Software improves accuracy of 3D image calibration

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Stemmer Imaging is now offering the new CVB Metric 3D and CVB Merge 3D measurement tools to enhance the accuracy of three-dimensional measurements in industrial vision applications. CVB Metric 3D and CVB Merge 3D enable 3D images to be calibrated more accurately and overcome potential problems in laser triangulation image acquisition resulting from shadows in the laser line. These new tools have been added to the 3D suite of tools in Common Vision Blox (CVB) version 10.2, the programming library that fully supports all 32-Bit versions of Microsoft Windows 7.

Most common 3D acquisition technologies do not provide a calibrated image. Although many 3D applications can work reliably with non-calibrated images, calibration is essential for some applications. CVB Metric 3D enables a 3D space to be calibrated by measuring a defined calibration object. Once calibrated, data point area or volume can be directly measured to sub-pixel accuracy. To improve accuracy, the calibration can be made using the combined resultant image from CVB Merge 3D.

CVB Merge 3D is used in combination with multiple cameras to overcome any systematic deficiency in laser line triangulation and to make sure all flaws and defects will be detected during the inspection. Deficiencies in laser line triangulation arise when the surface structure of the object causes shadows in the laser line. This prevents the extraction of local height information at these positions, meaning that flaws at these positions cannot be detected. Acquiring images from the same laser line using multiple cameras set at different angles produces images with shadows at different positions. CVB Merge 3D consolidates these different images into a single height image having a complete surface that only lacks height information if all the input images contain shadows at exactly the same place.

Stemmer Imaging Sales & Marketing Director, Mark Williamson, says: "These new tools have been introduced as a direct result of working closely with customers to solve their real 3D measurement problems. Our considerable experience in this field has taught us that the biggest source of errors in measurement arises from variations in hardware, including distortion from the optical system. As Europe's largest independent supplier of vision technology, we highly recommend that customers contact us early on in these applications so that we can help specify the best configuration to deliver the required accuracy."

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