5,999 research outputs found
Calipso: Physics-based Image and Video Editing through CAD Model Proxies
We present Calipso, an interactive method for editing images and videos in a
physically-coherent manner. Our main idea is to realize physics-based
manipulations by running a full physics simulation on proxy geometries given by
non-rigidly aligned CAD models. Running these simulations allows us to apply
new, unseen forces to move or deform selected objects, change physical
parameters such as mass or elasticity, or even add entire new objects that
interact with the rest of the underlying scene. In Calipso, the user makes
edits directly in 3D; these edits are processed by the simulation and then
transfered to the target 2D content using shape-to-image correspondences in a
photo-realistic rendering process. To align the CAD models, we introduce an
efficient CAD-to-image alignment procedure that jointly minimizes for rigid and
non-rigid alignment while preserving the high-level structure of the input
shape. Moreover, the user can choose to exploit image flow to estimate scene
motion, producing coherent physical behavior with ambient dynamics. We
demonstrate Calipso's physics-based editing on a wide range of examples
producing myriad physical behavior while preserving geometric and visual
consistency.Comment: 11 page
Geometric robustness of deep networks: analysis and improvement
Deep convolutional neural networks have been shown to be vulnerable to
arbitrary geometric transformations. However, there is no systematic method to
measure the invariance properties of deep networks to such transformations. We
propose ManiFool as a simple yet scalable algorithm to measure the invariance
of deep networks. In particular, our algorithm measures the robustness of deep
networks to geometric transformations in a worst-case regime as they can be
problematic for sensitive applications. Our extensive experimental results show
that ManiFool can be used to measure the invariance of fairly complex networks
on high dimensional datasets and these values can be used for analyzing the
reasons for it. Furthermore, we build on Manifool to propose a new adversarial
training scheme and we show its effectiveness on improving the invariance
properties of deep neural networks
Sufficient dimension reduction based on an ensemble of minimum average variance estimators
We introduce a class of dimension reduction estimators based on an ensemble
of the minimum average variance estimates of functions that characterize the
central subspace, such as the characteristic functions, the Box--Cox
transformations and wavelet basis. The ensemble estimators exhaustively
estimate the central subspace without imposing restrictive conditions on the
predictors, and have the same convergence rate as the minimum average variance
estimates. They are flexible and easy to implement, and allow repeated use of
the available sample, which enhances accuracy. They are applicable to both
univariate and multivariate responses in a unified form. We establish the
consistency and convergence rate of these estimators, and the consistency of a
cross validation criterion for order determination. We compare the ensemble
estimators with other estimators in a wide variety of models, and establish
their competent performance.Comment: Published in at http://dx.doi.org/10.1214/11-AOS950 the Annals of
Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical
Statistics (http://www.imstat.org
Motion from "X" by Compensating "Y"
This paper analyzes the geometry of the visual motion estimation problem in relation to transformations of the input (images) that stabilize particular output functions such as the motion of a point, a line and a plane in the image. By casting the problem within the popular "epipolar geometry", we provide a common framework for including constraints such as point, line of plane fixation by just considering "slices" of the parameter manifold. The models we provide can be used for estimating motion from a batch using the preferred optimization techniques, or for defining dynamic filters that estimate motion from a causal sequence. We discuss methods for performing the necessary compensation by either controlling the support of the camera or by pre-processing the images. The compensation algorithms may be used also for recursively fitting a plane in 3-D both from point-features or directly from brightness. Conversely, they may be used for estimating motion relative to the plane independent of its parameters
Real-time model-based video stabilization for microaerial vehicles
The emerging branch of micro aerial vehicles (MAVs) has attracted a great interest for their indoor navigation capabilities, but they require a high quality video for tele-operated or autonomous tasks. A common problem of on-board video quality is the effect of undesired movements, so different approaches solve it with both mechanical stabilizers or video stabilizer software. Very few video stabilizer algorithms in the literature can be applied in real-time but they do not discriminate at all between intentional movements of the tele-operator and undesired ones. In this paper, a novel technique is introduced for real-time video stabilization with low computational cost, without generating false movements or decreasing the performance of the stabilized video sequence. Our proposal uses a combination of geometric transformations and outliers rejection to obtain a robust inter-frame motion estimation, and a Kalman filter based on an ANN learned model of the MAV that includes the control action for motion intention estimation.Peer ReviewedPostprint (author's final draft
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