Category: Publications

MRPT-related papers

What’s this?
This is a repository of scientific papers whose experimental results were carried out using the MRPT library and tools. Along with each paper, you’ll also find the corresponding datasets, the source code used for the experiments and/or instructions/scripts to reproduce the results.
If you want to add a paper to this list, just contact us and we’ll include it.

See also: direct search in Google Scholar for publications mentioning MRPT.

Posted in Publications

TechRep: A tutorial on SE(3) transformation parameterizations and on-manifold optimization

“A tutorial on SE(3) transformation parameterizations and on-manifold optimization”J.L. Blanco, Technical report, 2010. (PDFBibtex). Updated: 14/AUG/2012.
Abstract: An arbitrary rigid transformation in SE(3) can be separated into two parts, namely, a translation and a rigid rotation. This technical report reviews, under a unifying viewpoint, three common alternatives to representing the rotation part: sets of three (yaw-pitch-roll) Euler angles, orthogonal rotation matrices from SO(3) and quaternions. It will be described: (i) the equivalence between these representations and the formulas for transforming one to each other (in all cases considering the translational and rotational parts as a whole), (ii) how to compose poses in each representation and (iii) how the uncertainty of the poses (when modeled as Gaussian distributions) is affected by these transformations and compositions. Some brief notes are also given about the Jacobians required to implement least-squares optimization on manifolds, an very promising approach in recent SLAM literature. The text reflects which MRPT C++ library functions implement each of the described algorithms. All the implementations have been thoroughly validated by means of unit testing. read more

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SLAM Book (2012)

Title: Simultaneous Localization and Mapping for Mobile Robots: Introduction and Methods
Authors: Fernández-Madrigal, J.A. and Blanco, J.L.
Release date: 2012
ISBN: 978-1466621046
Pages: 497


Available in:

Description As mobile robots become more common in general knowledge and practices, as opposed to simply in research labs, there is an increased need for the introduction and methods to Simultaneous Localization and Mapping (SLAM) and its techniques and concepts related to robotics. =&2=& investigates the complexities of the theory of probabilistic localization and mapping of mobile robots as well as providing the most current and concrete developments. This reference source aims to be useful for practitioners, graduate and postgraduate students, and active researchers alike.

Erratum (last update: Feb 2017)

Errata location Says… Should say…
Page 200, eq. (20) Remove all four minus signs.

Summary of contents

Part I: The Foundations of Mobile Robot Localization and Mapping

CHAPTER 1: Introduction

CHAPTER 2: Robotic Bases

CHAPTER 3: Probabilistic Bases

CHAPTER 4: Statistical Bases

Part II: Mobile Robot Localization

CHAPTER 5: Robot Motion Models

CHAPTER 6: Sensor Models

CHAPTER 7: Mobile Robot Localization with Recursive Bayesian Filters read more

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Paper: J.L. Blanco’s Phd Thesis

Contributions to Localization, Mapping and Navigation in Mobile RoboticsPhD Thesis, Jose-Luis Blanco-Claraco, November 13th, 2009.
Downloads: PDF (12.6Mb) – Citation (Bibtex) – Slides (17.5 Mb) – Slides+videos (196 Mb)
Abstract: This thesis focuses on the problem of enabling mobile robots to autonomously build world models of their environments and to employ them as a reference to self–localization and navigation. For mobile robots to become truly autonomous and useful, they must be able of reliably moving towards the locations required by their tasks. This simple requirement gives raise to a myriad of problems that has populated research in the mobile robotics community for decades. Among these issues, two of the most relevant are: (i) secure autonomous navigation while avoiding collisions and (ii) the employment of an adequate world model for robot self-referencing within the environment and also for locating places of interest. In spite of presenting contributions regarding mobile robot navigation, the main focus of this thesis is on the latter problem, usually referred to as Simultaneous Localization and Mapping (SLAM). One of the most interesting contributions of this thesis is a novel approach to extend SLAM to large-scale scenarios by means of a seamless integration of geometric and topological map building in a probabilistic framework that estimates the hybrid metric-topological (HMT) state space of the robot path. The proposed framework unifies in an elegant manner the research areas of topological mapping, reasoning on topological maps and metric SLAM, providing also a natural integration of SLAM and the “robot awakening” problem. Other contributions presented in this thesis cover a wide variety of topics, such as optimal estimation in particle filters, a new probabilistic observation model for laser scanners based on consensus theory, a novel measure of the uncertainty in grid mapping, an efficient method for range-only SLAM, a grounded method for partitioning large maps into submaps, a multi-hypotheses approach to grid map matching, and a mathematical framework for extending simple obstacle avoidance methods to realistic robots.
PhD Awards: read more

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An alternative to the Mahalanobis distance for determining optimal correspondences in data association

“An alternative to the Mahalanobis distance for determining optimal correspondences in data association”. J.L. Blanco, J. Gonzalez-Jimenez, J.A. Fernandez-Madrigal. IEEE Transactions on Robotics (T-RO), vol. 28, no.4, 980-986, 2012. (BibtexDraft PDF)

DOI: 10.1109/TRO.2012.2193706

Abstract: The most common criteria for determining data association rely on minimizing the squared Mahalanobis distance (SMD) between observations and predictions. We hold that the SMD is just a heuristic, while the alternative matching likelihood (ML) is the optimal statistic to be maximized. Thorough experiments undoubtedly confirm this idea, with false positive reductions of up to 16%. read more

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6 DoF SLAM using a ToF Camera: The challenge of a continuously growing number of landmarks

“6 DoF SLAM using a ToF Camera: The challenge of a continuously growing number of landmarks”Siegfried Hochdorfer, Christian Schlegel, IROS 2010 – (Link).

