System for Automated Geoscientific Analyses (SAGA)

written by Grant Hamilton
Basic Information
Name: System for Automated Geoscientific Analyses
Acronym/Other Names: SAGA
Author/Owner/Steward: Jürgen Böhner and Olaf Conrad, Institute for Geography, University of Hamburg, Germany
Type: Free, open source standalone program
Platform: Windows, Unix-like operating systems
Download: http://sourceforge.net/projects/saga-gis/

Description

SAGA is a free and open source GIS program. It excels in performing analysis of raster files, but it also supports vector in the form of ESRI shapefiles. The native raster file format is the .sgrd, but other raster formats are supported, including ESRI and Surfer grids. SAGA is written in C++ with the ability for advanced users to code their own “modules” (tools/functions).

SAGA can be integrated with Kosmo, another free open source GIS program to support more vector formats and functions and with R, a free open source statistical program by users familiar with C++.

The following modules are standard:

  • File access: interfaces to various table, vector, image and grid file formats, including shapefiles, ESRI grids (ASCII and binary), and numerous grid file formats that are supported by the GDAL library, in addition to the native SGRD format of SAGA GIS.
  • Filter for grids: Gaussian, Laplacian, multi-directional Lee filter. The Laplacian filter is useful for image processing. The Lee filter is useful for reducing noise in DEMs.
  • Gridding: interpolation from vector data using triangulation, nearest neighbor, inverse distance.
  • Geostatistics: residual analysis, ordinary and universal kriging, single and multiple regression analysis, variance analysis.
  • Grid calculator: combine grids through user defined functions.
  • Grid discretization: skeletonization, segmentation.
  • Grid tools: merging, resampling, gap filling.
  • Image classification: cluster analysis, box classification, maximum likelihood, pattern recognition, region growing.
  • Projections: various coordinate transformations for vector and grid data (using Proj4 and GeoTrans libraries), georeferencing of grids.
  • Simulation of dynamic processes: TOPMODEL (a hydrology modelling tool), nitrogen distributions, erosion, landscape development.
  • Terrain analysis: geomorphometrical calculations such as slope, aspect, curvatures, curvature classification, analytical hillshading, sink elimination, flow path analysis, catchment delineation, solar radiation, channel lines, relative altitudes.
  • Vector tools: polygon intersection, contour lines from grid.

References

SAGA User Group Association. (n.d.). SAGA homepage. http://www.saga-gis.org/en/index.html

Böhner, J., et al. (2006). Digital Soil Mapping in SAGA GIS. Conference presentation. http://eusoils.jrc.ec.europa.eu/esdb_archive/ESBN/Esbn_Zagreb/Presentations/DSM/DSM_SAGA_Ringeler.pdf

  • Presentation by the SAGA team on their use of the program in soils mapping.

    • SAGA User Group Association. (n.d.). References. http://www.saga-gis.org/en/about/references.html

  • Download articles on SAGA (some in German), manuals, and technical guides.

Contact Information

Contact Name: Jürgen Böhner
Contact Email: boehner@geowiss.uni-hamburg.de
URL: http://www.saga-gis.org/en/index.html

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