WO2021083853A1

WO2021083853A1 - System for use in determining the change in elevation and/or lateral displacement of a geographic location over time, and a link for such a system

Info

Publication number: WO2021083853A1
Application number: PCT/EP2020/080102
Authority: WO
Inventors: Niels Olaf Vinther JENSEN; Karsten VOGNSEN
Original assignee: Geopartner Inspections A/S
Priority date: 2019-10-28
Filing date: 2020-10-27
Publication date: 2021-05-06

Abstract

The present invention relates to a system for use in determining the change in elevation of a geographic location over time. The system comprises a) a retroreflector; b) a link adapted for supporting, tilting, and rotating said retroreflector; and c) a base adapted for supporting the link and for being positioned on the ground.

Description

System for use in determining the change in elevation and/or lateral displacement of a geographic location over time, and a link for such a system

Technical field of the invention

The present invention relates to satellite radar measurements of altitude changes on the earth's surface, and more particularly to a ground system for such measurements.

Background of the invention

When extreme rain and storm hit the land, basements, roads and houses in low- lying areas are flooded - causing major damage.

One of the most important uses of elevation data is to map flood risk and identify the areas where it is necessary to build dikes or establish new corridors that can lead the water away.

Some countries, such as Denmark, store detailed information on the altitude conditions in their territory, which can be used to map where the rainwater flows during extreme weather conditions, such as cloudbursts. These elevation data provide the opportunity to produce detailed and accurate maps showing the penetration and distribution of water in the city and along coasts and streams for the entire territory. The data are also used by municipalities and state authorities in the long-term planning of climate change efforts.

As the ground surface level in a given area is not static, it is important to continuously update the elevation data. Hence, it is an object of the present invention to provide a system that can do exactly that.

Summary of the invention

The purpose of the present invention is to establish a series of radar reflectors on ground to measure altitude changes on the earth's surface from satellites (vertical land movement). Knowledge about elevation changes is very important for the infrastructure, from stability monitoring of, for example, major buildings and railway dams to ensure that sewerage systems are functional throughout the budgeted lifetime. The climate is changing with more extreme weather conditions, where the earth is rising and lowering, and the sea level is rising in line with the global warming and melting of the ice caps. It places greater demands on monitoring a country's dikes, and questions arise whether they have the right height and strength to withstand the pressure of the water masses.

Data is collected or calculated on an ongoing basis, and land movements can be projected and included in the local and national climate adaptation.

A first aspect relates to a system for use in determining the change in elevation and/or lateral displacement of a geographic location over time, the system comprising:

- a retroreflector;

- a link adapted for supporting, tilting, and rotating said retroreflector; and

- a base adapted for supporting the link and for being positioned on the ground.

The use of space technology to monitor the evolution of the earth is rapidly evolving, and therefore new satellites with improved technologies can be expected to allow for better resolution in the radar images. One suitable existing technology is the synthetic aperture radar (SAR) system that generally operates at a frequency between 400 Mhz and 10 Ghz, and is installed on satellite platforms orbiting at an altitude between 250 - 800 km. The radar antenna is directed towards earth in an orthogonal way with respect to the direction of motion of the platform with a so-called "off-nadir" angle, between 20 - 80 degrees with respect to the Nadir direction, i.e. perpendicularly to the earth. The distance the SAR device travels over a target in the time taken for the radar pulses to return to the antenna creates the large synthetic antenna aperture (the size of the antenna). Interferometric synthetic aperture radar, abbreviated InSAR, uses two or more synthetic aperture radar (SAR) images to generate maps of surface deformation or digital elevation, using differences in the phase of the waves returning to the satellite. The technique can potentially measure millimeter-scale changes in deformation over spans of days to years.

In one or more embodiments, the system further comprises a satellite comprising a synthetic aperture radar system, or the like.

The present invention provides a link that allows for fast and easy mounting of a multitude of radar retroreflectors, and to accommodate for future changes in satellite orbits, changed camera angles, new types of retroreflectors, and new types of radar systems utilizing retroreflectors.

The term “retroreflector” as used herein defines a reflector, which returns a radar beam to its source, regardless of the angle of incidence. Suitable non-limiting examples of retroreflectors may be found in EP2585850 or W018236215, hereby incorporated by reference, but could alternatively be a corner retroreflector.

The base should be configured not to sink into the ground. This could be done by mounting the base onto a stabile foundation, such as a concrete foundation. The base needs not to be mounted directly on the ground but could also be mounted on an object on the ground, such as on a roof top. The link is adapted for supporting, tilting, and rotating the retroreflector. The existence of means for rotating and tilting the retroreflector allows for precisely positioning of the retroreflector for use for a specific satellite in a specific orbit, with a specific camera angle. Furthermore, it allows for exchange of old types of mounted retroreflectors to new types of retroreflectors without having to remove or change the link and the base. Thereby, historic data will still be valid for the same measuring point as the base is kept in place.

