Thanks for the input Martin.
I can understand that 41K points may be an issue but even when I request a much smaller bounding box in order to significantly reduce the number of points being used I still don’t get anything displayed.
The data is a regular grid of points with a 1.25 x 1.25 degree spacing. The CRS is EPSG:4326. Would you be able to suggest suitable values for the other parameters, namely:
Scale, convergence, minObservations, maxObservationDistance (not sure if this should be meters or degrees), pixelsPerCell and queryBuffer?
From: Martin Davis [mailto:mdavis@anonymised.com]
Sent: 08 January 2013 17:28
To: Chris Haste
Cc: Andrea Aime; geoserver-users@lists.sourceforge.net
Subject: Re: [Geoserver-users] gs:Heatmap problems
Looks ok as far as it goes, but the other parameters are important as well.
41K points is probably pushing the bounds of BarnesSurface a bit too much. it’s really designed to interpolate relatively few scattered observations.
If you have a regular grid of observations there’s probably better and faster algorithms to use (although I’m not sure what would be the best choice.
On Tue, Jan 8, 2013 at 7:18 AM, Chris Haste <CHaste@anonymised.com> wrote:
Well my initial attempts at this are resulting in nothing being displayed, so I’d like to check whether I have some of the basics correct.
I have an SQL View Layer called TemperatureMap. The SQL in this view returns a table of two columns: location of type Point and temperature of type Float.
I have set the appropriate (I think) parts of the SLD as follows:
TemperatureMap
…
<ogc:Function name=“gs:BarnesSurface”>
<ogc:Function name=“parameter”>
ogc:Literaldata</ogc:Literal>
</ogc:Function>
. . .
<ogc:Function name=“parameter”>
ogc:LiteralvalueAttr</ogc:Literal>
ogc:Literaltemperature</ogc:Literal>
</ogc:Function>
Is this correct?
From: Chris Haste [mailto:CHaste@anonymised.com]
Sent: 08 January 2013 14:20
To: Andrea Aime
Cc: geoserver-users@lists.sourceforge.net
Subject: Re: [Geoserver-users] gs:Heatmap problems
Ah!
Thanks Andrea, I will go and try that one!
From: andrea.aime@anonymised.com [mailto:andrea.aime@anonymised.com] On Behalf Of Andrea Aime
Sent: 08 January 2013 14:18
To: Chris Haste
Cc: geoserver-users@lists.sourceforge.net
Subject: Re: [Geoserver-users] gs:Heatmap problems
On Tue, Jan 8, 2013 at 3:14 PM, Chris Haste <CHaste@anonymised.com> wrote:
Hi Andrea,
I’m not sure I understand. Are you saying that I don’t have a sufficient number of points in my data? I have a regular grid of points covering the entire globe at 1.25 x 1.25 degree intervals. Is this not dense enough?
I’m saying a heatmap shows a color based on the different concentration of points, not their value, so if the grid is regular it’s normal that
you get a solid color.
If you want to interpolate a value contained in the attributes of the points instead you have to use the Barnes surface instead.
See some docs here: http://suite.opengeo.org/docs/cartography/rt/barnes.html
Cheers
Andrea
From: andrea.aime@anonymised.com [mailto:andrea.aime@anonymised.com] On Behalf Of Andrea Aime
Sent: 08 January 2013 14:09
To: Chris Haste
Cc: geoserver-users@lists.sourceforge.net
Subject: Re: [Geoserver-users] gs:Heatmap problems
On Tue, Jan 8, 2013 at 3:03 PM, Chris Haste <CHaste@anonymised.com> wrote:
Hi List,
I have been trying to use the new heatmap transformation in version 2.2.3 but I think I must be doing something wrong.
I wish to display a layer defined using an SQL view. The query simply returns a Grid of points and for each point there is a temperature value, I am using the round function in the query to round the temperature value to the nearest integer.
I am using the SLD below, copied from the example and modified to (hopefully) work with my data. However, the entire map is produced in one colour (#FFFF00) but when I query the map by clicking on it in an Openlayers preview it shows correct values for the Temperatures and different locations on the map yield different values.
Any ideas?
Heatmaps are about point density, if you want to interpolation function you should look at the Barnes surface transformation
instead
Cheers
Andrea
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Our support, Your Success! Visit http://opensdi.geo-solutions.it for more information.
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Technical Lead
GeoSolutions S.A.S.
Via Poggio alle Viti 1187
55054 Massarosa (LU)
Italy
phone: +39 0584 962313
fax: +39 0584 1660272
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