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

[Jon Oxtoby]

I'm not sure if this would be of help or not.  The data I'm working with is
irregularly shaped polygons that can be one of 6 different colors.  Each
frame of the radar the polygons change not only position but also shape,
possibly color, and some may cease to exist while new ones are introduced.
 Considering this isn't a standard set of polygons that are just moving I
don't think your method really applies to my case but if you see a way I
could use it please let me know.


On Fri, Feb 24, 2012 at 3:51 AM, Milo van der Linden <milo at dogodigi.net>wrote:

> 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
> volgende:
>
>> 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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