»SimVision« – Simulation-Based Visual Inspection for the Industry

Rule-based Synthetic Data Meets Artificial Intelligence

Development of coated cutting tools is a highly specialized and expensive process. Coating enhances the tool’s cutting performance and extends its lifetime. When the coating is not applied correctly, the tool will malfunction and potentially cause further damage to the object it was cutting. However, the coating defects are measured in micrometers and are close to impossible to collect in a catalogue. How can automate the inspection process? This is where the rule-based synthetic data comes into play. In the »SimVision« project, researchers from the Fraunhofer Institutes ITWM, IGD and IST work together with TU Wien to develop scalable pipeline for training Artificial Intelligence with synthetic data.

»SimVision« stands for »Simulation-Based Visual Inspection«. A central component is the creation of a synthetic data set for Machine Learning with synthetic image data that is realistic enough to prepare AI models for practical use. But how realistic does this data need to be? How does the data influence inspection accuracy? And how can we model defects which we have never seen? These questions are at the heart of the research.

Application Example: Increasing Efficiency Through Automated Inspection in Production

The components inspected in the project include cutting tools with diamond coatings of different granularity, causing varying appearance. Conventional AI-based methods reach their limits when it comes to reflective, textured or geometrically complex surfaces and little training data is available. Such surfaces make it difficult to reliably detect defects such as delamination, scratches, cracks or wear and tear.

In »SimVision«, we are developing a flexible inspection system that automatically inspects surface quality at different stages of coating production. The inspection system is made possible by our rule-based synthetic data. It means that the synthetic data is based on mathematical models of surface texture, defects and tool geometry. By controlling all the parameters, we can generate photorealistic training data with a wide variety of possible surface conditions, including edge cases. This improves the accuracy, flexibility and cost-efficiency of the inspection system.

Overarching Goals of the Project: Flexible Quality Inspection Through AI

  1. Optimization of Image Synthesis Processes: Physics-based modeling of surfaces, defects and light reflections creates realistic, synthetic training data for AI models.
  2. Establishing Simulation-Based Visual Inspection as a New Research Discipline: With a focus on industrial knowledge transfer, we develop practical solutions that can be quickly transferred to real production processes.
Side by side comparison of end mill cutter inspection images. From left to right: real image, synthetic image with surface defects, and ground truth mask.
© Fraunhofer ITWM
Side by side comparison of end mill cutter inspection images. From left to right: real image, synthetic image with surface defects, and ground truth mask.

Multidisciplinarity and International Collaboration Makes the Research Go Further

Development of a powerful synthetic data generation pipeline requires a number of different experts. In this project we have modelling, rendering and domain experts working together. Fraunhofer IST provides domain expertise and focuses on surface manufacturing, coating and characterization. Our team at Fraunhofer ITWM specializes in inspection planning and machine vision, as well as synthetic dataset generation. In collaboration with Fraunhofer IGD, it also works on mathematical surface appearance, geometric modeling, and processing. TU Wien contributes expertise in photorealistic image simulation and rendering.

Synthetic data is a term that has become ubiquitous in AI community over the last few years. It is a promise that highly specialized industrial AI solutions will indeed be possible. However, it relies on computer graphics and its capacity to generate high fidelity images. Fidelity takes time and if one needs tens of thousands of high-resolution images, it is crucial to explore optimization possibilities. This is where TU Wien comes into play with their path guiding and advanced denoising algorithms.

Simulation of edge defects and subcoating uneven surfaces
© Fraunhofer ITWM
Simulation of edge defects and subcoating uneven surfaces
Simulation of edge defects and subcoating uneven surfaces
© Fraunhofer ITWM

Next-Generation Virtual Inspection with V-POI

Best research can be done when previous work is extended instead of starting from scratch. An important tool here is V-POI, a software for virtual inspection planning developed by Fraunhofer ITWM. Our software allows illumination, camera positions and inspection sequences to be tested virtually before the inspection system is even built. The inspection plan is further used to generate photorealistic, perfectly labeled, synthetic data. Within »SimVision«, V-POI is extended not only to include surface textures and defects specific to coated tools, but for the first time to include control over geometrical feature variation such as edge rounding, thickness tolerancing and geometrical deformations, developed by Fraunhofer IGD.

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Parametric CAD geometry deformation enables controlled geometry variation within and outside of manufacturing tolerances. Given the high precision of the production process, we also show exaggerated values for illustration purpose. © Fraunhofer IGD

Projekt-Treffen am Fraunhofer IST
© Fraunhofer IST
Project meeting at the Fraunhofer IST: (from left to right) Dr. Petra Gospodnetic, Hiroyuki Sakai, Dr. Christian Stein, Juraj Fulir, Dr. Johannes Sebastian Mueller-Roemer, Marcus Stegemann, Dr. Markus Höfer, Natascha Jeziorski, Runzhou Mao, Dr. Dennis Barton. Not in this photo: Dr. Prof. Michael Wimmer, Sarah Baron, Christian Freude, Jasmin Heyser.

Outlook: New Standards for AI in Automated Quality Inspection

»SimVision« is doing pioneering work in the field of simulation-based visual inspection for highly detailed visual inspection. The simulation methods developed and tested within the project have the capacity to enable new ways for increasing AI robustness and enable its use in industrial environments where defects are scarce, but critical when they do appear.
 

Our Project Partners

Funding and Duration of the Project

»SimVision« is funded as an ICON project. ICON stands for »Integrated Collaboration for Optical and Non-Destructive Testing«. The project will run for three years and started in March 2024.