Institute National Of Linformation Geographique Et Forestiere Ign

Le Touquet – Paris-Plage, France

Institute National Of Linformation Geographique Et Forestiere Ign

Le Touquet – Paris-Plage, France

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Moradi A.,CNRS Paris Institute of Global Physics | Metivier L.,Institute National Of Linformation Geographique Et Forestiere Ign | de Viron O.,CNRS Paris Institute of Global Physics | de Viron O.,CNRS Coastal and Marine Environment Laboratory | And 2 more authors.
International Journal of Remote Sensing | Year: 2014

Moderate-Resolution Imaging Spectroradiometer (MODIS) optical and infrared data are used to monitor changes in the Caspian Sea coastline. The information extracted from MODIS images is converted into total water volume and mean lake level by combining a digital elevation model (DEM) with remote-sensing data. The elevation estimates were enhanced by reprocessing the MODIS data at the sub-pixel scale. The water volume variations estimated from MODIS data along with DEM are compared to other estimations derived from altimetry data sets, and show fair agreement. © 2014, © 2014 Taylor & Francis.


Leban J.M.,French National Institute for Agricultural Research | Leban J.M.,Institute National Of Linformation Geographique Et Forestiere Ign | Peiffer M.,French National Institute for Agricultural Research | Bontemps J.-D.,French National Institute for Agricultural Research | And 3 more authors.
Annals of Forest Science | Year: 2016

Annals of Forest Scienceis publishing a series of review papers to celebrate 50 years of activities as a journal in forest and wood science. The reviews emphasize the extent to which forest and wood sciences changed and developed as a large array of disciplines devoted to complex objects with sometimes many conflicting issues. © 2015, INRA and Springer-Verlag France.


Lisein J.,University of Liège | Lisein J.,University Paris Est Creteil | Bonnet S.,University of Liège | Lejeune P.,University of Liège | And 2 more authors.
Revue Francaise de Photogrammetrie et de Teledetection | Year: 2014

Recent development of small unmanned aerial systems opens the door for their use in forest mapping, as both the spatial and temporal resolution of drone imagery better suit local-scale investigation than traditional remote sensing tools. An original photogrammetric workflow, based on the open source toolbox MICMAC, was set up to model the forest canopy surface from low-altitude aerial images. In combination with a LiDAR digital terrain model, the elevation of vegetation was determined after a fine co-registration of the photogrammetric canopy surface model. The investigation of different images matching strategies is performed within MICMAC and their performance in modelling the outer canopy is compared. Although photogrammetric reconstruction do not account for small peaks and gaps in the canopy surface, our results have shown the potential of drones to accurately estimate canopy height in broadleaf stands, confirming thus the feasibility of modeling height growth from UAV images time series.


Ory J.,Institute National Of Linformation Geographique Et Forestiere Ign | Ory J.,University Paris Est Creteil | Christophe S.,Institute National Of Linformation Geographique Et Forestiere Ign | Christophe S.,University Paris Est Creteil | And 3 more authors.
Cartographic Journal | Year: 2015

The process of reading a topographic map requires users to recognize and learn the cartographic symbols of the key (or legend) while interpreting the territory as depicted on the map at a given level of abstraction (the form and nature of features, their saliency and relationships). We present the results of an empirical user study that aims to identify and assess the main graphical characteristics that are used by map users to recognize the design principles which constitute the topographic mapping style adopted by IGN (Institut National de l’Information Gé ographique et Forestière), France. Our results suggest that 91% of the participants were able to recognize an IGN-France topographic map amongst other topographic map products. We also determine which graphical characteristics play a role in the recognition of this cartographic style, either by visual memory or by visual perception, and identify the representation of relief, including contour lines and shaded relief, as one of the major graphical characteristics of the topographic mapping style of IGN-France. Moreover, the participants of our study considered the representation of touristic POI (points of interest), toponymy, typography, the main roads network, the individual buildings and the forests, to be essential for stylistic recognition. © The British Cartographic Society 2015.


Lisein J.,University of Liège | Lisein J.,University Paris Est Creteil | Bonnet S.,University of Liège | Lejeune P.,University of Liège | And 2 more authors.
Revue Francaise de Photogrammetrie et de Teledetection | Year: 2014

Recent development of small unmanned aerial systems opens the door for their use in forest mapping, as both the spatial and temporal resolution of drone imagery better suit local-scale investigation than traditional remote sensing tools. An original photogrammetric workflow, based on the open source toolbox MICMAC, was set up to model the forest canopy surface from low-altitude aerial images. In combination with a LiDAR digital terrain model, the elevation of vegetation was determined after a fine co-registration of the photogrammetric canopy surface model. The investigation of different images matching strategies is performed within MICMAC and their performance in modelling the outer canopy is compared. Although photogrammetric reconstruction do not account for small peaks and gaps in the canopy surface, our results have shown the potential of drones to accurately estimate canopy height in broadleaf stands, confirming thus the feasibility of modeling height growth from UAV images time series.


