179 research outputs found
Fitting quadrics with a Bayesian prior
Quadrics are a compact mathematical formulation for a range of primitive surfaces. A problem arises when there are not enough data-points to compute the model but knowledge of the shape is available. This paper presents a method for fitting a quadric with a Bayesian prior. We use a matrix normal prior in order to favour ellipsoids on ambiguous data. The results show the algorithm to cope well when there are few points in the point cloud, competing with contemporary techniques in the area
A Minimalist Approach to Type-Agnostic Detection of Quadrics in Point Clouds
This paper proposes a segmentation-free, automatic and efficient procedure to
detect general geometric quadric forms in point clouds, where clutter and
occlusions are inevitable. Our everyday world is dominated by man-made objects
which are designed using 3D primitives (such as planes, cones, spheres,
cylinders, etc.). These objects are also omnipresent in industrial
environments. This gives rise to the possibility of abstracting 3D scenes
through primitives, thereby positions these geometric forms as an integral part
of perception and high level 3D scene understanding.
As opposed to state-of-the-art, where a tailored algorithm treats each
primitive type separately, we propose to encapsulate all types in a single
robust detection procedure. At the center of our approach lies a closed form 3D
quadric fit, operating in both primal & dual spaces and requiring as low as 4
oriented-points. Around this fit, we design a novel, local null-space voting
strategy to reduce the 4-point case to 3. Voting is coupled with the famous
RANSAC and makes our algorithm orders of magnitude faster than its conventional
counterparts. This is the first method capable of performing a generic
cross-type multi-object primitive detection in difficult scenes. Results on
synthetic and real datasets support the validity of our method.Comment: Accepted for publication at CVPR 201
Generic Primitive Detection in Point Clouds Using Novel Minimal Quadric Fits
We present a novel and effective method for detecting 3D primitives in
cluttered, unorganized point clouds, without axillary segmentation or type
specification. We consider the quadric surfaces for encapsulating the basic
building blocks of our environments - planes, spheres, ellipsoids, cones or
cylinders, in a unified fashion. Moreover, quadrics allow us to model higher
degree of freedom shapes, such as hyperboloids or paraboloids that could be
used in non-rigid settings.
We begin by contributing two novel quadric fits targeting 3D point sets that
are endowed with tangent space information. Based upon the idea of aligning the
quadric gradients with the surface normals, our first formulation is exact and
requires as low as four oriented points. The second fit approximates the first,
and reduces the computational effort. We theoretically analyze these fits with
rigor, and give algebraic and geometric arguments. Next, by re-parameterizing
the solution, we devise a new local Hough voting scheme on the null-space
coefficients that is combined with RANSAC, reducing the complexity from
to (three points). To the best of our knowledge, this is the
first method capable of performing a generic cross-type multi-object primitive
detection in difficult scenes without segmentation. Our extensive qualitative
and quantitative results show that our method is efficient and flexible, as
well as being accurate.Comment: Submitted to IEEE Transactions on Pattern Analysis and Machine
Intelligence (T-PAMI). arXiv admin note: substantial text overlap with
arXiv:1803.0719
Scale Estimation with Dual Quadrics for Monocular Object SLAM
The scale ambiguity problem is inherently unsolvable to monocular SLAM
without the metric baseline between moving cameras. In this paper, we present a
novel scale estimation approach based on an object-level SLAM system. To obtain
the absolute scale of the reconstructed map, we derive a nonlinear optimization
method to make the scaled dimensions of objects conforming to the distribution
of their sizes in the physical world, without relying on any prior information
of gravity direction. We adopt the dual quadric to represent objects for its
ability to fit objects compactly and accurately. In the proposed monocular
object-level SLAM system, dual quadrics are fastly initialized based on
constraints of 2-D detections and fitted oriented bounding box and are further
optimized to provide reliable dimensions for scale estimation.Comment: 8 pages, 6 figures, accepted by IROS202
Towards an Interactive Humanoid Companion with Visual Tracking Modalities
The idea of robots acting as human companions is not a particularly new or original one. Since the notion of “robot ” was created, the idea of robots replacing humans in dangerous, dirty and dull activities has been inseparably tied with the fantasy of human-like robots being friends and existing side by side with humans. In 1989, Engelberger (Engelberger
User-guided free-form asset modelling
In this paper a new system for piecewise primitive surface recovery on point clouds is presented, which allows a novice user to sketch areas of interest in order to guide the fitting process. The algorithm is demonstrated against a benchmark technique for autonomous surface fitting, and, contrasted against existing literature in user guided surface recovery, with empirical evidence. It is concluded that the system is an improvement to the current documented literature for its visual quality when modelling objects which are composed of piecewise primitive shapes, and, in its ability to fill large holes on occluded surfaces using free-form input
Real-Time Hand Tracking Using a Sum of Anisotropic Gaussians Model
Real-time marker-less hand tracking is of increasing importance in
human-computer interaction. Robust and accurate tracking of arbitrary hand
motion is a challenging problem due to the many degrees of freedom, frequent
self-occlusions, fast motions, and uniform skin color. In this paper, we
propose a new approach that tracks the full skeleton motion of the hand from
multiple RGB cameras in real-time. The main contributions include a new
generative tracking method which employs an implicit hand shape representation
based on Sum of Anisotropic Gaussians (SAG), and a pose fitting energy that is
smooth and analytically differentiable making fast gradient based pose
optimization possible. This shape representation, together with a full
perspective projection model, enables more accurate hand modeling than a
related baseline method from literature. Our method achieves better accuracy
than previous methods and runs at 25 fps. We show these improvements both
qualitatively and quantitatively on publicly available datasets.Comment: 8 pages, Accepted version of paper published at 3DV 201
User-guided free-form asset modelling
In this paper a new system for piecewise primitive surface recovery on point
clouds is presented, which allows a novice user to sketch areas of interest in
order to guide the fitting process. The algorithm is demonstrated against a
benchmark technique for autonomous surface fitting, and, contrasted against
existing literature in user guided surface recovery, with empirical evidence.
It is concluded that the system is an improvement to the current documented
literature for its visual quality when modelling objects which are composed of
piecewise primitive shapes, and, in its ability to fill large holes on occluded
surfaces using free-form input
S3LAM: Structured Scene SLAM
International audienceWe propose a new SLAM system that uses the semantic segmentation of objects and structures in the scene. Semantic information is relevant as it contains high level information which may make SLAM more accurate and robust. Our contribution is twofold: i) A new SLAM system based on ORB-SLAM2 that creates a semantic map made of clusters of points corresponding to objects instances and structures in the scene. ii) A modification of the classical Bundle Adjustment formulation to constrain each cluster using geometrical priors, which improves both camera localization and reconstruction and enables a better understanding of the scene. We evaluate our approach on sequences from several public datasets and show that it improves camera pose estimation with respect to state of the art
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