Augmented reality (AR) lends itself to presenting visual instructions on how to assemble or disassemble an object. Splitting the assembly procedure into shorter steps and presenting the corresponding instructions in AR supports their comprehension. However, one can still misinterpret instructions and make errors while manipulating the object. While previous work supports detecting the occurrence of errors, we investigate handling such errors. This requires knowledge of the error at runtime of the application. Starting from a categorization of the errors, we investigate how to automatically derive common error states to generate training data. We introduce an extension to a state-of-the-art deep-learning-based object detector for supporting the detection of assembly states at real-time update rates, based on contrastive learning. We evaluated the proposed detector, showing that it outperforms the state-of-the-art, and we demonstrate our work with an AR application that alerts the user if errors occur and provides visual help to correct the error.

Presenting tutorials in augmented reality is a compelling application area, but previous attempts have been limited to objects with only a small numbers of parts. Scaling augmented reality tutorials to complex assemblies of a large number of parts is difficult, because it requires automatically discriminating many similar-looking object configurations, which poses a challenge for current object detection techniques. In this paper, we seek to lift this limitation. Our approach is inspired by the observation that, even though the number of assembly steps may be large, their order is typically highly restricted: Some actions can only be performed after others. To leverage this observation, we enhance a state-of-the-art object detector to predict the current assembly state by conditioning on the previous one, and to learn the constraints on consecutive states. This learned ‘consecutive state prior’ helps the detector disambiguate configurations that are otherwise too similar in terms of visual appearance to be reliably discriminated. Via the state prior, the detector is also able to improve the estimated probabilities that a state detection is correct. We experimentally demonstrate that our technique enhances the detection accuracy for assembly sequences with a large number of steps and on a variety of use cases, including furniture, Lego and origami. Additionally, we demonstrate the use of our algorithm in an interactive augmented reality application.

This paper presents guitARhero, an Augmented Reality application for interactively teaching guitar playing to beginners through responsive visualizations overlaid on the guitar neck. We support two types of visual guidance, a highlighting of the frets that need to be pressed and a 3D hand overlay, as well as two display scenarios, one using a desktop magic mirror and one using a video see-through head-mounted display. We conducted a user study with 20 participants to evaluate how well users could follow instructions presented with different guidance and display combinations and compare these to a baseline where users had to follow video instructions. Our study highlights the trade-off between the provided information and visual clarity affecting the user's ability to interpret and follow instructions for fine-grained tasks. We show that the perceived usefulness of instruction integration into an HMD view highly depends on the hardware capabilities and instruction details.

Among the most compelling applications of Augmented Reality are spatially registered tutorials. The effort of creating such instructions remains one of the obstacles precluding a wider use. We propose a system that is capable of extracting 3D instructions in a completely model-free manner from demonstrations, based on volumetric changes. The instructions are visualised later in an interactive Augmented Reality guidance application, on a mobile head-mounted display. We enable a technology that can be used by anyone in an ad-hoc tabletop setup for assemblies with rigid components.

We present a system for generating and visualizing interactive 3D Augmented Reality tutorials based on 2D video input, which allows viewpoint control at runtime. Inspired by assembly planning, we analyze the input video using a 3D CAD model of the object to determine an assembly graph that encodes blocking relationships between parts. Using an assembly graph enables us to detect assembly steps that are otherwise difficult to extract from the video, and generally improves object detection and tracking by providing prior knowledge about movable parts. To avoid information loss, we combine the 3D animation with relevant parts of the 2D video so that we can show detailed manipulations and tool usage that cannot be easily extracted from the video. To further support user orientation, we visually align the 3D animation with the real-world object by using texture information from the input video. We developed a presentation system that uses commonly available hardware to make our results accessible for home use and demonstrate the effectiveness of our approach by comparing it to traditional video tutorials.