Synthetic Defect Geometries of Cast Metal Objects Modeled via 2d Voronoi Tessellations

TL;DR

This paper introduces a parametric modeling approach using 2D Voronoi tessellations to generate synthetic defect geometries on cast metal objects, aiding in training data creation for machine learning-based defect detection in non-destructive testing.

Contribution

It presents a novel, controllable method for creating synthetic defect data using Voronoi-based models, applicable to various NDT techniques and defect types.

Findings

Enables large, variable synthetic defect datasets.

Allows inclusion of rare defect types.

Facilitates pixel-perfect annotation for machine learning.

Abstract

In industry, defect detection is crucial for quality control. Non-destructive testing (NDT) methods are preferred as they do not influence the functionality of the object while inspecting. Automated data evaluation for automated defect detection is a growing field of research. In particular, machine learning approaches show promising results. To provide training data in sufficient amount and quality, synthetic data can be used. Rule-based approaches enable synthetic data generation in a controllable environment. Therefore, a digital twin of the inspected object including synthetic defects is needed. We present parametric methods to model 3d mesh objects of various defect types that can then be added to the object geometry to obtain synthetic defective objects. The models are motivated by common defects in metal casting but can be transferred to other machining procedures that produce similar defect shapes. Synthetic data resembling the real inspection data can then be created by using a physically based Monte Carlo simulation of the respective testing method. Using our defect models, a variable and arbitrarily large synthetic data set can be generated with the possibility to include rarely occurring defects in sufficient quantity. Pixel-perfect annotation can be created in parallel. As an example, we will use visual surface inspection, but the procedure can be applied in combination with simulations for any other NDT method.