International Archives of Photogrammetry and Remote Sensing. Vol. XXXII Part 7C2, UNISPACE III, Vienna, 1999 
19 
I5PR5 
UNISPACE III - ISPRS Workshop on 
“Resource Mapping from Space” 
9:00 am -12:00 pm, 22 July 1999, VIC Room B 
Vienna, Austria 
ISPRS 
Figure 7: Mapping from Satellite Imagery' from Spot MS (France), Spot Pan (France), KFA 1000 (Russia), aerial photography 
1:20 000, existing map 1:25 00 
The suitability for mapping from a particular type of imagery 
has already been investigated in the early 1980’s. There are 
three criteria to be met: 
■ planimetric accuracy, which is scale dependent 
■ elevation accuracy, which depends on parallaxes created 
by the different image geometry from two different 
imaging positions 
■ detectability, which relates to the spatial resolution, which 
may be achieved by a particular sensor system. 
Even though aerial photography, which has been digitized into 
different pixel sizes on the ground can hardly distinguish more 
than 6 bits of grey values as opposed to recent digital sensors 
with 10 or more bit of grey level distinction these early results 
are still generally valid: 
Planimetric accuracy of a map is generally related to ±0.2 mm 
at publishing scale according to U.S. mapping standards. This 
criterion mainly relates to worldwide mapping practices for the 
original mapping scale, but not for generalized maps at smaller, 
derived scales, in which the planimetry is often shifted to 
accommodate conflicts in the depiction of objects. Even in the 
original mapping scales buildings or building blocks, roads and 
rivers are shifted in some national map bases for this purpose. 
But in general this means from the data acquisition side, that the 
following planimetric standards are usually accepted: 
wmm 
1: 10 000 
± 2 m 
1: 25 000 
± 5m 
1: 50 000 
± 10 m 
1:100 000 
± 20 m 
1:200 000 
± 40 m 
Elevation accuracy is generally a function of terrain slope. 
Depending on terrain slope a certain contour interval is 
specified. The reliability of contouring is generally accepted as 
being 5 times the point measuring accuracy in height, regardless 
of whether the contours are originally measured in a 
photogrammetric plotting instrument, or whether they are 
interpolated on the basis of a measured digital elevation model 
(D.E.M.) grid. 
¡|lii||li|||| 
1 m 
± 0.2 m 
flood plane 
2m 
± 0.4 m 
“ 
5 m 
± 1 m 
“ 
10 m 
± 2 m 
20 m 
± 4 m 
“ 
50 m 
±10 m 
100 m 
±20 m 
high mountains 
The detectability of objects, given sufficient contrast as a 
function of grey level discrimination, was formerly measured in 
terms of photographic resolution stated as line pairs per mm 
(lp/mm). Nowadays this photographic resolution must be 
compared to 2 to 5 pixels at image scale related to IFOV on the 
ground. 
Early tests with photographic resolutions have been carried out 
for specific objects to be recognized and identified from the 
imagery. They established a minimum pixel size for the 
detectability of the following objects: