DE102022001920A1 - Test field and method for testing hyperspectral sensors - Google Patents

Abstract

Test field for testing hyperspectral sensors, with a base, with a plurality of maps on the base, a first map, the first map having a Siemens star, with at least 36 inwardly tapered wedges, the wedges being white, black and colorful and a colorful wedge is always framed by a white and a black wedge and the colorful wedges have different colors, a second map, with a plurality of aluminum strips, the aluminum strips are made of aluminum foil, with the aluminum strips being the same distance from each other and the strips arranged next to each other are.

Description

The invention relates to a test field and a method for testing hyperspectral sensors in flying systems.

Test patterns for hyperspectral sensors are known from the prior art. Among other things, Siemens stars are known as test patterns. The geometric quality of optical sensors can be determined using a Siemens star. A Siemens star consists of a circle with alternating white and black circular sectors. The quality of an optical imaging system can be checked with the help of the Siemens star.

From the disclosure document DE102006048767 A1 is a device for adjusting and calibrating an infrared system, which can be used in particular for recording and evaluating thermal images, which comprises a thermally radiating body in a housing, the surface of the thermally radiating body to be recorded consisting of at least two partial patterns which have different radiation densities Have infrared range and from which a test pattern is formed, so that this test pattern represents differently bright areas in the infrared range, known.

It is the object of the present invention to enable a simple and quick check of the quality of a hyperspectral sensor.

This task is solved by technical objects according to the independent claims. Technically advantageous embodiments are the subject of the dependent claims, the description and the drawings.

According to one aspect, the object according to the invention is achieved by a test field for testing hyperspectral sensors, with a weatherproof base, with a first map on the base, the first map having a Siemens star, with at least 36 inwardly tapered wedges, the wedges being white, black and are colorful and a colorful wedge is always framed by a white and black wedge and the colorful wedges have different colors, with a second map on the base, with aluminum strips and the aluminum strips are made of aluminum foil, with the aluminum strips being the same distance from each other and the strips are arranged next to each other.

By applying several characteristic maps to the base of the test field, an accelerated, simplified and precise quality test and quality assessment of hyperspectral sensors, especially of flying systems, can be carried out. The advantage of the solution according to the invention lies in the coordinated or correlated compilation of characteristic maps. In a single operation, the properties and capabilities of the hyperspectral sensor can be determined according to the geometric, radiometric and spectral quality of the image resolution. The base is weatherproof and printable. With a weatherproof base, the test field can also be used in adverse weather conditions. The base can be, for example, a white vehicle fabric tarpaulin, which can be printed.

The first map is used to test the visible color spectrum in the wave range from 380 nm to 750 nm of the hyperspectral sensor and to test the resolution. The first map therefore has a colored Siemens star, which has inwardly tapering wedges in white, black and color. It allows determining the quality of the hyperspectral sensor in terms of imaging performance at maximum contrast of color in relation to black, no emission and to white, full emission. The wedges in color have different body colors. The color of a body depends on the parts that are reflected and absorbed and its illumination. Each color wedge has a different body color. Any color from red to violet can be used as body colors for the color wedges, with the color wedges replicating the color gradient of a rainbow.

The second map is used to test the infrared spectrum in the wave range from 750 nm to 1 mm of the hyperspectral sensor. For this purpose, strips of aluminum foil are glued on. The aluminum strips are glued to the weatherproof base of the test field. The aluminum strips are the same distance apart and have the same dimensions in length and width. The aluminum foil ensures thermal radiation reflection, which is detected by the hyperspectral sensor in order to be able to determine the quality of the hyperspectral sensor.

In a technically advantageous embodiment of the test field, the test field has a third map with rubber strips. The strips are made of rubber and are glued to the base and are the same distance apart from each other. Furthermore, the rubber strips have the same dimensions. The rubber strips have the advantage that they store heat radiation.

In a further technically advantageous embodiment of the test field, a fourth characteristic map is printed on the base. The fourth map consists of at least 4 Siemens stars, with the wedges alternating between black and white. The number of wedges of black or white are multiples of ²ⁿ . The Siemens stars can be used, for example, in 8, 16, 32 and 64 beam versions. The quality of the modulation transfer function can be determined directly using the various Siemens stars. This also makes it possible to determine the -3 dB imaging limit of the hyperspectral sensor.

