Publications de Christoph Strecha

A new method to determine multi-angular reflectance factor from lightweight multispectral cameras with sky sensor in a target-less workflow applicable to UAV

Dai Shi, Christoph Strecha, Manuel Simon Paul Cubero-Castan

A new physically based method to estimate hemispheric-directional reflectance factor (HDRF) from lightweight multispectral cameras that have a downwelling irradiance sensor is presented. It combines radiometry wilh photogrammetric computer vision to derive ...

ELSEVIER SCIENCE INC2019

BRIEF: Computing a Local Binary Descriptor Very Fast

Pascal Fua, Vincent Lepetit, Mustafa Özuysal, Michael Calonder, Christoph Strecha, Tomasz Piotr Trzcinski

Binary descriptors are becoming increasingly popular as a means to compare feature points very fast and while requiring comparatively small amounts of memory. The typical approach to creating them is to first compute floating-point ones, using an algorithm ...

Institute of Electrical and Electronics Engineers2012

LDAHash: Improved Matching with Smaller Descriptors

Pascal Fua, Christoph Strecha

SIFT-like local feature descriptors are ubiquitously employed in computer vision applications such as content-based retrieval, video analysis, copy detection, object recognition, photo tourism, and 3D reconstruction. Feature descriptors can be designed to ...

Institute of Electrical and Electronics Engineers2012

Pose estimation of landscape images using DEM and orthophotos

François Golay, Devis Tuia, Timothée Produit, Christoph Strecha

In this paper, we propose a methodology for the estimation of the pose of oblique landscape images. Knowledge about the pose is needed for using such images in augmented reality applications or to allow projection of pixels in a GIS for spatial analysis. W ...

2012

Efficient Large Scale Multi-View Stereo for Ultra High Resolution Image Sets

Pascal Fua, Engin Tola, Christoph Strecha

We present a new approach for large scale multi-view stereo matching, which is designed to operate on ultra high resolution image sets and efficiently compute dense 3D point clouds. We show that, by using a robust descriptor for matching purposes and high ...

Springer Verlag2012

The Accuracy of Automatic Photogrammetric Techniques on Ultra-light UAV Imagery

Jean-Christophe Zufferey, François Gervaix, Dario Floreano, Pascal Fua, Antoine Beyeler, Olivier Küng, Christoph Strecha

This paper presents an affordable, fully automated and accurate mapping solutions based on ultra-light UAV imagery. Several datasets are analysed and their accuracy is estimated. We show that the accuracy highly depends on the ground resolution (flying hei ...

2011

PHOTOGRAMMETRIC PERFORMANCE OF AN ULTRA LIGHT WEIGHT SWINGLET UAV

Julien Vallet, Christoph Strecha

2011

Dynamic and Scalable Large Scale Image Reconstruction

Pascal Fua, Christoph Strecha

Recent approaches to reconstructing city-sized areas from large image collections usually process them all at once and only produce disconnected descriptions of image subsets, which typically correspond to major landmarks. In contrast, we propose a framewo ...

2010

Large occlusion completion using normal maps

Pascal Fua, Andrea Fossati, Engin Tola, Christoph Strecha

Dense disparity maps can be computed from wide-baseline stereo pairs but will inevitably contain large areas where the depth cannot be estimated accurately because the pixels are seen in one view only. A traditional approach to this problem is to introduce ...

2010

Surface Construction by a 2-D Differentiation-Integration Process: A Neurocomputational Model for Perceived Border Ownership, Depth, and Lightness in Kanizsa Figures

Christoph Strecha

Human visual perception is a fundamentally relational process: Lightness perception depends on luminance ratios, and depth perception depends on occlusion (difference of depth) cues. Neurons in low-level visual cortex are sensitive to the difference (but n ...

2010

BRIEF: Binary Robust Independent Elementary Features

Pascal Fua, Vincent Lepetit, Michael Calonder, Christoph Strecha

We propose to use binary strings as an efficient feature point descriptor, which we call BRIEF. We show that it is highly discriminative even when using relatively few bits and can be computed using simple intensity difference tests. Furthermore, the descr ...

Springer-Verlag New York, Ms Ingrid Cunningham, 175 Fifth Ave, New York, Ny 10010 Usa2010

Making Background Subtraction Robust to Sudden Illumination Changes

Pascal Fua, Julien Pilet, Christoph Strecha

Modern background subtraction techniques can handle gradual illumination changes but can easily be confused by rapid ones. We propose a technique that overcomes this limitation by relying on a statistical model, not of the pixel intensities, but of the ill ...

Springer-Verlag New York, Ms Ingrid Cunningham, 175 Fifth Ave, New York, Ny 10010 Usa2008

A Generative Model for True Orthorectification

Pascal Fua, Christoph Strecha

Orthographic images compose an efficient and economic way to represent aerial images. This kind of information allows to measure two-dimensional objects and relate these to Geographic Information Systems. This paper deals with the computation of a true ort ...

2008

On Benchmarking Camera Calibration and Multi-View Stereo for High Resolution Imagery

Pascal Fua, Christoph Strecha

In this paper we want to start the discussion on whether image based 3-D modelling techniques can possibly be used to replace LIDAR systems for outdoor 3D data acquisition. Two main issues have to be addressed in this context: (i) camera calibration (inter ...

2008

IA Generative Model for True Orthorectification

Pascal Fua, Christoph Strecha

Orthographic images compose an efficient and economic way to represent aerial images. This kind of information allows to measure two-dimensional objects and relate these to Geographic Information Systems. This paper deals with the computation of a true ort ...

2008