How to execute a Cross Tabulation

The cross tabulation operation allows to compute the intersection areas between the classes of two thematic IL's. To use this function is necessary the project to be active.

The operation will be executed between the IL's in the raster format. The data has to have the same horizontal and vertical resolution, the same number of lines and columns ("pixels") and understand the same terrain coordinates.

The cross tabulation compares two information layers classes, determining the intersections distribution. The results are presented in two dimensional tables, as shown in the example below.

analise10.gif - 12654,0 K

In the example above it is possible to observe that the intersection area between the "Cerrado" class of the "Land Use" IL with the flat class of the "Geomorphic" IL is 298.56 Km2. The SPRING presents the tabulated values for the number of pixels between the classes and the area values in hectares.


Executing cross tabulation:

  • activate in the "Control Panel" a thematic category and an associated IL, which has the raster polygons;
  • select in the main menu Thematic - Cross Tabulation.... The "Cross Tabulation" window is presented. Notice that the Current IL in the step above is presented;
  • click on Intersection Infolayer... to select the second thematic IL, also in a raster format. The "Categories and Layers" window is presented. Click on Apply after selecting the desired IL;
  • click on Apply  or  click on Export Worksheet...
  • when Executing, a text file (ASCII format) with the values (as in the table above) is created in the file system. This file can be edited and manipulated as desired.
  • when Export Worksheet... generates and export one of the values in the spreadsheet format in a text file (ASCII). The "Save As" window is presented. Select or Change the name and click on Save.
    • the suggested name corresponds to the category, that generates the second column (CATEG_<categoryname> )
    • if the file already exists, the "substitution" will be as follows: the previous file will be kept as <filename>_OLD.txt, the new file will be created with all the lines in the previous file, adding the new lines and there will be classes consistency (new classes generate new columns)
    • the worksheet is cumulative and can be imported in the "EXCEL" format to compute the classes areas summation from several projects
    • the worksheet exported via "Classes Measures" can be used to data accumulation of "Cross Tabulation" and vice-versa
    • column delimitation = semi-colon character (;)
    • numerical data : decimal separator = dot character (.) and thousands separator = none (non existent)

    See the example below:

    PROJECT;CATEG_Cartatema;PI;WRSTM;UF;DATA;UNID;REPRES;T_PI;T_CLASSES;T_NAOCLASSIF; TC_CATEG;TC_PI;T_BACKGROUND;forest;not_forest;...
    P02_047_00565_300702;Cartatema;classif2002;00565;AC;300702;(kmxkm);repres_matriz;0.0;0.0;0.0;
    states;states;4.474800;4570.279200;...
    P02_047_00565_300702;Cartatema;classif2002;00565;AM;300702;(kmxkm);repres_matriz;0.0;0.0;0.0;
    states;states;21.186000;20956.1760;...


See also:
Programming in LEGAL
Consulting a database.
How to get the system conceptual information


Other geographical analysis options in the Spring