Aerial 3D Mapping with Continuous Time ICP for Urban Search and Rescue

Fast reconnaissance is essential for strategic decisions during the immediate response phase of urban search and rescue missions. Nowadays, UAVs with their advantageous overview perspective are increasingly used for reconnaissance besides manual inspection of the scenario. However, data evaluation is often limited to visual inspection of images or video footage. We present our LiDAR-based aerial 3D mapping system, providing real-time maps of the environment. UAV-borne laser scans typically offer a reduced field of view. Moreover, UAV trajectories are more flexible and dynamic compared to those of ground vehicles, for which SLAM systems are often designed. We address these challenges by a two-step registration approach based on continuous time ICP. The experiments show that the resulting maps accurately represent the environment

Molecular Background of Pi Deficiency-Induced Root Hair Growth in Brassica carinata – A Fasciclin-Like Arabinogalactan Protein Is Involved

Formation of longer root hairs under limiting phosphate (P) conditions can increase the inorganic P (Pi) uptake. Here, regulatory candidate genes for Pi deficiency-induced root hair growth were identified by comparison of massive analysis of cDNA ends (MACE) provided expression profiles of two Brassica carinata cultivars (cv.) differing in their root hair response to Pi deficiency: cv. Bale develops longer root hairs under Pi deficiency, but not cv. Bacho. A split-root experiment was conducted for the differentiation between locally and systemically regulated genes. Furthermore, plants were exposed to nitrogen and potassium deficiency to identify P-specific reacting genes. The latter were knocked out by CRISPR/Cas9 and the effect on the root hair length was determined. About 500 genes were differentially expressed under Pi deficiency in cv. Bale, while these genes did not respond to the low P supply in cv. Bacho. Thirty-three candidate genes with a potential regulatory role were selected and the transcriptional regulation of 30 genes was confirmed by quantitative PCR. Only five candidate genes seemed to be either exclusively regulated locally (two) or systemically (three), whereas 25 genes seemed to be involved in both local and systemic signaling pathways. Potassium deficiency affected neither the root hair length nor the expression of the 30 candidate genes. By contrast, both P and nitrogen deficiency increased the root hair length, and both affected the transcript levels in 26 cases. However, four genes reacted specifically to Pi starvation. These genes and, additionally, INORGANIC PHOSPHATE TRANSPORTER 1 (BcPHT1) were targeted by CRISPR/Cas9. However, even if the transcript levels of five of these genes were clearly decreased, FASCICLIN-LIKE ARABINOGALACTAN PROTEIN 1 (BcFLA1) was the only gene whose downregulation reduced the root hair length in transgenic hairy roots under Pi-deficient conditions. To the best of our knowledge, this is the first study describing a fasciclin-like arabinogalactan protein with a predicted role in the Pi deficiency-induced root hair elongation

Evaluation of a Backpack-Mounted 3D Mobile Scanning System

Recently, several backpack-mounted systems, also known as personal laser scanning systems, have been developed. They consist of laser scanners or cameras that are carried by a human operator to acquire measurements of the environment while walking. These systems were first designed to overcome the challenges of mapping indoor environments with doors and stairs. While the human operator inherently has the ability to open doors and to climb stairs, the flexible movements introduce irregularities of the trajectory to the system. To compete with other mapping systems, the accuracy of these systems has to be evaluated. In this paper, we present an extensive evaluation of our backpack mobile mapping system in indoor environments. It is shown that the system can deal with the normal human walking motion, but has problems with irregular jittering. Moreover, we demonstrate the applicability of the backpack in a suitable urban scenario

Evaluation of a Backpack-Mounted 3D Mobile Scanning System

Recently, several backpack-mounted systems, also known as personal laser scanning systems, have been developed. They consist of laser scanners or cameras that are carried by a human operator to acquire measurements of the environment while walking. These systems were first designed to overcome the challenges of mapping indoor environments with doors and stairs. While the human operator inherently has the ability to open doors and to climb stairs, the flexible movements introduce irregularities of the trajectory to the system. To compete with other mapping systems, the accuracy of these systems has to be evaluated. In this paper, we present an extensive evaluation of our backpack mobile mapping system in indoor environments. It is shown that the system can deal with the normal human walking motion, but has problems with irregular jittering. Moreover, we demonstrate the applicability of the backpack in a suitable urban scenario

Curvefusion — A Method for Combining Estimated Trajectories with Applications to SLAM and Time-Calibration

Mapping and localization of mobile robots in an unknown environment are essential for most high-level operations like autonomous navigation or exploration. This paper presents a novel approach for combining estimated trajectories, namely curvefusion. The robot used in the experiments is equipped with a horizontally mounted 2D profiler, a constantly spinning 3D laser scanner and a GPS module. The proposed algorithm first combines trajectories from different sensors to optimize poses of the planar three degrees of freedom (DoF) trajectory, which is then fed into continuous-time simultaneous localization and mapping (SLAM) to further improve the trajectory. While state-of-the-art multi-sensor fusion methods mainly focus on probabilistic methods, our approach instead adopts a deformation-based method to optimize poses. To this end, a similarity metric for curved shapes is introduced into the robotics community to fuse the estimated trajectories. Additionally, a shape-based point correspondence estimation method is applied to the multi-sensor time calibration. Experiments show that the proposed fusion method can achieve relatively better accuracy, even if the error of the trajectory before fusion is large, which demonstrates that our method can still maintain a certain degree of accuracy in an environment where typical pose estimation methods have poor performance. In addition, the proposed time-calibration method also achieves high accuracy in estimating point correspondences

