Method for determining linear resolution on terrain taking into account horizontal angle of field of view of earth remote sensing aerial complexes

Abstract

FIELD: technical physics.SUBSTANCE: invention for use in testing optical-electronic systems (OES) for remote sensing of the Earth. The claimed method for determining the linear resolution is characterized by the fact that line target sheets are installed on the ground, with a priori specified values of the altitude and flight course of the aircraft (A / C), aerial photography of the targets is performed, the aerial photographs are processed, and an estimate of the linear resolution per pixel of the A / C OES is calculated as the arithmetic mean of the values of the estimates obtained from the decoded images of the line targets, each of which corresponds to the minimum width of the line in the recognized groups of lines, and the linear resolution on the ground is determined taking into account the contrast of the line target. At the same time, while performing aerial photography, the line target measures the viewing angle and the horizontal angle of the field of view of the OES, and calculates the linear resolution of the line target taking into account the viewing angle and the horizontal angle of the field of view of the OES.EFFECT: increase in the accuracy of linear resolution assessment.1 cl, 1 tbl

Description

[0001] The invention relates to technical physics and can be used in conducting flight (natural) tests of aviation complexes for remote sensing of the Earth for the purpose of their qualimetry based on the analysis and processing of images of ground-based line targets in the visible range.

[0002] The closest analogue known from the prior art is a method for determining the linear resolution on the ground of the optoelectronic system of an aircraft (patent for invention RU 2732784), according to which, along and across the flight path of an aircraft equipped with an optoelectronic system, target sheets are laid out on the ground and stretched horizontally as much as possible using pegs. These target sheets are dark rectangular sheets made of inextensible rubberized fabric with absolutely white strokes applied to them. Then, with a priori specified values ​​of the altitude and flight course of the aircraft, aerial photography is performed of the areas of the terrain with the stroke targets placed on them, the aerial photographs are processed and an estimate of the linear resolution on the ground of the optoelectronic system of the aircraft is calculated as the arithmetic mean of the values ​​of the estimates obtained by all operators-decoders for all images of the target.each of which is the minimum stroke width in the recognized stroke groups in which all the strokes are observed separately along their entire length, with the target consisting of a set of 19 square stroke groups, each group having 3 parallel strokes of the same length and width, the ratio of the length and width of each stroke being 5:1, with the stroke widths in the target sets being 0.01; 0.02; 0.03; 0.04; 0.05; 0.06; 0.07; 0.08; 0.09; 0.1; 0.2; 0.3; 0.4; 0.5; 0.6; 0.7; 0.8; 0.9; 1.0 m, the stroke groups are sequentially arranged on the target web in order of increasing stroke width, aligned along the edge of the web, and the web is equipped with a radio frequency identification tag.

[0003] Also known is a method for determining the linear resolution per pixel of an optical-electronic system of an aircraft, characterized by the fact that on the ground along and across the flight path of an aircraft equipped with an optical-electronic system, target sheets are laid out and, using pegs, stretched horizontally as much as possible, which are dark sheets of inextensible rubberized fabric with absolutely white strokes applied to them, then, with a priori specified values ​​of the altitude and flight course of the aircraft, an aerial survey of the areas of the terrain with the placed line targets is carried out, the aerial photographs are processed and an estimate of the linear resolution per pixel of the optical-electronic system of the aircraft is calculated as the arithmetic mean of the values ​​of the estimates obtained by all operators-decoders for all the decoded images of the line targets, each of which corresponds to the minimum width of the stroke in the recognized groups of strokes,

[0004] distinguished in that, simultaneously with the aerial photography, when the aircraft flies over the line target, the brightness of the white and dark lines is measured on the ground and the real contrast of the line target is calculated using the formula , where L с andL т – results of brightness measurements of light and dark strokes of the target, cd / m 2 ,

[0005] calculate the value of the linear resolution on the ground of the optical-electronic system for a given contrast of the line target, for which the linear resolution on the ground is calculated. р in the line world of a priori given contrastK ТТЗ according to the formula

[0006] ,

[0007] whereL ЛЭ – the value of the linear resolution on the ground obtained during the flight experiment, - a priori given contrast of the line world, - real contrast of the line world.

[0008] The disadvantage of these technical solutions is the need to maintain the direction of aerial photography strictly perpendicular to the line target (nadir), as well as the low accuracy of determining the linear resolution on the ground of optical-electronic systems due to the lack of consideration of the viewing angle and the horizontal angle of the field of view when calculating the linear resolution on the ground of the optical-electronic system of the aircraft.

