5,424 research outputs found
Volume-based Semantic Labeling with Signed Distance Functions
Research works on the two topics of Semantic Segmentation and SLAM
(Simultaneous Localization and Mapping) have been following separate tracks.
Here, we link them quite tightly by delineating a category label fusion
technique that allows for embedding semantic information into the dense map
created by a volume-based SLAM algorithm such as KinectFusion. Accordingly, our
approach is the first to provide a semantically labeled dense reconstruction of
the environment from a stream of RGB-D images. We validate our proposal using a
publicly available semantically annotated RGB-D dataset and a) employing ground
truth labels, b) corrupting such annotations with synthetic noise, c) deploying
a state of the art semantic segmentation algorithm based on Convolutional
Neural Networks.Comment: Submitted to PSIVT201
SkiMap: An Efficient Mapping Framework for Robot Navigation
We present a novel mapping framework for robot navigation which features a
multi-level querying system capable to obtain rapidly representations as
diverse as a 3D voxel grid, a 2.5D height map and a 2D occupancy grid. These
are inherently embedded into a memory and time efficient core data structure
organized as a Tree of SkipLists. Compared to the well-known Octree
representation, our approach exhibits a better time efficiency, thanks to its
simple and highly parallelizable computational structure, and a similar memory
footprint when mapping large workspaces. Peculiarly within the realm of mapping
for robot navigation, our framework supports realtime erosion and
re-integration of measurements upon reception of optimized poses from the
sensor tracker, so as to improve continuously the accuracy of the map.Comment: Accepted by International Conference on Robotics and Automation
(ICRA) 2017. This is the submitted version. The final published version may
be slightly differen
A deep learning pipeline for product recognition on store shelves
Recognition of grocery products in store shelves poses peculiar challenges.
Firstly, the task mandates the recognition of an extremely high number of
different items, in the order of several thousands for medium-small shops, with
many of them featuring small inter and intra class variability. Then, available
product databases usually include just one or a few studio-quality images per
product (referred to herein as reference images), whilst at test time
recognition is performed on pictures displaying a portion of a shelf containing
several products and taken in the store by cheap cameras (referred to as query
images). Moreover, as the items on sale in a store as well as their appearance
change frequently over time, a practical recognition system should handle
seamlessly new products/packages. Inspired by recent advances in object
detection and image retrieval, we propose to leverage on state of the art
object detectors based on deep learning to obtain an initial productagnostic
item detection. Then, we pursue product recognition through a similarity search
between global descriptors computed on reference and cropped query images. To
maximize performance, we learn an ad-hoc global descriptor by a CNN trained on
reference images based on an image embedding loss. Our system is
computationally expensive at training time but can perform recognition rapidly
and accurately at test time
Real-time self-adaptive deep stereo
Deep convolutional neural networks trained end-to-end are the
state-of-the-art methods to regress dense disparity maps from stereo pairs.
These models, however, suffer from a notable decrease in accuracy when exposed
to scenarios significantly different from the training set, e.g., real vs
synthetic images, etc.). We argue that it is extremely unlikely to gather
enough samples to achieve effective training/tuning in any target domain, thus
making this setup impractical for many applications. Instead, we propose to
perform unsupervised and continuous online adaptation of a deep stereo network,
which allows for preserving its accuracy in any environment. However, this
strategy is extremely computationally demanding and thus prevents real-time
inference. We address this issue introducing a new lightweight, yet effective,
deep stereo architecture, Modularly ADaptive Network (MADNet) and developing a
Modular ADaptation (MAD) algorithm, which independently trains sub-portions of
the network. By deploying MADNet together with MAD we introduce the first
real-time self-adaptive deep stereo system enabling competitive performance on
heterogeneous datasets.Comment: Accepted at CVPR2019 as oral presentation. Code Available
https://github.com/CVLAB-Unibo/Real-time-self-adaptive-deep-stere
Robust Visual Correspondence: Theory and Applications
Visual correspondence represents one of the most important tasks in computer vision. Given two sets of pixels (i.e. two images), it aims at finding corresponding pixel pairs belonging to the two sets (homologous pixels). As a matter of fact, visual correspondence is commonly employed in fields such as stereo correspondence, change detection, image registration, motion estimation, pattern matching, image vector quantization. The visual correspondence task can be extremely challenging in presence of disturbance factors which typically affect images. A common source of disturbances can be related to photometric distortions between the images under comparison. These can be ascribed to the camera sensors employed in the image acquisition process (due to dynamic variations of camera parameters such as auto-exposure and auto-gain, or to the use of different cameras), or can be induced by external factors such as changes of the amount of light emitted by the sources or viewing of non-lambertian surfaces at different angles. All of these factors tend to produce brightness changes in corresponding pixels of the two images that can not be neglected in real applications implying visual correspondence between images acquired from different spatial points (e.g. stereo vision) and/or different time instants (e.g. pattern matching, change detection). In addition to photometric distortions, differences between corresponding pixels can also be due to the noise introduced by camera sensors. Finally, the acquisition of images from different spatial points or different time instants can also induce occlusions. Evaluation assessments have also been proposed which compared visual correspondence approaches for tasks such as stereo correspondence (Chambon & Crouzil, 2003), image registration (Zitova & Flusser, 2003) and image motion (Giachetti, 2000)
Clinical, radiographic, and histologic evaluation of maxillary sinus lift procedure using a highly purified xenogenic graft (Laddec(®))
The aim of this study was to evaluate the clinical, radiographic and histologic results when a highly purified xenogenic bone (Laddec(®)) was used as grafting material in maxillary sinuses
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