Application of open-source photogrammetric software MicMac for monitoring surface deformation in laboratory models

Quantifying deformation is essential inmodern laboratorymodels of geological systems. This paper presents a new laboratory monitoring method through the implementation of the open-source software MicMac, which efficiently implements photogrammetry in Structure-from-Motion algorithms. Critical evaluation is provided using results from two example laboratory geodesy scenarios: magma emplacement and strike-slip faulting. MicMac automatically processes images fromsynchronized cameras to compute time series of digital elevation models (DEMs) and orthorectified images of model surfaces. MicMac also implements digital image correlation to produce high-resolution displacements maps. The resolution of DEMs and displacement maps corresponds to the pixel size of the processed images. Using 24 MP cameras, the precision of DEMs and displacements is similar to 0.05mm on a 40 x 40 cm surface. Processing displacement maps with Matlab (R) scripts allows automatic fracturemapping on themonitored surfaces. MicMac also offers the possibility to integrate 3-Dmodels of excavated structures with the corresponding surface deformation data. The high resolution and high precision of MicMac results and the ability to generate virtual 3-D models of complex structures make it a very promising tool for quantitative monitoring in laboratory models of geological systems.