Yo Elven brothers and sisters, let's get down with the mapping. This article will provide a rudimentary implementation of a MapInfo .TAB flle to SVG converter, initially showing points only.

Note: 2004/03/21, I never did get this posted properly on SourceForge, but Bill Thoen has now adopted the code from this article and has extended it considerably.. essentially, the successor to the effort I made can now be found at MapInfo SVG on GISnet.com.

Mapping with SVG

As I'm sure many of you are aware, SVG lends itself wonderfully to online presentation of map data. Combined with the capabilities of Javascript and the DOM, the possibilities for interactivity and analysis are boundless.

See these articles for excellent implementations of maps with SVG.

Vector-based Web Cartography: Enabler SVG by Andreas Neumann and Andréas Winter

Vienna - Social Patterns and Structures by Andreas Neumann

Preparing data for SVG-mapping

However, massaging mapping data into SVG format can be a tedious and unforgiving process which may involve countless hours preparing and fine-tuning Perl scripts.

Ideally what could be done is find some way for users to prepare the map layout in a common GIS package like MapInfo or ArcView, and then use a translation program to automatically render the map in SVG, potentially complete with options for mouse-over events, data selection, etc.

MapInfo SVG Conversion

This article will limit itself to illustrating the basic programming techniques involved in exporting data from MapInfo to SVG and initially only convert points.

First, I'd like to walk you through the conversion process and then we will step back through the code. You will need MapInfo 5.5 or higher (not tested with earlier versions, probably works fine down to 4.0?). Download the workspace, caps table, and program with source code in this package.

Unzip the package and open the StateCapitals.wor workspace (you may need to hack at it if you are using MapInfo 4.5 or earlier). Thanks to the Geographic Names Information System for the data. Next, run the program (you may need to re-compile it if you are using MapInfo 5.0 or earlier). Name the output Capitals.svg and save it in the directory where you unzipped everything else.

If you do not have MapInfo and are trying to follow along, here's the desired svg output file. Next, open the html file and you should see the capitals.

MapInfo SVG Converter

Now let's look at the program. I'll just make this very high-level, you can use the MapBasic reference and the SVG references on this site for details. Open the .mb file. You may use a text editor if you do not have MapBasic (preferably something that will give you line numbers.)

The first section pops up the dialog for output. Obviously there's a lot of room for enhancements, I always like to do all my MapBasic as "engines" which only present a user dialog if they don't find the input in an .ini file. This has not been done yet.

Lines 29-59 do the calculations to map the x/y coordinates to pixels.

Lines 72-125 loop through the layers and each object and convert any points.

What's Next?

This program as written only does points and doesn't read and preserve any styles or labeling. There are two really great MapInfo to SVG exporters out there already which are full-featured and do a fairly decent job of re-creating a mapper window in SVG, and even go beyond the capabilities of MapInfo to allow you to use advanced SVG techniques.

Map2SVG contact Dr. Franz-Josef Behr

SVGExport Utility contact Dany Bouchard of DBx Geomatics

I am not aware of any such programs for other GIS platforms. Our program does not intend to fill the space of either of those programs, but rather may serve as a nucleus or jumping off point for applications where you have specific requirements or needs which require access to the source code such as batch processing.

Let me know if there's anyone who would like to contribute to this effort. I have applied to put this up on SourceForge.