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

Processing and loading rasters with GDAL VRT


Though PostGIS has plenty of functions for working with rasters, it is sometimes more convenient and more efficient to work on the source rasters before importing them into the database. One of the times when working with rasters outside the database is more efficient is when the raster contains subdatasets, typically found in HDF4, HDF5, and NetCDF files.

Getting ready

In this recipe, we will preprocess a MODIS raster with the GDAL VRT format to filter and rearrange the subdatasets. Internally, a VRT file is comprised of XML tags. This means we can create a VRT file with any text editor. But since creating a VRT file manually can be tedious, we will use the gdalbuildvrt utility.

The MODIS raster we use is provided by NASA, and is available in the source package.

You will need GDAL built with HDF4 support to continue with this recipe, as MODIS rasters are usually in the HDF4-EOS format.

The following screenshot shows the MODIS raster used in this recipe...