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Masterarbeit von Leonarda Usela-Rohenkohl

 

Course: Geoinformatik 

 

Theme: Comparative Studies of the Image Processing Systems IDRISI and ERDAS Imagine

 

Supervising Tutor: Prof. Dr.-Ing. Fredie Kern

 

Time needed for Completion: 15.08.2007 to 15.02.2008 

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Content

Background

Objective

Result

Summary

Pro and Contra

IDRISI

ERDAS

 

 

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Background / Problem

 

The ongoing challenge in the remote-sensing industry is to make high-quality data accessible to more users for an affordable price. IDRISI and ERDAS belong to the most widely used notable proprietary software. Image processing operations modify the numeric values contained in an image according to specific algorithmic rules, to highlight or extract certain trends in the data which indicate features of interest.

 

Due to immense and complex functionalities only for the main operational area of the image processing had been carried out (e.g.  exercises from the Module Digital Image Processing, FH Mainz, Geoinformatic and Survey, Prof. Dr.-Ing. Fredie Kern) in both programs.

 

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Objective

 

This study presents a comparison between two different image processing systems. IDRISI Andes is a GIS and Image processing system and ERDAS IMAGINE 9.1 a digital image processing software package. Since the main objective of this study is the comparison of two image processing softwares, exercises were carried out on image processing techniques which then and determined the capability, functionality and user friendliness of both programs.

 

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Result

 

According to the three general steps in processing a digital image the following functions were executed: Pre processing carrying out Geometric Corrections; for the comparison in Display and Image Enhancement were executed via practices in Import/Export, Point operations, Local Operations, Image Reduction, Image Magnification, Contrast Adjustment, Spatial Filtering, Fourier Transformations, Principal Components Analysis; for the Information Extraction: Supervised Classification and Unsupervised Classification was carried out.

 

 

In the above example (LandSAT year 2000 and 2002 Dessau, Germany) IDRISI was used for Unsupervised Classification with later reclassification to create a boolean image to mask all classes except the water class. From the two boolean images a CROSS classification was carried out in IDRISI to represent the flood area, the combination 0/1 represents the flood area , the class 1/0 represents irrigation area in 2000.

 

Flood area 0/1 was calculated to 4 174,31 Hectares.

 

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Summary

 

Both IDRISI Andes and ERDAS IMAGINE 9.1 include an enhanced processing system and functions and worked out equally good.

 

IDRISI Andes is offered for an affordable and very competitive price, which makes it very attractive to beginners as well as for practitioners. Nevertheless it is also very suitable for professionals, if a wide range of data formats and vector integration is not required.

 

ERDAS IMAGINES 9.1 is a very complete Image Processing Software, good structured and documented and equally usable for beginners as for professionals. It is user-friendly and has wide functionalities. Beginning researchers may prefer standard settings like it is possible in IDRISI while professional will appreciate individual specifications. ERDAS covers a huge range of data formats, image processing tools and offers integration with ESRI ArcGIS as well as raster and vector integration. .A disadvantage is the very high price, especially for private users who want to get started getting familiar with Image Processing Software.

 

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Pro and Contra

 

IDRISI

ERDAS

Large range of classifiers, some innovative (neural networks, decision trees)

Special modules: change detection, time series, fuzzy logic

Decision support tools

Geostatistical modules

Affordable price (between 500 -1000€)

Student versions available

World-wide IDRISI Resource Centres

Low system requirements

Excellent documentation, tutorials, help

 

Good integration with ESRI ArcGIS

Good raster and vector integration

Vector analytical tools

Comprehensive import/export module

Tools for ortho-rectification, stereo tools

Powerful projection engine

Flexible licensing

World-wide distribution network

 

 

 

Only DOS

No lineage

DOS and UNIX

Image Lineage

no good vector support/integration

Hardware locked licensing

High price (professional ca. 7000,-€)

 

 

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IDRISI

IDRISI consists of a main interface program and a collection of nearly 250 program modules that provide facilities for the input, display and analysis of geographic data. The Toolbar icons are integrated.

 

 

 

 

 

 

A special feature in IDRISI is the IDRISI EXPLORER, a general purpose utility to manage and explore IDRISI files and projects and is used to set your project environment, manage your group files, review metadata, display files, and simply organize your data with such tools as copy, delete, rename, and move commands. The IDRISI Explorer can be used to view the structure of IDRISI file formats and to drag and drop files into IDRISI dialog boxes.

 

IDRISI is a GIS and Image processing system developed by Clark Labs (see glossary). The latest version of IDRISI is known as IDRISI Andes, released in April 2006, the 32-bit version designed for Windows NT, now in its third release. IDRISI Andes is an integrated GIS and Image Processing software solution, covering the full spectrum of GIS and remote sensing needs from database query, to spatial modelling, to image enhancement and classification. IDRISI is used by researchers and professionals across industries in over 175 countries.

 

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ERDAS

ERDAS is organised in a main panel, these icons represent the various components and add-on modules.

 

 

 

 

 

ERDAS is a GIS, Remote Sensing, and Photogrammetry software. ERDAS is a broad collection of software tools and automated routines designed specifically to process imagery. It allows you to extract data from images like a seasoned professional, regardless of your experience or education.

ERDAS is a wholly owned subsidiary of Leica Geosystems and operates as the Geographic Imaging unit within the Leica Geosystems GIS & Mapping Division.

In 1978 in Atlanta, USA , ERDAS pioneered the first integrated rasters GIS and image processing system on PC basis. Until today ERDAS was also established as international market leaders with the product of the same name in over 105 countries. In the Federal Republic of Germany ERDAS is available since 1984. Whereby the user circle is formed predominantly from universities, research institutes, international organizations and, particularly in the last years, from private businesses and authorities. Among the ranges of application rank among other things land use mapping and changes, cartography, demographic investigations, ecological data acquisition and evaluations, photogrammetric applications etc..

The latest versions of IMAGINE are designed to complement ESRI’s ArcGIS software

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