International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B6. Istanbul 2004 
  
astronomically. The lengths of the base lines are approximately 
8 to 30 km. 
4.5.3 Geodetic Chain: The Geodetic Chains are composed of 
well-conditioned triangles, where the sides are about 60 km 
(between 30 to 190 km). Chains consist of a rows of polygons, 
composed of a number of triangles, or a double row of triangles 
forming a single row of quadrilaterals. Fig 3. is a schematic 
representation, the real figure is not so regular) 
  
  
  
  
  
Base N 1 abe 
  
  
Fig 3. Geodetic control network of Namibia 
4.5.4 Primary Triangulation: The areas inside the geodetic 
chains are covered with a network of triangulation. The side of 
a primary triangle is 30 to 60 km. 
4.5.5 Secondary Triangulation: The Secondary Triangulation 
consists of densification of the Primary Triangulation with 
triangles of about 12 to 18 km sides 
see Fig 4. 
  
Fig 4. densification of triangulation network 
4.5.5 Tertiary Triangulation: The Tertiary Triangulation 
consists of densification of the Secondary Triangulation with 
triangles of about 3 to 6 km sides 
4.5.6 Town Survey Marks: This is the final densification of 
the control network, which consists of marked traverse stations 
on the road surface, in township and built up areas. 
4.5.7 GPS Network: There are 8 GPS control points in 
WGS84 
10 
4.5.8 Altimetry: The mean see level is determined by taking 
tide observations at various points along the coast. À network 
of precise levelling is being carried out. Heights of trig points 
are connected to precise benchmarks. The elevations are 
determined by observing vertical angles. There is no geoid 
model in Namibia. 
4.6 Unit of distance measurement 
The S. African Unit of distance measurement were; 
1 Cape rood = 12 Cape feet 
| Cape foot = 1.033 English feet 
The Chain = 100 links = 66 English feet 
4.7 Conversion to international meters 
1 South African Geodetic Foot = 0.304 797 265 4 international 
meters 
1 Geodetic Cape foot 
international meters 
| Geodetic Cape rood 
meters 
= 0.314 855 575 16 
= 3.788 266 902 2 international 
The Unit of measurement in Namibia is the Legal meter 
applied in Germany 
1 Legal meter = 1.000 013 596 5 International meters 
5. PRACTICE OF SURVEYING IN NAMIBIAN 
CADASTRE DEPARTMENT. 
The cadastre department does not carry out the cadastre 
surveying, this being contracted out to private surveying 
companies. The cadastre department performs the quality 
control, which consists of checking the accuracy threshold, as a 
consequence of which sometimes companies have to repeat the 
measurements. 
Areas of properties are computed using Geomedia software 
"qoe 2 
(Intergraph), within 1 m^ accuracy. 
5.1 Cadastral Data Base. 
The Namibian Cadastral Database is developed by digitizing 
existing cadastral map, and completed by adding digital data, 
resulting from the project contracted by different private 
companies. The method of data acquisition applied by those 
companies is GPS acquisition techniques. 
6. COMMENTS ON EXISTING 
SYSTEMS/PROCEDURES 
6.1 Ground control point Network 
As the density of the Ground control points is insufficient and 
their accuracy is not homogenous, it is proposed to carry a 
densification of those control points using GPS, which is a 
rather fast method of ground control point densification. Next 
carry an overall adjustment of all ground control points. It is 
obvious that the overall adjustment of the existing control 
points can be done before densification step, and repeated after 
densification step. Note, that the coordinates of all cadastral