In a further technically advantageous embodiment of the test field, a fifth characteristic map is printed on the base. The fifth map consists of a bar in the shape of a rectangle, with the rectangle reflecting the color gradient of a rainbow over the long side. The spectral precision of the hyperspectral sensor can be determined using the color gradient of a rainbow.

In a further technically advantageous embodiment of the test field, there is a sixth characteristic field with a gray bar in the form of a rectangle. The gray bar consists of several small rectangles arranged next to each other, one small rectangle has a gray tone. Along the long side of the gray bar, the rectangles are sorted from light to dark in shades of gray. Due to the grayscale, the radiometric precision of the aerial image sensor can be determined.

In a further technically advantageous embodiment of the test field, a seventh map with 6 sub-maps, the sub-maps being arranged next to one another, each consists of four longitudinal and four transverse strips of the same width and length. The submaps are arranged in descending geometric width. The sub-maps are reduced by 25% compared to the previous sub-map. The seventh map is used to adjust a direction of movement when the hyperspectral sensor is moved past the test field. The hyperspectral sensor can, for example, be located on a flying system and fly over the test field. The seventh map also enables the calculation of the modulation transfer function to determine the image quality of the hyperspectral sensor.

In a further technically advantageous embodiment of the test field, the base has a black frame. The black frame allows the test field to be precisely laid out in the field and to accurately record the actual size. Furthermore, the black frame allows the test field to be laid out without distortion.

1. a) Bedrucken der Unterlage des Testfeldes mit den druckbaren Kennfeldern,
2. b) Durchführen einer hyperspektralen Vermessung des gedruckten Testfeldes zur Ermittlung eines kalibrierten Farbspektrums,
3. c) Aufbringen der Streifen auf die Unterlage des Testfelds,
4. d) Verbringen und Auslegen des Testfeldes,
5. e) Erfassen des Testfeldes durch den hyperspektralen Sensor,
6. f) Auswerten der Daten des hyperspektralen Sensors,
7. g) Bestimmen der Eigenschaften und Fähigkeiten des hyperspektralen Sensors.

The test field procedure for testing hyperspectral sensors includes the following steps:

1. a) printing the test field base with the printable maps,
2. b) carrying out a hyperspectral measurement of the printed test field to determine a calibrated color spectrum,
3. c) applying the strips to the base of the test field,
4. d) moving and laying out the test field,
5. e) recording the test field by the hyperspectral sensor,
6. f) evaluating the data from the hyperspectral sensor,
7. g) Determine the characteristics and capabilities of the hyperspectral sensor.

The base of the test field is printed with the characteristics, for example with an RGB or a CMYK color printer. A spectral measurement of the printed test field is then carried out. The printed colors may deviate from the defined color values, therefore the spectral measurement of the test field is carried out with the first and second test patterns in order to have a calibrated color spectrum for testing the hyperspectral sensor. The strips to be glued are then attached.

• 1 das erste Kennfeld mit einem farbigen Siemensstern, wobei die schwarzen und weißen Keile jeweils einen farbigen Keil einrahmen. Die farbigen Keile sind in Graustufen dargestellt.
• 2 eine mögliche Anordnung der verschiedenen Kennfelder für ein Testfeld.
• 3 eine einfache Prinzipskizze mit einem hyperspektralen Luftbild-Sensor an einem fliegenden System über einem Testfeld.

Embodiments of the invention are shown in the drawings and are described in more detail below. Show it:

• 1 the first map with a colored Siemens star, with the black and white wedges each framing a colored wedge. The colored wedges are shown in grayscale.
• 2 a possible arrangement of the different maps for a test field.
• 3 a simple schematic sketch with a hyperspectral aerial image sensor on a flying system over a test field.

1 shows the first map 10 with a Siemens star, with black wedges 11, with white wedges 12 and colored wedges 13. The colored wedges 13 are shown in grayscale. Furthermore, the colored wedges 13 are framed by the black and white wedges 11, 12.

