The effect of seasonal variation on automated land cover mapping from multispectral airborne laser scanning data

Multispectral airborne laser scanning (MS-ALS) sensors are a new promising source of data for auto-mated mapping methods. Finding an optimal time for data acquisition is important in all mapping applica-tions based on remotely sensed datasets. In this study, three MS-ALS datasets acquired at different times of the growing season were compared for automated land cover mapping and road detection in a suburban area. In addition, changes in the intensity were studied. An object-based random forest classi-fication was carried out using reference points. The overall accuracy of the land cover classification was 93.9% (May dataset), 96.4% (June) and 95.9% (August). The use of the May dataset acquired under leafless conditions resulted in more complete roads than the other datasets acquired when trees were in leaf. It was concluded that all datasets used in the study are applicable for suburban land cover map-ping, however small differences in accuracies between land cover classes exist

Measuring surface moisture on a sandy beach based on corrected intensity data of a mobile terrestrial LiDAR

Surface moisture plays a key role in limiting the aeolian transport on sandy beaches. However, the existing measurement techniques cannot adequately characterize the spatial and temporal distribution of the beach surface moisture. In this study, a mobile terrestrial LiDAR (MTL) is demonstrated as a promising method to detect the beach surface moisture using a phase-based Z&F/Leica HDS6100 laser scanner mounted on an all-terrain vehicle. Firstly, two sets of indoor calibration experiments were conducted so as to comprehensively investigate the effect of distance, incidence angle and sand moisture contents on the backscattered intensity by means of sand samples with an average grain diameter of 0.12 mm. A moisture estimation model was developed which eliminated the effects of the incidence angle and distance (it only relates to the target surface reflectance). The experimental results reveal both the distance and incidence angle influencing the backscattered intensity of the sand samples. The standard error of the moisture model amounts to 2.0% moisture, which is considerably lower than the results of the photographic method. Moreover, a field measurement was conducted using the MTL system on a sandy beach in Belgium. The accuracy and robustness of the beach surface moisture derived from the MTL data was evaluated. The results show that the MTL is a highly suitable technique to accurately and robustly measure the surface moisture variations on a sandy beach with an ultra-high spatial resolution (centimeter-level) in a short time span (12 x 200 m per minute)

Southern Great Plains Expansion of Glyphosate Resistant Brassica Napus L.: Management and Mapping

Brassica napus L. production has become more predominant in the United States. Increased yield in rotational systems and the increased market for this crop have created a potential for B. napus expansion into regions where it is not currently utilized. This has created a gap of knowledge that is necessary for proper management and implementation of this crop. The objectives of this project were to determine potential controls for volunteer weed issues found in B. napus cropping systems, as well as control of volunteer/weed B. napus in wheat cropping systems that have been incorporated in the southern latitudes of the Great Plains. A secondary objective was the refinement and potential implementation of a new precision farming tool Terrestrial Laser Scanning (TLS). Findings suggest that application of Potassium salt of Glyphosate had significant (P≤0.05) impact on weed control in B. napus cropping systems and chemicals such as Flufenacet and Bromoxynil were found to be best in control of volunteer/weed B. napus in a Triticum aestivum L. system with high significance (P≤0.05) when compared to untreated control trials. TLS was found to be effective in regards to discriminating monocots in a B. napus cropping system or discrimination of B. napus in a Triticum aestivum L. cropping system using a combination of intensity value and structural characteristics

LASERSCANNER CYCLOSTRATIGRAPHY. A REMOTE SENSING APPROACH FOR THE EXTRACTION OF LONG TIME SERIES FROM LARGE OUTCROPS

Terrestrial Laser Scanners (TLSs) permit to capture three dimensional models of outcrops in the form of point clouds. Each point of a point cloud is the result of a sampling operation on the outcrop’s surface, made trough a laser beam. This operation records the 3D coordinates of the point and the backscattered laser energy as an intensity value. Potentially, the intensity can be converted into a reflectance and used to discriminate different materials. When series composed of limestone and marl alternations are considered, TLS intensity can be used as a proxy for the lithology and converted into intensity-logs which were demonstrated to be a promising source of time series for cyclostratigraphic analysis. This thesis started from that result and had the main goal of exploiting that method to produce long time series, which are essential to the study of long period (> 1 Myr) Milankovitch cycles in sediments. In this perspective the following themes were investigated: a) The effect exerted on measured intensities by shales and chert. Limestone, clay (shales) and chert make most of many deep water sedimentary successions. b) The identification of a simple method to normalize the intensities, to minimize the effects of distance from the outcrop and of the incidence angle of the laser beam. c) The creation of a software package, composed by a C++ library and a Graphical User Interface (GUI) for simplifying the user interaction with the data that is needed for generating the time series. Three case studies from the Central-Italy Apennines have been considered: I) The Smirra section (Scaglia Rossa Fm. and Scaglia Variegata Fm. ), composed of pelagic calcareous homogenites was the playgroud to compare TLS intensities to calcimetric analyses carried out on samples taken from the outcrop. Results demonstrate that TLS can be used as a proxy for CaCO 3 content even in series characterized by minimal lithological variations. II) The Mulini section (Maiolica Fm.). TLS sensitivity to chert was investigated by comparing laboratory-measured reflectance spectra to TLS intensity. It is shown that the low-reflectance of chert can be exploited to distinguish it from limestone. A method based on a Support Vector Machine (SVM) classifier was thus implemented to recognize chert semi-automatically on TLS point clouds. III) The Vispi Quarry (Maiolica Fm., Marne a Fucoidi Fm., Scaglia Bianca Fm.). In this outcrop an almost continuous 200m-thick stratigraphic succession is exposed spanning from the upper Maiolica Fm. to the Bonarelli level, and representing ca. 20 Myrs. This outcrop was ideal to tackle the problem of retrieving long time series for cyclostratigraphic analysis. An original method and dedicated software were developed to achieve this task. With these original tools, it was possible to produce a 150m-long time series with resolution down to the centimeter, starting from ∼ 30 point clouds. The methods and algorithms introduced to cope with the long time series creation from point clouds have been implemented in a C++ library, names SPC . Easy access to the data structures and methods defined in SPC is instead provided by a GUI, in the form of a toolbar for the CloudCompare software. The proposed toolkit is available over the internet at https://github.com/ luca-penasa