The importance of depth perception in the interactions that humans have within their nearby space is a well established fact. Consequently, it is also well known that the possibility of exploiting good stereo information would ease and, in many cases, enable, a large variety of attentional and interactive behaviors on humanoid robotic platforms. However, the difficulty of computing real-time and robust binocular disparity maps from moving stereo cameras often prevents from relying on this kind of cue to visually guide robots' attention and actions in real-world scenarios. The contribution of this paper is two-fold: first, we show that the Efficient Large-scale Stereo Matching algorithm (ELAS) by A. 2010 for computation of the disparity map is well suited to be used on a humanoid robotic platform as the iCub robot; second, we show how, provided with a fast and reliable stereo system, implementing relatively challenging visual behaviors in natural settings can require much less effort. As a case of study we consider the common situation where the robot is asked to focus the attention on one object close in the scene, showing how a simple but effective disparity-based segmentation solves the problem in this case. Indeed this example paves the way to a variety of other similar applications.
Depth is a natural cue to be used when the robot's attention needs to be focused on close entities in its workspace. For example, consider a very common situation for a humanoid robotic platform, like the one where a human stands in front of the robot showing to it an object to be recognized or grasped. Both motion- and appearance-based approaches to focus the robot's attention on the object of interest would impose many constraints on this even simple Human-Robot Interaction (HRI) scenario. Indeed, color-based methods work under strict assumptions on the light conditions, kind of background (preferably a table or a wall) and generally fail in cluttered settings. Model-based methods, beyond being affected to some extent by the same limitations, need a model of the object to be known a-priori. Motion-based methods (see, e.g., @cite_12 ) work under the obvious assumption that the objects are moving, the speed of the object being often critical for the detection. Instead, when the robot is required to look at something we are showing to it, or which is located nearby, the most distinguishing feature is simply the fact that the object of interest is closer to the robot than the background.
@cite_12
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The ability to perceive humans is an essential requirement for safe and efficient human-robot interaction. In real-world applications, the need for a robot to interact in real time with multiple humans in a dynamic, 3-D environment presents a significant challenge. The recent availability of commercial color-depth cameras allow for the creation of a system that makes use of the depth dimension, thus enabling a robot to observe its environment and perceive in the 3-D space. Here we present a system for 3-D multiple human perception in real time from a moving robot equipped with a color-depth camera and a consumer-grade computer. Our approach reduces computation time to achieve real-time performance through a unique combination of new ideas and established techniques. We remove the ground and ceiling planes from the 3-D point cloud input to separate candidate point clusters. We introduce the novel information concept, depth of interest, which we use to identify candidates for detection, and that avoids the computationally expensive scanning-window methods of other approaches. We utilize a cascade of detectors to distinguish humans from objects, in which we make intelligent reuse of intermediary features in successive detectors to improve computation. Because of the high computational cost of some methods, we represent our candidate tracking algorithm with a decision directed acyclic graph, which allows us to use the most computationally intense techniques only where necessary. We detail the successful implementation of our novel approach on a mobile robot and examine its performance in scenarios with real-world challenges, including occlusion, robot motion, nonupright humans, humans leaving and reentering the field of view (i.e., the reidentification challenge), human-object and human-human interaction. We conclude with the observation that the incorporation of the depth information, together with the use of modern techniques in new ways, we are able to create an accurate system for real-time 3-D perception of humans by a mobile robot. Learning to predict scene depth from RGB inputs is a challenging task both for indoor and outdoor robot navigation. In this work we address unsupervised learning of scene depth and robot ego-motion where supervision is provided by monocular videos, as cameras are the cheapest, least restrictive and most ubiquitous sensor for robotics. Previous work in unsupervised image-to-depth learning has established strong baselines in the domain. We propose a novel approach which produces higher quality results, is able to model moving objects and is shown to transfer across data domains, e.g. from outdoors to indoor scenes. The main idea is to introduce geometric structure in the learning process, by modeling the scene and the individual objects; camera ego-motion and object motions are learned from monocular videos as input. Furthermore an online refinement method is introduced to adapt learning on the fly to unknown domains. The proposed approach outperforms all state-of-the-art approaches, including those that handle motion e.g. through learned flow. Our results are comparable in quality to the ones which used stereo as supervision and significantly improve depth prediction on scenes and datasets which contain a lot of object motion. The approach is of practical relevance, as it allows transfer across environments, by transferring models trained on data collected for robot navigation in urban scenes to indoor navigation settings. The code associated with this paper can be found at this https URL. For robot to perform its tasks competently, robustly and in the right context it has to understand the course of its actions and their consequences. For example, imagine the robot being tasked with the clean up of the breakfast table. The robot is confronted with a heavily cluttered scene and has to be able to tell waste, dirty, clean and valuable objects apart. The robot shall be equipped with the knowledge that will, for instance, stop it from throwing away an expensive item. Herein proposed approach elevates robot’s perception skills in that it utilizes its capabilities to interact with the clutter of objects. This allows for better segmentation and finally also better object recognition by means of constraining the recognition to a region or regions of interest. Similar to [1] and [2], we propose a system that uses a robot arm to induce motions in a scene to enable effective object segmentation. Our system employs a combination of the following techniques: i) estimation of a contact point and a push direction of the robot’s end effector by detecting the concave corners in the cluttered scene, ii) feature extraction using features proposed by Shi and Tomasi and tracking using optical flow, and iii) a novel clustering algorithm to segment the objects. Segmentation of rigid objects from a video stream of objects being moved by the robot has been addressed by Fitzpatrick [3] and [4]. In contrast, our arm motion is not pre-planned but adapts to the scene, we make use of the 3D data to segment the object candidates from the background and we use a novel clustering approach for the segmentation of textured objects. Overview of the whole system is shown in Fig. 2. The system will be demostrated live during the workshop. Mobile robotics has achieved notable progress, however, to increase the complexity of the tasks that mobile robots can perform in natural environments, we need to provide them with a greater semantic understanding of their surrounding. In particular, identifying indoor scenes, such as an Office or a Kitchen, is a highly valuable perceptual ability for an indoor mobile robot, and in this paper we propose a new technique to achieve this goal. As a distinguishing feature, we use common objects, such as Doors or furniture, as a key intermediate representation to recognize indoor scenes. We frame our method as a generative probabilistic hierarchical model, where we use object category classifiers to associate low-level visual features to objects, and contextual relations to associate objects to scenes. The inherent semantic interpretation of common objects allows us to use rich sources of online data to populate the probabilistic terms of our model. In contrast to alternative computer vision based methods, we boost performance by exploiting the embedded and dynamic nature of a mobile robot. In particular, we increase detection accuracy and efficiency by using a 3D range sensor that allows us to implement a focus of attention mechanism based on geometric and structural information. Furthermore, we use concepts from information theory to propose an adaptive scheme that limits computational load by selectively guiding the search for informative objects. The operation of this scheme is facilitated by the dynamic nature of a mobile robot that is constantly changing its field of view. We test our approach using real data captured by a mobile robot navigating in Office and home environments. Our results indicate that the proposed approach outperforms several state-of-the-art techniques for scene recognition.