Processing Digital Maps - Programming GPS and OpenStreetMap Applications with Java - page 79

Chapter 7

Processing Digital Maps

7.1 Introduction

In the last chapter, traces were displayed on top of a map image for an
observer to visually validate the trace. For a computer, these images are
practically useless, and it would be almost impossible for the computer to
identify roads. A machine can only interpret digital maps describing the
mapped area by structured information |often referred to as spatial data.
In the context of the ROAF project, digital maps are vital for the ori-
entation of real objects. Digital maps bind real objects and real-object
applications together. Externally, the map describes the object's environ-
ment, while the object can internally make a decision in which direction to
go.
This chapter describes how to process digital maps for dedicated appli-
cations with a map compiler. At the open source project openstreetmap ,
you can find free digital-map data for your geographical area to set up your
own OSM map compiler.

7.2 Overview

Part II introduced the basics of geodesy, how to match geographical co-
ordinates with the globe's surface, and we learned that consumer GPS
devices supply satisfactory results. The next two chapters can be seen as
an excursion into digital maps and navigable networks, which are needed
to explore any area on the globe with a real object. This chapter will guide
the reader to process OSM deliveries to significantly reduce map data. The
next chapter will show how to process this data into a cartographic part,
a network part, and an administrative part from one map source.
We will go through a complete cycle of processing digital maps with a
simple map compiler in the resources folder: The steps are as follows:

1. Collecting map details. The first step to create a digital map is
the collection of geometry data in the field, as demonstrated with the

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