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Predicting the variability in pedestrian travel rates and times using crowdsourced GPS data / Michael J. Campbell in Computers, Environment and Urban Systems, vol 97 (October 2022)  

Public [article]  inComputers, Environment and Urban Systems > vol 97 (October 2022) . - n° 101866 Titre : Predicting the variability in pedestrian travel rates and times using crowdsourced GPS data Type de document : Article/Communication Auteurs : Michael J. Campbell, Auteur ; Philip E. Dennison, Auteur ; Matthew Thompson, Auteur Année de publication : 2022 Article en page(s) : n° 101866 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géomatique [Termes IGN] base de données localisées [Termes IGN] Californie (Etats-Unis) [Termes IGN] chemin le moins coûteux, algorithme du [Termes IGN] données issues des réseaux sociaux [Termes IGN] durée de trajet [Termes IGN] mobilité urbaine [Termes IGN] navigation pédestre [Termes IGN] pente [Termes IGN] planification urbaine [Termes IGN] trace GPS [Termes IGN] Utah (Etas-Unis) Résumé : (auteur) Accurately predicting pedestrian travel times is critically valuable in emergency response, wildland firefighting, disaster management, law enforcement, and urban planning. However, the relationship between pedestrian movement and landscape conditions is highly variable between individuals, making it difficult to estimate how long it will take broad populations to get from one location to another on foot. Although functions exist for predicting travel rates, they typically oversimplify the inherent variability of pedestrian travel by assuming the effects of landscapes on movement are universal. In this study, we present an approach for predicting the variability in pedestrian travel rates and times using a large, crowdsourced database of GPS tracks. Acquired from the outdoor recreation website AllTrails, these tracks represent nearly 2000 hikes on a diverse range of trails in Utah and California, USA. We model travel rates as a function of the slope of the terrain by generating a series of non-linear percentile models from the 2.5 th to the 97.5 th by 2.5 percentiles. The 50 th percentile model, representing the hiking speed of the typical individual, demonstrates marked improvement over existing slope-travel rate functions when compared to an independent test dataset. Our results demonstrate novel capacity to estimate travel time variability, with modeled percentiles being able to predict actual percentiles with less than 10% error. Travel rate functions can also be applied to least cost path analysis to provide variability in travel times. Numéro de notice : A2022-599 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.compenvurbsys.2022.101866 Date de publication en ligne : 20/08/2022 En ligne : https://doi.org/10.1016/j.compenvurbsys.2022.101866 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101452 [article]

Climatic sensitivities derived from tree rings improve predictions of the forest vegetation simulator growth and yield model / Courtney L. Giebink in Forest ecology and management, vol 517 (August-1 2022)  

Public [article]  inForest ecology and management > vol 517 (August-1 2022) . - n° 120256 Titre : Climatic sensitivities derived from tree rings improve predictions of the forest vegetation simulator growth and yield model Type de document : Article/Communication Auteurs : Courtney L. Giebink, Auteur ; R. Justin DeRose, Auteur ; Mark Castle, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : n° 120256 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] cerne [Termes IGN] croissance des arbres [Termes IGN] gestion forestière [Termes IGN] inventaire forestier étranger (données) [Termes IGN] modèle de croissance végétale [Termes IGN] modèle de simulation [Termes IGN] Picea (genre) [Termes IGN] Pinus ponderosa [Termes IGN] Pseudotsuga menziesii [Termes IGN] puits de carbone [Termes IGN] rendement [Termes IGN] Utah (Etas-Unis) [Termes IGN] variation saisonnière [Vedettes matières IGN] Végétation et changement climatique Résumé : (auteur) Forest management has the potential to contribute to the removal of greenhouse gasses from the atmosphere via carbon sequestration and storage. To identify management actions that will maximize carbon removal and storage over the long term, models are needed that accurately and realistically represent forest responses to changing climate. The most widely used growth and yield model in the United States (U.S.), the Forest Vegetation Simulator (FVS), which also forms the basis for several forest carbon calculators, does not currently include the direct effect of climate variation on tree growth. We incorporated the effects of climate on tree diameter growth by combining tree-ring data with forest inventory data to parameterize a suite of alternative models characterizing the growth of three dominant tree species in the arid and moisture-limited state of Utah. These species, Pinus ponderosa Dougl. ex Laws, Pseudotsuga menziesii var. glauca Mayr (Franco), and Picea engelmannii Parry ex Engelm., encompass the full elevational range of montane forest types. The alternative models we considered differed progressively from the current FVS large-tree diameter growth model, first by changing to an annual time step, then by adding interannual climate effects, followed by model simplification (removal of predictors), and finally, complexification, including effects of spatial variation in climate and two-way interactions between predictors. We validated diameter growth predictions from these models with independent observations, and evaluated model performance in terms of accuracy, precision, and bias. We then compared predictions of future growth made by the existing large-tree diameter growth model used in FVS, i.e., without climate effects, to those of our updated models, including those with climate effects. We found that simpler models of tree growth outperform the current FVS model, and that the incorporation of climate effects improves model performance for two out of three species, in which growth is currently overpredicted by FVS. Diameter growth projected with improved, climate-sensitive models is less than the future tree growth projected by the current climate-insensitive FVS model. Tree rings can be used to identify and incorporate drivers of growth variation into a stand-level growth and yield model, giving more accurate predictions of the carbon uptake potential of forests under climate change. Numéro de notice : A2022-390 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article DOI : 10.1016/j.foreco.2022.120256 Date de publication en ligne : 12/05/2022 En ligne : https://doi.org/10.1016/j.foreco.2022.120256 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=100681 [article]

