# Gravillons tutorial

• You can find this dataset at :http://logiciels.ign.fr/?Telechargement,20
Datasets are available at the bottom of the page, in part test datasets. Then, UnZip the ".zip" archive.
• There is also a direct link to download it in zip format here : http://micmac.ensg.eu/data/gravillons_dataset.zip

## Presentation

This dataset was created by L.Girod at the University of Oslo, Norway. This dataset was acquired to model a volcano model created by O.Galland. File present in the directory are :

• 4 images : 1.JPG, 2.JPG, 3.JPG, 4.JPG.
• GCPs coordinates : Dico-Appuis.xml.
• Mesure of GCPs in images : Mesure-Appuis.xml.
• 2 commands scripts : gravillons.sh (Linux) et gravillons.bat (Windows)

During this tutorial, we will approach general concepts, for more details, go further in tutorials or directly in commands pages.

## Tutorial

### 1 Tie-Points search

The first step of each MicMac pipline is to look for tie points (points that are seen in more than one image), this step is call image matching and performed by the command Tapioca :

mm3d Tapioca All ".*.JPG" 1500

The All option is used here because we know that all the images are going to have tie points with each other (they all depict the same area).