Developing Geospatial Solutions using Open Source

This is one of the three books identified by the Education and Curriculum Committee that should be written. The other books are Using Open Source GIS and Developing Web Mapping Solutions Using Open Source.

Approach for writing this book

Using the application and programming language categories from http://freegis.org we'll gather problems or use cases, maybe divide them into subproblems, and describe how they can be solved using the free tools.

The tools are programming languages, libraries, command line tools, and customizable applications.

This book is about "I know which problem I need to solve and it can't be solved, at least easily or without trouble, by simply using some free GIS tool".

We exclude web mapping problems from this one since it is the topic of book 3.

Provide here an analysis of the meta problem description above.

Copy the categories and

programming languages: C, C , Java, Python, Tcl/Tk, Perl, (Visual) Basic, PHP, C#, Fortran, Delphi, Ruby, SWF, Other (Other has zero entries in freegis.org).

GPS related

• Problem: Share GPS data between applications
  • Subproblem: Parse GPX
  • Explanation: GPX is an XML application for GPS data. Parsing gives us the GPS data.

• Problem:
  • Subproblem: GeoTag Media
  • Explanation:

• Problem:
  • Subproblem: Track logs
  • Explanation:

• Problem: Edit a GPS track
  • example data
  • Requirements: Show the track on a map as editable lines, show the coordinates on a spreadsheet allowing edits, link the two representations
  • Subproblem: Import the GPS track to the editor
  • Subproblem: Export the track from the system

• Problem: Merge GPS tracks
  • Explanation: Allow you to view several GPS traces, delete certain points, and average others together.
  • Use: You survey a route several times, and want a single trace of the best average over the traces

Use case	Description	Perl	Ruby	Python	Shell
Parse GPX	What is GPX?	Perl based solution	Ruby based solution	PyGPX	shp2gpx.sh and gpx2shp.sh(scripts calling 'gpsbabel')
GeoTag Media		RDFWeb geoloc_media.pl (original geoloc_media)	Ruby?	Python?	Shell?
Track logs		Geo::Track::Log	Ruby	Python	Shell?
Track merge			Ruby?	Python?	gpsbabel can perform related GPS track operations

Projection-Conversion

• Problem: Convert between WGS84 and local projections
• Problem: Convert from lat long to easting and northing, as used on printed maps

Check out the Axis Order Confusion issue which arises whenever adressing geographic coordinates with IT systems.

Use case	Description	Perl	Ruby	Python	Java	JavaScript	Shell
Change between projections	Perform a Helmert Transform	MySociety Code		geo_helper.py	Jcoord	JScoord	cs2cs tool
Convert from lat long to easting northing		Geo::Coordinates::OSGB		geo_helper.py	Jcoord	JScoord	cs2cs tool
Work with old maps / data in Cassini Projection	Convert between Cassini and its base elipsoid			geo_helper.py		cassini-coord.js

GPS and EXIF

• Problem: Extract GPS exif tags from photos
• Problem: Add GPS exif tags at the time a photo is taken
• Problem: Add GPS exit tags to photos, based on the time they were taken and a GPS track

Use case	Description	Perl	Ruby	Python
Get GPS EXIF data	Extract lat and long from GPS Exif tags			pexif
Set GPS EXIF date	Add lat and long GPS Exif tags			pexif