Authors are with the Collaborative Center for Applied Research (, Ulm, Germany.

Online video with results from this paper:

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Optimal Filtering for Non-Parametric Observation Models: Applications to Localization and SLAM

“An Optimal Filtering Algorithm for Non-Parametric Observation Models in Robot Localization”ICRA 2008, Pasadena (California, USA), May 19-23, 2008. (PDF) – (Slides)

Abstract: The lack of a parameterized observation model in robot localization using occupancy grids requires the application of sampling-based methods, or particle filters. This work addresses the problem of optimal Bayesian filtering for dynamic systems with observation models that cannot be approximated properly as any parameterized distribution, which includes localization and SLAM with occupancy grids. By integrating ideas from previous works on adaptive sample size, auxiliary particle filters, and rejection sampling, we derive a new particle filter algorithm that enables the usage of the optimal proposal distribution to estimate the true posterior density of a non-parametric dynamic system. Our solution avoids approximations adopted in previous approaches at the cost of a higher computational burden. We present simulations and experimental results for a real robot showing the suitability of the method for localization. read more

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Paper:UWB Particle Filter Localization

“Mobile Robot Localization based on Ultra-Wide-Band Ranging: A Particle Filter Approach”Robotics and Autonomous Systems (2009) 

(BibtexPDF, DOI: 10.1016/j.robot.2008.10.022)

Abstract: This article addresses the problem of mobile robot localization using Ultra-Wide-Band (UWB) range measurements. UWB is a radio technology widely used for communications that recently is receiving increasing attention also for positioning applications. In these cases, the position of a mobile transceiver is determined from the distances to a set of fixed, well-localized beacons. Though this is a well-known problem in the scientific literature (the trilateration problem), the peculiarities of UWB range measurements (basically, distance errors and multipath effects) demand a different treatment to other similar solutions as for example those based on laser. This work presents a thorough experimental characterization of UWB ranges within a variety of environments and situations. From these experiments we derive a probabilistic model which is then employed by a particle filter to combine different readings from real UWB beacons as well as the vehicle odometry. To account for the possible offset error due to multipath effects, the state tracked by the particle filter includes the offset of each beacon in addition to the planar robot pose (x,y,φ), both estimated sequentially. We show real experimental results for a robot moving in indoor scenarios covered by three UWB beacons that validate our proposal . read more

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Paper: Stereo Vision Models for RBPF SLAM

“Stereo vision-specific models for Particle Filter-based SLAM”Robotic and Autonomous Systems – PDF.

Abstract:This work addresses the SLAM problem for stereo vision systems under the unified formulation of particle filter methods. In contrast to most existing approaches to visual SLAM, the present method does not rely on restrictive smooth camera motion models, but on computing incremental 6D pose differences from the image flow through a probabilistic visual odometry method. Moreover, our observation model, which considers both the 3D positions and the SIFT descriptors of the landmarks, avoids explicit data association between the observations and the map by marginalizing the observation likelihood over all the possible associations. We have experimentally validated our research with two experiments in indoor scenarios. read more

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Paper: RO-SLAM with SOG

“Efficient Probabilistic Range-Only SLAM”, IROS 2008 – PDF – Slides PPT
Abstract: This work addresses Range-Only SLAM (RO-SLAM) as the Bayesian inference problem of sequentially tracking a vehicle while estimating the location of a set of beacons without any prior information. The only assumptions are the availability of odometry and a range sensor able of identifying the different beacons. We propose exploiting the conditional independence between each beacon distribution within a Rao-Blackwellized Particle Filter (RBPF) for maintaining independent Sum of Gaussians (SOGs) for each map element. It is shown then that a proper probabilistic observation model can be derived for online operation with no need for delayed initializations. We provide a rigorous statistical comparison of this proposal with previous work of the authors where a Monte-Carlo approximation was employed instead for the conditional densities. As verified experimentally, this new proposal represents a significant improvement in accuracy, computation time, and robustness against outliers. read more

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Paper: Subjective Local Maps for Hybrid Metric-Topological SLAM

Subjective Local Maps for Hybrid Metric-Topological SLAMRobotics and Autonomous Systems, 2009 – (PDF).

