OK, I seem to be getting color now. I was basing my weights on the 50-100,
but I just discovered in the docs that heatmap wants 0-1. So I made some
changed the color map, though I'm not sure that then maps properly to my
values. I do however get a heatmap to show up - which illustrated to me
the fact that I probably don't want a heatmap (it radiates outside of my
filter region, among other problems). Is there another method that would
provide a 1-to-1 mapping of feature geometry to color, without changing
where things are drawn?
On Wed, Feb 19, 2014 at 3:55 PM, Jeremy Lindsey <lind...@mosaicatm.com>wrote:
> Hello,
>
> I'm working on a project that has gridded weather data, stored in a
> postgis database. The database isn't really doing anything special with
> it, just entering one record (including a geometry column) for each cell in
> the grid. For hi-resolution weather information, this means that it can
> produce a large number of records.
>
> Until now, we have been using WFS to filter and retrieve the regions that
> we want and draw the results in our OpenLayers based web interface. We
> have javascript code that sets the color for each small polygon based on
> the value of another attribute of each feature. For one example, this
> could be percentage likelihood of precipitation or other weather. The end
> result basically looks like a heat map with higher percent regions having a
> more intense color than the lower percentage areas.
>
> As I mentioned though the dataset and be quite large. Unless you are
> filtering down to a pretty small area, then the query and rendering just
> takes too long. So the last couple days I've been experimenting with
> retrieving the data as a WMS layer instead of a WFS/vector layer. The
> results are promising. The data is properly filtered and returns much
> faster. (I beleive this is because its just returning a fixed 256x256
> image that does not need to grow in size like the raw WFS/GML would). The
> only problem is I can't figure out how to color it properly. By default,
> it was using the red point style and it all returned red. I tried other
> raster based styles, but since my data was not truly returned as raster, it
> failed (at least I assume that is why it failed).
>
> I then came across the vector-to-raster based heatmap style that could be
> applied via WPS. I installed the extension and tried the gs:heatmap as
> explained here:
>
>
> http://docs.geoserver.org/stable/en/user/styling/sld-extensions/rendering-transform.html
>
> I made a couple adjustments to fit my schema and gridval values (between
> 50 and 100) and assigned some random colors. It does not throw any
> exceptions, but I also do not see any colors showing up on my map. I have
> attached the style definition that I'm currently trying to use.
>
> As you have probably guessed, a lot of these concepts are still pretty new
> to me. I'd appreciate any tips that any of you might have to help me
> figure this out.
>
> Thanks!
>
> Jeremy
>
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