Inferencing hourly traffic volume using data-driven machine learning and graph theory / Zhiyan Yi in Computers, Environment and Urban Systems, vol 85 (January 2021)  

Public [article]  inComputers, Environment and Urban Systems > vol 85 (January 2021) . - n° 101548 Titre : Inferencing hourly traffic volume using data-driven machine learning and graph theory Type de document : Article/Communication Auteurs : Zhiyan Yi, Auteur ; Xiaoyue Cathy Liu, Auteur ; Nikola Markovic, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : n° 101548 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Analyse spatiale [Termes IGN] apprentissage automatique [Termes IGN] classification barycentrique [Termes IGN] échantillonnage de données [Termes IGN] Extreme Gradient Machine [Termes IGN] inférence statistique [Termes IGN] modèle de simulation [Termes IGN] planification [Termes IGN] théorie des graphes [Termes IGN] trafic routier [Termes IGN] Utah (Etas-Unis) Résumé : (auteur) Traffic volume is a critical piece of information in many applications, such as transportation long-range planning and traffic operation analysis. Effectively capturing traffic volumes on a network scale is beneficial to Transportation Systems Management & Operations (TSM&O). Yet it is impractical to install sensors to cover a large road network. To address this issue, spatial prediction techniques are widely performed to estimate traffic volumes at sites without sensors. In retrospect, most relevant studies resort to machine learning methods and treat each prediction location independently during the training process, ignoring the potential spatial dependency among them. This paper presents an innovative spatial prediction method of hourly traffic volume on a network scale. To achieve this, we applied a state-of-the-art tree ensemble model - extreme gradient boosting tree (XGBoost) - to handle the large-scale features and hourly traffic volume samples, due to the model's powerful scalability. Moreover, spatial dependency among road segments is taken into account in the proposed model using graph theory. Specifically, we created a traffic network graph leveraging probe trajectory data, and implemented a graph-based approach - breadth first search (BFS) - to search neighboring sites in this graph for computing spatial dependency. The proposed spatial dependency feature is subsequently incorporated as a new feature fed into XGBoost. The proposed model is tested on the road network in the state of Utah. Numerical results not only indicate high computational efficiency of the proposed model, but also demonstrate significant improvement in prediction accuracy of hourly traffic volume comparing with the benchmarked models. Numéro de notice : A2021-004 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1016/j.compenvurbsys.2020.101548 Date de publication en ligne : 24/09/2020 En ligne : https://doi.org/10.1016/j.compenvurbsys.2020.101548 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96271 [article]

Retrieval of spectral reflectance of high resolution multispectral imagery acquired with an autonomous unmanned aerial vehicle: AggieAir™ / Bushra Zaman in Photogrammetric Engineering & Remote Sensing, PERS, vol 80 n° 12 (December 2014)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 80 n° 12 (December 2014) . - pp 1139 - 1150 Titre : Retrieval of spectral reflectance of high resolution multispectral imagery acquired with an autonomous unmanned aerial vehicle: AggieAir™ Type de document : Article/Communication Auteurs : Bushra Zaman, Auteur ; Austin Jensen, Auteur ; Shannon R. Clemens, Auteur ; Mac McKee, Auteur Année de publication : 2014 Article en page(s) : pp 1139 - 1150 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s) [Termes IGN] bande infrarouge [Termes IGN] drone [Termes IGN] éclairement énergétique [Termes IGN] étalonnage de capteur (imagerie) [Termes IGN] image à haute résolution [Termes IGN] image multibande [Termes IGN] orthophotoplan numérique [Termes IGN] prise de vue aérienne [Termes IGN] radiance [Termes IGN] réflectance spectrale [Termes IGN] Utah (Etas-Unis) Résumé : (auteur) This research presents a new semi-automatic model for converting raw AggieAir™ footprints in visible and near-infrared (Nin) bands into reflectance images. AggieAir, a new unmanned aerial vehicle (UAV) platform, is flown autonomously using pre-programmed flight plans at low altitudes to limit atmospheric effects. The UAV acquires high-resolution, multispectral images and has a flight duration of about 30 minutes. The sensors on board are twin cameras with duplicate settings and automatic mode disabled. A white Barium Sulfate (BaSO4j panel is used for reflectance calibration and in situ irradiance measurements. The spatial resolution of the imagery is 25 cm; the radiometric resolution is 8-bit. The raw images are mosaicked and orthorectified and the model converts their digital numbers (DN) to reflectance values. Imagery, acquired around local solar noon over wetlands on the Great Salt Lake. Utah, is used to illustrate the results. The model generates high quality images and the results are good. The reflectance values of vegetation in the NIR, Green and Red hands extracted at the test locations are consistent. The image processing, reflectance calculations, accuracy issues, with the proposed method are discussed. Numéro de notice : A2014 670 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.14358/PERS.80.12.1139 En ligne : https://doi.org/10.14358/PERS.80.12.1139 Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=75129 [article]

