Browsing by Author "Ritz, Martin"

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    CultArc3D_mini: Fully Automatic Zero-Button 3D Replicator
    (The Eurographics Association, 2018) Ritz, Martin; Knuth, Martin; Santos, Pedro; Fellner, Dieter W.; Sablatnig, Robert and Wimmer, Michael
    3D scanning and 3D printing are two rapidly evolving domains, both generating results with a huge and growing spectrum of applications. Especially in Cultural Heritage, a massive and increasing amount of objects awaits digitization for various purposes, one of them being replication. Yet, current approaches to optical 3D digitization are semi-automatic at best and require great user effort whenever high quality is desired. With our solution we provide the missing link between both domains, and present a fully automatic 3D object replicator which does not require user interaction. The system consists of our photogrammetric 3D scanner CultArc3D_mini that captures an optimal image set for 3D geometry and texture reconstruction and even optical material properties of objects in only minutes, a conveyor system for automatic object feed-in and -out, a 3D printer, and our sensor-based process flow software that handles every single process step of the complex sequence from image acquisition, sensor-based object transportation, 3D reconstruction involving different kinds of calibrations, to 3D printing of the resulting virtual replica immediately after 3D reconstruction. Typically, one-button machines require the user to start the process by interacting over a user interface. Since positioning and pickup of objects is automatically registered, the only thing left for the user to do is placing an object at the entry and retrieving it from the exit after scanning. Shortly after, the 3D replica can be picked up from the 3D printer. Technically, we created a zero-button 3D replicator that provides high throughput digitization in 3D, requiring only minutes per object, and it is publicly showcased in action at 3IT Berlin.
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    Fully Automatic Mechanical Scan Range Extension and Signal to Noise Optimization of a Lens-Shifted Structured Light System
    (The Eurographics Association, 2021) Kutlu, Hasan; Ritz, Martin; Santos, Pedro; Fellner, Dieter W.; Hulusic, Vedad and Chalmers, Alan
    Digitization of cultural heritage is of growing importance, both for its preservation for coming generations in the face of looming dangers of natural decay or intentional destruction, and current generations, that increasingly have access to virtual cultural heritage for interactive exploring or scientific analysis. These goals can only be achieved by 3D replicas at reasonable quality and resolution, to come as close as possible to the original. This brings about several challenges to overcome. The challenge of digitizing huge numbers of artefacts is addressed by CultLab3D, the first fully automatic 3D digitization system. Another challenge is the size of objects, as each digitization system is designed for a certain optimum measurement range, leaving which results in loss of quality. Due to optical and mechanical constraints, most systems are not able to faithfully reconstruct objects under a certain size limit in their full geometric detail. Historic coins are one good example, where the deterioration of the surface structure in most cases has progressed to a degree that it not even is perceptible through the fingernail. This challenge is addressed by a modular extension of CultLab3D, the MesoScanner, which is a structured light system that breaks limits in depth resolution through a mechanical lens-shifting extension, allowing physically shifting of fringe patterns on top of the well-known multi-period phase shift method. This is where this work adds two major improvements: First, the signal to noise ratio and thus reconstruction quality has been improved significantly through several algorithmic processing steps. Second, the physical limitation of the measurement range was removed using a 2D actuator steering the object mount, thus allowing for a measurement range at theoretically arbitrary size. This opens up the fully automatic handling of two scenarios: Complete digitization of objects exceeding the measurement range, and unsupervised digitization of large collections of small objects in one run.