Video : Thor Vollset – Tordivel presents 3D Stereo Vision and Vision Guided Robots

After its positive première in 2014, the inspect application forum followed up with a successful and increasingly international event on the Vision in Stuttgart this year. Altogether, more than 350 visitors to the fair, half of them from abroad, took the opportunity to attend the diverse 30-minute talks and gain detailed insights into the current application and development possibilities in machine vision.

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Check the video at Inspect

3D Stereo Vision and Vision Guided Robots

Under the motto “Vison 4.0 – Smart Vision for Smart Factories,” innovative systems and solutions were presented from the fields of Best Practice, 3D Inspection, Automotive, Robotics, Virtual Reality, Food & Beverage and Embedded Vision.

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Calibrator2D – Automatic UltraWide angle lens calibration

scorpionxii-64x64This post is the first in series of Scorpion Vision Software tool improvements included in upcoming – Scorpion Vision XII.

Working with 3D Stereo Vision we have learned that completely removing lens distortion is extremely important – this require the best sub-pixel grid location algorithms. In 3D Robot Vision significant value is added by moving closer using wideangle lenses.

We also use this capability to make high precision 3D Stereo Vision system for our OEM customer using low cost lenses and cameras in the smallest form-factor.

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Calibration Grid with Ultra Wide Lens

We are proud to state that we have added “Auto Grid Detection” that starts in the center of the images and locates all points that is located with proper quality. This means that Calibrator2D will use all visible grid points that are visible in the image – this will ensure almost 100 % coverage of the image.

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Calibrator 2D – Auto Grid Settings

The Calibrator2D.Setup page shows the user feedback after calibrating this image. We see that only the corners are left uncalibrated – where the lens more or less sees to infinity 🙂

The average error is subpixel 1/5th of pixel. The maximum correction of a pixel is 48.9 pixels – the pixel size is 0.9 mm equal to 45 mm.

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Prefilter – a new great feature in Scorpion Vision 10.2.1.586

The upcoming 10.2.1.586 release includes a new prefilter feature for many tools, these have been added in the recent months. The last tool to be updated is the important feature is the 2D Calibrator tool. This tools provides the means and the a requirement to get sub-pixel accuracy in machine vision – this is important for 2D but also the foundation for the Scorpion 3D Stinger Technology.

The standard calibrator with no pre-filter applied:

The image below shows the calibrator with no pre-filter applied. The calibration image is difficult to use because of low contrast. The calibrator quality measure says that the RMS is 0.180 pixels or 1 / 5.5 pixels.

Scorpion Vision's Calibrator with no prefilter

Scorpion Vision’s Calibrator with no prefilter

Applying a Normalising filter and a small blur

The Prefilter is active with the following command: “N101,255b3”. This means that Image Normalisation with a block size of 101 is first applied the result image is then blurred with a block size of 3.

The important effect to the image is the following:

  • Constrast is much better
  • All image intensity skew or variations are removed
  • The thresholding of the markers are now easy
  • The accuracy is marginally improved – also important

Read more about the available pre-filter options: ImageFilters.htm

Calibrator tool with prefilter active

Calibrator tool with prefilter active

Changing polynominal order from 5 to 9 – improved the accuracy by 60% 

The RMS goes from 0.172 to 0.110 – this means that the optical resolution goes from 1/6 th of a pixel to 1 /9 th of a pixel or 110 / 172 or 60% by changing a single number from 5 to 9. 

In a 3D robot vision system you can hear this when the robot is picking 🙂

The polynominal order is very important - almost double the accuracy

The polynominal order is very important – almost doubles the accuracy

Video – Accurate wide angle web camera lens calibration

We have added GridMapping as an option to use every grid point when calibrating extremely wide angle lenses for use in 2D and 3D machine vision applications.