Friday, 23 September 2011

"Vectors are your friend"

HTML5 Canvas was a natural extension for  Its distinction is to post vectors on the web, overlaying rasters like any GIS, and with a optional postGIS running in the background. Not only does this speed up drawing maps on the web, it also allows massive amounts - in the millions of points, lines and polygons - to render PDQ (pretty darn quickly) - thus Vectors are your friend - my moderately complex maps benefit from even clean&crisper renderings of polygons as expected and of tiled images especially.

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This is my old Medieval Fenlands map in East Anglia with 10 layers at 2000 polygons each and two web mapping services - zoom in an out to appreciate its speed.

Here's NOAA's Global Self-consistent, Hierarchical, High-resolution Geography Database, as well as USGS earthquake and plate boundary map - not insignificant vector maps that zoon in&out quickly... try it out!

@giscloud is still new so there is a way to go yet - as some of the tweets that increased 1500% in the last few days indicate - labelling, scale dependency, layers and legends, etc. Note also that as this relies on HTML5: pre-rel. 9 Internet Explorer that don't support it will automatically revert maps to their original rendition.

Fifteen years ago Argus' distinction from ArcView and Mapinfo was to render in less than 5 s. all 50 US states and 3000+ county polygons. And about that time Hipparchus claimed to map the solar system at metric scale... One could say that:
What goes around, goes around, goes around again,
da-na-na da-na-na da-na-na my friend say
Where you gonna run to? When it gonna end?


  1. Thanks for the informative post. Canvas will be a great improvement to online GIS (since it's natively supported over Flash) but will still have the limitation of bandwidth required to send down the polygon coordinates. We ran into this limitation with our flash based mapping api and since moved towards a system where the server generates the tiles. Now, we can dynamically map detailed geography, like census block groups
    (see the demographic and political examples)
    and it's compatible with the full range of browsers.

  2. Indeed I posted an example of yours here