Seismic data collected at the Tinguatón volcano (Lanzarote, Canary Islands) during the European Space Agency (ESA) testing campaign PANGAEA-X 2018

This dataset contains the seismic data collected between 19 and 21 November 2018 at the Tinguatón volcanic region (Los Volcanes Natural Park, Geoparc of Lanzarote, Canary Islands, Fig. 1), within the A1TRAP experiment which formed part of the Analog-1 geology and science support activity (Rossi et al., 2019). Analog 1 was part of a larger European Space Agency (ESA) testing campaign PANGAEA-X 2018 (Bessone et al., 2018), aimed at integrating astronaut training-data collection, documentation, analogue field geology procedures with remote sensing and in situ geophysical methods. Single-station, free-field ambient seismic noise data were collected along two orthogonal profiles: Traverse A, crossing the Tinguatón volcano, and Traverse B passing alongside it (Fig. 1c). Traverse A is ESE-WNW oriented and aligned to the regional fault (as well as along the fissure vent inside the volcano crater), and consists of 12 stations (P1-P12), approximately 50 m apart, with a total profile length of 620 m. Traverse B is NNW-SSE oriented and orthogonal to the regional fault strike, and consists of 9 stations (P13-P20), approximately 50 m apart, with a total profile length of 390 m. Data were collected using a Tromino® model ENGY digital tromograph (Micromed, 2011). This is an ultralight all-in-one device, using a compact 3-directional, 24-bit digital seismometer developed by MoHo s.r.l. (1 dm3 volume and 1 kg weight), including both sensors and the data acquisition system, and works at frequencies down to 0.3 Hz. This seismograph is equipped with three orthogonal electrodynamic sensors (velocimeters), powered by two 1.5 V AA batteries. It includes an internal Global Positioning System (GPS) antenna and does not have any external cables. For all the measurements, the seismometer’s axis referred to as N-S was aligned to N15W direction, i.e., the strike of the western edge of the Tinguatón volcano, the area’s main topographic feature. Good ground coupling on scoria deposits or highly weathered basalt was obtained by using three, 6 cm-long metal spikes screwed into the base of the unit. The seismometer was levelled. Each seismic noise acquisition involved a 16-minute trace length with a 1024 Hz sampling rate, in accordance with the recommendations from SESAME Project (Bard et al., 2004). Four MASW (Multichannel Analysis of Surface Waves) active seismic surveys (A3_5, A7, A8_10, A18_19) were undertaken along the two profiles (Fig. 1c) to acquire the shear wave velocity of the shallow layer which was later to be used to constrain the H/V inversion. These surveys were carried out using the same equipment, along with a wireless trigger by MoHo s.r.l., and a heavy metal plate struck with a 5 kg hammer for the generation of compressional waves. A redundancy test, which involved ground energization by an ESA astronaut (Matthias Maurer) jumping up and down, was also performed (Fig. 1c). This test tried to mimic deployment and testing during possible future planetary missions. However, this test did not provide satisfactory results in term of signal clarity. The seismometer was kept fixed on the ground while shot points were moved at increasing distances involving a 5 m minimum offset and 1 m spacing for the first 11 shots and 5 m spacing for subsequent shots for total profile lengths ranging between 50 m and 100 m (Fig. 1c). Each MASW acquisition involved a 3 s trace window with a 512 Hz sampling rate. The data are presented in ASCII format files. The recordings of each channel were saved all together in the same file. Information about each file was printed on the header of the same file. Acknowledgements The authors are grateful to ESA and all PANGAEA-X 2018 staff, particularly Loredana Bessone and Matthias Maurer for their participation in data collection during some of the experiments and to the MilesBeyond Team, particularly Francesco Maria Sauro for his logistical support. We also thank MoHo s.r.l., particularly Jeremy Magnon, for providing instrumental support. References Bessone, L., et al., 2018, Testing technologies and operational concepts for field geology exploration of the Moon and beyond: the ESA PANGAEA-X campaign, Geophysical Research Abstract, #EGU2018-4013. Micromed, 2011. Dati tecnici Tromino e download pacchetto software Grilla. Available online from the website http://www.tromino.it. Bard, P., Duval, A., Koehler, A., Rao, S., 2004, Guidelines for the Implementation of the H/V Spectral Ratio Technique on Ambient Vibrations Measurements, Processing and Interpretation. SESAME H/V User Guidelines., pp. 1–62. Available online: http://sesame.geopsy.org/SES_Reports.htm. Rossi, A.P., et al., 2019, Morphometry and trafficability of planetary analogue terrains based on very high resolution remote sensing imagery, Geophysical Research Abstract, #EGU2019-17614.ambient seismic noise, MASW, HVSR passive seismic stratigraph