[OpenLayers-Users] Animating vector polygons generated from separate data files

Milo van der Linden milo at dogodigi.net
Fri Feb 24 03:51:36 EST 2012

I use a method for emergency vehicles that does a json diff to:

- move objects that have really moved
- change attributes and thus symbology that really changed
- a combination of both

Every 3 sec. without trouble

Currently only for points. It requires jquery. Would it be of any help?
Op 24 feb. 2012 02:21 schreef "Jon Oxtoby" <joxtoby27 at gmail.com> het

> I'm working on a project which displays radar data on a map of the US.
>  This data is currently stored in KML format with one file per radar
> snapshot.  Snapshots are taken every 5 minutes, therefore to display one
> hours worth of data requires 12 files.  The method I'm currently using is
> to create a new vector layer for each data file consisting of polygons from
> the KML files.  I then use setVisibility(false) to hide the layer and add
> it to the map.  Once all layers are created I use a timer to loop through
> the layers making the current layer visible and the previous layer
> invisible every 100ms to animate the radar display.  This works but
> consumes an awful lot of memory (3 hours worth of data, or 36 layers,
> consumes almost 300MB).  I'm trying to find a solution which uses much less
> memory as the end goal is to be able to load up 24 hours worth of data at a
> time for display.
> I do not need to use KML - I can reformat the data files into whatever
> format is best suited to the task.  I tried a similar approach using WMS
> layers and a shapefile format served by MapServer but the redrawing of the
> layers couldn't really keep up and the memory footprint wasn't much better
> than the vector layers.  Also when I zoom in using the WMS format it makes
> things even worse as the new tiles need to be loaded in for each zoom
> level, whereas the vectors are drawn immediately.
> Does anyone have any suggestions for improving this setup?  I was
> originally going to post this to the dev list but thought I'd first see if
> there was any native functionality that I'm overlooking.
> Thanks for any help
> Jon
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