Another idea:
With RFC 96 adding time support to mapcache, maybe it would be possible
to create a server-side app the can request tiles from mapcache, and
create and Flash script to display them based on your slider. Or create
an animated gif, not that you have much control over that after it is
created. But some ideas to chew on.
-Steve W
On 4/9/2013 11:52 AM, Brent Fraser wrote:
Bob,
I'm not sure I've successfully visualized your solution, but I do
appreciate your problem. While the web mapping community has come up
with decent set of concepts and tools for spatially navigating data
(pan, zoom, etc), we seem to be lacking a standard, intuitive (?) set of
tools for temporally exploring data with a strong geospatial connection.
Some of the temporal concepts stolen from geography that we'll have
to deal with: event extents, event resolution/density, temporal scale
(especially with respect to animation),...
I think the eventual solution will be JavaScript-based, maybe nearly
the size of OpenLayers effort. I'm leaning towards having separate
panel (like we tend to have for the legend, etc) for time navigation.
For layout and interaction ideas, have a look at the D3 examples
(https://github.com/mbostock/d3/wiki/Gallery), particularly the
CrossFilter (http://square.github.com/crossfilter/) example.
Sorry, no solution; just encouragement...
Best Regards,
Brent Fraser
On 4/9/2013 7:48 AM, Basques, Bob (CI-StPaul) wrote:
All,
Ok, granted weird title for a posting.
I have a little reporting project that I’m thinking about related to
GPS tracking. Bouncing the idea off of folks here in the hopes that
someone may have tried this somewhere else or maybe has a better way.
I need to generate a slider control for handling sorting through the
GPS data for individual vehicles on a daily basis. The idea is to
build a rapid, visually oriented, lookup system for the data. To
begin with, I would like to start the process by querying for the data
for a single GPS ID for a 24 hour period, generate a time based slider
control that can be used to pick a point in time, and then have a
slippy map (OpenLayers) auto zoom to that location, once a location
has been decided on.
I found an example on the Openlayers site for the slippy map part, I
have a service (yet to build) that can grab the location data by time
increments of 24 hours, but the slider part is looking like it might
be a bit intensive if built in a standard way. The data for the GPS
devices can come in all sorts of time resolutions, some are based on
15 – 20 sec updating, while others are using 3 sec update increments.
The resulting 24hr dataset can be somewhat sizeable as a result.
Here is my weird idea. Make the Slider into a MapServer map call
that is aggregated at certain time increments (Map tile pyramid
levels, only in a single direction, left/right) if the slider is
zoomed more resolution of time appears for picking the location in the
slippy map. The slider becomes a real wide but not very tall map but
only for displaying, and picking by the user a new time increment.
This approach should therefore compensate for browser view size as
well as density of time data, by making an appropriately sized, scaled
tile on demand. It should also be adaptable in the future to starting
out with larger time increments to show where GPS activity was, and
then to zoom in on that time increment for detailed analysis.
Ok, I’m ready, tell me it’s a stupid way to go . . .
Bobb
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