The Hotspot Density method is now called Advanced method of Heatmap.
The Advanced dialog exposes all of the options available and you can use it to compute any of the Heatmaps already described - and more. For example, you can use the Advanced method to compute weighted sample count and density Heatmaps. It also provides access to advanced concepts such as sample grouping. The Advanced dialog provides initial sample selection and data conditioning options as well as control over the output raster geometry, format and other options.
Advanced Heatmap Options
- Parameter Unit
Specifies whether spatial parameters are defined in cell units or distance units. The units should be supported by MapInfo Pro, for example, the options for Distance unit include: US Survey feet, yards, rods, chains, miles, nautical miles, millimeters, centimeters, meters, inches, links and kilometers. If you choose Distance, you need to select a distance unit from the Distance Unit drop-down list.
- More Options
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Smoothing Method - You can apply smoothing on the gridded data to produce smoother surface. Smoothing is used to enhance the sharpness of an image or improve the appearance of the edges. Select a suitable Smoothing method and level for your data.
Smoothing Level - Move the smoothing slider to set the smoothing level for the output raster. You can set a value between 0 to 6. A value of zero applies no smoothing. A value of 6 applies maximum smoothing.
Kernel - Commonly, a kernel density estimator (KDE) function is introduced to weight the input samples - usually as a function of normalized distance between the sample and estimation positions. The method supports the following KDE functions: Uniform, Triangle, Epanechnikov, Quartic, Triweight, Gaussian and Cosinus.
Normalize by Area - Normalizes the output cell values by cell area.
Coincident Points Method - The gridding engine can pre-process the input source data to identify points that are spatially coincident. In general, two points are spatially coincident if they lie within a specified distance of each other. When the distance is set to zero, then the points are coincident if the X and Y coordinates are computationally indistinguishable from one another. For more information see, Coincident Point Method.
- Search Options
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Search Modes defines how the interpolation algorithm searches for input data points within the search neighborhood. The shape of the search neighborhood will be dictated by the type and distribution of the input data. The following search modes are available:
- Spherical - Performs an equidistant radial search within the search neighborhood. The search distance is defined by the Major Axis Search parameter, which is defined in Parameter Units. For optimum performance, it is advisable to keep the search distance small. A value less than or equal to 5x of the output cell size is usually sufficient. Spherical search is best applied when the variation in the spatial distribution of the input data is considered isotropic.
- Elliptical - Performs an elliptical search within the specified search neighborhood. The shape of the ellipse is defined by the Major Axis Search and Minor Axis Search parameters. The Major Axis Search defines the maximum width (x axis) of the search ellipse and the Minor Axis Search defines the minimum width (y axis). Major Axis Orientation defines the rotation angle of the ellipses Major search axis, measured clockwise from North (0 degrees). An elliptical search is best applied when some directional anisotropy is known to exist in the spatial distribution of the input data.
A default search radius will be calculated for you. If you wish to enter a specific distance then you can do so by typing the required values into the Major Axis Search box. To apply anisotropic search, choose elliptical search mode and enter a value into the Minor Axis Search and Major Axis Orientation box. The size of the Major axis search must be larger than the minor search axis.
- Raster Geometry
In the Raster Geometry section, specify the cell size and raster bounds for the output raster. For more information, see Defining Raster Geometry.
If required, click More Options to specify category and sub category of the output projection. If the input file is MapInfo .TAB, projection values are read from the input file, which you can override here.
- Category - The Category drop-down list consists of all projection systems supported by MapInfo Pro. For example, Longitude/Latitude, Universal Transverse Mercator (ED 50), Universal Transverse Mercator (NAD 27 for Canada), etc.
- Sub Category - The Sub-Category drop-down list consists of the type of projection based on the selected projection system.