Dirk Holz | Bonn Universität (original) (raw)

Papers by Dirk Holz

Decomposing sensory measurements into coherent parts is a fundamental prerequisite for scene unde... more Decomposing sensory measurements into coherent parts is a fundamental prerequisite
for scene understanding that is required for solving complex tasks, e.g., in
the eld of mobile manipulation. In this article, we describe methods for ecient
segmentation of range images and organized point clouds. In order to achieve
real-time performance in complex environments, we focus our approach on simple
but robust solutions. We present a fast approach to surface reconstruction
in range images and organized point clouds by means of approximate polygonal
meshing. The obtained local surface information and neighborhoods are then
used to 1) smooth the underlying measurements, and 2) segment the image into
planar regions and other geometric primitives. A comparative evaluation using
publicly available data sets shows that our approach achieves state-of-the-art
performance while being signi cantly faster than other methods.

2010 IEEE International Conference on Robotics and Automation, 2010

We propose a 3D obstacle avoidance method for mobile robots. Besides the robot's 2D laser range f... more We propose a 3D obstacle avoidance method for mobile robots. Besides the robot's 2D laser range finder, a Timeof-Flight camera is used to perceive obstacles that are not in the scan plane of the laser range finder. Existing approaches that employ Time-of-Flight cameras suffer from the limited fieldof-view of the sensor. To overcome this issue, we mount the camera on the head of our anthropomorphic robot Dynamaid. This allows to change the gaze direction through the robot's pan-tilt neck and its torso yaw joint.

Proceedings - IEEE International Conference on Robotics and Automation

Joint attention between a human user and a robot is essential for effective human-robot interacti... more Joint attention between a human user and a robot is essential for effective human-robot interaction. In this work, we propose an approach to person awareness and to the perception of showing and pointing gestures for a domestic service robot. In contrast to previous work, we do not require the person to be at a predefined position, but instead actively approach and orient towards the communication partner. For perceiving showing and pointing gestures and for estimating the pointing direction a Time-of-Flight camera is used. Estimated pointing directions and shown objects are matched to objects in the robot's environment. Both the perception of showing and pointing gestures as well as the accurary of estimated pointing directions have been evaluated in a set of different experiments. The results show that both gestures are adequatly perceived by the robot. Furthermore, our system achieves a higher accuracy in estimating the pointing direction than is reported in the literature fo...

2011 IEEE/RSJ International Conference on Intelligent Robots and Systems, 2011

In this paper, we present a novel multi-resolution approach to efficiently mapping 3D environment... more In this paper, we present a novel multi-resolution approach to efficiently mapping 3D environments. Our representation models the environment as a hierarchy of probabilistic 3D maps, in which each submap is updated and transformed individually. In addition to the formal description of the approach, we present an implementation for tabletop manipulation tasks and an information-driven exploration algorithm for autonomously building a hierarchical map from sensor data. We evaluate our approach using real-world as well as simulated data. The results demonstrate that our method is able to efficiently represent 3D environments at high levels of detail. Compared to a monolithic approach, our maps can be generated significantly faster while requiring significantly less memory.

2009 IEEE/RSJ International Conference on Intelligent Robots and Systems, 2009

Time-of-Flight cameras constitute a smart and fast technology for 3D perception but lack in measu... more Time-of-Flight cameras constitute a smart and fast technology for 3D perception but lack in measurement precision and robustness. The authors present a comprehensive approach for 3D environment mapping based on this technology. Imprecision of depth measurements are properly handled by calibration and application of several filters. Robust registration is performed by a novel extension to the Iterative Closest Point algorithm. Remaining registration errors are reduced by global relaxation after loop-closure and surface smoothing. A laboratory ground truth evaluation is provided as well as 3D mapping experiments in a larger indoor environment.

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2013

Limiting factors for increasing autonomy and complexity of truly autonomous systems (without exte... more Limiting factors for increasing autonomy and complexity of truly autonomous systems (without external sensing and control) are onboard sensing and onboard processing power. In this paper, we propose a hardware setup and processing pipeline that allows a fully autonomous UAV to perceive obstacles in (almost) all directions in its surroundings. Different sensor modalities are applied in order take into account the different characteristics of obstacles that can commonly be found in typical UAV applications. We provide a complete overview on the implemented system and present experimental results as a proof of concept.

Mobile Robots Navigation, 2010

Lecture Notes in Computer Science, 2014

In this paper, we describe system and approaches of our team NimbRo@Home that won the RoboCup@Hom... more In this paper, we describe system and approaches of our team NimbRo@Home that won the RoboCup@Home competition 2013. We designed a multi-purpose gripper for grasping typical household objects in pick-and-place tasks and also for using tools. The tools are complementarily equipped with special handles that establish form closure with the gripper, which resists wrenches in any direction. We demonstrate tool use for opening a bottle and grasping sausages with a pair of tongs in a barbecue scenario. We also devised efficient deformable registration methods for the transfer of manipulation skills between objects of the same kind but with differing shape. Finally, we enhance human-robot interaction with a remote user interface for handheld PCs that enables a user to control capabilities of the robot. These capabilities have been demonstrated in the open challenges of the competition. We also explain our approaches to the predefined tests of the competition, and report on the performance of our robots at RoboCup 2013.

