DE102022125348A1 - Watercraft for validating multi- and hyperspectral optical data - Google Patents

Abstract

In a watercraft for validating multi- and hyperspectral optical data from bodies of water with - at least one floating body, - at least one drive unit for driving the floating body on a body of water, - at least one first measuring device for directly or indirectly measuring a measured variable relevant for the validation of the multi- and hyperspectral optical data, preferably the measured variable is the Remote Sensing Reflectance (Rrs), - at least one control device for controlling the drive unit, it is provided that the drive unit is an omnidirectional drive unit and the control device is designed to control the omnidirectional drive unit such that the device can be moved in any direction on the body of water and can be rotated as desired about a substantially vertical axis independently of this.

Description

The invention relates to a watercraft for validating multi- and hyperspectral optical data in the area of water according to claim 1, and a method for validating multi- and hyperspectral optical data in the area of water according to claim 13.

It is known to validate multi- and hyperspectral optical data in the area of water. In known devices, at least one measuring device can be provided for directly or indirectly measuring a measurement variable relevant to the validation of the multi- and hyperspectral optical data. The main measurement variable is the Remote Sensing Reflectance (Rrs). Watercraft are often used for this purpose. Watercraft can be, for example, ships or boats. The watercraft have at least one floating body. Furthermore, at least one drive unit is usually provided for driving the floating body on a body of water and at least one control device for controlling the drive unit.

A common problem with known devices is that the measurements are influenced by the characteristics of the watercraft used, to the detriment of accuracy.

The object of the present invention is therefore to create a device and a method with which more precise measurements are possible.

The features of claims 1 and 13 serve to solve this problem.

The invention advantageously provides that the drive unit is an omnidirectional drive unit and the control device is designed to control the omnidirectional drive unit in such a way that the device can be moved in any direction on the body of water and independently thereof about a substantially vertical axis can be rotated as desired.

The present invention has the advantage that the drifting of the watercraft can be avoided. The drifting can be counteracted by means of the omnidirectional drive unit and the control of the omnidirectional drive unit. Since measuring the measurement quantity relevant for the validation of the multi- and hyperspectral optical data can often take several seconds to minutes, a much more precise measurement can be carried out by avoiding drift.

The invention has the advantage that the watercraft can be unmanned.

The previous state of the art had the disadvantage that manned ships and/or boats were often used for previously known measurements of the measurement quantity relevant for the validation of multi- and hyperspectral optical data, but these often have superstructures or similar and people are present on the ship or boat. This has the disadvantage that the superstructures and the people can reflect light in the direction of the measuring device or shade the incoming radiation from the upper hemisphere. This distorts the measurement result.

The invention also has the advantage that an undesirable change in the orientation of the watercraft can be prevented by freely rotating it about a vertical axis. An undesirable or uncontrolled change to the watercraft can otherwise lead to an undesirable change in the measurement geometry in relation to the desired angle relative to the sun, as well as a change in the influence of the ship/boat on the measurement, such as by casting shadows. With the present invention, these disadvantages are avoided.

At least one position determination device can be provided for determining the current position, the position determination device preferably being a GPS position determination device.

The drive unit can be controlled depending on the data determined by means of the position determining device.

The control device can be designed to control the drive unit in such a way that the position and/or the alignment or orientation of the device remains constant, at least during the measurement for the validation of the multi- and hyperspectral optical data.

The alignment or orientation can remain constant with respect to a fixed point, such as a fixed point on land.

The control device can have a manual operating mode and/or an automatic operating mode, wherein in the manual operating mode control commands can be specified by an operator.

In manual operating mode, the control device can also be operated remotely.

The at least one first measuring device can be at least a spectrometer.

By means of the first measuring device, the radiation from the upper hemisphere (E _d ) and/or the radiance of the sky (L _s ) and/or the rising radiation from the water (L _u ) can be measured.

An evaluation device can be provided which determines the remote sensing reflectance (Rrs) values measured by the measuring device. The evaluation device can be provided on or at the watercraft. Alternatively, it can also be provided externally.

The watercraft can be a boat, a ship or a floating platform.

A probe can be provided which is connected to the floatable body located on the body of water via a rope-like element and a data transmission element, the probe being able to be lowered underwater by means of a device for raising and lowering the probe, the probe having at least a second measuring device for measuring the spectral reflection of the water bottom. The data transmission element can be a cable for data transmission.

