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Vision analysis of gauge field

Original image of gauge field 1 fig.1 

Gauge field 2 fig.2 

Hough field fig.3 

Determining orientation using blank segments fig.4 

Analysis of the mark fig.5 

Result of the analysis of gauge field 1 fig.6 

Result of the analysis of gauge field 2 fig.7

Virtually any machine vision system requires some sort of calibration. This calibration converts distances in the image (measured in pixels) to the distances of real world (feet, inches, etc.). It also determines the object's orientation relative to the camera and accounts for distortions introduced by camera's lens. That is why it is important to perform the calibration procedure prior to actual measurements. Such procedure is usually executed with the help of gauge fields – a set of marked distances between each (in real world units) are known. An application used for calibration should find all marks in the gauge field, enumerate them and determine orientation of field relative to camera.

Our customer has been using two different sets of gauge fields and required the Labview™ application to analyze it. The first field represented a set of markers, each of which contained a binary coded number (see illustrations for details) where each mark was processed independently from the others and the field orientation was computed from the positions of the enumerated marks. The second field represented a set of intersecting parallel and perpendicular lines. In this second field, each mark is the intersection of two lines (grid) providing accuracy because of the density of the intersections. The image should be processed as whole, however, it is important to note that two segments in the field (grid) have been left blank giving the key to the orientation of the image. The most effective way to process such an image is using Hough algorithm (hence the second gauge field is generally referred to as the Haugh field).

XInstruments developed a Labview™ based applications to analyze the two different gauge fields, proving to be fast and reliable.  This allowed our customer to migrate their solutions to a Labview™ environment.

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