Assessing the relationship between ground measurements and object-based image analysis of land cover classes in Pinyon and Juniper Woodlands / April Hulet in Photogrammetric Engineering & Remote Sensing, PERS, vol 79 n° 9 (September 2013)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 79 n° 9 (September 2013) . - pp 799 - 808 Titre : Assessing the relationship between ground measurements and object-based image analysis of land cover classes in Pinyon and Juniper Woodlands Type de document : Article/Communication Auteurs : April Hulet, Auteur ; Bruce A. Roundy, Auteur ; Steven L. Petersen, Auteur ; et al., Auteur Année de publication : 2013 Article en page(s) : pp 799 - 808 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] analyse comparative [Termes IGN] analyse d'image numérique [Termes IGN] arbre (flore) [Termes IGN] Californie (Etats-Unis) [Termes IGN] carte de la végétation [Termes IGN] classification dirigée [Termes IGN] données de terrain [Termes IGN] image infrarouge [Termes IGN] Nevada (Etats-Unis) [Termes IGN] occupation du sol [Termes IGN] Oregon (Etats-Unis) [Termes IGN] Pinus (genre) [Termes IGN] plantation forestière [Termes IGN] Utah (Etas-Unis) Résumé : (Auteur) Land managers need to rapidly assess vegetation composition and bare ground to effectively evaluate and manage shrub steppe communities that have been encroached by pinyon and juniper trees. We used an object-based image analysis (obia) approach to estimate land cover classes found in pinyon-juniper woodlands, and evaluated the relationship between ground measurements and OBIA land cover measurements. We acquired high-spatial resolution color-infrared imagery for five sites with a Vexcel UltraCamX digital camera in June 2009. We simultaneously collected ground-based cover measurements within 30 m x 33 m subplots. OBIA mean land cover class differences by site ranged from underestimating litter by 3 percent to overestimating live trees by 1 percent when compared to ground-based measurements. Overall accuracy for thematic maps was 84 percent with a Kappa statistic of 0.80. Although OBIA cover estimates varied slightly from ground cover estimates, methods provide land managers with options for prioritizing management practices and enabling monitoring at an operational scale. Numéro de notice : A2013-505 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article DOI : 10.14358/PERS.79.9.799 En ligne : https://doi.org/10.14358/PERS.79.9.799 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32643 [article]

Classification of urban tree species using hyperspectral imagery / R. Jensen in Geocarto international, vol 27 n° 5 (August 2012)  

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Estimating urban leaf area index (LAI) of individual trees with hyperspectral data / R. Jensen in Photogrammetric Engineering & Remote Sensing, PERS, vol 78 n° 5 (May 2012)  

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Terrestrial laser scanning for use in virtual outcrop geology / S.J. Buckley in Photogrammetric record, vol 25 n° 131 (September - November 2010)  

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Potential of Cartosat-1 images for topographic mapping / Costas Armenakis in Geomatica, vol 62 n° 1 (March 2008)  

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An automated, objective procedure for selecting representative field sample sites / S.D. Warren in Photogrammetric Engineering & Remote Sensing, PERS, vol 56 n° 3 (march 1990)  

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Successful use of Landsat Thematic Mapper data for mapping hydrocarbon microseepage-induced mineralogic alteration, Lisbon valley, Utah / D.B. Segal in Photogrammetric Engineering & Remote Sensing, PERS, vol 55 n° 8 (august 1989)  

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Thematic Mapper laser profile resolution of holocene lake limit, Great Salt Lake Desert, Utah / J.A. Merola in Remote sensing of environment, vol 28 n° 1 (April - June 1989)  

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Backscatter and dielectric measurements from rocks of south-eastern Utah at C-band, X-band and KU-band / R. Swanson in International Journal of Remote Sensing IJRS, vol 9 n° 4 (April 1988)  

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Exploration of crustal mantle material for the Earth and Moon using reflectance spectroscopy / C.M. Pieters in Remote sensing of environment, vol 24 n° 1 (February 1988)  

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