MapInfo Pro

Classification

Classification is the process of assigning output values that depend on a specific set of input values. These operations can also be thought of as the purposeful re-coloring of maps.  

There are two types of Classification:

•        Continuous Classification

•        Categorical Classification

Continuous Classification

Continuous classification helps in classifying values ranges into a specific number of groups. For example, a raster depicting slope map can be classified into group of eight based on directional degrees.  

Categorical Classification

Categorical classification involves replacing individual values with new values. For example, a raster depicting slope map can be classified into directional names viz. north, northeast, east, southeast, south, south, southeast, west, northwest or can be represented in the form of numeric values such 1 to 8.

How to Classify Raster Datasets in MapInfo Professional?

The Classify tool enables you to reclass values in a classified grid to make the data more suitable for your analysis. When you reclass a raster, you generate a new classified raster.

Steps for Classification of Raster Data

• Open a raster file in the map window and On the RASTER tab, in the Operations group, click Raster Operations and then click the Classify button to display the Classify dialog box.

• Select either Numeric or Classified as output raster type from the Output raster type drop-down list. Classified option is selected in this illustration.
  • If you select Classified, Change the name of the class by double clicking on the Class column corresponding to the class you want to change and assign a new class. You can change color for the class by clicking the Color column. Rows can be inserted or deleted to add/delete new class.
  • If you select Numeric, all the classes that are present in the input raster are listed. Each class is assigned a default value. If you want to edit the value, click on the New Value column corresponding to the class you want to change and assign a new value.

• Select either Continuous or Discrete from the Class Interval Type drop-down list.
  • Continuous Interval - Example: Temperature, Precipitation, Slope, Aspect
  • Discrete Interval - Example: Soil, Land Use, Zoning
• Click Derive Class Color From to choose a color from the color table. The output class will derive color from the selected color table. You can Save the classification profile into a text file and can reuse later by Clicking Load to load the existing classification profile. You can load the classification profile from a csv or text file. Color changes can be done by double clicking the color palette as well.

• Click Intervals to modify the input classification range and the number of classifications or bins in the output raster.
  • Input Data Range - The input data range as specified in the input file. You cannot edit the Minimum or Maximum value.
  • Class Intervals - In the Class Intervals section, you can specify the numerical width of your class. Specify values for Minimum or lower class limit and Maximum or upper class limit. There are two methods available for class intervals of Interval Spacing or Number of Intervals.
    • Select Interval Spacing, type a value in the Value field, and click OK. The value represents the interval spacing between the cell values. For example, if you have a raster with value ranges from (10 - 100), (100 - 200), and (200 - 300), changing the interval length to 150 will produce an output raster with value ranges from (10 - 250) and (250 - 300).
    • Select Number of Intervals, type a value in the Value field, and click OK. The intervals are divided evenly. For example, if you enter 15 in the Value field, the new classification profile will have 25 intervals, with the minimum and maximum cell values adjusted evenly over the intervals. 

• Use Null for Undefined Class - Select this check-box to use null values in the output raster for undefined class intervals.
  • Click OK to apply the changes. The interval gets updated.
•  In the Output File box enter the name you want to specify for your output file. Click to browse to the location in your computer to save the output file and select the required output file format. Click Display to display the classified output file on the map window.
• Click Process to start classifying an aspect raster in the output on the map window. The aspect map is created from the Elevation raster data.

Why Classification is important?

Classification thus helps in various applications such as Simplification (create clusters/groups for analysis), enable replacing values based on new information and help create common scales for scoring/ranking/weighted analysis.