12,054 research outputs found
Towards 3D Motion Estimation from Deformable Surfaces
Estimating the pose of an imaging sensor is a central research problem. Many solutions have been proposed for the case of a rigid environment. In contrast, we tackle the case of a non-rigid environment observed by a 3D sensor, which has been neglected in the literature. We represent the environment as sets of time-varying 3D points explained by a low-rank shape model, that we derive in its implicit and explicit forms. The parameters of this model are learnt from data gathered by the 3D sensor. We propose a learning algorithm based on minimal 3D non-rigid tensors that we introduce. This is followed by a Maximum Likelihood nonlinear refinement performed in a bundle adjustment manner. Given the learnt environment model, we compute the pose of the 3D sensor, as well as the deformations of the environment, that is, the non-rigid counterpart of pose, from new sets of 3D points. We validate our environment learning and pose estimation modules on simulated and real data
Estimating the Pose of a 3D Sensor in a Non-Rigid Environment
Estimating the pose of an imaging sensor is a central research problem. Many solutions have been proposed for the case of a rigid environment. In contrast, we tackle the case of a non-rigid environment observed by a 3D sensor, which has been neglected in the literature. We represent the environment as sets of time-varying 3D points explained by a low-rank shape model, that we derive in its implicit and explicit forms. The parameters of this model are learnt from data gathered by the 3D sensor. We propose a learning algorithm based on minimal 3D non-rigid tensors that we introduce. This is followed by a Maximum Likelihood nonlinear refinement performed in a bundle adjustment manner. Given the learnt environment model, we compute the pose of the 3D sensor, as well as the deformations of the environment, that is, the non-rigid counterpart of pose, from new sets of 3D points. We validate our environment learning and pose estimation modules on simulated and real data
Low Power Depth Estimation of Rigid Objects for Time-of-Flight Imaging
Depth sensing is useful in a variety of applications that range from
augmented reality to robotics. Time-of-flight (TOF) cameras are appealing
because they obtain dense depth measurements with minimal latency. However, for
many battery-powered devices, the illumination source of a TOF camera is power
hungry and can limit the battery life of the device. To address this issue, we
present an algorithm that lowers the power for depth sensing by reducing the
usage of the TOF camera and estimating depth maps using concurrently collected
images. Our technique also adaptively controls the TOF camera and enables it
when an accurate depth map cannot be estimated. To ensure that the overall
system power for depth sensing is reduced, we design our algorithm to run on a
low power embedded platform, where it outputs 640x480 depth maps at 30 frames
per second. We evaluate our approach on several RGB-D datasets, where it
produces depth maps with an overall mean relative error of 0.96% and reduces
the usage of the TOF camera by 85%. When used with commercial TOF cameras, we
estimate that our algorithm can lower the total power for depth sensing by up
to 73%
Optical techniques for 3D surface reconstruction in computer-assisted laparoscopic surgery
One of the main challenges for computer-assisted surgery (CAS) is to determine the intra-opera- tive morphology and motion of soft-tissues. This information is prerequisite to the registration of multi-modal patient-specific data for enhancing the surgeon’s navigation capabilites by observ- ing beyond exposed tissue surfaces and for providing intelligent control of robotic-assisted in- struments. In minimally invasive surgery (MIS), optical techniques are an increasingly attractive approach for in vivo 3D reconstruction of the soft-tissue surface geometry. This paper reviews the state-of-the-art methods for optical intra-operative 3D reconstruction in laparoscopic surgery and discusses the technical challenges and future perspectives towards clinical translation. With the recent paradigm shift of surgical practice towards MIS and new developments in 3D opti- cal imaging, this is a timely discussion about technologies that could facilitate complex CAS procedures in dynamic and deformable anatomical regions
Efficient Continuous-Time SLAM for 3D Lidar-Based Online Mapping
Modern 3D laser-range scanners have a high data rate, making online
simultaneous localization and mapping (SLAM) computationally challenging.
Recursive state estimation techniques are efficient but commit to a state
estimate immediately after a new scan is made, which may lead to misalignments
of measurements. We present a 3D SLAM approach that allows for refining
alignments during online mapping. Our method is based on efficient local
mapping and a hierarchical optimization back-end. Measurements of a 3D laser
scanner are aggregated in local multiresolution maps by means of surfel-based
registration. The local maps are used in a multi-level graph for allocentric
mapping and localization. In order to incorporate corrections when refining the
alignment, the individual 3D scans in the local map are modeled as a sub-graph
and graph optimization is performed to account for drift and misalignments in
the local maps. Furthermore, in each sub-graph, a continuous-time
representation of the sensor trajectory allows to correct measurements between
scan poses. We evaluate our approach in multiple experiments by showing
qualitative results. Furthermore, we quantify the map quality by an
entropy-based measure.Comment: In: Proceedings of the International Conference on Robotics and
Automation (ICRA) 201
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