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

Rotating geometries


Among the many functions that PostGIS provides, geometry manipulation is a very powerful addition. In this recipe, we will explore a simple example of using the ST_Rotate function to rotate geometries. We will use a function from the Improving proximity filtering with KNN – advanced recipe to calculate our rotation values.

Getting ready

ST_Rotate has a few variants: ST_RotateX, ST_RotateY, and ST_RotateZ, with the ST_Rotate function serving as an alias for ST_RotateZ. Thus, for two-dimensional cases, ST_Rotate is a typical use case.

In the Improving proximity filtering with KNN – advanced recipe, our function calculated the angle to the nearest road from a building's centroid or address point. We can symbolize that building's point according to that rotation factor as a square symbol, but more interestingly, we can explicitly build the area of that footprint in real space and rotate it to match our calculated rotation angle.

How to do it...

Recall our function from the Improving...