[postgis-users] Simple Point Density Surface

Doug_Newcomb at fws.gov Doug_Newcomb at fws.gov
Wed Apr 25 11:12:02 PDT 2012

        Looking at  - 
.  Why not convert the raster cell centers to points , do a query on the 
point layer for a square centered on the raster derived point  whose 
dimensions are given by the number of tiles in your neighborhood.  return 
the number of points divided by the area of the square.  ( neighborhoods 
are usually odd numbers of cells, 3x3, 5x5, etc so you have an equal 
number around the center cell)  . 

        The kernel optoin requires more thought


Doug Newcomb 
Raleigh, NC
919-856-4520 ext. 14 doug_newcomb at fws.gov
The opinions I express are my own and are not representative of the 
official policy of the U.S.Fish and Wildlife Service or Dept. of the 
Interior.   Life is too short for undocumented, proprietary data formats.

JamesH <james.holmes at newcastle.ac.uk> 
Sent by: postgis-users-bounces at postgis.refractions.net
04/25/2012 01:15 PM
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[postgis-users] Simple Point Density Surface

Hi all,

I am looking to take a point dataset and generate a point density raster 
PostGIS, similar to the ArcGIS Point Density tool in Spatial Analyst.

What I believe I need to do is to define a neightbourhood around each 
raster cell centre and calculate a density value for each pixel based on 
number of points that fall within that neighbourhood.

Ideally to recreate the same results, I would like to define a 
with a radius of 8 cells - most likely a square neighbourhood.

I have been considering this for a while but I really cannot understand 
to acheive this.

Any advise or help would be greatly appreciated.

Kind Regards,
James Holmes

GIS Undergraduate
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