106,850 research outputs found
Object-Proposal Evaluation Protocol is 'Gameable'
Object proposals have quickly become the de-facto pre-processing step in a
number of vision pipelines (for object detection, object discovery, and other
tasks). Their performance is usually evaluated on partially annotated datasets.
In this paper, we argue that the choice of using a partially annotated dataset
for evaluation of object proposals is problematic -- as we demonstrate via a
thought experiment, the evaluation protocol is 'gameable', in the sense that
progress under this protocol does not necessarily correspond to a "better"
category independent object proposal algorithm.
To alleviate this problem, we: (1) Introduce a nearly-fully annotated version
of PASCAL VOC dataset, which serves as a test-bed to check if object proposal
techniques are overfitting to a particular list of categories. (2) Perform an
exhaustive evaluation of object proposal methods on our introduced nearly-fully
annotated PASCAL dataset and perform cross-dataset generalization experiments;
and (3) Introduce a diagnostic experiment to detect the bias capacity in an
object proposal algorithm. This tool circumvents the need to collect a densely
annotated dataset, which can be expensive and cumbersome to collect. Finally,
we plan to release an easy-to-use toolbox which combines various publicly
available implementations of object proposal algorithms which standardizes the
proposal generation and evaluation so that new methods can be added and
evaluated on different datasets. We hope that the results presented in the
paper will motivate the community to test the category independence of various
object proposal methods by carefully choosing the evaluation protocol.Comment: 15 pages, 11 figures, 4 table
Visual Landmark Recognition from Internet Photo Collections: A Large-Scale Evaluation
The task of a visual landmark recognition system is to identify photographed
buildings or objects in query photos and to provide the user with relevant
information on them. With their increasing coverage of the world's landmark
buildings and objects, Internet photo collections are now being used as a
source for building such systems in a fully automatic fashion. This process
typically consists of three steps: clustering large amounts of images by the
objects they depict; determining object names from user-provided tags; and
building a robust, compact, and efficient recognition index. To this date,
however, there is little empirical information on how well current approaches
for those steps perform in a large-scale open-set mining and recognition task.
Furthermore, there is little empirical information on how recognition
performance varies for different types of landmark objects and where there is
still potential for improvement. With this paper, we intend to fill these gaps.
Using a dataset of 500k images from Paris, we analyze each component of the
landmark recognition pipeline in order to answer the following questions: How
many and what kinds of objects can be discovered automatically? How can we best
use the resulting image clusters to recognize the object in a query? How can
the object be efficiently represented in memory for recognition? How reliably
can semantic information be extracted? And finally: What are the limiting
factors in the resulting pipeline from query to semantics? We evaluate how
different choices of methods and parameters for the individual pipeline steps
affect overall system performance and examine their effects for different query
categories such as buildings, paintings or sculptures
Subspace Alignment Based Domain Adaptation for RCNN Detector
In this paper, we propose subspace alignment based domain adaptation of the
state of the art RCNN based object detector. The aim is to be able to achieve
high quality object detection in novel, real world target scenarios without
requiring labels from the target domain. While, unsupervised domain adaptation
has been studied in the case of object classification, for object detection it
has been relatively unexplored. In subspace based domain adaptation for
objects, we need access to source and target subspaces for the bounding box
features. The absence of supervision (labels and bounding boxes are absent)
makes the task challenging. In this paper, we show that we can still adapt sub-
spaces that are localized to the object by obtaining detections from the RCNN
detector trained on source and applied on target. Then we form localized
subspaces from the detections and show that subspace alignment based adaptation
between these subspaces yields improved object detection. This evaluation is
done by considering challenging real world datasets of PASCAL VOC as source and
validation set of Microsoft COCO dataset as target for various categories.Comment: 26th British Machine Vision Conference, Swansea, U
Vessel tractography using an intensity based tensor model with branch detection
In this paper, we present a tubular structure seg- mentation method that utilizes a second order tensor constructed from directional intensity measurements, which is inspired from diffusion tensor image (DTI) modeling. The constructed anisotropic tensor which is fit inside a vessel drives the segmen- tation analogously to a tractography approach in DTI. Our model is initialized at a single seed point and is capable of capturing whole vessel trees by an automatic branch detection algorithm developed in the same framework. The centerline of the vessel as well as its thickness is extracted. Performance results within the Rotterdam Coronary Artery Algorithm Evaluation framework are provided for comparison with existing techniques. 96.4% average overlap with ground truth delineated by experts is obtained in addition to other measures reported in the paper. Moreover, we demonstrate further quantitative results over synthetic vascular datasets, and we provide quantitative experiments for branch detection on patient Computed Tomography Angiography (CTA) volumes, as well as qualitative evaluations on the same CTA datasets, from visual scores by a cardiologist expert
Deep Learning for Detecting Multiple Space-Time Action Tubes in Videos
In this work, we propose an approach to the spatiotemporal localisation
(detection) and classification of multiple concurrent actions within temporally
untrimmed videos. Our framework is composed of three stages. In stage 1,
appearance and motion detection networks are employed to localise and score
actions from colour images and optical flow. In stage 2, the appearance network
detections are boosted by combining them with the motion detection scores, in
proportion to their respective spatial overlap. In stage 3, sequences of
detection boxes most likely to be associated with a single action instance,
called action tubes, are constructed by solving two energy maximisation
problems via dynamic programming. While in the first pass, action paths
spanning the whole video are built by linking detection boxes over time using
their class-specific scores and their spatial overlap, in the second pass,
temporal trimming is performed by ensuring label consistency for all
constituting detection boxes. We demonstrate the performance of our algorithm
on the challenging UCF101, J-HMDB-21 and LIRIS-HARL datasets, achieving new
state-of-the-art results across the board and significantly increasing
detection speed at test time. We achieve a huge leap forward in action
detection performance and report a 20% and 11% gain in mAP (mean average
precision) on UCF-101 and J-HMDB-21 datasets respectively when compared to the
state-of-the-art.Comment: Accepted by British Machine Vision Conference 201
Registration of retinal images from Public Health by minimising an error between vessels using an affine model with radial distortions
In order to estimate a registration model of eye fundus images made of an
affinity and two radial distortions, we introduce an estimation criterion based
on an error between the vessels. In [1], we estimated this model by minimising
the error between characteristics points. In this paper, the detected vessels
are selected using the circle and ellipse equations of the overlap area
boundaries deduced from our model. Our method successfully registers 96 % of
the 271 pairs in a Public Health dataset acquired mostly with different
cameras. This is better than our previous method [1] and better than three
other state-of-the-art methods. On a publicly available dataset, ours still
better register the images than the reference method
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