CIP A 2003 XIX th International Symposium, 30 September - 04 October, 2003, Antalya, Turkey 
The distance between the centres of gravity of 14 lakes in the 
Pfyffer's relief and in the current reference data is very diverse 
and reaches the values from 129 m to 1460 m. However, when 
the wrong position of the lakes is not considered (after the 
translation to the reference centre of gravity), the common area 
in respect to the reference data is only in two cases less than 
60%. The total relative shape dissimilarity also shows rather a 
good result: only in three cases this ratio is more than 60%. 
Useful information about the representation of the lake form in 
the historical data is given by the not common areas divided by 
the reference perimeter (average shape difference). This 
measure reaches the value of less than 200 m by the 80% of the 
analysed data, what is significantly better than the relief 
parameters listed in Table 2. This fact underlines the good local 
accuracy of the relief features after their absolute position had 
been corrected. 
4.5 Comparison of the height models 
The DTM of Pfyffer's relief transformed to the national 
coordinate system is compared with the current DTM. The 
procedure is performed as a comparison of the reference 
regular raster and the irregular point cloud of the historical 
data (nearest neighbour interpolation). According to 
expectations the biggest height differences are located in the 
southern alpine part of the relief (Figure 10). The unusually big 
values in the histogram should not be understood as errors in 
Pfyffer's height measurement: they can rather be explained by 
the wrong position of several mountains. After removing the 
worst 2% of the data set as outliers (white spots in the lower 
part of the Figure 10), the average height difference in absolute 
values reaches 177 m (corresponding to 1.6 cm in the relief). 
This is a very respectable number for area-wide height 
measurements at the end of 18 th century, because the maps at 
that time usually do not contain any height information. 
Figure 10. The difference DTM and a histogram 
(current DTM minus Pfyffer's relief) 
5. CONCLUSIONS 
On the example of the relief model of Switzerland, constructed 
by Franz Ludwig Pfyffer in 1762-1786, methods for 3D 
reconstruction and accuracy analysis of historical reliefs were 
shown. An interesting feature of the photogrammetric part of 
the project is the unusual combination of aerial and close-range 
applications: a big landscape mapping process is performed in 
an artificial environment of the cellar room of a museum. Since 
a very precise DTM is required, manual measurements of the 
surface were applied. The complete digital data set was 
archived for the documentation of the cultural heritage. 
For the first time the relief of Franz Ludwig Pfyffer has been 
quantitatively evaluated. As there is an absolute lack of written 
documents concerning the relief construction, the applied 
procedures represent the only possible way of the exploration 
of this chapter of the Swiss history. The a-posteriori standard 
deviation of spatial vector on identical points, reaching 3.2 cm 
within the 26 m 2 big relief shows a surprising accuracy of the 
relief constructed long time before the first Swiss national 
triangulation network was established. In particular, the precise 
representation of the third dimension is remarkable for that 
time. The presented approaches extend the procedures used in 
the history of cartography to the vertical coordinate direction. 
In addition, some innovative methods for the analysis of 
polygonal features of the old maps and relief models as well as 
for the visualization are suggested. 
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