Contour tool creates contour lines (isolines) from a raster surface. The contour lines are used to illustrate topographic map such as valleys, hills, and the steepness of slopes. The contour intervals is the difference in elevation between successive contour lines. In addition to elevation, this tool can also create contours of other data such as temperature, precipitation, pollution, or atmospheric pressure from a raster surface. The distribution of contour lines displays how the values of the data change across the surface.
Contouring is widely used for spatial analysis in the following ways:
- To mark changes in elevation at certain intervals of surface raster (Digital Elevation Model)
- To find areas containing certain chemicals, fertilizers, or moisture levels of surface raster.
- To find patterns of ground pollution of surface raster that were created from interpolated soil samples.
Telecom companies contour their cell phone coverage maps to show signal strength over certain areas, then use these contours for spatial analysis. For example, to find out all customers that lie within low signal strength area (dropped call zones).
You can apply contouring on all the supported rasters formats in MapInfo Pro Advanced. For a list of supported raster format see, Supported Raster Formats.
The example below shows a surface raster showing valleys, hills, and the steepness of slopes.
In MapInfo Pro Advanced, you can create following types of contour:
- Polyline - In this type, you can generate a contour polyline map where
the lines are threaded through the surface raster. The contour levels will depend on
the range of cell values to be contoured or the contour intervals/spacing. The
contour line style will depend on polyline style specified in Contour dialog. The
image below shows a contour map of polylines:
If you zoom in on the contour map with labeling turned on, you will see contour level value associated with each polyline.
On the Contours dialog box, click the Intervals... button to change the interval range, interval method, and style for the contours.
Region - In this type, you can generate a contour region map where regions are created for cells falling in specified range. You can define a contour region interval and style in the Contour dialog box. In the output file, each contour region will have the lower and upper bounds of the region.
If you zoom in on the contoured map with labeling turned on, you will see the label for the region.
The image below shows the region interval range for the contoured output: