Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Patent
1991-10-01
1993-07-27
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
356152, G01N 2186, G01C 1102
Patent
active
052312925
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a device for photogrammetrically surveying an object. Such devices are typically used for surveying motor vehicles, as discussed the paper "Fotogrammetrische Vermessung von Kraftfahrzeugen" (Photogrammetric surveying of motor vehicles) in ATZ 91 (1989) 6. In the case of this known device, surveying the object concerned is performed in such a way that photos of the object are taken as it were from a number of directions by means of at least two cameras containing the sensors and are evaluated in a computer; said computer supplies a digital data record, which precisely describes the dimensions of the object.
However, a prerequisite for achieving a satisfactory measurement result is that the spatial position of the sensors, i.e. of the cameras, relative to one another and relative to the object, i.e., the so-called outer orientation, and the position of the objectives lenses relative to the sensors assigned to them, the so-called inner orientation of the measuring equipment (cameras), are precisely known. This problem of outer orientation is particularly prominent when the sensors can be positioned individually, i.e., independently of one another, as a result of which a better adaptation of the imaging-beam paths to the respective objects in comparison with a fixed coupling of the sensors is possible.
According to the cited prior art, the inner and/or outer orientation is performed by there being arranged in the object space reference systems, for example graduated scales, which thus form as it were reference patterns in a spatial position which is defined in absolute terms and are imaged by means of the sensors as well as stored. The stored reference patterns are then taken into consideration by the computer in the evaluation of the images of the object supplied by the sensors.
SUMMARY OF THE INVENTION
The invention is based on the object of designing a device of the generic type in such a way that the positioning of the sensors, that is to say in the final analysis of the cameras also containing the perspective centers, relative to the object is not affected by the imaging of the reference pattern.
It is essential for the invention that although the reference pattern is arranged in a defined, fixed spatial position, it is outside the imaging-beam paths of the sensors, so that when positioning the sensors relative to one another and relative to the respective object there is no need to consider the accommodation of the reference pattern in these beam paths. The imaging of the reference pattern by means of the sensors is performed using optical deviating means, for example partially transmitting mirrors or prisms in the imaging-beam paths of the sensors. It is then possible to arrange a reference pattern, assigned to all the sensors, for example also relatively far away from the object and for example to cast a mirror image of this reference pattern onto all the sensors. In the case of a direct imaging of the reference pattern, said pattern would have to be arranged in the area of the object, which presents difficulties in particular in the case of small objects of which the shape is to be recorded exactly by the device.
BRIEF DESCRIPTION OF THE DRAWINGS
An illustrative embodiment of the invention is explained below with reference to the figure, which schematically shows a device containing three sensors.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The object to be surveyed is denoted by 1. Arranged around it in differing spatial position are three cameras 2, 3 and 4, which in each case contain as essential component parts a sensor 5, 6 and 7 as well as an objective lens 8, 9 and 10. The imaging-beam paths of the individual cameras or sensors are denoted by 11, 12 and 13. As is evident, the cameras 2, 3 and 4 can be positioned individually, i.e independently of one another, with respect to the object 1, so that their position can be chosen with regard to the optimum surveying of the respective object.
Not shown, since known with respect to i
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Lee John R.
Leica Aarau AG
Nelms David C.
LandOfFree
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