Book Image

PostGIS Cookbook - Second Edition

By : Pedro Wightman, Bborie Park, Stephen Vincent Mather, Thomas Kraft, Mayra Zurbarán
Book Image

PostGIS Cookbook - Second Edition

By: Pedro Wightman, Bborie Park, Stephen Vincent Mather, Thomas Kraft, Mayra Zurbarán

Overview of this book

PostGIS is a spatial database that integrates the advanced storage and analysis of vector and raster data, and is remarkably flexible and powerful. PostGIS provides support for geographic objects to the PostgreSQL object-relational database and is currently the most popular open source spatial databases. If you want to explore the complete range of PostGIS techniques and expose related extensions, then this book is for you. This book is a comprehensive guide to PostGIS tools and concepts which are required to manage, manipulate, and analyze spatial data in PostGIS. It covers key spatial data manipulation tasks, explaining not only how each task is performed, but also why. It provides practical guidance allowing you to safely take advantage of the advanced technology in PostGIS in order to simplify your spatial database administration tasks. Furthermore, you will learn to take advantage of basic and advanced vector, raster, and routing approaches along with the concepts of data maintenance, optimization, and performance, and will help you to integrate these into a large ecosystem of desktop and web tools. By the end, you will be armed with all the tools and instructions you need to both manage the spatial database system and make better decisions as your project's requirements evolve.
Table of Contents (18 chapters)
Title Page
Packt Upsell
Contributors
Preface
Index

Warping and resampling rasters


In the previous recipe, we processed a MODIS raster to extract only those subdatasets that are of interest, in a more suitable order. Once done with the extraction, we imported the MODIS raster into its own table.

Here, we make use of the warping capabilities provided in PostGIS. This ranges from simply transforming the MODIS raster to a more suitable projection, to creating an overview by resampling the pixel size.

Getting ready

We will use several PostGIS warping functions, specifically ST_Transform() and ST_Rescale(). The ST_Transform() function reprojects a raster to a new spatial reference system (for example, from WGS84 to NAD83). The ST_Rescale() function shrinks or grows the pixel size of a raster.

How to do it...

The first thing we will do is transform our raster, since the MODIS rasters have their own unique spatial-reference system. We will convert the raster from MODIS Sinusoidal projection to US National Atlas Equal Area (SRID 2163).

Before we transform...