Image Statistics by Polygon

This tool performs statistical analysis from Polygons or Thematic Classes. The statistic parameters presented are:

  • PIXEL NUMBER
  • MINIMUM
  • MAXIMUM
  • AMPLITUDE
  • MEAN
  • VARIANCE
  • AVERAGE DEVIATION
  • ASSIMETRY
  • KURTOSIS
  • COEFICIENTE OF VARIATION
  • MEDIAN
  • MODE


To use such tool it is necessary that:
INPUT:

1- Choose a Thematic, Cadastral, or Labeled Image Infolayer that contains Polygons or Thematic Classes;
2- Select the Image, Grid, or Thematic Image IL that you want to analyze from one same category.

OUTPUT:

1- Report with the parameters above only for the selected Polygon or Class - option  Selected Polig. or Selected Class.

2- Non-Spatial Table with all the parameters of every Polygon or Thematic Classes of the loaded IL  - option Every Polig. or Every Class.

NOTE: In case the input IL is a cadastral map with objects associated, the output  non-spatial table will have, besides the statistical attributes, attributes such as the GEOID, Label, Object Name. This will allow this table to be linked to the object table (see linking Tables), enriching thus the query resources.

Following we present the procedures for acquisition of statistics.

Executing the statistical analysis over the images:

  • load in the "Control Panel" the category and the IL that contains Polygons or Thematic Classes. It can be a thematic, cadastral, or labeled image IL (resultant of a segmentation). Draw the chosen IL on the active display;
  • Click on Tools - Image statistics using polygons... on the main menu. The associated window is presented;
  • Note that the name of the active IL should be on the title bar of the window;
  • Select from the list the Category that contains the Images, Grids or Thematic Images to be analyzed;
  • Select from the list Image one or more IL's;
  • Click on Entity and choose:
    • if All - you must select in the button Object Category...(only for cadastral IL as the active IL) the object associated to the active map, for there could be more than one. Type in Table Name the name of the table to be created.
    • if Selected - the cursor changes into the point mode. Click on the drawing area over the Polygon or Thematic Classes to be analyzed. Note that the Polygon or Thematic Class is selected;
  • Click on Execute to perform the calculations.

RESULT 1: If the option was All, the non-spatial table will be available in the database. If you wish to edit or see the contents of this table use the window "Non-Spatial Data" available in Edit - Table... .

RESULT 2: If the option was Selected, the window "
Data Report" will present the values of the polygon. For another polygon, select again in the drawing area and click again on Execute.

See also:
Defining a data model .
Edit non-spatial table.
Linking Tables .
Database queries.