Calc Kernel Map

Description

This functor calculates the kernel density of an event map representing a point pattern.

Inputs

Name	Type	Description
Events	Map Type	Map showing the location of events. Events are represented by non-null cells, indicating the number of occurrences on the cell.
Bandwidth	Real Value Type	Radius, in meters, of the disc centered on each cell within which events contribute to the kernel estimate.

Optional Inputs

Name	Type	Description	Default Value
Mask	Map Type	Map whose null cells mask the kernel calculation.	.none
Null Value	Null Value Type	Null value of the calculated kernel map.	.default

Outputs

Name	Type	Description
Kernel Map	Map Type	Map showing the kernel density estimate for each cell.

Group

Statistics

Notes

Kernel density estimation produces a continuous estimate of the spatial intensity of a point pattern, making it possible to explore hotspots and other patterns in the distribution of events even when overlapping points would make visual inspection misleading.

Increasing Bandwidth spreads the density estimate over a wider area around each cluster: with a large bandwidth the density appears flatter and local features are obscured, while a small bandwidth reveals local hotspot patterns more sharply.

The kernel function used is the quartic function k(h) = (3/PI)*(1-h^2)^2.

References

Bailey, T. and Gatrell, A., 1995: Interactive Spatial Data Analysis. Longman, Harlow.

Silverman, W., 1986: Density estimation. Chapman and Hall, London.

Internal Name

CalcKernelMap