[0009] The technical objective of the claimed invention is to develop an arsenal of methods for qualimetry of optical-electronic aviation complexes for remote sensing of the Earth during their testing.

[0010] The solution to the technical problem is ensured by the fact that on the ground, along and across the flight path of an aircraft equipped with an optical-electronic aviation complex for remote sensing of the Earth, target sheets are laid out and, using pegs, stretched horizontally as much as possible, which are dark sheets of inextensible rubberized fabric with absolutely white strokes applied to them, then, with a priori specified values ​​of the altitude and flight course of the aircraft, an aerial survey of the areas of the terrain with the placed line targets is carried out, the aerial photographs are processed and an estimate of the linear resolution per pixel of the optical-electronic aviation complex for remote sensing of the Earth is calculated as the arithmetic mean of the values ​​of the estimates obtained by all operators-decipherers for all the decoded images of the line targets, each of which corresponds to the minimum width of a stroke in the recognized groups of strokes,Simultaneously with the aerial photography, when the aircraft flies over the line target, the sighting angle and horizontal angle of the field of view of the OES are measured on the ground using the on-board measurement system, the value of the linear resolution on the ground of the optical-electronic aviation complex for remote sensing of the Earth for a given contrast of the line target is calculated, for which the linear resolution on the ground L is calculated, р in the line world of a priori given contrastK ТТЗ according to the formula , where L ЛЭ – the value of the linear resolution on the ground obtained during the flight experiment, - a priori given contrast of the line world, – the actual contrast of the line target, calculates the value of the linear resolution on the ground of the optical-electronic aviation complex taking into account the viewing angle α and the horizontal angle of the field of view ECO

[0011] , calculate the arithmetic mean value of the linear resolution on the ground, obtained by all decoders for all decoded images: , where m is the total number of decryption results.

[0012] The technical result achieved by the combination of features of the claimed invention consists in increasing the accuracy of estimating the linear resolution on the ground of optical-electronic systems of manned and unmanned aerial vehicles based on the recalculation of the viewing angle and the horizontal angle of the field of view of the optical-electronic systems.

[0013] The implementation of the claimed method consists of performing the following sequence of actions.

[0014] 1. Installation of a dashed line on the ground along and across the direction of flight of the aircraft (manned or unmanned).

[0015] 2. Determination of the viewing angle α and the horizontal field of view angle α гThe measurement is carried out using the parameters of the on-board measurement system simultaneously with aerial photography of the line target.

[0016] 3. Determining the actual contrast of the line target by measuring the brightness of white and dark lines on the ground. Brightness measurements are conducted simultaneously with aerial photography as the aircraft flies over the line target. Contrast is determined using the formula , where L с andL т – results of brightness measurements of light and dark strokes of the target, cd / m 2 .

[0017] 4. Aerial photography of the terrain using a visible range target placed on it using an optoelectronic aerial system at specified altitude and flight path values. Testing (flights) are conducted in clear weather conditions.

[0018] 5. When performing flights, it is necessary to ensure such a lateral distance from the aircraft's flight path of the visible range line target located on the earth's surface so that the images of the visible range line target fall in the center of the frame.

[0019] 6. The longitudinal and transverse axes of the visible range dashed target stripes must be within ±10° of the lines perpendicular and parallel to the flight direction, respectively, in the absence of objects shading the surface of the area on which the target is located.

[0020] 7. The visible range target image should be in the center of the frame.

[0021] 8. To calculate the linear resolution estimate on the ground of the optical-electronic aviation complex, it is necessary to obtain at least 20 images of the visible range line target.

[0022] 9. The analysis of the received images must be performed by at least three decoder operators.

[0023] 10. Analysis of the obtained images of the visible range line target on an automated workstation of image visualization equipment. The image is analyzed by sequentially reading the image of each line of the target with different spatial frequency values ​​along its entire length.

[0024] 11. Based on the aerial photography results, a selection of images is made from a visible range line target, located in the center of the frame, obtained with angular oscillations of the aircraft not exceeding permissible values ​​(images in which the location of the line target from the center of the frame is no more than 20% of the capture width of the optical-electronic aircraft complex are accepted for consideration).

