Journal cover Journal topic
Geoscientific Instrumentation, Methods and Data Systems An interactive open-access journal of the European Geosciences Union
Geosci. Instrum. Method. Data Syst., 4, 23-34, 2015
© Author(s) 2015. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
11 Feb 2015
Image georectification and feature tracking toolbox: ImGRAFT
A. Messerli1,2 and A. Grinsted1 1Centre for Ice and Climate, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark
2Section for Glaciers, Snow and Ice, Hydrology Department, Norwegian Water Resources and Energy Directorate, P.O. Box 5091 Majorstua, 0301 Oslo, Norway
Abstract. The use of time-lapse camera systems is becoming an increasingly popular method for data acquisition. The camera setup is often cost-effective and simple, allowing for a large amount of data to be accumulated over a variety of environments for relatively minimal effort. The acquired data can, with the correct post-processing, result in a wide range of useful quantitative and qualitative information in remote and dangerous areas. The post-processing requires a significant amount of steps to transform images into meaningful data for quantitative analysis, such as velocity fields. To the best of our knowledge at present a complete, openly available package that encompasses georeferencing, georectification and feature tracking of terrestrial, oblique images is still absent. This study presents a complete, yet adaptable, open-source package developed in MATLAB, that addresses and combines each of these post-processing steps into one complete suite in the form of an "Image GeoRectification and Feature Tracking" (ImGRAFT: toolbox. The toolbox can also independently produce other useful outputs, such as viewsheds, georectified and orthorectified images. ImGRAFT is primarily focused on terrestrial oblique images, for which there are currently limited post-processing options available. In this study, we illustrate ImGRAFT for glaciological applications on a small outlet glacier Engabreen, Norway.

Citation: Messerli, A. and Grinsted, A.: Image georectification and feature tracking toolbox: ImGRAFT, Geosci. Instrum. Method. Data Syst., 4, 23-34, doi:10.5194/gi-4-23-2015, 2015.
Publications Copernicus
Short summary
The use of time-lapse cameras is becoming an ever more popular method of observing changes in the natural environment. This study provides an overview of the newly developed Image GeoRectification And Feature Tracking toolbox (ImGRAFT). The paper outlines the main function of the toolbox and describes each of the key processes needed to transform a pair of terrestrial time-lapse images into a velocity field. The tool is presented using a case study of glacier surface motion at Engabreen, Norway.
The use of time-lapse cameras is becoming an ever more popular method of observing changes in...