Procedure and equipment for production of line data

Details Procedure and equipment for production of line data Procedure and equipment for production of line data

1995-03-03

1998-09-08

Bost, Dwayne

Image analysis

Pattern recognition

Feature extraction

382199, 382266, G06K 946

Patent

active

058057293

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The present invention relates to a process and device or apparatus for the production of line data.
Processes or procedures of this type are used in particular in the design of motor vehicles, in order to convert the geometric contours of a motor vehicle body model into line data, which can then be further processed using computer-aided design (CAD) processes. For this purpose the scale model is scanned by a coordinates measurement machine used as a measurement recorder. From this data recorded at different measurement points of the geometry of the model a grid pattern is produced. From this grid pattern the line data are finally created. This known procedure has numerous disadvantages which considerably restrict its facility for use. In order to be able to reproduce the contours of the scanned model with satisfactory precision, it is essential that the person operating the coordinates measurement equipment has adequate experience. In fact, with reference to the quality of the line data to be created, the choice of the scanning points is extremely critical and must be specified for each model afresh depending upon the surface to be scanned. Consequently for each individual case complicated considerations are necessary regarding the position of the selected measurement points, which make high demands of the operating personnel. Thus a disadvantage of the known procedure is that it is extremely time consuming. From production of the model via scanning until the data become available in computer coded form as a rule about six months pass by, with the pure data recording and conversion taking about three months. But with the pressure of competition which obtains at present in the automobile industry, expressed in the catchphrase "fast to market", a preparation time of this length is not only uneconomic, but also no longer tolerable.
Moreover, with the known procedure there is the disadvantage that it is only practicable for relatively simple shaped outer surfaces. Mechanical scanning of the surface to be converted into line data requires that the measurement points selected must be accessible to a mechanical probe. But with complicated shaped surfaces with numerous narrow recesses--such as the heat exchanger of a radiator--this can only be done with great difficulty if at all.
From DE 38 18 534 and DE 39 21 093 there is known a process for depiction of the locally resolved distribution of physical dimensions on a display as well as equipment to carry out this process. With this process, in the first stage correlated measurements are recorded at measurement points using a measurement recorder with specific characteristics of a measurement subject. The analogue output signals created by the measurement recorder are converted into digital values. These digital values are then stored in the storage section of a measurement memory allocated to each measurement recorder. From the digital values stored in the measurement memory, an initial picture in matrix form, corresponding to the local arrangement of the measurements, with individual quadrates of lateral length s is created. A second picture in matrix form with individual quadrates of lateral length b=s/2n is created from Pixel figures forming a Pixel data field, with the measurement data field and the Pixel data field being regarded as superimposed upon each other. Thereafter, for each Pixel of the Pixel data field a Pixel value is calculated from the quadratic environment surrounding this Pixel in the Pixel data field centrally in such a manner that each digital value recorded from the environment surrounding the measurement data field and stored there is weighted with a portion of the area contained by multiplication in the form of a product, the sum of all the products is formed and this sum--if necessary is divided by the sum of all portions of the area of the surrounding environment as a quotient--is stored in the Pixel memory at the relevant position. With the known procedure the disadvantage is that through this creation of a

REFERENCES:
patent: 4908872 (1990-03-01), Toriu et al.
Comput. & Graphics, Vo. 9, No. 1, pp. 69-70, 1985, VDAFS--An Interface to Transfer Surface Description Data Between CAD Systems, P. Rehwald.
Solftware Kurier, 1991, pp. 98-105, Dreidimensionale Rekonstruktion auf der Basis segmentierender bildgebender Verfahren, A. Wischnik.
Computer Vision, Dana H. Ballard--Christopher M. Brown, pp. 119-143.

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