[mapserver-dev] RFC-108 : heatmap generation

[thomas bonfort]

> One other thought for you, are you considering stacked points in your equations.  Points in the exact same location do occur quite regularly.  Things like census values and anything Parcel (centroid) related for example.

those are handled transparently (a pixel with two samples will weight
twice as much as a pixel with a single sample)

>
> Bobb
>
>
> -----Original Message-----
> From: thomas bonfort [mailto:thomas.bonfort at gmail.com]
> Sent: Thursday, January 30, 2014 3:41 PM
> To: Basques, Bob (CI-StPaul)
> Cc: mapserver-dev at osgeo.org
> Subject: Re: [mapserver-dev] RFC-108 : heatmap generation
>
> Bob,
> I had initially planned to support line or polygon shapes, but gave up because of the extra complexity (features would need to be rasterized into the intermediate accumulation grid), and the ambiguity that arises as to what weight to assign to each rasterized pixel (should each pixel be assigned the intensity of the whole feature, or should we divide that by the number of pixels that were actually affected by the feature). I'll have a second look to see if this is a feasible addition, but I'd say that the first iteration will only be applicable to point datasets.
>
> regards,
> thomas
>
> On 30 January 2014 22:12, Basques, Bob (CI-StPaul) <bob.basques at ci.stpaul.mn.us> wrote:
>> Thomas,
>>
>> Just one suggestion related to features used for clustering, can you consider using LINE features as well.  My particular need could use points as described and probably still work nicely.  My specific need is for applying heat mapping to trail (GPS, Average Daily Traffic) lines, these lines are generated from points sequences though, so this would still be doable as RFC describes.
>>
>> There are occasional instances where long segments are introduced into the GPS data collections where a GPS lock goes missing for a while, these long lines are the things I would like incuded in a heatmap output.  Maybe there is a way to interpolate some points along a line that would still work with the scribed system as another mode of processing.
>>
>> Good stuff all around either way.
>>
>> History trivia, ask Steve L. sometime, about some heat-map work we did more than ten years ago now for an online mapping interface.
>>
>> Bobb
>>
>>
>> -----Original Message-----
>> From: mapserver-dev-bounces at lists.osgeo.org
>> [mailto:mapserver-dev-bounces at lists.osgeo.org] On Behalf Of Thomas
>> Bonfort
>> Sent: Thursday, January 30, 2014 10:58 AM
>> To: mapserver-dev at osgeo.org
>> Subject: [mapserver-dev] RFC-108 : heatmap generation
>>
>> Devs,
>>
>> please have a look at RFC-108 [1]. The associated code and the RFC are still beta, so there's still plenty of room for modification or remarks.
>>
>> best regards,
>> thomas
>>
>> [1] http://mapserver.org/development/rfc/ms-rfc-108.html
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>