Autonomous Navigation for Unmanned Aerial Systems - Visual Perception and Motion Planning

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Camera Selection and Flight Planning for Post Processing 3D Reconstruction Automatization

Currently available 3D reconstruction and aerial mapping solutions based on the Structure-from-Motion (SfM) and bundle adjustment, require careful equipment selection/configuration (camera, optics and imaging parame-ters’ settings), accurate flight planning (number of images and their overlap percentage) and often user inter-vention during post processing. This paper studies the various factors affecting the quality of the final 3D recon-struction, their dependencies and trade-offs trying to push the whole 3D reconstruction and aerial mapping solu-tions to a more automated scheme with minimum user intervention. We address the design trade-offs between the camera and the flight plan parameters and their effect on the images’ quality and the number and quality of matched features consequently. Then we consider the camera calibration as a fundamental stage in the SfM framework that affects afterwards the depth estimation and point cloud densification steps. An automated pho-togrammetry calibration solution - based on the Caltech Camera Calibration Matlab Toolbox and Andreas Geiger corner detector- is implemented and tested, allowing for a user-free precise camera calibration process. Finally, a professional photogrammetry application software based on the SfM (PIX4Dmappper) is used to assess the use of additional data sets - like the commonly used GPS data – on the overall resulting 3D reconstruction quality in terms of model richness and accuracy. Two geo-localization data sets (standard GPS used by the UAV autopilot and an L1/L2 GPS corrected with PPK) were used with various stated uncertainty bounds processed with the same images’ data set. The comparison of the resulting 3D reconstructed models highlights the decisive im-portance of identifying the actual uncertainty bounds - combining the equipment nominal uncertainty with the system introduces factors like the camera capture/GPS synchronization- instead of using relaxed (larger) uncer-tainty bounds or tighter bounds

Prevalence of occult celiac disease in females with iron deficiency in the United States: an NHANES analysis

Aim: The prevalence of celiac disease (CD) in patients with iron deficiency (ID) is estimated at 0–6% in European countries. The prevalence of celiac disease in patients with iron deficiency in the USA is unknown. Given the treatable nature of gluten hypersensitivity, estimating the prevalence of CD in patients with ID can help to determine the need to screen these patients for occult CD. Methods: Data were obtained from the NHANES database, a nationally representative health survey conducted from 2009 to 2010. We included 2,105 females aged 6 years or older. Iron deficiency was defined as serum ferritin level <20 ng/ml and considered positive for celiac disease when subjects were tested positive for both immunoglobulin A (IgA) tissue transglutaminase antibody and IgA endomysial antibody. Subjects were divided between two groups (ID and non-ID). The association of CD and ID, which was the primary outcome, was obtained after adjusting for other covariates using logistic regression. Results: Among the sample of 2,105 subjects, 569 had ID and 1536 did not have ID. Five people were identified as having CD among the ID group, as were two people in the non-ID group. After adjusting for selected covariates, the prevalence of CD was higher in female subjects with ID with OR of 12.5 (95% CI 1.74–90). Conclusions: The overall prevalence of celiac disease in the USA’ female population is low, however, the prevalence is higher in subjects with iron deficiency. Further prospective studies are needed to validate our findings

Genetic Gain in Wheat Grain Yield and Nitrogen Use Efficiency at Different Nitrogen Levels in an Irrigated Hot Environment

Improved nitrogen use-efficient cultivars could be the most economically beneficial and environmentally friendly approach to reduce pollution associated with excessive N fertilization. The performance and genetic gain in grain yield and nitrogen use efficiency (NUE) of a historical set of 12 bread wheat cultivars released for a heat-stressed environment were investigated at four N levels (0 (N0), 43 (N43), 86 (N86), and 129 (N129) kg/ha) for two seasons. Averaged across seasons, increasing N level from N0 to N43, N86, and N129 resulted in yield increases ranging from 4−45%, 13–69%, and 34–87% at N43, N86, and N129, respectively. These yield increases were associated with increases in biomass (r = 0.86, P<0.01). Regressing grain yield of cultivars released during 1960 to 2006 against the year of release showed no trend at N0 and positive nonsignificant trends at N43;. however, significant positive trends were found at N86 and N129 with genetic gain rates of 12.65 and 15.76 kg ha−1 year−1, respectively. This gain was associated with progresses in harvest index (HI) at N43, N86, and N129 but not at N0. On the other hand, during the period from 1960 to 1990, the genetic gain in grain yield at N86 was 24.5 kg ha−1 year−1. Regressing NUE against the year of release showed significant linear trends at N86 and N129 (R2 = 0.511 and R2 = 0.477, respectively), but not at N43. The results indicate that breeders improved grain yield and NUE over 46 years under the heat-stressed environment of Sudan although the rate of increase in yield has been slowed down in recent years. Further improvement in NUE might require broadening the genetic diversity and simultaneous evaluation at low and high N levels