In one or more embodiments, the retroreflector is integrated into a piece of furniture, such as a bench, sofa, chair, table, or the like. This configuration hides the true function of the retroreflector and at the same time provides a new function for people to appreciate.

In one or more embodiments, the link comprises:

- a support unit having a first end and a second end;

- a first plate tiltably connected to the support unit at the first end; and

- a second plate tiltably connected to the support unit at the second end. This configuration allows for a very precise angulation of the retroreflector relative to the satellite. Basically, the support unit can tilt relative to the base, and the retroreflector may tilt relative to the support unit.

In one or more embodiments, the support unit is shaped as a rectangular prism, such as a square prism. Alternatively, the support unit may be formed as a rectangular tube, such as a square tube. In both cases, the support unit comprises a first and a second pair of opposing sides; and wherein the first plate is tiltably connected to the first pair of opposing sides of said prism or tube, and wherein the second plate is tiltably connected the second pair of opposing sides of said prism or tube.

In order to make the link operable by one person, the support unit may in one or more embodiments comprise 2-4 plate-shaped protrusions, preferably four, each with a threaded channel formed therein, into which channel is positioned a threaded bolt; wherein at least one bolt, preferably two bolts, when turned, is adapted to push on the first plate tiltably connected to said support unit, and wherein at least one bolt, preferably two, when turned, is adapted to push on the second plate tiltably connected to said support unit, thereby being able to tilt said plates relative to said support unit.

In one or more embodiments, the retroreflector comprises a third plate rotatably coupled to the link’s first plate. This configuration allows the retroreflector to be rotated relative to the link.

In order to make it possible for one person to adjust the orientation of the retroreflector relative to a satellite, the third plate, in one or more embodiments comprises a protrusion extending from its outer rim towards the first plate; wherein the first plate comprises a protrusion extending from its outer rim away from the third plate; and wherein said protrusions are coupled by a bolt that when turned is adapted to rotate said plates relative to one another. The bolts may in some embodiments be spring-biased.

In one or more embodiments, the first plate comprises a rotation limiting guide recess, and wherein the third plate comprises a stop pin configured for rotatably engaging with said rotation limiting guide recess. The rotation limiting guide recess and the stop pin have three functions. They secure that the two plates will not displace sideward relative to one another. Furthermore, they secure that the two plates are connected, such that the retroreflector stays connected to the link. Finally, the length of the rotation limiting guide recess decides the extent that the plates may be rotated relative to each other.

In order to make it possible for one person to adjust the orientation of the retroreflector relative to a satellite, the base, in one or more embodiments, comprises a fourth plate rotatably coupled to the link’s second plate. This configuration allows the link to be rotated relative to the base.

In order to make it possible for one person to adjust the orientation of the retroreflector relative to a satellite, the fourth plate, in one or more embodiments comprises a protrusion extending from its outer rim towards the second plate; wherein the second plate comprises a protrusion extending from its outer rim away from the fourth plate; and wherein said protrusions are coupled by a bolt that that when turned is adapted to rotate said plates relative to one another. The bolts may in some embodiments be spring-biased.

In one or more embodiments, the support unit is shaped as a square tube with cutouts in its upper and lower rim; wherein a) a base is positioned at the center of the first plate, which is adapted for receiving a prism reflector, e.g. a magnetic ball prism reflector and/or b) a base is positioned at the center of the second plate, which is adapted for receiving a prism reflector, e.g. a magnetic ball prism reflector.

A second aspect relates to the use of a system according to the present invention for determining the change in elevation and/or lateral displacement of a geographic location over time.

A third aspect relates to the use of a system according to the present invention for determining the change in elevation over time and for mapping flood risks.

A fourth aspect relates to the use of a system according to the present invention for determining the change in elevation over time and for identifying areas where it is necessary to build dikes or establish new corridors that can lead the water away. A fifth aspect relates to the use of a system according to the present invention for determining the change lateral displacement of a geographic location over time.

It should be noted that embodiments and features described in the context of one of the aspects of the present invention also apply to the other aspects of the invention.

As used in the specification and the appended claims, the singular forms "a",

"an", and "the" include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from "about" or "approximately" one particular value and/or to "about" or "approximately" another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about", it will be understood that the particular value forms another embodiment.

