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ILWIS 3.31 Update

ILWIS 3.31 Update

ILWIS 3.31 is released in June 2007. It is a service pack on ILWIS 3.3 Academic.

ILWIS 3.31 is the last service pack made available by ITC. With this, ILWIS 3.3 is enhanced with new functions and bugfixes that were developed after the release of ILWIS 3.3, but that were not yet made available as an official service pack. ILWIS 3.4 Open is derived from ILWIS 3.31; in ILWIS 3.4 Open, copyrighted components were removed in order to be able to offer it as open source software.


  • Instructions
  • Hydrologic Flow Operations
  • Spatial Multiple Criteria Evaluation (SMCE)
  • Projections
  • Classify operation
  • Import/Export
  • Bug Fixes
  • Registration code


Make sure you are logged in as administrator!

  1. Download patch331.exe to a temporary directory
  2. Run the 3.31 patch to update ILWIS 3.3 Academic
  3. In the dialog "Locate system to update", locate your ILWIS 3.3 folder and click "Open"
  4. Click "Yes" in the Update dialog
  5. Confirm the location by clicking "Yes"

Hydrologic Flow Operations

  • The Flow Direction operation algorithm now includes parallel drainage correction over flat surface,
  • A 'cut terrain' option was added to Fill sinks,
  • Added operations 'Flow Length to Outlet' and 'Flow Path Longitudinal Profile',
  • Many more improvements were made in the functionality, the calculation and the user-interface of Catchment Merge, Horton Statistics and others.

Spatial Multiple Criteria Evaluation (SMCE)

  • Added options to generate contour maps from both intermediate and final suitability maps,
  • Added option to view the standardized version of a criterion.


  • Added 3 variants of 3D-datum-transformation commands, assuming user-defined Bursa-Wolf or Molodensky-Badekas datums,
  • Added Hungarian EOV projection. The implementation is based on,
  • Added Hungarian Datum 1972,
  • Added Mercator Scaled projection,
  • Added GRS 67 ellipsoid ("Geodetic Reference System 1967"),
  • Added ellipsoidal cases for Goode, Mollweide and cylinder Sinusoidal projections,
  • Added a table-operation "findazimdist" that computes the geodetic (ellipsoidal) distance and the azimuth between latlon or projected coordinates from two given columns.

Classify operation

Added spectral angle classifier.


Export to Shapefile now also exports the coordinate system to a .PRJ file.

Bug Fixes

Most important bug fixes in 3.31 are:

  • Large polygon files are now properly exported to the Shape file format,
  • The Clustering operation now allows value maps, the maximum number of classes increased to 255, and calculation is more accurate,
  • The precision of the MapList Statistics operation increased, and sum and count are added to the list of statistic functions.

Registration code

ILWIS no longer requires a registration code to run.