2010 IEEE Safety Security and Rescue Robotics, 2010

... Sebastian Blumenthal Deparment of Computer Science II Bonn-Rhein-Sieg University SanktAugusti... more ... Sebastian Blumenthal Deparment of Computer Science II Bonn-Rhein-Sieg University SanktAugustin, NRW, Germany sebastian.blumenthal@inf.h-brs.de Peter Molitor Fraunhofer IAIS Schloss Birlinghoven Sankt Augustin, NRW, Germany peter@molitor.biz Dirk Holz Dep. ...

Micro aerial vehicles (MAVs) pose speci c constraints on onboard sensing, mainly limited payload ... more Micro aerial vehicles (MAVs) pose speci c constraints on onboard
sensing, mainly limited payload and limited processing power. For
accurate 3D mapping even in GPS denied environments, we have designed
a light-weight 3D laser scanner speci cally for the application on
MAVs. Similar to other custom-built 3D laser scanners composed of a
rotating 2D laser range nder, it exhibits di erent point densities within
and between individual scan lines. When rotated fast, such non-uniform
point densities in
uence neighborhood searches which in turn may negatively
a ect local feature estimation and scan registration. We present
a complete pipeline for 3D mapping including pair-wise registration and
global alignment of 3D scans acquired in-
ight. For registration, we extend
a state-of-the-art registration algorithm to include topological information
from approximate surface reconstructions. For global alignment,
we use a graph-based approach making use of the same error metric
and iteratively re ne the complete vehicle trajectory. In experiments, we
show that our approach can compensate for the e ects caused by different
point densities up to very low angular resolutions and that we
can build accurate and consistent 3D maps in-
ight with a micro aerial
vehicle.

RoboCup@Home is an application-oriented league within the annual RoboCup events. It focuses on do... more RoboCup@Home is an application-oriented league within the annual RoboCup events. It focuses on domestic service robots and mobile manipulators interacting with human users. Participating robots need to solve tasks ranging from following and guiding human users to delivering objects, e.g., in a supermarket. In this paper, we present the @Home league and how it evolved over the last seven years since its existence. We place particular emphasis on how we evaluate the teams' performances over the years and how we use the obtained statistics to drive the development of the league. This process is shown in detail on two examples-following human guides, and finding and manipulating objects. Finally, we will outline possible future directions and developments.

Man-made objects such as mechanical construction parts can typically be described as a compositio... more Man-made objects such as mechanical construction parts can typically be described as a composition of shape primitives like cylinders, planes, cones and spheres. We propose a robust method for the detection and pose estimation of such objects in 3D point clouds. Our main contribution is to enhance a probabilistic graph-matching approach that detects objects using 3D shape primitives with distinct 2D primitives such as circular contours. With this extension, our method copes with difficult occlusion situations and can be applied for object manipulation in complex scenarios such as grasping from a pile or bin-picking. We demonstrate the performance of our approach in a comparison with a state-of-the-art feature-based method for objects of generic shape and a primitive-based approach using only 3D shapes and no contours.

This paper presents the different omnidirectional sensors developed at Fraunhofer Institute for I... more This paper presents the different omnidirectional sensors developed at Fraunhofer Institute for Intelligent Analysis and Information Systems (IAIS) during the past decade. It envelops cheap USB / Firewire webcams to expensive high end cameras, continuously rotation 3D laser scanner, rotating infrared cameras and a new panoramic camera Spherecam. This new spherical camera is presented in detail compared to the other sensors. Beside the camera hardware we also categorize the omni cameras according to their price, connection and operating platform dependences and present the associated camera drivers and possible applications. Consider this paper as hardware descriptions of vision systems. Algorithms for ominidirectional vision systems are not discussed.

3D laser scanners composed of a rotating 2D laser range scanner exhibit different point densities... more 3D laser scanners composed of a rotating 2D laser range scanner exhibit different point densities within and between individual scan lines. Such non-uniform point densities influence neighbor searches which in turn may negatively affect feature estimation and scan registration. To reliably register such scans, we extend a state-of-the-art registration algorithm to include topological information from approximate surface reconstructions. We show that our approach outperforms related approaches in both refining a good initial pose estimate and registering badly aligned point clouds if no such estimate is available. In an example application, we demonstrate local 3D mapping with a micro aerial vehicle by registering sequences of non-uniform density point clouds acquired in-flight with a continuously rotating lightweight 3D scanner.