[0025] 12. Carrying out decoding of selected images of the visible range line target.

[0026] 13. Determination of a recognized group of strokes in which all strokes are observed separately along their entire length and the smallest width group of strokes in which all strokes are distinguished separately along their entire length (there is a visual perception of the difference in the level of gray tone on the screen between each light stripe and the adjacent dark stripes along their entire length).

[0027] 14. Enlarge the image of the recognized group of strokes of the line target to the limit value, determine on the image the distance between adjacent white strokes of the target of the recognized group of strokes.

[0028] 15. The final value of the linear resolution on the ground is taken as the arithmetic mean value obtained by all decipherers for all deciphered images.

[0029] ,

[0030] where m is the total number of decryption results.

[0031] 16. Performing the calculation of the linear resolution on the ground (L р) according to the stroke world of the given contrast in the tactical and technical assignment

[0032] ,

[0033] where - a real contrast of worlds,L ЛЭ - linear resolution on the terrain obtained in the flight experiment.

[0034] 17. Calculation of the linear resolution value taking into account the viewing angle of the OES and the horizontal angle of the field of view of the line target on the ground

[0035] ,

[0036] where α is the viewing angle of the OES, - horizontal angle of the field of view of the OES, corresponding to the recognized size of the stroke of the stroke target [Tishchenko AI, Artyshchenko SV A mathematical model of the detection probability of the point target by the operator of the payload electro-optical system for unmanned aerial vehicle, J. Sib. Fed. Univ. Eng. & Technol., 2020, 13(3), 328-337].

[0037] Example

[0038] The results of the flight experiment are presented in Table 1. The LRM was estimated without taking into account the viewing angles (at nadir) and at different viewing angles of the OESα=30...50°, - horizontal field of view angle OESα=10...20°. As a result of the implementation of the claimed method, the accuracy of LRM estimation increased by 2...2.6%.

[0039] Table 1 - Results of the flight experiment

[0040] Flight experiment 1 2 3 4 LRM Lp, m 0,05 0,05 0,05 0,05 Field of view angle, ° 10 20 20 10 Sight angle α,° 50 30 40 40 LRM Li, m 0,0487 0,0489 0,0512 0,051 Increase in the accuracy of LRM estimation, % 2,6 2,2 2,4 2

[0041] The difference of the declared method is that, in order to increase the accuracy of the linear resolution assessment on the ground, the sighting angle and the horizontal angle of the field of view are taken into account, which is measured simultaneously with the aerial photography of the line target during the flight of the aircraft.

[0042] The technical result achieved by the combination of features of the claimed invention consists in increasing the accuracy of the assessment of the linear resolution on the ground of the optical-electronic aviation complex of manned and unmanned aerial vehicles based on the value of the focal length of the optical-electronic aviation complex.

Claims

A method for determining the linear resolution on the ground of aerial systems for remote sensing of the Earth (ERS), characterized by the fact that on the ground along and across the flight path of an aircraft (AC) equipped with an optical-electronic aviation system for ERS, target sheets are laid out and stretched horizontally as much as possible using pegs. These target sheets are dark sheets made of inextensible rubberized fabric with absolutely white strokes applied to them, then, with a priori specified values ​​of the altitude and flight course of the AC, an aerial survey is carried out of areas of the terrain with the placed stroke targets, the aerial photographs are processed and an estimate of the linear resolution per pixel of the optical-electronic aviation system for ERS is calculated as the arithmetic mean of the values ​​of the estimates obtained by all operators-decipherers for all decoded images of the stroke targets, each of which corresponds to the minimum width of a stroke in the recognized groups of strokes, characterized in that,that simultaneously with the aerial photography, when the aircraft flies over the line target, the viewing angle α and the horizontal angle of the field of view are measured, OES, calculate the value of the linear resolution on the ground of the optical-electronic aviation complex of remote sensing for a given contrast of the line target, for which they perform a calculation of the linear resolution on the ground L р in the line world of a priori given contrastK ТТЗ according to the formula , where L ЛЭ – the value of the linear resolution on the ground obtained during the flight experiment, – a priori given contrast of the stroke world, – the actual contrast of the line target, the linear resolution value of the line target on the ground is calculated taking into account the viewing angle and the horizontal angle of the field of view of the OES , where α is the viewing angle of the OES, – horizontal angle of the field of view of the OES, corresponding to the recognized size of the stroke of the stroke target.