Tutorials

Velocity mapping using Cosi Corr
You can download here (240 Mo) a zip file containing a tutorial about COSI-Corr. A tool to co-register and correlate satellite images.

Brief description :

Precise orthorectification/coregistration of satellite imagery is required for numerous applications in glaciology. In particular, this is a mandatory step to map glacier velocities [Berthier et al., 2005; Kääb, 2005] or to measure changes in the extent of ice-covered areas [Berthier et al., 2009; Paul et al., 2002; Racoviteanu et al., 2009]. COSI-Corr is a free software that is a "plug-in" on ENVI and can achieve precise orthorectification. It was developed by a group in Caltech.

The present tutorial is a case study for Horcones Glacier inferior in the Mont Aconcagua area. A scientific paper including these data is in press in JGR - Earth Surface [Pitte et al., in press]


DEM coregistration
You can download here (78 Mo) a zip file containing a tutorial explaining two methods of DEM coregistration.

Brief description :

The comparison of digital elevation models (DEMs) is getting more and more commonly used to measure glacier elevation changes and, with a proper assumption on the density of the material gained/loss, to estimate the glacier-wide or region-wide mass balance. However, the DEMs (two or more) needs first to be adjusted to account for horizontal/vertical shift between them. It is obvious that the vertical shift will bias the mass balance. Maybe this is less obvious for the horizontal shift. When two DEMs are shifted horizontally, elevation difference are large and clearly related to the aspect (azimuth of the main slope) of the terrain (Nuth and Kääb 2011). Given that glacier generally have a preferred orientation, their elevation changes would be severely biases if extracted readily from those shifted DEM. DEMs needs to be adjusted horizontally and vertically first. Two methods of DEM coregistration are compared in this tutorial (Berthier et al. 2007, Nuth & Kääb, 2011)

The present tutorial is a case study for ASTER DEMs containing the Horcones Glacier inferior in the Mont Aconcagua area. A scientific paper including these data is in press in JGR - Earth Surface [Pitte et al., in press]




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