The device for raising and lowering the probe can be a winch.

The at least one second measuring device can be a spectrometer.

• - Antreiben eines schwimmbaren Körpers auf einem Gewässer mittels zumindest einer Antriebseinheit,
• - Messen einer für die Validierung der multi- und hyperspektralen optischen Daten relevante Messgröße mittels zumindest einer ersten Messeinrichtung, vorzugsweise ist die Messgröße die Remote Sen-sing Reflectance (Rrs),
• - Steuern der Antriebseinheit mittels einer Steuereinrichtung, wobei
• - die Antriebseinheit eine omnidirektionale Antriebseinheit ist und wobei die omnidirektionale Antriebseinheit derart gesteuert wird, dass die Vorrichtung in jede beliebige Richtung auf dem Gewässer fortbewegt werden kann und davon unabhängig um eine im Wesentlichen vertikale Achse beliebig drehbar ist.

According to the present invention, a method for validating multi- and hyperspectral optical data from waters may further be provided, comprising the following steps:

• - driving a floatable body on a body of water by means of at least one drive unit,
• - measuring a measurement variable relevant to the validation of the multi- and hyperspectral optical data using at least a first measuring device, preferably the measurement variable is the remote sensing reflectance (Rrs),
• - Controlling the drive unit by means of a control device, wherein
• - the drive unit is an omnidirectional drive unit and wherein the omnidirectional drive unit is controlled in such a way that the device can be moved in any direction on the body of water and can be independently rotated in any direction about a substantially vertical axis.

Exemplary embodiments of the present invention will be explained in more detail below with reference to the drawings.

• 1 ein Wasserfahrzeug der vorliegenden Erfindung
• 2 erste Messeinrichtung
• 3 ein Wasserfahrzeug in der Draufsicht
• 4 das Wasserfahrzeug nach 3 mit Verlauf der Strahlung
• 5 das Wasserfahrzeug aus 3 in einer Seitenansicht
• 6 das Wasserfahrzeug in einer weiteren Seitenansicht
• 7 das Wasserfahrzeug nach 6 mit Verlauf der Strahlung
• 8 das Wasserfahrzeug mit Sonde
• 9 das Wasserfahrzeug mit abgesenkter Sonde

It shows schematically:

• 1 a watercraft of the present invention
• 2 first measuring device
• 3 a watercraft in top view
• 4 the watercraft 3 with the course of the radiation
• 5 the watercraft 3 in a side view
• 6 the watercraft in another side view
• 7 the watercraft 6 with the course of the radiation
• 8th the watercraft with probe
• 9 the watercraft with the probe lowered

1 shows a watercraft 1 for validating multi- and hyperspectral optical data in the area of waters 5. As in 1 As shown, such a watercraft 1 has at least one floating body 2. In the exemplary embodiment shown, two floating bodies 2 are shown. The watercraft 1 also has a drive unit 4 for driving the floating body 2 in the body of water 5. In the exemplary embodiment shown, the drive unit 4 has nozzles, preferably propeller nozzles, which are rigidly mounted, preferably offset by 90 degrees to one another. The nozzles are arranged in such a way that they can navigate the watercraft 1 in any direction with the control device 8 by controlling the speed. The watercraft can, for example, hold its position against wind and current without the watercraft turning.

Regardless of this, rotation about the vertical axis 10 is possible both while driving and on the spot in order to assume a desired measuring position. The drive unit 4 formed by the nozzles is an omnidirectional drive unit 4. The control device 8 is designed to control the omnidirectional drive unit 4 in such a way that the watercraft 1 can be moved in any direction on the body of water 5 and independently of this about the essentially vertical axis 10 can be rotated as desired.

In 1 Furthermore, a probe 13 is shown, which is more precisely related to the 8th and 9 shown described.

The first measuring device 6 for the direct and indirect measurement of a measurement quantity relevant for the validation of the multi- and hyperspectral optical data can be configured with respect to 2 be explained in more detail. In 2 a structure of the at least one first measuring device is shown only schematically.

und hat die Einheit sr^-1.

