A new method for testing wide range horizontal field angle

In order to solve the problems of small measurement range, large error and low efficiency of laboratory optical field angle testing, a high-precision, easy -operating, high-efficient, and widely used horizontal field angle test method is proposed. It comes to a conclusion that the test method can reduce the experimental error through the analysis of the principle of the field of view error and the calculation of laboratory simulation. The simulation results show that for cameras with a field of view of more than 150 degrees, the measurement error can be reduced by 37 degrees, and when the field of view of the camera under test is close to 170 degrees, the method can reduce the measurement error by nearly 54 degrees. Meanwhile, a wide-range horizontal field angle measurement method is proposed. The camera under test is moved on the supporting mobile platform to image the target test board, and then the imaging target is read by reading the scale value on the test board calculates the angle of the camera under test. This method can effectively avoid the measurement error of the angle caused by the distance between the center of the lens surface and the center of the entrance pupil, so as to quickly obtain the angle of view test results, and improve the testing accuracy, and it is also suitable for cameras that measure a wide range of field angles (wide-angle camera or fisheye camera, etc.) to solve the problem of laboratory testing a wide range of horizontal field angles.

Towards Finding the Optimum Position in the Visual Field for a Head Worn Display Used for Task Guidance with Non-registered Graphics

Where should a HWD be placed in a user's visual field? We present two studies that compare comfort, preference, task efficiency and accuracy for various HWD positions. The first study offsets a 9.2° horizontal field-of-view (FOV) display temporally (toward the ear) from 0° to 30° in 10° steps. 30° proves too uncomfortable while 10° is the most preferred position for a simple button-pushing game, corroborating results from previous single-task reading experiments. The second experiment uses a Magic Leap One to compare 10° x 10° FOV interfaces centered at line-of-sight, temporally offset 15° (center-right), inferiorly offset 15° (bottom-center), and offset in both directions (bottom-right) for an order picking task. The bottom-right position proved worst in terms of accuracy and several subjective metrics when compared to the line-of-sight position.

On the influence of magnetic topology on the propagation of internal gravity waves in the solar atmosphere

The solar surface is a continuous source of internal gravity waves (IGWs). IGWs are believed to supply the bulk of the wave energy for the lower solar atmosphere, but their existence and role for the energy balance of the upper layers is still unclear, largely due to the lack of knowledge about the influence of the Sun’s magnetic fields on their propagation. In this work, we look at naturally excited IGWs in realistic models of the solar atmosphere and study the effect of different magnetic field topographies on their propagation. We carry out radiation-magnetohydrodynamic simulations of a magnetic field free and two magnetic models—one with an initial, homogeneous, vertical field of 100 G magnetic flux density and one with an initial horizontal field of 100 G flux density. The propagation properties of IGWs are studied by examining the phase-difference and coherence spectra in the k h − ω diagnostic diagram. We find that IGWs in the upper solar atmosphere show upward propagation in the model with predominantly horizontal field similar to the model without magnetic field. In contrast to that the model with predominantly vertical fields show downward propagation. This crucial difference in the propagation direction is also revealed in the difference in energy transported by waves for heights below 0.8 Mm. Higher up, the propagation properties show a peculiar behaviour, which require further study. Our analysis suggests that IGWs may play a significant role in the heating of the chromospheric layers of the internetwork region where horizontal fields are thought to be prevalent. This article is part of the Theo Murphy meeting issue ‘High-resolution wave dynamics in the lower solar atmosphere’.

Stitching of depth and color images from multiple RGB-D sensors for extended field of view

Existing commodity RGB-D sensors have a limited field of view compared with a nearly 360° horizontal field of view of Lidar. This article presents a method to extend the field of view by stitching depth and color images from multiple RGB-D sensors to form a depth and a color panorama. Firstly, a set of 3-D matched key points are constructed based on 2-D matched key points and corresponding depth values to estimate transformation matrices between multiple RGB-D sensors. Then, depth and color images are projected to the 3-D space using estimated transformation matrices to construct textured 3-D points. Finally, projecting textured 3-D points to a compositing surface can create the depth panorama and the color panorama. Experiments validated the accuracy and efficiency of the proposed method.

EMERGENCE OF MECHANICAL SOIL EROSION ON SLOPES AND WAYS TO REDUCE IT

The work is devoted to the mathematical description of the process of occurrence and flow of mechanical soil erosion on slope fields and ways to reduce it. The dependences of mechanical erosion on the steepness of the slope, the type and parameters of the working unit, the direction of movement of the unit relative to the horizontal field are given. The obtained mathematical dependences allow us to calculate the displacement of the soil down the slope, depending on the type and parameters of the working unit and on the technology of tillage used. Purpose of the study. Reduction of mechanical soil erosion in slope fields by improving technologies and structural and technological parameters of tillage and seeding machines. Calculations showed that when the unit moves at an angle θ = 45 ÷ 70° to the horizontal of the field, the maximum displacement of the soil occurs by the lower wing of the working body (Δ1). Minimal mechanical soil erosion is provided for lancet working bodies when the unit moves relative to the horizontal of the field at an angle of 90 ± 35°, for unilateral working bodies - 120 ± 40°. It is desirable to avoid the direction of movement of the unit θ ≈ 0 ... 70°, when maximum mechanical erosion is observed when processing by one-sided working bodies (plow bodies) exceeding mechanical erosion when moving along the field horizontals 1.5 times.