All CT-based metrology depends on an accurate surface determination in the voxel model. The better the surface determination, the smaller the measurement uncertainty. 

Our surface determination:

• Ensures minimum measurement uncertainty.
• Is subvoxel-accurate and locally adaptive, allowing for the measurement of details smaller than a voxel.
• Processes grey values of individual voxels based on the grey values of the surrounding voxels, making surface determination markedly more accurate than relying on a single greyscale threshold value.
• Offers an interval-based mode that enables high-accuracy, locally adaptive surface determination, even within an automated environment and under changing grey value conditions.
• Offers a multi-material mode that allows for simultaneous determination of the surfaces of multiple materials within a volume, resulting in one component per material.

Alignment to a nominal part or a coordinate system is crucial for measurement results. It enables the extraction and comparison of nominal and measured dimensions and the investigation of assemblies.

With VG software, you can:

• Align any data set to a reference data set or a coordinate system using point-, surface-, and geometry-based approaches:
  • Point-based: RPS and 3-2-1 alignment
  • Surface-based: Best fit, also with constraints or partial areas, as well as feature-based, focusing on characteristic areas
  • Geometry-based: Sequential alignment enables the imitation of physical alignments, creating corresponding pairs of geometry one after another, thereby decreasing the degrees of freedom. The remaining degrees can be adjusted to achieve the best fit for the whole or partial model.
• Tolerance alignment results to determine their quality
• Use custom and local coordinate and datum systems, providing automated measurement updates when changing alignments
• Use a non-rigid alignment as part of the Manufacturing Geometry Correction Module

Extracting geometry elements from scans is the basis for evaluating dimensions and tolerances. 

VG software enables you to:

• Extract geometry elements from scans
• Automatically recognise the type of geometry element using "Smart Expand"
• Control geometry element fitting by border distance, density, angular deviation, fit method (like Gauss or Chebycheff), and constraining to a position or axes
• Use algorithms verified by PTB and NIST*.

* PTB- and NIST-verified: This software contains the Volume Graphics Metrology Kernel VGMK 2023.1.0, which passed the PTB test for “Evaluation software based on minimum-zone method for coordinate measuring machines” and the PTB test for “Evaluation software based on least-squares method for coordinate measuring machines” , and which was verified by the NIST “Algorithm Testing and Evaluation Program for Coordinate Measuring Systems”. The test results were obtained under Windows (64 bit).