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4 Overview on Low Cost Systems 
Recent developments in close range 
photogrammetry such as  multi-image bundle 
triangulation, new devices for image 
measurement and computer control have created 
the presuppositions for the development of low 
cost photogrammetric systems. Especially in 
architectural photogrammetry, quite a few 
systems have appeared on the market in the last 
years. They cover the whole spectrum of 
analytical photogrammetry as described above. 
Often réseau cameras are used in connection 
with them. This enables the correction of image 
deformations, caused by film shrinkage and non- 
planarity of the film. A few of the systems are 
listed below. A division is made according to 
chapters two and three of this paper. 
4.1 Systems with Monoscopic Image 
Measurement 
4.1.1 Elcovision 
The Elcovision system provides software to 
compensate image deformations, by calculation 
the réseau correction. The used camera has to 
be calibrated beforehand, because no self- 
calibration during the bundle adjustment is 
performed. Up to 12 models can be calculated 
simultaneously with a bundle adjustment 
program. The monoscopic evaluation of the two- 
image-model afterwards is supported by 
graphical functions and can be viewed on the 
monitor. 
4.1.2 Foto 3D 
The Foto 3D system [WIEMANN 1992] uses non- 
metric cameras. The orientation procedure 
differs from that described in the above 
systems. Instead of calculating relativ and 
absolute orientation or computing a bundle 
adjustment, Foto 3D uses a 3D to 2D projective 
transformation, which is comparable with the 
direct linear transformation [ABDEL-AZIZ, 
KARARA 1971]. It doesn't need any information 
on the interior orientation parameters of the 
used camera, but the coordinates of the 
exposure station and 4 controll points per 
image have to be known. The user can choose 
between multi and single image evaluation. 
4.1.3 MR2 
The MR2 system compensates image deformation 
with a calculated réseau correction. A multi 
image orientation with simultaneous camera 
calibration is done with the bundle adjustment. 
After the bundle orientation the multi-image 
evaluation process is carried out usually with 
four images, and the coordinates of all 
measured points including standard deviations 
are calculated with spatial intersection. They 
can be viewed on the screen and can be 
manipulated with some graphic routines. A 
single image rectification is posible as well.