scholarly journals Influence of the Sun Position and Platform Orientation on the Quality of Imagery Obtained from Unmanned Aerial Vehicles

2020 ◽  
Vol 12 (6) ◽  
pp. 1040 ◽  
Author(s):  
Aleksandra Sekrecka ◽  
Damian Wierzbicki ◽  
Michal Kedzierski
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Correction Method ◽  
Accurate Information ◽  
The Sun ◽  
Aerial Vehicles ◽  
The Difference ◽  
Third Dimension

Images acquired at a low altitude can be the source of accurate information about various environmental phenomena. Often, however, this information is distorted by various factors, so a correction of the images needs to be performed to recreate the actual reflective properties of the imaged area. Due to the low flight altitude, the correction of images from UAVs (unmanned aerial vehicles) is usually limited to noise reduction and detector errors. The article shows the influence of the Sun position and platform deviation angles on the quality of images obtained by UAVs. Tilting the camera placed on an unmanned platform leads to incorrect exposures of imagery, and the order of this distortion depends on the position of the Sun during imaging. An image can be considered in three-dimensional space, where the x and y coordinates determine the position of the pixel and the third dimension determines its exposure. This assumption is the basis for the proposed method of image exposure compensation. A three-dimensional transformation by rotation is used to determine the adjustment matrix to correct the image quality. The adjustments depend on the angles of the platform and the difference between the direction of flight and the position of the Sun. An additional factor regulates the value of the adjustment depending on the ratio of the pitch and roll angles. The experiments were carried out for two sets of data obtained with different unmanned systems. The correction method used can improve the block exposure by up to 60%. The method gives the best results for simple systems, not equipped with lighting compensation systems.

A method for autonomous collision-free navigation of a quadrotor UAV in unknown tunnel-like environments

Robotica ◽  
2021 ◽  
pp. 1-27
Author(s):  
Taha Elmokadem ◽  
Andrey V. Savkin
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Autonomous Underwater Vehicles ◽  
Three Dimensional ◽  
Underwater Vehicles ◽  
Practical Implementation ◽  
Challenging Problem ◽  
Quadrotor Uav ◽  
Navigation Algorithm ◽  
Aerial Vehicles ◽  
Quadrotor Uavs

Abstract Unmanned aerial vehicles (UAVs) have become essential tools for exploring, mapping and inspection of unknown three-dimensional (3D) tunnel-like environments which is a very challenging problem. A computationally light navigation algorithm is developed in this paper for quadrotor UAVs to autonomously guide the vehicle through such environments. It uses sensors observations to safely guide the UAV along the tunnel axis while avoiding collisions with its walls. The approach is evaluated using several computer simulations with realistic sensing models and practical implementation with a quadrotor UAV. The proposed method is also applicable to other UAV types and autonomous underwater vehicles.

Development of a three-dimensional color rendition space for tunable solid-state light sources

2021 ◽  
Vol 2021 (29) ◽  
pp. 136-140
Author(s):  
Dorukalp Durmus
Keyword(s):  
Solid State ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Color Discrimination ◽  
Continuous Measure ◽  
Light Sources ◽  
Vast Number ◽  
Lighting Systems ◽  
Single Number

The quality of building electric lighting systems can be assessed using color rendition metrics. However, color rendition metrics are limited in quantifying tunable solid-state light sources, since tunable lighting systems can generate a vast number of different white light spectra, providing flexibility in terms of color quality and energy efficiency. Previous research suggests that color rendition is multi-dimensional in nature, and it cannot be simplified to a single number. Color shifts under a test light source in comparison to a reference illuminant, changes in color gamut, and color discrimination are important dimensions of the quality of electric light sources, which are not captured by a single-numbered metric. To address the challenges in color rendition characterization of modern solid-state light sources, the development of a multi-dimensional color rendition space is proposed. The proposed continuous measure can quantify the change in color rendition ability of tunable solid-state light devices with caveats. Future work, discretization of the continuous color rendition space, will be carried out to address the shortcomings of a continuous three-dimensional space.

The Quality Analysis of Hallux Valgus Videos on YouTube

2021 ◽  
Author(s):  
Enes Sari ◽  
Levent FAZLI Umur
Keyword(s):  
Hallux Valgus ◽  
Information Quality ◽  
Statistical Significance ◽  
Poor Quality ◽  
Quality Analysis ◽  
Accurate Information ◽  
Youtube Videos ◽  
The Mean ◽  
The Difference

BACKGROUND:The aim of this study was to evaluate the information quality of YouTube videos on hallux valgus. METHODS:A YouTube search was performed using the keyword 'hallux valgus' to determine the first 300 videos related to hallux valgus. A total of 54 videos met our inclusion criteria and evaluated for information quality by using DISCERN, Journal of the American Medical Association (JAMA) and hallux valgus information assessment (HAVIA) scores. Number of views, time since the upload date, view rate, number of comments, number of likes, number of dislikes, video power index (VPI) values were calculated to determine video popularity. Video length (sec), video source and video content were also noted. The relation between information quality and these factors were statistically evaluated. RESULTS:The mean DISCERN score was 30.35{plus minus}11.56 (poor quality) (14-64), the mean JAMA score was 2.28{plus minus}0.96 (1-4), and the mean HAVIA score was 3.63{plus minus}2.42 (moderate quality) (0.5-8.5). Although videos uploaded by physicians had higher mean DISCERN, JAMA, and HAVIA scores than videos uploaded by non-physicians, the difference was not statistically significant. Additionally, view rates and VPI values were higher for videos uploaded by health channels, but the difference did not reach statistical significance. A statistically significant positive correlation was found between video length and DISCERN (r= 0.294, p= 0.028), and HAVIA scores (r= 0.326, p= 0.015). CONCLUSIONS:This present study demonstrated that the quality of information available on YouTube videos about hallux valgus was low and insufficient. Videos containing accurate information from reliable sources are needed to educate patients on hallux valgus, especially in less frequently mentioned topics such as postoperative complications and healing period.

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