Geoinformation, monitoring and assessment Environment

Updated October 1998

Land cover and land use

AFRICOVER Interpretation and Mapping System (AIMs)


Introduction

In the framework of the Africover Programme, it is necessary to analyze and interpret a very large amount of satellite imagery to generate digital cartography at 1:200,000/250,000 scale (1:100,000 scale for some specific areas) for African countries. As an example, for the East Africa module (the Italian Trust Fund project GCP/RAF/287/ITA) of the Africover Programme approximately 400 images should be processed and interpreted, in order to extract around 1000 map sheets. To enable easy, rapid and accurate satellite image analysis and interpretation an integrated image processing and analysis a software tool is required.

Existing available commercial software packages do not fulfil all the required functions; it has therefore been necessary to develop a system through the integration and upgrading of an existing software program. The system should is based on an available Image Processing (IP) software program, modified to support special functions and it includes specific software program modules developed within FAO, in particular it integrates the Land Cover Classification System developed in FAO, to help imagery classification and interpretation.

The Africover Interpretation and Mapping System (AIMs) image processing software is a module devoted to on video image interpretation with specific functions as specified below.

The core of the IP standard image processing package, that is the Multiscope software by MATRA Systems & Information, contains all the basic image processing functions with particular emphasis on the following functionalities:

Basic concepts of AIMs

1. Functions for working site and production management

The AIMs module includes a database and interactive tools for data base management (creation, consultation, modifying) of documents (maps) to be produced. The project activities envisage the application of the AIMs software through the interactive designation either by sheet name or number, through the pointing of a graphical work site map or by designation of co-ordinates (geographic and cartographic systems). The database must make possible the display of the general overview of the project working area (up to 900 sheets), and provide a detailed view of a region. The display indicates geographic frames of sheets (maps) and existing original images and results files, vectorial and processed images. The working management tool guides the production sequence and launch map-editing directly from the working site or sub-working site or be organized in work packages for each operator.

2. Continuous georeferenced working space

The AIMs module works on a predefined geographic area. When a working area is defined in geographic co-ordinates, all data (and only such data) that belong to this geographic area can be retrieved and used. The photointerpreter must be able to freely work in this "georeferenced working space" and able to draw polygons in a multiple window environment from one image or ancillary data (scanned raster maps, vector polygons or lines) to another one without any limitation of data mosaiking, different data spatial resolution, different type of localization systems of different documents (cartographic or geographic).

3. User defined working scale

The user of the AIMs module is able to preset a user defined working scale. A relation between size of the "georeferenced working space", data/screen resolution and chosen scale is set up in order to allow the user to work on the screen, at the scale he/she has chosen, independently from the type of data (with different resolution) used. The user is able to roam, at the defined scale, inside the all "georeferenced working space" or to select one of the sub areas in which the total working space is divided (defined by the system).

It is possible at any point of the interpretation work to obtain an overview of how the total area ("georeferenced working space") has been subdivided, to load new subareas and/or to identify those for which the work has been completed.

4. Basic digital image processing functions

The AIMs has all the basic image processing functions on line (mainly radiometric/spectral enhancements, filters and classifications functions).

5. Link with the Land Cover Classification System software

The AIMs module must have a direct link with the Land Cover Classification System (LCCS) developed by FAO. The LCCS is an expert system programmed in Access that allows the user to create any type of land cover classes saving them in a specific database called "Legend".

The LCCS software is completely integrated in the AIMs module. The LCCS will assist the user during the interpretation work for polygon encoding. The LCCS Legend Module must always be active in AIMs. When the user has generated a vector polygon a simple double clicking on a specific class in the "Legend" will generate automatic encoding. To generate a "Legend" list the user must have previously generated a number of classes in the LCCS Classification Module. This action, that is generation of a class, can be repeated at any time the user defines a new class that is not present in the "Legend" list; in this case the LCCS Classification Module is expected to be activated. The class is then generated and automatically saved in the "Legend" list. Subsequently, the encoding of the polygon should be applied according to the modalities explained above.

The other two modules of LCCS, that is the Field Data and Translator Modules, are also integrated.


Contact addresses

For technical questions about AIMs and LCCS:
Antonio Di Gregorio
GCP/RAF/287/ITA Africover East Africa Project
c/o FAO Representation Kenya
P.O. Box 30470, Nairobi, KENYA
Fax: ++254 2 860302
Email: antonio.digregorio@africover.org

For acquisition of AIMs and LCCS:
John S. Latham
Environment and Natural Resources Service (SDRN)
Research, Extension and Training Division
Viale delle Terme di Caracalla
00100 Rome, ITALY
Fax: ++39 06 570 55731
Email: john.latham@fao.org

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