ILWIS 3.0 SUMMARY PRESENTATION

ILWIS is an acronym for the Integrated Land and Water Information System.

It is a Geographic Information System (GIS) with Image Processing capabilities. ILWIS has been developed by the International Institute for Aerospace Survey and Earth Sciences (ITC), Enschede, The Netherlands.

1. SOKOINE UNIVERSITY OF AGRICULTURE

Department of Engineering sciences and
Technology
BSc.Irrigation and water resources engineering
LRM 112:GEOGRAPHIC INFORMATION
SYSTEM
(GIS)
ILWIS PRESENTATION-GROUP 02
Instructor:Prof. D.N kimaro
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2. INTRODUCTION TO ILWIS 3.0
ILWIS is an acronym for the Integrated Land
and Water Information System.

 It is a Geographic Information System (GIS)
with Image Processing capabilities. ILWIS has
been developed by the International Institute
for Aerospace Survey and Earth Sciences
(ITC), Enschede, The Netherlands.

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3. To start ILWIS, double-click the ILWIS icon on the desktop.
ILWIS Main window
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4. Where can ILWIS be applied?
•In land use planning, GIS is used to evaluate the
consequences of different scenarios in the development of a
region.
•In geology, GIS is used to find the most suitable places for
mining, or to determine areas subject to natural hazards.
•Areas that may be affected by pollution are analyzed
using GIS functions.
•Extensions of cities are planned, based on analysis of
many spatial and temporal patterns, etc. In order to be able
to make the right decisions, access to different sorts of
information is required. The data should be maintained and
updated and should be used in the analysis to obtain useful
information. In this process ILWIS can be an important tool.
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5. In ILWIS,the link between spatial and attribute data is the key to
get real information. Only by combining spatial and attribute data
we can get answers to questions such as: Where are the land use
units with a value more than 250?
example
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6. Main concepts of ILWIS 3.0
Structure of spatial data in ILWIS

