ıter that 
server. 
s possi- 
system. 
package 
that has 
sed as a 
ons are 
9 based 
nterface 
program 
within a 
| to run 
d WiT^ 
ality of 
urned to 
program 
s VGIS. 
WS 
  
| of 
and 
ults 
ed 
ype 
Figure 4 depicts the general layout of VGIS. The user is only 
communicating with the WiT? user interface and self-explain- 
ing Motif^ windows. The underlying GIS and all administra- 
tive tasks are completely hidden from the user. All WiT? im- 
age processing operators have been replaced by VGIS functions 
that are described in the following section. 
Input 
5SlapeAspect Basins Drainage Viewshed 
   
  
  
  
    
  
  
  
  
thematic 
  
Figure 5 shows the modified WiT? menu for the selection of 
VGIS functions. When a menu item is selected, the respective 
group window opens and the actual function may then be se- 
lected (TerrainAnalysis in Figure 5). In addition to the eight 
groups of analytical GIS operations, the menu contains a group 
Interactive that supplies functions to control the processing 
plan. 
The operations are grouped according to Albrecht (1996). He 
provides an extensive discussion of each operator. Figure 6 
shows the operations of a number of functional group windows. 
Input/Output: 
Interpolation: 
Input, Output 
linear, Rhumbline, greatCircle, 
idw, potential, trend, global, 
Contours, Kriging 
Search: thematic, byRegion, Classification 
LocationAnalysis: Buffer, Corridor, Overlay2, 
Overlay3, Overlay4, Thiessen 
TerrainAnalysis: SlopeAspect, Basins, Drainage, 
Viewshed 
Distribution/Neighborhood: Proximity, Diffusion, Neighbor 
SpatialAnalysis: Pattern, mvAnalysis, Centrality, 
Shape 
Measurements: Number, Histogram, Distance, 
Direction, Mean, perimeter, 
Acreage, Height, Volume, 
Surface, Adjacency, Skewness, 
Compactness, Variation, 
fractalDim, Similarity, Topology 
byRegion 
     
      
Buffer Corridor Ouerlay2 
SlopeAspect 
  
Pattern 
        
  
Ouerlay3 
  
        
Ouerlay4 Thiessen 
  
  
Proximity 
  
  
Figure 6. VGIS functions divided into thematic groups 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B2. Vienna 1996