Willis P.,Institute National Of Linformation Geographique Et Forestiere Ign | Willis P.,CNRS Paris Institute of Global Physics | Bock O.,CNRS Pascal Institute | Bar-Sever Y.E.,Jet Propulsion Laboratory
International Association of Geodesy Symposia | Year: 2014

We reprocessed DORIS for all of 2010, using the latest model and strategy improvements to estimate Zenith Tropospheric Delays (ZTDs), as well as tropospheric horizontal gradients for about 60 ground stations. These results were compared to recent GPS-based estimates obtained at the Jet Propulsion Laboratory (JPL). After discussing some of the data processing options and current limitations of the DORIS data, we showthat the DORIS-GPS comparisons possess a high degree of correlation (average being 0.97), and that total zenith delay estimates from the two techniques agree at the 3 mm level on average with 8.6 mm total RMS, with better results being obtained when a 5° elevation cutoff angle is used for DORIS. While these DORIS results cannot be used for real-time weather prediction, they could contribute to scientific investigations for climatology, thanks to the homogenous tracking network of the DORIS system, as well as the long-term history of the observation time series. © Springer-Verlag Berlin Heidelberg 2014.


Saria E.,Ardhi University | Saria E.,Purdue University | Calais E.,Ecole Normale Superieure de Paris | Altamimi Z.,Institute National Of Linformation Geographique Et Forestiere Ign | And 3 more authors.
Journal of Geophysical Research: Solid Earth | Year: 2013

We analyzed 16 years of GPS and 17 years of Doppler orbitography and radiopositioning integrated by satellite (DORIS) data at continuously operating geodetic sites in Africa and surroundings to describe the present-day kinematics of the Nubian and Somalian plates and constrain relative motions across the East African Rift. The resulting velocity field describes horizontal and vertical motion at 133 GPS sites and 9 DORIS sites. Horizontal velocities at sites located on stable Nubia fit a single plate model with a weighted root mean square residual of 0.6 mm/yr (maximum residual 1 mm/yr), an upper bound for plate-wide motions and for regional-scale deformation in the seismically active southern Africa and Cameroon volcanic line. We confirm significant southward motion (∼ 1.5 mm/yr) in Morocco with respect to Nubia, consistent with earlier findings. We propose an updated angular velocity for the divergence between Nubia and Somalia, which provides the kinematic boundary conditions to rifting in East Africa. We update a plate motion model for the East African Rift and revise the counterclockwise rotation of the Victoria plate and clockwise rotation of the Rovuma plate with respect to Nubia. Vertical velocities range from - 2 to +2 mm/yr, close to their uncertainties, with no clear geographic pattern. This study provides the first continent-wide position/velocity solution for Africa, expressed in International Terrestrial Reference Frame (ITRF2008), a contribution to the upcoming African Reference Frame (AFREF). Except for a few regions, the African continent remains largely under-sampled by continuous space geodetic data. Efforts are needed to augment the geodetic infrastructure and openly share existing data sets so that the objectives of AFREF can be fully reached. © 2013. American Geophysical Union. All Rights Reserved.


Saunier J.,Institute National Of Linformation Geographique Et Forestiere Ign | Auriol A.,French National Center for Space Studies | Tourain C.,French National Center for Space Studies
Advances in Space Research | Year: 2016

The DORIS system measures distances between phase centers of onboard and ground antennas to determine the position of the satellites in their orbits. To this end, the ground antenna phase center position must be known in a terrestrial reference frame. Its position is linked and defined with respect to the antenna reference point (ARP), a conventional physical point for which coordinates are assigned. Although the determination of the ARP position with respect to ground markers can be achieved by traditional surveys, the connection with the actual measurement point (phase center) is far more difficult to determine. This is the main concern explored in this paper. Regardless of the need for a good antenna characterization, CNES and IGN jointly worked to establish a first error budget of the ground antenna position. With this aim in view, each component was clearly identified and studied separately. We distinguished between errors from manufacturing and from site surveying and, on the other hand, errors affecting horizontal and vertical position. The knowledge of the antenna geometry and the guarantee of a good reproducibility in the manufacturing process are essential. Based on these requirements, we have defined new manufacturing specifications to create a new antenna type: Starec type C. Compared to the previous antenna (Starec type B), the standard uncertainty of the 2. GHz phase center position in the vertical direction has been reduced from 5. mm to 1. mm. Following this work, we provide for the new Starec antenna (type C) total uncertainties involved in the ground antenna positioning in a local reference frame: 2. mm in the horizontal plane, 2.5. mm for the vertical component and 3.2. mm in three-dimensional combination. We also propose for DORIS new definitions of conventional points and a new method to determine ground antennas position that were not possible before this manufacturing specifications change. © 2016 COSPAR.

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