON. However there are some
CouchApps that offers extra features. The GeoCouch-Utils is a CouchApp
that provides spatial functions and a set of scripts. For instance, the radius
function (similar to buffer analysis functions) takes as input parameters
a point and a radius in meters, and fi lters the bounding box result set by
circular radius (only works on points). Furthermore, GeoCouch-Utils allows
other output formats including: KML, CSV, and GeoJSON.
Other spatial features of GeoCouch are described below:
• SRID: the coordinate system is obtained from the input data (GeoJSON)
and re-projection operations are not supported;
• Functions: GeoCouch does not support topological functions (equals,
disjoint, intersect, touches, crosses, overlaps) or analysis functions
(buffer, convexHull) or set functions (intersection, union, difference,
symDifference).
MongoDB
MongoDB is an open source, document-oriented, NoSQL system written
in C++. MongoDB was developed by the company 10gen.
Main Features
A database in MongoDB contains one or more collections of documents.
Documents are stored in the BSON format (similar to JSON, but in a
binary representation for effi ciency reasons and to support additional data
types).
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Shp2geocouh, http://github.com/maxogden/shp2geocouch
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