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

Working with basic raster information and analysis


So far, we've checked and imported the PRISM and SRTM rasters into the chp05 schema of the postgis_cookbook database. We will now proceed to work with the rasters within the database.

Getting ready

In this recipe, we explore functions that provide insight into the raster attributes and characteristics found in the postgis_cookbook database. In doing so, we can see if what is found in the database matches the information provided by accessing gdalinfo.

How to do it...

PostGIS includes the raster_columns view to provide a high-level summary of all the raster columns found in the database. This view is similar to the geometry_columns and geography_columns views in function and form.

Let's run the following SQL query in the raster_columns view to see what information is available in the prism table:

SELECT 
  r_table_name, 
  r_raster_column, 
  srid, 
  scale_x, 
  scale_y, 
  blocksize_x, 
  blocksize_y, 
  same_alignment, 
  regular_blocking, ...