Geomatics Applications to Contemporary Social and Environmental Problems in Mexico

Trends in geospatial technologies have led to the development of new powerful analysis and representation techniques that involve processing of massive datasets, some unstructured, some acquired from ubiquitous sources, and some others from remotely located sensors of different kinds, all of which complement the structured information produced on a regular basis by governmental and international agencies. In this chapter, we provide both an extensive revision of such techniques and an insight of the applications of some of these techniques in various study cases in Mexico for various scales of analysis: from regional migration flows of highly qualified people at the country level and the spatio-temporal analysis of unstructured information in geotagged tweets for sentiment assessment, to more local applications of participatory cartography for policy definitions jointly between local authorities and citizens, and an automated method for three dimensional (3D) modelling and visualisation of forest inventorying with laser scanner technology

Optic Flow Estimation using the Hermite Transform

In this paper we present a spatiotemporal energy based method to estimate movement from an image sequence. A directional energy is defined in terms of the Radon projections of the Hermite transform. Radon transform provides a suitable representation for image orientation analysis, while Hermite transform describes image features locally in term of Gaussian derivatives. These operators have been used in computer vision for feature extraction and are relevant in visual system modeling. A directional response defined from the directional energy is used to estimate local motion as well as to compute a confidence matrix. This matrix provides a confidence measure for our estimate and it is used to propagate the velocity information toward directions with high uncertainty. With this results, there can be applications ranging from motion compensation, and tracking of moving objects, to segmentation and video compression