Renaud Mathieu

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Effective assessment of biodiversity in cities requires detailed vegetation maps.To date, most remote sensing of urban vegetation has focused on thematically coarse landcover products. Detailed habitat maps are created by manual interpretation of aerialphotographs, but this is time consuming and costly at large scale. To address this issue, wetested the(More)
a Council for Scientific and Industrial Research (CSIR), Natural Resources and Environment (NRE), Earth Observation Group, P.O. Box 395, Pretoria 0001, South Africa b Department of Global Ecology, Carnegie Institution for Science, 260 Panama Street, Stanford, CA 94305, USA c RIT: Center for Imaging Science, Digital Imaging and Remote Sensing Group, 54 Lomb(More)
Recent technological improvements have made possible the development of lightweight GPS-tagging devices suitable to track medium-to-small sized animals. However, current inferences concerning GPS performance are based on heavier designs, suitable only for large mammals. Lightweight GPS-units are deployed close to the ground, on species selecting(More)
Differences in within-species phenology and structure are controlled by genetic variation, as well as topography, edaphic properties, and climatic variables across the landscape, and present important challenges to species differentiation with remote sensing. The objectives of this paper are as follows: 1) to evaluate the classification performance of a(More)
The European hedgehog is a significant predator species of rare and endangered ground-nesting birds in the riverbeds of the Waitaki Basin, South Island, New Zealand. Studies focusing on the movements and habits of this species have generally been limited to broad-scale radio-tracking studies or incidental trap-catch data. Within our study, we aimed to(More)
We propose to fuse the high spatial content of two 250-m spectral bands of the Moderate Resolution Imaging Spectroradiometer (MODIS) into its five 500-m bands using wavelet-based multiresolution analysis. Our objective was to test the effectiveness of this technique to increase the accuracy of snow mapping in mountainous environments. To assess the(More)
Woody biomass dynamics are an expression of ecosystem function, yet biomass estimates do not provide information on the spatial distribution of woody vegetation within the vertical vegetation subcanopy. We demonstrate the ability of airborne light detection and ranging (LiDAR) to measure aboveground biomass and subcanopy structure, as an explanatory tool to(More)
The management of vegetated areas by urban planners relies on detailed and updated knowledge of their nature and distribution. Manual photo-interpretation of aerial photographs is efficient, but is time consuming. Image segmentation and object-oriented classifications provide a tool to automatically delineate and label vegetation units. Object-oriented(More)
We report on the design and construction of a Global Positioning System (GPS) backpack to collect positional data of European hedgehogs Erinaceus europaeus. The device consisted of a microGPS unit plus a VHF transmitter to facilitate unit recovery. It was constructed to articulate when the animal rolled up and to prevent snagging on objects or nests.(More)
Spectral signatures for samples of the same species of vegetation have high variability [1] and when comparing spectrally similar species the problem is further enhanced [2]. Hence techniques that are presently used for image classification and/or spectral unmixing often cannot be directly used for vegetation studies to distinguish spectrally similar(More)