4th Vietnam School of Earth Observation
Generation of digital elevation models using remote sensing data
September 9-13, 2024, ICISE, Quy Nhon, Vietnam
September 9-13, 2024, ICISE, Quy Nhon, Vietnam
Digital elevation model (DEM) is an important topographic product and essential demand for a wide variety of disciplines and communities including geomorphology (coastal survey, soil sciences), vegetation studies (agriculture, forestry), defense, hydrology, natural hazards (floods, landslides), urban areas, archeology, etc. The third dimension is now accessible from remote sensing. Three techniques are available: image correlation, topographic LiDAR and InSAR.
Image correlation: Photogrammetry has emerged as a key technique for generating DEMs. Several free software packages are available for this purpose, including MicMac, developed by IGN in collaboration with IPGP, CARS from CNES and Ames Stereo Pipeline from NASA, among others. These programs are versatile and adaptable to objects of all scales. They efficiently handle small-scale objects using ground-based acquisition, buildings or soils using drone acquisition, as well as entire cities or natural landscapes using aircraft (e.g., aerial photography) or satellite acquisition (e.g., Pleiades). Additionally, these softwares offer robust georeferencing capabilities, enabling users to anchor their end products in local, global or absolute coordinate systems.
Topographic LiDAR: Recently, airborne Light Detection and Ranging (LiDAR) systems have emerged as a highly efficient tool for generating DTMs. Their main advantage lies in the direct collection of three-dimensional using a laser with wavelengths in the visible, near and shortwave infrared. These systems are particularly well-suited to measuring the topography beneath forest canopies and determining tree heights, by calculating the difference between the altitude of the top of the canopy and the ground level. Airborne LiDARs can also be used to assess the height of urban building. These systems pave the way for the next generation of spaceborne sensors, such as ATLAS on ICESat-2 and GEDI on the International Space Station (ISS), heralding a new era in space data collection.
Interferometric synthetic-aperture radar: InSAR is a powerful tool that exploit the phase difference between two SAR images to build accurate DEMs. For example, the global DTM generated by the Shuttle Radar Topography Mission (SRTM) has been use for many years by the scientific community. Since the launch of the European Sentinel-1 satellites in 2014, SAR data have been freely available on Vietnam, with a temporal repeatability of 12 (or 6) days and a spatial resolution of 10-20 m. Compared with optical data, SAR data are not yet widely used. This is often due to difficulties in processing, analyzing and interpreting the data. The summer school will provide participants with knowledge, methods and free software such as ESA's SNAP to learn or progress in the use of SAR data to generate digital terrain models.
Lectures, tutorials and practical work in the field will be given in English by experts in this domain. They will be complemented by seminars given by Vietnamese researchers on various applications relating to Vietnam. The school is aimed at researchers and data users (students at the end of their master's degree, PhD students, young scientists) interested in the generation or use of digital terrain models acquired by remote sensing (drone, airplane, satellite) in their research and application activities. Applications are open to participants from Vietnam, to a limited number of participants from Southeast Asia and France. Participants will be able to present their own research (short oral presentations and posters). There will be opportunities to establish research collaborations between participants and speakers, and to share ideas and discussions on new research topics.
Chair: Stéphane Jacquemoud (IPGP-UPC, Paris, France)
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