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7. ILWIS uses different types of objects.
•Data objects. Raster maps, polygon maps, segment maps, point
maps, tables and columns are called data objects. They contain the
actual data.
•Service objects. Service objects are used by data objects; they
contain accessories that data objects need besides the data itself.
Domains, representations, coordinate systems and georeferences are
called service objects.
• Container objects. Container objects are collections of data objects
and/or annotation:
•map lists, object collections, map views, layouts and annotation text.
•Special objects. Special objects are histograms, sample sets, two-
dimensional tables, matrices, filters, user-defined functions and
scripts
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8. A domain in ILWIS stores the set of possible
data ‘values’ (class names, IDs or values) that
should be available in a map, table or column.
ILWIS uses domains extensively and for many
operations you should decide in advance about
the domain of a resulting map: a class map, an
ID map, or a value map. This enables you to
have a direct control over your data types, e.g.
having the domain as a separate object you can
have a direct look at the kind of data are stored
in your maps.
Domains include Value domains, class domains,
ID domains and The image domains
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9. THREE STANDARD COORDINATE SYSTEMS
IN ILWIS
1)Latlon: Geographical coordinates in degrees.
2) LatlonWGS84: Geographical coordinate
system using the WGS84 datum.
3)Unknown: When coordinates are not known.
This coordinate system should not be used.
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10. What is georeferences?
A georeference is a service object, which stores the
relation between the rows and columns in raster
map(s) and the ground-coordinates (X, Y). A
georeference is needed for raster maps and uses a
coordinate system. If you work with several raster
maps of the same area, and you want to overlay them
(e.g. with the Cross operation). it is important that all
maps have the same number of rows and columns,
and the same pixel size. The pixels in both maps thus
refer to the same position on the ground. Therefore all
raster maps of the same area should have the same
georeference.
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11. FOUR PHASES THAT YOU HAVE TO GO THROUGH
WHEN YOU WORK WITH GEOGRAPHIC DATA IN ILWIS:
1.DATA INPUT
2.DATA MANAGEMENT
3.DATA ANALYSIS
4.DATA OUTPUT
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12. 1. Spatial data input
Analysis and modeling in a GIS requires input of relevant
data. The data consist of two types: spatial data representing
geographic features (points, lines and areas) and attribute data
(descriptive information). Data input should be done with
utmost care,as the results of analyses heavily depend on the
quality of the input data.
In ILWIS, data can be entered by:
I.Digitizing, if you want to use data from analog (paper) maps;
II.Keyboard entry, for entering tabular data;
III.Scanning, if you want to use paper prints of satellite images,
aerial photographs, maps and pictures;
IV.Importing existing data files from other sources.
The most common method of entering spatial data in ILWIS is
digitizing.
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13. In ILWIS, there are seven main types of coordinate
systems:
- Boundary Only: corners of map in X,Y; no projection possible.
- Projection: corners of map in X,Y; optional projection and optional ellipsoid
and datum.
- LatLon: corners of map in LatLon; optional ellipsoid and datum.
- Formula: coordinates calculated by mathematical formula based on another
existing coordinate system.
- TiePoints: table with pairs of coordinates (master-slave) to define a relation
between the two, using a conformal, affine, second order, projective, etc.
transformation.
- Direct Linear: to digitize vector features from an (hardcopy) aerial
photograph on the digitizer. Table containing XYZ coordinates and digitizer
coordinates. DTM of the area required; no fiducial marks on aerial photograph.
- Ortho Photo: to digitize vector features from an (hardcopy) aerial
photograph on the digitizer. Table containing XYZ coordinates and digitizer
coordinates. DTM of the area required; fiducial marks on aerial photograph
and camera information required.
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14. ONSCREEN DIGITIZING
•Screen digitizing is the process of creating
and/or editing a segment or point map while an
existing raster map is as a background in a
map window. The raster map can be for
instance a band of a satellite image, a color
composite, a scanned map, or a scanned
photograph.
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15. ONSCREEN DIGITIZING (CONT….)
The background map or photo needs to have a
georeference of type:
- Tiepoints: for satellite imagery;
- Direct Linear: when the photograph is taken
with a normal camera;
- Orthophoto: when the aerial photograph is
taken with a professional photogrammetric
camera and has fiducial marks.
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16. Digitizing a point map
(kilwa masoko,Tanzania),digitized point map
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17. Digitizing a segment map
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18. Digitized segment map of kilwa
masoko,Tanzania
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19. Digitizing contour lines
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20. Creating a polygon map
A polygon map can be created using the following
steps:
- Digitizing the boundaries of the polygons as
segments in the Segment editor;
- Checking the segments in the Segment editor;
- Digitizing the labels of the polygons as a point
map in the Point editor;
- Polygonizing the segments using the point
map as labels in the Segment editor
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21. Digitized polygon map of kilwa
masoko,Tanzania

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22. Monoplotting on the digitizer
Monoplotting is the activity of digitizing segments and
points from an aerial photograph while correcting relief and
camera tilt distortion. During digitizing the is transforming
the gathered coordinates such that they fit on a topographic
map defined with a Cartesian coordinate system.
The transformation requires a DTM, in the form of a raster
map, whose georeference has the same Cartesian coordinate
system, or at least a similar system which is convertible into
the one of the created segment or point map. The DTM is
needed to compute the distortions due to the relief in the
terrain. To digitize on aerial photographs you need to create
a coordinate system Direct Linear or a coordinate system
Orthophoto.
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23. 2. Spatial data management
Important concepts to know in this section
•the import of raster and vector maps from different
file formats.
•The topic of map projections is treated, and how you
can change maps from one projection to another
•The tools for vector data management are shown, and
the vector to raster conversion is demonstrated.
•The tools for the management of raster maps are
explained.
•focuses on the conversion of domains
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25. The end
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