Prefilter – a new great feature in Scorpion Vision

The upcoming 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