In this paper, we address the problem of camera pose estimation using 2D and 3D line features, also known as PnL (Perspective-n-Line) with a known vertical direction. The minimal number of line correspondences required to estimate the complete camera pose is 3 (P3L) in the general case, yielding to a minimum of 8 possible solutions. Prior knowledge of the vertical direction, such as provided by common sensors (e.g. Inertial Measurement Unit, or IMU), reduces the problem to a 4 Degree of Freedom (DoF) problem and outputs a single solution. We benefit this fact to decouple the remaining rotation estimation and the translation estimation and we present a twofold contribution: (1) we present a linear formulation of the PnL problem in Plücker lines coordinates with a known vertical direction, including a Gauss-Newton-based orientation and location refinement to compensate IMU sensor noise. (2) we propose a new efficient RANdom SAmple Consensus (RANSAC) scheme for both feature pairing and outliers rejection based solely on rotation estimation from 2 line pairs. This greatly diminishes the computational cost compared to a RANSAC3 or RANSAC4 scheme. We evaluate our algorithms on synthetic data and on our own real dataset. Experimental results show state of the art results in term of accuracy and runtime, when facing 2D noise, 3D noise and vertical direction sensor noise. Index Terms-Computer Vision for Other Robotic Applications, Sensor Fusion, Localization I. INTRODUCTION Camera pose estimation consists in determining the position and the orientation of a camera with respect to a reference frame. This process requires known correspondences between real world features and their projection onto the image plane. When these features are points, we refer to the well-studied Perspective-n-Point (PnP) problem [1] [2] [3] [4] [5]. In the case of line features, we are facing the challenging, more recent and less studied Perspective-n-Line (PnL) problem. A recent review of the latter methods is presented in [6]. Once the 2D and 3D lines extraction process is completed, feature pairing is not a simple task: lines lack effective descriptors, and descriptor-based pose estimation methods are computationally more expensive.