[mapserver-dev] RFC-108 : heatmap generation

thomas bonfort thomas.bonfort at gmail.com
Mon Feb 10 05:08:29 PST 2014


>> Only other thing I wonder about is the kerneldensity_attribute. Often you have non-numeric values that you'd like to apply. In my case we have high, medium and low values for wildfire susceptibility. High values would contribute more to intensity. I'm not sure how the feature attribute is use, but any idea on we might work from those?
> That's what I was trying to hint at in the second point of
> http://mapserver.org/development/rfc/ms-rfc-108.html#open-issues . We
> sorta use the same mechanism for CHART layers, where the value of each
> class is read from the style->size; that could also be used in your
> case, e.g.:
>
> layer
>  type point
>  name "input-heatmap"
>  classitem "risk"
>  class
>   expression "high"
>   style
>    size 5
>   end
>  end
>  class
>   expression "medium"
>   style
>    size 3
>   end
>  end
>  class
>   expression "low"
>   style
>    size 1
>   end
>  end
> end
>
> To mimick the proposed ATTRIBUTE=VAL processing you'd use
>
> class
>  style
>   size [val]
>  end
> end
>
> I find the syntax rather clunky, but it is clearly more powerful.
> thoughts? could this be done differently?

I have updated the RFC and code to use this class->style->size
notation for specifying alternate weightings. The default is to use
uniform weighting if the source vector layer has no CLASSes defined.
Although the syntax is a little more verbose than the proposed
PROCESSING "ATTRIBUTE=attr" notation, it is much more feature-full and
closer to classical mapfile notation.

regards,
thomas


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