Abstract: Hybrid maps where local metric sub-maps are kept in the nodes of a graph-based topological structure are gaining relevance as the focus of robot Simultaneous Localization and Mapping (SLAM) shifts towards spatial scalability and long-term operation. In this paper we examine the applicability of spectral graph partitioning techniques to automatically generate metric sub-maps by establishing groups in the sequence of observations gathered by the robot. One of the main aims of this work is to provide a probabilistically grounded interpretation of such a partitioning technique in the context of generating these local maps. We also discuss how to apply it to different kinds of sensory data (stereo images and laser range scans) and how to consider them simultaneously. An important feature of our approach is that it implicitly takes into account the intrinsic characteristics of the sensors, such as the sensor field of view, to perform the partitioning instead of applying heuristics supplied by a human as in other works, and thus the robot builds “subjective” local maps. The ideas presented here are supported by experimental results from a real mobile robot as well as simulations for statistical analysis. We discuss the effects of considering different combinations of sensors in the resulting clustering of the environment. read more

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Paper: Occupancy Grid Matching

Paper: J.L. Blanco, J. Gonzalez-Jimenez, J.A. Fernandez-Madrigal, “A Robust, Multi-Hypothesis Approach to Matching Occupancy Grid Maps”, Robotica, 2013 (DOI, draft PDF).

Abstract:This article presents a new approach to matching occupancy grid maps by means of finding correspondences between a set of sparse features detected in the maps. The problem is stated here as a special instance of generic image registration. To cope with the uncertainty and ambiguity that arise from matching grid maps, we introduce a modified RANSAC algorithm which searches for a dynamic number of internally consistent subsets of feature pairings from which to compute hypotheses about the translation and rotation between the maps. By providing a (possibly multi-modal) probability distribution of the relative pose of the maps, our method can be seamlessly integrated into large-scale mapping frameworks for mobile robots. This article provides a benchmarking of different detectors and descriptors, along extensive experimental results that illustrate the robustness of the algorithm with a 97% success ratio in loop-closure detection for ~1700 matchings between local maps obtained from four publicly available datasets. read more

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Paper: Extending Obstacle Avoidance Methods through Multiple Parameter-Space Transformations

“Extending Obstacle Avoidance Methods through Multiple Parameter-Space Transformations”Jose-Luis Blanco, Javier Gonzalez, and Juan-Antonio Fernandez-Madrigal, Autonomous Robots, 2008 –View article – PDF

Obstacle avoidance methods approach the problem of mobile robot autonomous navigation by steering the robot in real-time according to the most recent sensor readings, being suitable to dynamic or unknown environments. However, real-time performance is commonly gained by ignoring the robot shape and some or all of its kinematic restrictions which may lead to poor navigation performance in many practical situations. In this paper we propose a framework where a kinematically constrained and any-shape robot is transformed in real-time into a free-flying point in a new space where well-known obstacle avoidance methods are applicable. Our contribution with this framework is twofold: the definition of generalized space transformations that cover most of the existing transformational approaches, and a reactive navigation system where multiple transformations can be applied concurrently in order to optimize robot motion decisions. As a result, these transformations allow existing obstacle avoidance methods to perform better detection of the surrounding free-space, through “sampling” the space with paths compatible with the robot kinematics. We illustrate how to design these space transformations with some examples from our experience with real robots.
read more

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Paper: Malaga dataset 2009 with 6D ground truth

A Collection of Outdoor Robotic Datasets with centimeter-accuracy Ground TruthJose-Luis Blanco, Francisco-Angel Moreno, Javier Gonzalez, Autonomous Robots , 2009 – (Draft PDF) – (Official PDF )

Abstract: The lack of publicly accessible datasets with a reliable ground truth has prevented in the past a fair and coherent comparison of different methods proposed in the mobile robot Simultaneous Localization and Mapping (SLAM) literature. Providing such a ground truth renders specially challenging in the case of visual SLAM, where the world model is 3-dimensional and the robot path is 6-dimensional. This work addresses both the practical and theoretical issues found while building a collection of six outdoor datasets. It is discussed how to estimate the 6-d vehicle path from readings of a set of three Real Time Kinematics (RTK) GPS receivers, as well as the associated uncertainty bounds that can be employed to evaluate the performance of Visual SLAM methods. The vehicle was also equipped with several laser scanners, from which reference point clouds are built as a test-bed for other algorithms such as segmentation or surface fitting. All the datasets, calibration information and associated software tools are available for download. read more

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Derivation and Implementation of a Full 6D EKF-based Solution to Range-Bearing SLAM

Technical report: “Derivation and Implementation of a Full 6D EKF-based Solution to Range-Bearing SLAM”Jose-Luis Blanco, Perception and Mobile Robots Research Group, University of Malaga, Spain. (new version with corrected Jacobians, soon!, old version: PDF)
This document describes the theory behind the application kf-slam.

Bibtex info:

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Sparser Relative Bundle Adjustment (SRBA)

NOTICE: Since MRPT 1.3.2 (Oct 2015), SRBA is an independent project outside of the MRPT source tree. See its GitHub repo and page.

1. Theory

Bundle adjustment is the name given to one solution to visual SLAM based on maximum-likelihood estimation (MLE) over the space of map features and camera poses. However, it is by no way limited to visual maps, since the same technique is also applicable to maps of pose constraints (graph-SLAM) or any other kind of feature maps not relying on visual information. read more

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