• • Lw ist die das Wasser verlassende Strahldichte (engl. water leaving radiance)
• • Ed ist die Einstrahlung aus der oberen Hemisphäre (engl. downwelling irradiance)

The measurement variable relevant for the validation of the multi- and hyperspectral optical data is preferably the so-called Remote Sensing Reflectance (Rrs). It is defined as follows: $$\text{Rs}\left(\lambda \right)=Lw\left(\lambda \right)/Ed\left(\lambda \right)$$

and has the unit sr ^-1 .

• • Lw is the water leaving radiance
• • Ed is the downwelling irradiance from the upper hemisphere.

Lw cannot be measured directly because a measuring device 6′ directed at the surface of the body of water 5, preferably a spectrometer, sees the reflection of the sky Lr on the surface of the body of water in addition to Lw. The latter must therefore be subtracted from the measured rising radiation from the body of water Lu (upwelling radiance) in order to obtain Lw: $$Lw\left(\lambda \right)=Lu\left(\lambda \right)-Lr\left(\lambda \right)$$

To validate optical data, Lu and Ed can be measured just above the surface of the body of water 5. Since the sizes depend on the wavelength, spectrometers (wavelength range approx. 350-900 nm) are used for this purpose.

A common standard procedure according to Mobley (1999), which can be used for validation, recommends measuring Lu not vertically downwards, but at an angle deviating from vertical by 40° (off-nadir angle) in order to avoid reflections of the sun the surface of the water 5 (sun glitter or sun glint).

For the same reason, the measuring device 6', in particular the spectrometer used to measure Lu, should be positioned at an angle of 135° (rotation in the horizontal plane, azimuth difference) to the sun. In order to estimate Lr, the radiance of the sky (Lsky or Ls) is also measured at an angle deviating by 40° from the zenith (off-zenith angle). This is the portion of the radiation that is responsible for the reflections in the sky that the spectrometer measuring Lu sees.

The reflected radiance of the sky Lr can be estimated according to Mobley with: $$Lr\left(\lambda \right)~Ls\left(\lambda \right)-0.028$$

Instead of three different measuring devices 6 ', the watercraft can have three correspondingly aligned optics, which are shown in the following figures and are marked 14, 15. The radiation redirected with the optics 14, 15 can preferably be switched one after the other to the measuring device 6 via fiber optics in order to measure Lu, Ed and Ls. In the drawings, the optics for LS and Ed are both labeled 14, although they are actually two separate optics.

Ed can be measured not only directly by means of the optics 14 provided for this purpose, but also indirectly by means of the Lu optics 15, in front of which a horizontally aligned reflection standard is pushed, so that the results of these two methods for determining Ed can be compared with each other.

The off-nadir angle of the optics 15 for Lu and the off-zenith angle of the optics 14 for Ls can be adjustable. The angles can be adjusted electromechanically, for example. According to Mobley's method, 40° is set. However, angles other than those recommended by Mobley can be set.

According to Mobley, the azimuth difference of the measuring direction or the optics 14 relative to the sun is 135°. This is set by rotating the entire watercraft 1, whereby the orientation of the watercraft 1 must then be kept constant during the entire measurement. Since the watercraft must also maintain its position and counteract drift caused by wind and current, the special omnidirectional drive unit 4 is necessary, in which orientation and direction of travel are independent of each other.

In order to compensate for the rocking of the watercraft 1 caused by the wave movements, the optics 14, 15 are mounted on stabilizing mounts 16, so-called gimbals. The reference plane to which the measuring angles are set therefore always remains vertical.

3 shows the watercraft 1 in a top view. The floating bodies 2 can be seen, which are connected to one another via a machine frame 7. A control device 8 is also shown.

In addition, a position determination device 12 is provided for determining the current position. The position determination device 12 can preferably be a GPS position determination device.

The drive unit 4 can be controllable depending on the data determined by the position determining device 12.

As already mentioned, the optics 14 and 15 can also be seen, which are attached to the machine frame 7 via stabilizing mounting units 16.

In 4 is the same view as in 3 shown. The radiations L _u , L _s and E _d are also shown again. Furthermore, the sun 20 is also shown and the azimuth difference of the measuring device 6 or the optics 14 compared to the sun 20.

5 shows a side view. In the 5 the nozzles of the drive unit 4 are shown. The nozzles can be fixed or movable. Four nozzles are preferably provided. However, only three nozzles can also be provided. This depends on the geometry of the watercraft.

