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  • Book Overview & Buying Mastering PostGIS
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Mastering PostGIS

Mastering PostGIS

By : George Silva, Mikiewicz, Michal Mackiewicz , Nycz
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Mastering PostGIS

Mastering PostGIS

1 (1)
By: George Silva, Mikiewicz, Michal Mackiewicz , Nycz

Overview of this book

PostGIS is open source extension onf PostgreSQL object-relational database system that allows GIS objects to be stored and allows querying for information and location services. The aim of this book is to help you master the functionalities offered by PostGIS- from data creation, analysis and output, to ETL and live edits. The book begins with an overview of the key concepts related to spatial database systems and how it applies to Spatial RMDS. You will learn to load different formats into your Postgres instance, investigate the spatial nature of your raster data, and finally export it using built-in functionalities or 3th party tools for backup or representational purposes. Through the course of this book, you will be presented with many examples on how to interact with the database using JavaScript and Node.js. Sample web-based applications interacting with backend PostGIS will also be presented throughout the book, so you can get comfortable with the modern ways of consuming and modifying your spatial data.
Table of Contents (10 chapters)
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Topology-aware simplification


A very useful feature of a topology is the ability to simplify the feature geometry while maintaining its topological relationships. As we learned in Chapter 2, Spatial Data Analysis, the ST_SimplifyPreserveTopology function doesn't do that, despite its name. In this section, we will learn how to simplify features using topology functions.

Importing sample data

The data used as an example is extracted from the Czech hydrological dataset. Its location was mentioned at the beginning of the chapter, in the The data section. Now we'll import a DIBAVOD watershed layer into a database using ogr2ogr:

ogr2ogr -t_srs EPSG:32633 -f PostgreSQL "PG:dbname=mastering_postgis host=localhost user=osm password=osm" -lco GEOMETRY_NAME=geom -lco PRECISION=no -nln watershed_ord3  A08_Povodi_III.shp 

Next, we will convert the Simple Feature geometry to a topology with 2-meter precision:

SELECT topology.CreateTopology('water_topology', 32633, 1, FALSE); 
SELECT topology.AddTopoGeometryColumn...
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Mastering PostGIS
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