Brief description of the figures

Figure 1 shows a system according to the invention;

Figure 2 shows a second plate according to the invention; Figure 3 shows a first plate according to the invention;

Figure 4 shows a support unit according to the invention; and Figure 5 shows a system according to the invention.

Detailed description of the invention

In Figure 1 , an exemplary system according to the present invention is shown. The system comprises a retroreflector 110 (only a part of it is shown), a link 200 adapted for supporting the retroreflector, and a base 310 (only a part of it is shown) adapted for supporting the link and for being positioned on the ground. The link 200 is configured for tilting and rotating the retroreflector 110. In this specific embodiment this is performed by two different configurations. The link 200 comprises a support unit 210 is shaped as a square tube having a first end 212 and a second end 214, and a first and a second pair of opposing sides (more easily seen in Figure 4). The first plate 220 is tiltably connected to the support unit 210 at the first end 212 by its two tilt brackets 225. The tilt brackets 225 each comprises a guide recess 226 (more easily seen in Figure 3) having a curved path. A stop pin 219 is slidably engaged with the guide recess 226 and fixed to a side of the support unit 210. This configuration allows the first plate 220 to tilt relative to the support unit 210. The stop pin 219 is here configured as a bolt and nut such that it may be locked at any position along the curved path. In analogy, the second plate 230 is tiltably connected to the support unit 210 at the second end 214, and where the first plate 220 is tiltably connected to the first pair of opposing sides of the support unit 210, the second plate 230 is tiltably connected the second pair of opposing sides of said support unit 210. This configuration allows the first plate 220 to tilt in a different (orthogonal) direction than the second plate 230 relative to the support unit 210. A stop pin 219 is slidably engaged with the guide recess 236 (more easily seen in Figure 2) having a curved path in the tilt bracket 235 and fixed to a side of the support unit 210. The support unit 210 also comprises four plate-shaped protrusions 216, 217, one on each side, and each with a threaded channel formed therein, into which channel is positioned a threaded spring-biased bolt 218. The bolts function is, when turned, to push on the first 220 or second 230 plates to make it easier for a user to tilt the plates relative to support unit 210.

In order to make the retroreflector turn relative to the link, it comprises a third plate 110 rotatably coupled to the link’s first plate 220. In the embodiment in Figure 1 , the third plate 110 comprises a protrusion 112 extending from its outer rim towards the first plate 220. Similarly, the first plate 220 comprises a protrusion 222 extending from its outer rim away from the third plate 110. The protrusions 112, 222 are coupled by a bolt 224 that when turned is adapted to rotate said plates 110, 220 relative to one another. Furthermore, the first plate 220 comprises four curved rotation limiting guide recesses 223. The four rotation limiting guide recesses 223 are each rotatably engaged with a stop pin 111 connected to the third plate 110. The stop pins 111 are here configured as a bolt and nut such that it may be locked at any position along the curved path.

In order to make the link turn relative to the base, the base 310 comprises a fourth plate 310 rotatably coupled to the link’s second plate 230. The fourth plate 310 comprises a protrusion 312 extending from its outer rim towards the second plate 230. The second plate 230 comprises a protrusion 232 extending from its outer rim away from the fourth plate 310. The protrusions 312, 232 are coupled by a bolt that 234 that when turned is adapted to rotate said plates 310, 230 relative to one another. Furthermore, the second plate 230 comprises four curved rotation limiting guide recesses 233. The four rotation limiting guide recesses 233 are each rotatably engaged with a stop pin 311 connected to the fourth plate 310. The stop pins 311 are here configured as a bolt and nut such that it may be locked at any position along the curved path.

Figure 5 shows a system according to the invention, where the support unit 210 is shaped as a square tube with cutouts 211 in its upper and lower rim. Furthermore, a base 228 is positioned at the center of the first plate 220, which is adapted for receiving a prism reflector (not possible to see), e.g. a magnetic ball prism reflector. Similarly, a base 238 is positioned at the center of the second plate 230, which is adapted for receiving a prism reflector 400, e.g. a magnetic ball prism reflector. This configuration is a precaution to control from the ground if the measure altitude changes by the satellite are correct. Such a control may be performed by standard triangulation techniques, such as with a total station. Furthermore, these prism reflectors aid in obtaining a datum, e.g. by using a total station. A datum is a mathematical model that describes the part of the earth's surface to be measured. A datum allows the measured points to be positioned correctly in relation to each other. A third point to include in the datum could be a fixed point on the base 310 according to the present invention.