2 shows a test field 1 on a base 80 with a black frame 90 and various maps. The first map 10 with the colored Siemens star is arranged in the middle of the test field 1. The second map 20 is five Strips of aluminum foil arranged in the right area. Below the second map 20 is the third map 30 arranged with three strips of rubber. In the corners there are Siemens stars of the fourth map with different numbers of black and white wedges. The fifth map 50 with a color bar is located between two Siemens stars in the left part of the test field 1 of the fourth map 40. This is a rainbow color gradient, shown here in gray tones. The color gradient goes from red at the bottom to yellow to green to blue and ends in violet at the top. In the upper area of the test field 1, the gray bar and its small rectangles of the sixth map 60 are shown. The gray tones of the small rectangles become darker from left to right. In the lower part of the test field there is the seventh map 70 with sub-maps 71. 6 sub-maps 71 are shown. The sub-maps consist of four transverse and four longitudinal stripes. Furthermore, the sub-maps from left to right always become 25% smaller than the previous sub-map.

3 shows a flying system 100, such as a drone or an aircraft that is equipped with a hyperspectral aerial image sensor 110. The hyperspectral aerial image sensor flies over a test field 1. The test field 1 is located in a test area and was set up accordingly. The flying system 100 flies over to determine the properties and functionality of the hyperspectral aerial image sensor 110.

The functional sequence of the method is described in more detail below. To test a hyperspectral sensor, which is attached to a flying system or a vehicle, for example, maps are printed on the base of a test field. Depending on the printer, the respective color matrix must first be measured, as the real printing specifications do not correspond to the theoretical ones. For this purpose, the printed test field is measured hyperspectrally in order to obtain a calibrated color spectrum for later evaluation. The maps to be stuck on are then applied. Depending on the carrier system of the hyperspectral sensor, the test field is brought to a test area and laid out there. The test field can also be mounted on a frame and then moved to a test area using a vehicle. The test field is recorded by the hyperspectral sensor. This can be possible statically or while driving or flying, depending on the carrier system of the hyperspectral sensor. After the test field has been captured by the hyperspectral sensor, the captured images can be evaluated and the properties and functionality of the hyperspectral sensor can be determined.

Reference symbols

1

Test field

10

First map

11

Black wedge

12

White wedge

13

Colored wedge

20

Second map

30

Third map

40

Fourth map

50

Fifth map

60

Sixth map

70

Seventh map

71

Submap

80

document

90

Frame

100

Flying system

110

Hyperspectral sensor

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102006048767 A1 [0003]

Claims (8)

Test field for testing hyperspectral sensors, with - a base, - a plurality of maps on the base, - a first map, the first map having a Siemens star, with at least 36 inwardly tapering wedges, the wedges being white, black and colored and a colorful wedge always being framed by a white and a black wedge and the colorful wedges being different colors exhibit, - a second map, with a plurality of aluminum strips, the aluminum strips consist of aluminum foil, the aluminum strips being at the same distance from one another and the strips being arranged next to one another. test field Claim 1 , with a further map a third map, with a plurality of rubber strips, these rubber strips are made of rubber and these are arranged next to each other at the same distance from one another. Test field according to one of the preceding claims, with a further map, a fourth map, with at least four Siemens stars, the respective Siemens stars having alternating black and white wedges, each Siemens star having a different number of wedges, the number of wedges always being a multiple of 2 ⁿ is. Test field according to one of the preceding claims, with a further map, a fifth map, with a color bar in a rectangular shape in color, with a color gradient of a rainbow. Test field according to one of the preceding claims, with a further map a sixth map, that the sixth map consists of a gray bar, the gray bar has a rectangular shape and consists of small rectangles arranged next to one another, these small rectangles have different shades of gray. Test field according to one of the preceding claims, with a further test field a seventh map, the seventh map consists of six sub-maps, a sub-map always having four transverse and four longitudinal stripes of the same width and height, the sub-maps are arranged next to each other and the sub-maps to the previous one Submap will be 25% smaller in length and width. Test field according to one of the preceding claims, wherein the base has a black frame. Method with a test field according to one of the preceding claims, wherein the method comprises the following steps: a) printing at least one printable map on the document, b) carrying out a hyperspectral measurement of the printed first map, c) applying the second map with aluminum strips to the base, d) moving and aligning the test field, e) detecting the test field by the hyperspectral sensor, f) evaluating the data from the hyperspectral sensor, g) Determine the quality of the hyperspectral sensor in a single process according to geometric, radiometric and spectral quality of the image resolution.

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