MapAnalyst Online: Accuracy of old maps
Monday, October 27, 2008
MapAnalyst is a software for the accurate analysis of old maps. Its main purpose is to compute distortion grids and other types of visualizations that illustrate the geometrical accuracy and distortion of historical maps.
The software uses pairs of control points on an old map and on a new reference map. The control points are used to construct distortion grids, vectors of displacement, accuracy circles, and isolines of local scale and rotation. As a by-product, MapAnalyst also computes the old map's scale, rotation and statistical indicators.
Bernhard Jenny from ETH Zurich, author of this tool, is working with us on an online interface for the generation of the accuracy visualizations. Our online georeference tool will give excellent base for this functionality, because we will have there already a database of Ground Contol Points, which we use to reference the maps and to generate metadata. We would like to use those GCPs also to generate visualizations a la MapAnalyst directly from the webbrowser.
Right now we just have simple prototypes and a lot of work in front of us. But in the end, as soon as you specify the control points for your map, you will be able to get a visualization similar to the one you see in this blog post just by one click of a mouse. The visualization will appear directly over the web presentation of your map. There will also be a possibility to download a high quality print-ready version (probably in SVG format).
The prototypes of the accuracy analysis online visualization of an old map of Switzerland:MapAnalyst Online: Raster Demo
We will be using GeoJSON vector format like in this prototype to display the visualization:MapAnalyst Online: Vector Demo
MapAnalyst is an open-source project so the online version is going to be available as an open-source as well. We will post progress reports on this blog.