234 
Applications: 
The application of the method to produce base maps for dam building projects 
is described in two practical examples. In one case a geodimeter polygon was 
laid out along the mapping area (a river) which was 112 km in length. The 
mean side length in the polygon was 12 km. The first and the last point were 
triangle points. The distance between these points was 112 846.09 meter if 
computed by given coordinates and 112 847.56 meter determined by the geodi 
meter polygon. 
(1) Ekelund, L.: Modelltriangulering. — En ny metod for fotogrammetrisk stommàtning. Foto- 
grammetriska Meddelanden, Kungl. Tekniska Hôgskolan II: 1/1950. 
(2) — Photogrammetric Triangulation with separately oriented stereomodels, Photogrammetria 
VIII 1951—1952; 4. 
(3) — Mekanisk modelltriangulering (»Mechanical model triangulation»). Fotogrammetriska Med 
delanden, Institutionen for fotogrammetri, Kungl. Tekniska Hôgskolan, Stockholm 1954. 
M. Klintmalm (Suède) indique que la méthode de M. Ekelund a été appliqué 
en Islande avec de bons résultats en ce qui concerne la précision et le rende 
ment. Il recommande l’application de la méthode. 
M. Baetslé (Belgique) demande des détails sur la rotation des clichés et sur 
la détermination des points d’appui altimétriques. 
Répondant pour M. Ekelund sur le premier point, le président explique qu'il 
ne s’agit pas d'une inversion de la base, mais que la rotation change le signe 
des causes d’erreurs, notamment la distorsion différentielle, qui provoquent la 
déviation azimutale systématique. De sorte que la parabole des erreurs Y est 
transformée en une polygonale oscillant de part et d’autre d’une ligne droite. 
M. Ekelund indique ensuite que, pour les levés à grande échelle, les altitudes 
d’appui sont obtenues par nivellement géométrique, tandis que pour les travaux 
à petite échelle, on utilise une combinaison de nivellement géométrique et baro 
métrique. 
Mr. Klintmalm indicates that the method of Mr. Ekelund has been applied in Iceland with 
good results both for precision and economy. 
Answering Mr. Baetslé, the 'president explains that no basic-inversion is applied but that the 
rotation changes the sign of the errors, especially of the differential distortion, that causes the 
systematical azimuth error. 
Mr. Ekelund adds that for large-scale work, height-control is determined by levelling, for small- 
scale mapping a combination of geometric and barometric levelling is used. 
J. Zarzycki: Application La parole est ensuite donnée à M. J. Zarzycki (Canada) dont la communication 
ot Shoran to Establish es t intitulée; »Application of Shoran to Establish Horizontal Control for 
Horizontal Control. , 
(Publ. IIIZT) S notogrammetric Mapping of Inaccessible Areas». Resume: 
The tremendous development during the last years in the field of electronics 
has influenced the science of photogrammetry appreciably. Electronic instru 
ments developed during the war, mainly for navigational purposes, have been 
improved and new instruments designed to give the photogrammetrist an inde 
pendent mean of establishing the position of the nadir point of each individual 
aerial photograph at the moment of exposure, plus the corresponding ground 
elevation. 
Shoran and Iliran, its modified version, give the position while Radar Alti 
meter measures the profile of the terrain. 
It is self evident that this additional and independent information is of a great 
help in conducting aerotriangulations in inaccessible areas. 
In Canada, Shoran is being used not only by the Geodetic Survey of Canada 
to establish a primary net of geodetic control points, but it is also used by private 
mapping organizations; Canadian Aero Service and Spartan Air Services to 
establish secondary horizontal control for photogrammetric mapping of Canada’s 
Northland.