In this paper, we present a monocular direct semi-dense SLAM (Simultaneous Localization And Mapping) method that can handle both radial distortion and rolling-shutter distortion. Such distortions are common in, but not restricted to, situations when an inexpensive wide-angle lens and a CMOS sensor are used, and leads to significant inaccuracy in the map and trajectory estimates if not modeled correctly. The apparent naive solution of simply undistorting the images using pre-calibrated parameters does not apply to this case since rows in the undistorted image are no longer captured at the same time. To address this we develop an algorithm that incorporates radial distortion into an existing state-of-the-art direct semi-dense SLAM system that takes rolling-shutters into account. We propose a method for finding the generalized epipolar curve for each rolling-shutter radially distorted image. Our experiments demonstrate the efficacy of our approach and compare it favorably with the state-of-the-art in direct semi-dense rolling-shutter SLAM.

In this paper, we present a monocular Direct and Semi-dense SLAM (Simultaneous Localization And Mapping) system for rolling shutter cameras. In a rolling shutter camera, the pose is different for each row of each image, and this yields poor pose estimates and poor structure estimates when using a state-of-the-art semi-dense direct method designed for global shutter cameras. To address this issue in tracking, we model the smooth and continuous camera trajectory using a B-spline curve of degree k??1 for poses in the Lie algebra, se(3).We solve for the camera poses at each row-time by a direct optimisation of photometric error as a function of the control points of the spline. Likewise for mapping, we develop generalised epipolar geometry for the rolling shutter case and solve for point depths using photometric error. Although each of these issues has been previously tackled, to the best of our knowledge ours is the first full solution to monocular, direct (feature-less) SLAM. We benchmark our method for pose accuracy and map accuracy against the state-of-the-art semi-dense SLAM system, LSD-SLAM, demonstrating the improved efficacy of our approach when using rolling shutter cameras via synthetic sequences with known ground-truth and real sequences.

We propose a new approach for template-based extensible surface reconstruction from a single view. We extend the method of isometric surface reconstruction and more recent work on conformal surface reconstruction. Our approach relies on the minimization of a proposed stretching energy formalized with respect to the Poisson ratio parameter of the surface. We derive a patch-based formulation of this stretching energy by assuming local linear elasticity. This formulation unifies geometrical and mechanical constraints in a single energy term. We prevent local scale ambiguities by imposing a set of fixed boundary 3D points. We experimentally prove the sufficiency of this set of boundary points and demonstrate the effectiveness of our approach on different developable and non-developable surfaces with a wide range of extensibility.

We present a new multi-view 3D Euclidean reconstruction method for arbitrary uncalibrated radially-symmetric cameras, which needs no calibration or any camera model parameters other than radial symmetry. It is built on the radial 1D camera model [25], a unified mathematical abstraction to different types of radially-symmetric cameras. We formulate the problem of multi-view reconstruction for radial 1D cameras as a matrix rank minimization problem. Efficient implementation based on alternating direction continuation is proposed to handle scalability issue for real-world applications. Our method applies to a wide range of omni directional cameras including both dioptric and catadioptric (central and non-central) cameras. Additionally, our method deals with complete and incomplete measurements under a unified framework elegantly. Experiments on both synthetic and real images from various types of cameras validate the superior performance of our new method, in terms of numerical accuracy and robustness.

We investigate the problem of estimating the ego-motion of a multicamera rig from two positions of the rig. We describe and compare two new algorithms for finding the 6 degrees of freedom (3 for rotation and 3 for translation) of the motion. One algorithm gives a linear solution and the other is a geometric algorithm that minimizes the maximum measurement error-the optimal L{infinity} solution. They are described in the context of the General Camera Model (GCM), and we pay particular attention to multicamera systems in which the cameras have nonoverlapping or minimally overlapping field of view. Many nonlinear algorithms have been developed to solve the multicamera motion estimation problem. However, no linear solution or guaranteed optimal geometric solution has previously been proposed. We made two contributions: 1) a fast linear algebraic method using the GCM and 2) a guaranteed globally optimal algorithm based on the L{infinity} geometric error using the branch-and-bound technique. In deriving the linear method using the GCM, we give a detailed analysis of degeneracy of camera configurations. In finding the globally optimal solution, we apply a rotation space search technique recently proposed by Hartley and Kahl. Our experiments conducted on both synthetic and real data have shown excellent results.

We present a motion estimation algorithm for multi-camera systems consisting of more than one calibrated camera securely attached on a moving object. So, they move all together, but do not require to have overlapping views across the cameras. The geometrically optimal solution of the motion for the multi-camera systems under Linfinnorm is provided in this paper using a global optimization technique which has been introduced recently in the computer vision research field. Taking advantage of an optimal estimate of the essential matrix through searching rotation space, we provide the optimal solution for translation by using linear programming and branch & bound algorithm. Synthetic and real data experiments are conducted, and they show more robust and improved performance than the previous methods.

A well-known theoretical result for motion estimation using the generalized camera model is that 17 corresponding image rays can be used to solve linearly for the motion of a generalized camera. However, this paper shows that for many common configurations of the generalized camera models (e.g., multi-camera rig, catadioptric camera etc.), such a simple 17-point algorithm does not exist, due to some previously overlooked ambiguities. We further discover that, despite the above ambiguities, we are still able to solve the motion estimation problem effectively by a new algorithm proposed in this paper. Our algorithm is essentially linear, easy to implement, and the computational efficiency is very high. Experiments on both real and simulated data show that the new algorithm achieves reasonably high accuracy as well.

This paper introduces a novel, robust approach for 6DOF motion estimation of a multi-camera system with non-overlapping views. The proposed approach is able to solve the pose estimation, including scale, for a two camera system with non-overlapping views. In contrast to previous approaches, it degrades gracefully if the motion is close to degenerate. For degenerate motions the technique estimates the remaining 5DOF. The proposed technique is evaluated on real and synthetic sequences.