170 
5 
LANDSCAN GIS 
(nearest neighbour, bilinear, cubic 
convolution) 
Second and third order polynomial 
transformations 
- Accuracy checked by comparison with 
grid. 
Filtering 
- Linear using user-defined kernel 
- Non-linear filtering (median) 
- User defined weight and offset 
Editing of drop-outs 
Line fix 
- Replace isolated errors 
Transforms 
Fourier 
Slant 
Cosine 
Haar 
- Hadamard 
K-L 
- Principle component analysis 
Image Arithmetic 
- Logical and arithmetic operations 
- Add, multiply, divide, subtract 
AND, OR 
- Two images or image and constant 
- Animation 
Continuous and single step 
- Map overlay control and graphic annotation 
- Text 
Symbols 
- Isoline contours 
- Map grids superimposed on images 
- Scroll, pan, roam, scale, rotate, zoom 
- Contrast stretch 
Linear (manual and automatic) 
- Piecewise linear 
- Exponential 
- Logarithmic 
- LUT manipulation 
- Density slice 
- Pseudocolour 
- Pixel readback 
- Histogram of transect 
- Pixel value 
- Texture analysis 
Autocorrelation 
Variation 
- Local rank 
- Local grey-level 
- Image file handling 
- Image statistics 
- Mean 
- Standard deviation 
- Skewness 
- Kurtosis 
Image histograms 
Other facilities available include: 
5.1 Overview 
This section describes the design of the Geographic 
Information System (GIS), which is currently being 
implemented as an enhancement to the existing 
LANDSCAN systems. 
A GIS is a unifying concept for the storage, 
manipulation and interpretation of all types of 
spatial data. The two types of spatial data of 
particular relevance to the LANDSCAN GIS are: 
- Earth resources satellite data 
Digital map data. 
The use of a GIS is of great relevance for the 
integration of these and other spatial datasets, and 
through progressive enhancements to the LANDSCAN 
range, ESSG are making use of their Systems 
Engineering expertise in the following key areas of 
GIS design: 
- File creation, manipulation and display 
- Search, retrieval and query satisfaction 
- Output and display. 
Of equal importance is our experience of many 
different applications and end-users of satellite 
imagery and weather radar data. 
5.2 GIS hardware 
The proposed GIS will run on the standard LANDSCAN 
VAX hardware using the GEMS Image Processing System. 
The GEMS has several features that recommend it for 
GIS applications: 
Pixel addressing allows incorporation of 
vector data 
- Overlay planes allow digital maps to be 
superimposed on images 
- Image operations can be applied to Digital 
Terrain Models (DTMs) 
Use of LUTS for enhanced visual 
interpretation. 
The GIS will also be greatly enhanced by the 
addition of other hardware particularly: 
- Digitising tables 
Plotters. 
5.3 GIS software 
The GIS will be based on existing software: 
The ESSG Image Processing Library (IPL) 
- The LANDSCAN data-driven user-interface 
The GEMLIB software for GEMS. 
Additional software specific to the GIS is being 
implemented: 
Digital map input and formatting 
Transformation of vector data 
Vector-raster conversion 
- Raster-vector conversion 
- Contour to surface interpolation 
- Terrain model analysis 
Interpretation of stereographic images. 
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Archiving of images 
System message display. 
5.4 Input data 
Sources of data for the GIS include the following; 
Image formats (current) 
- Landsat TM 
Landsat MS 
SPOT 
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