topic Re: blurRadius - HeatmapRenderer in ArcGIS JavaScript Maps SDK Questions

blurRadius - HeatmapRenderer

LandcorAdmin — Tue, 07 Nov 2017 17:29:12 GMT

Hi to All members of this community,

I have been working on producing a heatmap using ArcGIS API 3.22.

It is working fine but the problem I have is with understanding of the blurRadius property.

Does anyone know what it actually means?

The explanation says: The radius (in pixels) of the circle over which the majority of each point's value is spread.

But how big is the pixel? Can we measure it in any sort of way?

For example: Default value is 10 - Does it mean that the blurRadius is equal to 10 m, 10 km etc.?

Thank you very much for your help.

Regards

Pavel

Re: blurRadius - HeatmapRenderer

RobertScheitlin__GISP — Tue, 07 Nov 2017 17:54:42 GMT

Pavel,

A pixel is a measurement of the screen:

http://whatis.techtarget.com/definition/pixel

So the default of 10 talking about 10 pixel on the screen which depending on the maps scale will determine the real world measurement.

Re: blurRadius - HeatmapRenderer

LandcorAdmin — Tue, 07 Nov 2017 19:17:37 GMT

Hi Robert,

thank you very much for your reply.

So, for example:

Zoom level: 14 = Resolution: 9.55 (based on Web map zoom levels updated | ArcGIS Blog)

10 pixel on the screen = 9.55 * 10 = 95.5 m ..this means that the blurRadius is equal to 95.5 m?

Is this correct?

Thank you.

Pavel

Re: blurRadius - HeatmapRenderer

RobertScheitlin__GISP — Tue, 07 Nov 2017 19:26:59 GMT

Pavel,

I am having a hard time understanding why you are worried about what a pixel equal in real world distance. The heat map blur uses the blurRadius to determine how points on the map are spread based on the number in a screen pixel.

Re: blurRadius - HeatmapRenderer

LandcorAdmin — Tue, 07 Nov 2017 19:41:06 GMT

I was wondering if there is any relationship between the blurRadius and the search area. I was thinking about it as an analog to the Kernel density function where the search radius is applied.

But in this case, if I understand well now, it is just the area where the Gaussian blur is used.

Thanks Robert.

Pavel