neters 6 EXAMPLE To solve this task with Erdas®, the user has to enter the follow- 
  
e that ing command sequences: 
lass is A sample exercise used in the first semester of the post gradu- 
nation ate course in environmental monitoring given at the University e Inlandc.img = Recode: forest + built up areas = 0, 
of Vechta shall illustrate the advantages of VGIS in a practical other = 1 = store as file 1.img 
application. The task is to locate the optimal site for a factory. o Inhydro.img = Search: 300 m buffer around surface 
terme- This task has previously been solved using the software pack- water = 10 pixel => store as file 2.im 
lepicts age Erdas/Imagine". This is then compared with the workflow e file 2i P E urb A e fs 
nits within the VGIS environment file 2.img = Recode: surface water + buffer = 0, other 
=] > file 3.img 
The task is as follows: e [Inputimg = Search: 450 m buffer around highways 
type (3,4) = 30 Pixel = file 4.img 
An site for a large factory in the area of lake Lanier, Georgia is e file 4.img = Recode: highways type 3,4 + other = 0, 
to be located, that fulfills the following six conditions: street buffer = 1 = file 5.img 
1) Environmentalists lobbied successfully that no forested e Input.img = Recode: urban + infrastructure = 0, other 
area should be used. For the same reason already built 
up areas are not feasible Le AE 
2) Pollution threats cause the factory to be located at least > Les A Fate gp Pandy Losm + Sandy 
=1, = | 7.img 
300 m off any surface water. 1 d J 
3) On the other hand, the factory should be easy to access; e Inputimg => Search: 3 km buffer around transforma- 
a first order highway must be within 450 m. tion stations = 100 pixel = file_8.img 
4) To save taxes, the factory should be sited outside of the e Overlay (minimum value dominate) file l.img and 
municipality of Gainesville. file 3.img — file 9.img 
5) A special construction requirement requires the factory e Overlay (Minimum value dominate) file 5.img and 
to be built on Madison Sandy Loam or Madison Sandy file 6.img = file 10.img 
Clay. | e Overlay (Minimum value dominate) file 9.img and 
6) Due to the high energy requirements, the transforma- file 10.img — file 11.img 
tion station should be less than 3 km away e "overlay (Minimum value dominate) Jile /L3mg and 
m The following thematic maps are available for the lake Lanier fife 7.img s. file 12.ma 
area e Overlay (Minimum value dominate) file 12.img and 
1) Inlandc.gis: land use classification file 8.img — opt site.img 
2) Inhydro.gis: hydrology 
3) Input.gis: political borders and infrastructure 
| 4) Insoils.gis: soil types 
  
NT 
8 
  
  
  
Input Classification 
       
      
  
  
   
    
   
  
     
   
    
File: Inlandc 
  
  
  
Input #1 -— overlays 
  
too few 
  
     
totype 1S name: display 
ta keeps 
perform- 
© allows 
next one 
pts other 
distance: 300 
Buffer 4H 
Bodl 
Input #3 
ctness of 
t of an 
ita. struc- 
ertheless 
d by em- 
anges to 
File: Input 
  
  
  
  
  
  
5 5s rpm > TY cr Tm "s r IT 
  
Figure 8. Solution of the site location for a factory with VGIS. 
87 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B2. Vienna 1996