DK11 for ActiveX | TatukGIS_XDK11.TGIS_GaussianHeatmap | Classes | Methods | Properties
Fast heatmap generator, creates superposition of normal (Gaussian) distribution for each data point.
// C# public class TGIS_GaussianHeatmap : ITGIS_GaussianHeatmap, ITGIS_VectorToGridAbstractEvents { }
' VisualBasic Public Class TGIS_GaussianHeatmap Implements ITGIS_GaussianHeatmap Implements ITGIS_VectorToGridAbstractEvents End Class
// Oxygene type TGIS_GaussianHeatmap = public class end;
Name | Visibility | Description | |
---|---|---|---|
AttachDelphiObj | public | Only for internal use of TatukGIS. _{ (Inherited from ITBaseObject) } | |
BusyEvent | public | _{ (Inherited from ITGIS_VectorToGridAbstractEvents) } | |
DelphiObj | public | Only for internal use of TatukGIS. _{ (Inherited from ITBaseObject) } | |
EstimateRadius | public | Calculates a "good choice" of the 3-sigma ("radius") of the Gaussian distribution. _{ } | |
Generate | public | Populates a pixel (grid) layer with values resulting from computations based on the set of sample points from the vector layer. _{ (Inherited from ITGIS_VectorToGridAbstract) } | |
Name | Visibility | Description | |
---|---|---|---|
Coordinate | public | Defines which coordinate is taken as interpolation value if the interpolation is not based on an attribute field; default is Z. _{ (Inherited from ITGIS_VectorToGridAbstract)} | |
DefaultValue | public | If UseDefaultValue is true, then this value will be set for each grid cell for which the interpolated value cannot be computed. _{ (Inherited from ITGIS_VectorToGridAbstract)} | |
Radius | public | 3-sigma ("radius") of the Gaussian distribution. _{} | |
UseDefaultValue | public | If true, then each grid cell for which the interpolated value cannot be computed will be set to DefaultValue. _{ (Inherited from ITGIS_VectorToGridAbstract)} | |
The heat map is a method of visual presentation of spatial point data values and concentration. Mathematically it is a sum of normal (Gaussian) distributions located at each sample point with peak values representing values associated with each point.
There are three different scenarios for generating a heat map:
Coordinate
property to the desired optionGenerate
methodGenerate
methodCoordinate
property is neglectedCoordinate
property to NoneGenerate
methodThe resulting grid values are normalized (linearly rescaled) so they do not exceed the values of the source data (minimum and maximum grid values are the same as the minimum and maximum source values).
The resulting heatmap is highly dependent on the Radius
parameter (3-sigma of the normal distribution). To easily set a reasonable value of Radius
, call the EstimateRadius
method before Generate
. The Radius
value set by the EstimateRadius
method is the average of the minimal distance between neighboring points, multiplied by 3.
A quick and great looking way to present quantitative data for easy, visual analysis.
This is neither an interpolation nor an approximation method! It is suitable only for specific kinds of analysis (like a distribution of frequency of events).