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Max error / Quality parameter in Workspace

This article will provide more information about Max error parameter in Artec Studio 11/12 and Quality parameter in Artec Studio 10 and older versions. 

 

What is Max error / Quality

  • It is an internal parameter which is calculated for every 3D-frame in the raw scan (neither in mm nor in %).
  • Max error is calculated for the whole raw scan as well and in this case it is equal to the number of the least accurate frame. Also it is an indication, whether frames in scan(s) are aligned according to each other and how precise this alignment is.
  • The bigger number means less accurate alignment, so the lower value of Max error is - the better.

 Acceptable range

Before you start analyzing your scans and frames, keep these two issues in mind:

  1. Max error parameter is accurate only after Global registration.
  2. The bigger the size of the scanned object is, the bigger acceptable Max error is.

For Artec Space Spider / Spider:

  • 0.0 – perfect
  • 0.1 – great
  • 0.2 – good
  • 0.3 – acceptable, if you don’t need maximum resolution on your fusion
  • 0.4 – acceptable, but only for large objects

 

For Artec Eva / Eva Lite:

  • 0.0-0.3 – great
  • 0.4-0.7 – great for large objects and acceptable for small and medium
  • 0.8-1.2 – acceptable for large and huge objects, but not acceptable for small and medium ones

 

Max error is beyond acceptable range in my project. Why?

First of all, make sure that you launch global registration algorithm with correct settings (more information can be found here).

If the settings are correct, check your raw data. As it is mentioned above, Max error is accurate only after global registration (GR).

Main GR principle is to find the most optimal position of every frame in all selected scans. So if GR indicates that some frames have abnormal Max error value or even "Failed" status, then the most likely such frames do not have enough geometry and/or texture features to be registered correctly according to other frames. There are several possible reasons of such issue:

  • 3D scanner operator captured part of the object or the whole object at the incorrect scanning distance, for example, too close or too far.
  • 3D scanning was performed at non-optimal scanning path and as the result, not enough surface was recorded per a 3D frame.
  • PC used for scanning session is below recommended requirements.

For example, an operator incorrectly captured part of the leg. See picture below: frame 74 does not have sufficient 3D geometry to be registered properly according to other frames in the scan.

Frame 169 is correctly captured:

Note: even if your data was captured incorrectly and has abnormal Max error, it is still possible to create a great 3D model with the help of powerful processing algorithms in Artec Studio. However, the best possible results are guaranteed, if the object was scanned correctly from the very beginning.

 

Max error and fusion resolution

Autopilot mode in Artec Studio 11/12 chooses the most optimal fusion type and its parameters based on Max error value.

If you use manual post processing, you can use recommended values listed below, however, please consider these values rather as a recommendation than a general rule.

Eva / Eva Lite:

  • You can use resolution = 1 in most cases
  • If your Max error is below 0.3, then fusion resolution can be lowered to 0.5, for example, if fine details are needed.
  • For Eva scans with acceptable Max error values or for large/huge objects, fusion resolution can be lowered to 2.0.

Space Spider / Spider:

  • For raw scans with 0.0 - 0.1 Max error use fusion resolution = 0.15
  • For raw scans with 0.2 Max error use fusion resolution = 0.2
  • For raw scans with acceptable Max error (0.3 and lower) use fusion resolution = 0.3.

 

We are here to help! If you have any questions or issues, please do not hesitate to contact our team by emailing support@artec-group.com or by clicking on "Ask Support" button on the upper part of the screen. We will always be happy to assist you and will get back to you as soon as we can.