Exploration of Blender to design a digital twin of multi camera metrology systems

After three industrial revolutions that transformed the agricultural and craft economy into one dominated by industry and machine manufacturing, a fourth industrial revolution has recently begun, plunging the world into an era of digitisation where new technologies such as the digital twin, the digital model, human-robot collaboration or the internet of things are being explored to create new models for agile factories that are reconfigurable, resilient, fast and knowledgeable.

In this new philosophy, called Industry 4.0, new needs in terms of worker safety, work supervision and quality control of goods have been developed, as well as new issues related to humans, economy, and technology development. Regarding these new paradigms, solutions based on multi-camera optical systems have been developed.

However, current physical available solutions are not necessarily optimised, cameras are installed according to geometry specificities such as being collinear, or through learning trial-and-error processes. Due to the recurrent nature of the optimisation problem, the development of virtual technologies generating new possibilities for virtualising the physical assets of the production chain, digital models or even potentially twins are being considered to solve this problem.

This research investigates the development of a digital model/twin of single and multi-camera optical systems to measure shapes and objects in an industrial environment. A literature survey was conducted to identify the solutions already developed, identifying their drawbacks to design an innovative system. Through this survey it was identified that the current modelling solutions are either mimicking the real-world in a simple way, or are designing the camera from its whole body to its radiometric map, which is time consuming, and maybe not lead to an accurate model.

An alternative at these designs was found in the 3D animation software, which use 3D virtual camera in its rendering process. Various pieces of 3D animation software exist, but Blender was chosen because it is open source, free, and offer divers tool such as ray-tracing and Python script.

The research presented maps the development of a digital model/twin of single and multi-camera optical systems in Blender through four steps: investigation whether Blender can be used as a digital base; designing a photorealistic digital model of the real-world; assessing the robustness of the model designed; and identification of positive and negative aspects of the modelling.

All experiments were completed in the real and virtual worlds to allow understanding and comparison of results.

The main conclusions of this research were the development of a digital representation of the real multi-camera network set up in Blender; the use of photorealism concepts; and the development of calibration routines for camera-based metrology systems modelled in Blender.