Fortunately, potential desktop GIS users have more freedom 
in trying out various alternatives. 
Finally, once the project leader is satisfied with his level of 
knowledge, he should then prepare a project plan. This plan 
must include costs, schedules, benefits and resource 
requirements. Once approved this plan should be adhered to 
as closely as possible. It should be noted that the development 
of this plan must not be taken lightly and that it is a key 
element to the success of the project. 
4.2 System Implementation 
The next stage of the project is to procure the elements 
required to implement the desktop GIS project. These 
elements are not that much different from other computer 
systems. The major elements of system implementation are: 
hardware, software, data and training procurement plus any 
custom application development that may be required. Each of 
these elements will now be explained in more detail. 
4.2.1 Desktop GIS Hardware Procurement 
The required hardware elements of a desktop GIS are the 
processing unit, the display unit, the data storage unit, the 
input devices and the output devices. The following table 
summarizes the principle hardware components, the device 
description and the primary function of the device. 
  
  
  
  
  
  
  
  
Component Description Function 
Processing Unit | IBM compatible software execution 
PC 
Display CRT User viewing 
Storage Devices | Hard disk software & data 
storage 
CD-ROM software & data 
input 
Tape unit backup 
Input Devices Digitizer manual map data 
input 
Scanner automatic raster 
(image) data input 
  
  
Output Devices | Laser Printer text & line and 
image graphics 
output 
Dot Matrix text & line and 
Printer image graphics 
output 
4.2.2 Desktop GIS Software Procurement 
The software required for desktop GISs is available from 
commercial suppliers. There are generally more combinations 
and more factors involved in hardware selection than 
software, mainly because the software for desktop GIS is very 
modular. In particular, the main software components required 
are: system, application, development and miscellaneous. A 
description of each of these software elements is included in 
the following table. 
  
  
  
Component Description Function 
System Operating System | Hardware and 
Software software control 
User Interface Human interaction and 
system control 
  
Network Communication with 
other systems 
  
Application GIS Spatial data input, 
  
  
  
  
  
  
  
  
Software manipulation and 
output 
Database Spatial data storage 
Personal Word processing, 
productivity Spreadsheets 
Development | Programming Custom application 
Software Tools development 
Miscellaneous | Device drivers Peripheral device 
control 
  
As with the purchase of hardware, the project leader must 
make decisions on the selection of software based not only on 
functionality, but also on the vendor, the software reliability, 
help line availability and support. 
4.2.3 Desktop GIS Data Procurement 
Perhaps one of the most neglected and misunderstood 
elements of any GIS system development are the data 
requirements. Often data procurement and manipulation will 
account for over half of the total system costs. As GIS 
technology matures, the costs of data and the costs of data 
input are decreasing. Many data providers are now able to 
provide spatial data in digital form. In addition, there are 
many data conversion companies who can now convert 
hardcopy material to digital form in a cost effective manner. 
The typical major data components of a desktop GIS are 
summarized in the following table. 
  
  
Pen Plotter line graphics output 
  
  
  
text & line and 
image graphics 
Ink jet printer 
  
  
  
output 
  
  
In addition to the selection of the type of equipment required, 
the project leader must also make decisions regarding the 
quality of the product, the amount of memory required, the 
reliability, the maintainability and the cost of consumables. 
  
  
  
  
  
  
Component | Description Function 
Base data Topographic data Accurate spatial 
data to which all 
other data 1s 
referenced. 
Thematic (Application specific | Spatial information 
data - Le.: climate, geocoded to the 
census, forestry, base reference data. 
economic) 
Attribute Textual information Data queries, 
data linked to the base analysis, modeling 
and thematic spatial and reporting. 
  
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B2. Vienna 1996 
  
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