6 another side view is shown. In 5 and 6 In addition, the vertical axis 10 is shown around which the watercraft 1 can rotate. Preferably, in the embodiments, the vertical axis 10 is the central axis of the entire floating body 2.

In 7 is the same side view as in 6 shown. From the 7 However, the radiation L _u and L _s and Ed are shown again.

In 8th the probe 13 is shown in more detail. The probe 13 can be connected to the floating bodies located on the body of water 5 via a rope-like element 22 and a data transmission element 23. In the exemplary embodiment shown, the probe 13 is indirectly connected to the floating bodies 2, since the probe is directly connected to the machine frame 7 and the machine frame 7 is connected to the floating bodies 2. The probe 13 can be lowered under water by means of a device 25 for raising and lowering the probe, wherein the probe 13 has at least one second measuring device 24 for measuring the spectral reflection of the bottom of the body of water 26.

The device 25 for raising and lowering the probe 13 can be a winch. The second measuring device 24 can be a spectrometer. In 9 the device is off 8th shown again in the front view. The probe 13 can be lowered to the bottom of the water.

Claims (14)

Watercraft (1) for validating multi- and hyperspectral optical data in the area of bodies of water (5) with - at least one floating body (2), - at least one drive unit (4) for driving the floating body (2) on a body of water (5), - at least one first measuring device (6) for directly or indirectly measuring a measured variable relevant for the validation of the multi- and hyperspectral optical data, preferably the measured variable is the remote sensing reflectance (Rrs), - at least one control device (8) for controlling the drive unit (4), characterized in that the drive unit (4) is an omnidirectional drive unit (4) and the control device (8) is designed to control the omnidirectional drive unit (4) such that the watercraft (1) can be moved in any direction on the body of water (5) and can be rotated as desired about a substantially vertical axis independently thereof. Watercraft to Claim 1 , characterized in that at least one position determining device is provided for determining the current position, wherein the position determining device is preferably a GPS position determining device. Watercraft to Claim 2 , characterized in that the drive unit can be controlled as a function of the data determined by means of the position determining device. Watercraft according to one of the Claims 1 until 3 , characterized in that the control device is designed to control the drive unit in such a way that the position and / or orientation of the device remains constant at least during the measurement for the validation of the multi- and hyperspectral optical data. Watercraft according to one of the Claims 1 until 4 , characterized in that the control device has a manual operating mode and/or an automatic operating mode, wherein control commands can be specified by an operator in the manual operating mode. Watercraft according to one of the Claims 1 until 5 , characterized in that the at least one first measuring device is at least one spectrometer. Watercraft according to one of the Claims 1 until 6 , characterized in that by means of the first measuring device the radiation from the upper hemisphere (E _d ) and/or the radiance of the sky (L _s ) and/or the rising radiation from the water (L _d ) can be measured. Watercraft according to one of the Claims 1 until 7 , characterized in that an evaluation device is provided which determines the remote sensing reflectance (Rrs) from values measured by the measuring device. Watercraft according to one of the Claims 1 until 8th , characterized in that the watercraft can be a boat, a ship or a floatable platform. Device according to one of the Claims 1 until 9 , characterized in that a probe is provided which is connected to the floating body located on the body of water via a rope-like element and a data transmission element, wherein the probe can be lowered under water by means of a device for raising and lowering the probe, wherein the probe has at least one second measuring device for measuring the spectral reflection of the bottom of the body of water. watercraft Claim 10 , characterized in that the device for raising and lowering the probe is a winch. Watercraft to Claim 10 or 11 , characterized in that the at least one second measuring device is a spectrometer. Method for validating multi- and hyperspectral optical data in the area of water by - driving a floatable body on a body of water by means of at least one drive unit, - measuring a measurement variable relevant for the validation of the multi- and hyperspectral optical data by means of at least one first measuring device, preferably the measurement variable is the remote sensing reflectance (Rrs), - controlling the drive unit by means of a control device, characterized in that the drive unit is an omnidirectional drive unit, wherein the omnidirectional drive unit is controlled such that the device can be moved in any direction on the body of water and can be rotated as desired about a substantially vertical axis independently thereof. Procedure according to Claim 13 , characterized in that the position and / or orientation of the swimmable body remains constant at least during the measurement for the validation of the multi- and hyperspectral optical data.

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