References

110 Retroreflector, Third plate

111 Stop pin

112 Protrusion

200 Link

210 Support unit

211 Cutout

212 First end

214 Second end

216 Protrusion

217 Protrusion

218 Bolt

219 Stop pin

220 First plate 222 Protrusion

223 Guide recess

224 Bolt

225 Bracket

226 Guide recess 228 Base 230 Second plate

232 Protrusion

233 Guide recess

234 Bolt

235 Bracket

236 Guide recess 238 Base

310 Base, Fourth plate

311 Stop pin

312 Protrusion 400 Prism reflector

Claims

1. A system for use in determining the change in elevation and/or lateral displacement of a geographic location over time, the system comprising:

- a retroreflector (110);

- a link (200) adapted for supporting said retroreflector; and

- a base (310) adapted for supporting the link and for being positioned on the ground; characterized in that the link (200) is configured for tilting and rotating said retroreflector (110).

2. The system according to claim 1 , further comprising a satellite comprising a synthetic aperture radar system, or the like.

3. The system according to any one of the claims 1-2, wherein said retroreflector is integrated into a piece of furniture, such as a bench, sofa, chair, table, or the like.

4. The system according to any one of the claims 1-3, wherein said link (200) comprises:

- a support unit (210) having a first end (212) and a second end (214);

- a first plate (220) tiltably connected to the support unit (210) at the first end (212); and

- a second plate (230) tiltably connected to the support unit (210) at the second end (214).

5. The system according to claim 4, wherein the support unit (210) is shaped as a) a rectangular prism, such as a square prism, or b) a rectangular tube, such as a square tube; wherein said support unit (210) comprises a first and a second pair of opposing sides; wherein the first plate (220) is tiltably connected to the first pair of opposing sides of said prism or tube, and wherein the second plate (230) is tiltably connected the second pair of opposing sides of said prism or tube.

6. The system according to any one of the claims 4-5, wherein said support unit (210) comprises 2-4 plate-shaped protrusions (216, 217) each with a threaded channel formed therein, into which channel is positioned a threaded bolt (218); wherein at least one bolt (218), when turned, is adapted to push on the first plate (220) tiltably connected to said support unit (210), and wherein at least one bolt (218), when turned, is adapted to push on the second plate (230) tiltably connected to said support unit (210), thereby being able to tilt said plates (220, 230) relative to said support unit (210).

7. The system according to any one of the claims 4-6, wherein said retroreflector (110) comprises a third plate (110) rotatably coupled to said link’s first plate (220).

8. The system according to claim 7, wherein said third plate (110) comprises a protrusion (112) extending from its outer rim towards said first plate (220); wherein said first plate (220) comprises a protrusion (222) extending from its outer rim away from said third plate (110); and wherein said protrusions (112, 222) are coupled by a bolt (224) that when turned is adapted to rotate said plates (110, 220) relative to one another.

9. The system according to claim 8, wherein said first plate (220) comprises a rotation limiting guide recess (223), and wherein said third plate (110) comprises a stop pin (111) configured for rotatably engaging with said rotation limiting guide recess (223).

10. The system according to any one of the claims 4-9, wherein said base (310) comprises a fourth plate (310) rotatably coupled to said link’s second plate (230).

11 . The system according to claim 10, wherein said fourth plate (310) comprises a protrusion (312) extending from its outer rim towards said second plate (230); wherein said second plate (230) comprises a protrusion (232) extending from its outer rim away from said fourth plate (310); and wherein said protrusions (312, 232) are coupled by a bolt that (234) that when turned is adapted to rotate said plates (310, 230) relative to one another.

12. The system according to claim 11 , wherein said second plate (230) comprises a rotation limiting guide recess (233), and wherein said fourth plate (310) comprises a stop pin (311 ) configured for rotatably engaging with said rotation limiting guide recess (233).

13. The system according to any one of the claims 4-12, wherein said support unit (210) is shaped as a square tube with cutouts (211 ) in its upper and lower rim; wherein a base (228) is positioned at the center of said first plate (220), which is adapted for receiving a prism reflector (400), e.g. a magnetic ball prism reflector.

14. The system according to any one of the claims 4-13, wherein said support (210) unit is shaped as a square tube with cutouts in its upper and lower rim; wherein a base (238) is positioned at the center of said second plate (230), which is adapted for receiving a prism reflector, e.g. a magnetic ball prism reflector.

15. Use of a system according to any one of the claims 1 -14 for determining the change in elevation and/or lateral displacement of a geographic location over time.

16. Use of a system according to any one of the claims 1 -14 for determining the change in elevation over time and for mapping flood risks.

17. Use of a system according to any one of the claims 1 -14 for determining the change in elevation over time and for identifying areas where it is necessary to build dikes or establish new corridors that can lead the water away.

18. Use of a system according to any one of the claims 1 -14 for determining the change lateral displacement of a geographic location over time.