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systematic acquisition of the necessary data. In 
addition the Landestopographie offers within their 
possibilities assistance for photogrammetric pro- 
jects of various purposes. 
For its mission the organisation has available a 
flight service (airplane "Grand Commander" with 
Wild RC-10 Camera), four evaluation instruments 
(one Wild A7, three Wild A8) and a well equipped 
Photolab, which can respond to most photographic 
requirements. 
The data acquisition for the map revision is orga- 
nized in such a way, that yearly an area is covered, 
which comprises about one sixth of the Swiss terri- 
tory. During the reporting period the first revision 
cycle was completed, thus a series of photographs 
exists which cover the country without any gaps. 
This material is accessible for various kinds of 
customers by way of a Photo-Archiv. Two years ago 
the Landestopography informed the public about 
the existence of the Photo-Archiv. A lively use of 
the material by the general public has developed. 
Special flights are arranged for the Swiss Glacier 
Commission according to a schedule which pro- 
vides photographic material of a large number of 
the more important glaciers. These dates serve 
mostly scientific investigations besides the surveil- 
lance of danger areas. 
Similarly, photographs are taken in support of the 
just recently consolidated UNESCO-MAB (Man and 
Biosphere) project. The Swiss contribution is di- 
rected towards studies in the area of the Jungfrau 
region for the purpose of investigating the ecology 
of mountainous terrain. The data collection requires 
the acquisition of black-white, color and false color 
photography. 
The revision work is accomplished on the above 
mentioned restitution equipment. The evaluation is 
made directly at the scale of 1:25 000 on coated 
glass plates. Because of the geometrically depend- 
able map contents the orientation of the revision 
photography can generally be made without special 
pass-point determination and without additional 
aerial triangulation. 
Noteworthy is an own development of the Landes- 
topography. An optically based imaging system 
allows the operator of a restitution instrument to 
observe the drawing utensil without turning the 
head. The image quality of the projected mapping 
area is superior to a conventional TV picture. This 
gadget has resulted in about 20 % time savings. 
The Swiss Federal Directorate for Surveying 
(“Eidg. Vermessungsdirektion”) 
Since the beginning of 1976 the flight service of the 
Vermessungsdirektion has a TWIN PIONEER TYP 
DHC-6-300 airplane to his disposal, equipped with 
a Wild RC-10 camera. The acquired photography 
serves primarily two tasks, namely the production of 
cadastral plans in mountainous area and the pro- 
duction and revision of the " Uebersichtsplan" (To- 
pographic map at scales 1:5000 and 1:10 000). 
Cadastral Surveys: 
The application of photogrammetry for cadastral 
purposes is restricted to alpin regions, which have 
only sparce or no population. The evaluation is 
strictly on a numerical basis. 
The areas to be surveyed are generally of limited 
extention requiring only small block figurations. 
The exclusive application of numerical methods— 
even for areas of less economical value—allows a 
certain degree of automation and offers an eco- 
nomical method to handle the problem of filling in 
small survey gaps. In Switzerland too the applica- 
tion of photogrammetry for cadastral purposes has 
found a keen competition by the methods of modern 
Tachymetry. 
Uebersichtspläne: 
(Grundbuchkarte 1 : 5000, 1 : 10 000) 
The project of establishing the original Uebersichts- 
pläne was actually completed several years ago. 
By the end of 1975, 97 % of the area was covered. 
This effort was almost exclusively executed by pho- 
togrammetric means for both positions and eleva- 
tions. 
During the reporting period the main interest focus- 
sed on the problem of plan revision especially on 
the possibility to use photogrammetric techniques. 
The new “Regulations about the duplication and re- 
vision of Uebersichtspläne with respect to Grund- 
buchsurveys” from November 28", 1974, state that 
in areas where parcel-surveys are nonexistent, the 
revision of the original plan shall be coordinated 
with the revision of the national map series of 
1:25 000. Consequently the corresponding photo- 
graphy must be used for identification purposes and 
to a certain extent for new plotting even for scales 
of 1:5000 and 1:10000. Praxis oriented experi- 
ments have led to the conclusion that the use of 
Orthophotos as “Uebersichtsplan” itself or as a 
means for revision, cause on account of identifica- 
tion problems more disadvantages than methodical 
improvements. 
Aerial photographs for the purpose of protecting 
cultural values: 
The Swiss Federal Government Supports since 
Some years ago a program to obtain photography 
which portrays typical village and town layouts with 
their roof patterns. 
During the reporting period 40 settlements were 
photographed in color for stereoscopic evaluation. 
The scale of photography is 1:2000 and the plott- 
ing scale 1 : 250. In addition quite numerous oblique 
photographs were made strictly for pictural repre- 
sentation. 
Photogrammetry and Güterzusammenlegung: 
For the registration of old ownership in areas which 
so far remained unsurveyed and in non-wooded 
areas classic graphical photogrammetric evaluation 
methods are almost exclusively used, as they have 
been successfully applied for many years. 
3. Photogrammetry at the Swiss Federal 
Institute for Forestry 
(Eidg. Anstalt für das forstliche Versuchswesen) 
Swiss Foresty has to deal with small area cultivation 
and rather complex ownership conditions. Support 
by accurate maps and reliable data about supply 
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