A hyperspectral image registration method

Abstract

The present application relates to a kind of hyperspectral image registration method, first step, acquisition visible light image and hyperspectral image: the registration board with number is uniformly scattered in the region to be photographed, each registration board is marked with an independent number on the upper surface, the upper surface of registration board is adjusted level, each local visible light image of the local of the region to be photographed is collected by unmanned aerial vehicle, and the hyperspectral image of the region to be photographed is collected by hyperspectral imager carried by unmanned aerial vehicle;Second step, image stitching: the local visible light image is spliced into the global visible light image of the region to be photographed by splicing software;Third step, hyperspectral image registration.The present application aims to provide a kind of hyperspectral image registration method, which can conveniently select the reference point in the visible light image of target area, solves the problem that existing registration method cannot reliably and conveniently select reference point in visible light image.

Description

Technical Field

[0001] This invention relates to the field of agricultural and forestry resource monitoring technology, and in particular to a hyperspectral image registration method. Background Technology

[0002] Hyperspectral imaging technology, based on numerous narrow-band image data, combines imaging and spectral techniques to detect the two-dimensional geometric space and one-dimensional spectral information of a target, acquiring continuous, narrow-band image data with high spectral resolution. Hyperspectral imaging can detect both the external morphology and internal quality of an object, much like spectral techniques. Furthermore, as a specialized optical diagnostic technique, hyperspectral imaging offers advantages such as diverse imaging systems, practical clinical diagnostic applications, and functional analytical methods, possessing the potential for in-situ, real-time live diagnosis. In addition, hyperspectral imaging is widely used in mineral surveys, environmental monitoring, and agricultural and forestry resource monitoring and estimation, and also has significant applications in the real-time image feature acquisition and analysis of military targets. Unmanned aerial vehicles (UAVs), as a general aviation platform, have significantly expanded and enhanced the application scope and depth of hyperspectral imaging.

[0003] Currently, registration of airborne hyperspectral images is mainly achieved through image features and spectral transformation. For example, patent CN115205348A utilizes relative motion estimation between mid-wave images and images of other spectral bands to achieve image registration; patent CN101281645 achieves image registration through scaling transformation, region selection, and by calculating the eigenvalues ​​of the image's autocorrelation matrix or covariance matrix. While these methods are efficient and simple to operate, they may suffer from significant autocorrelation and overlapping information between multiple features, resulting in seemingly good registration results but potentially large registration errors and inconsistent accuracy. To address this, those skilled in the art have designed a method combining third-party high-resolution visible light images for hyperspectral image registration. This method requires selecting several uniformly distributed reference points in the visible light image of the target region for registration. However, due to the randomness of objects in the target region, it is difficult to find suitable reference points in the visible light image for registration, leading to reduced registration accuracy. Summary of the Invention

[0004] The present invention aims to provide a hyperspectral image registration method that can conveniently select a reference point that meets the requirements in a visible light image of a target area, thus solving the problem that existing registration methods cannot reliably and conveniently select a reference point in a visible light image.

[0005] The above technical problems are solved by the following technical solution: a hyperspectral image registration method, comprising the following steps: First, acquiring visible light and hyperspectral images: Numbered registration plates are evenly distributed in the area to be photographed, each registration plate having a unique number marked on its upper surface. The upper surfaces of the registration plates are leveled, and local visible light images of various parts of the area to be photographed are acquired using a drone. Hyperspectral images of the area to be photographed are also acquired using a hyperspectral imager mounted on the drone. Second, image stitching: The local visible light images are stitched together to form a global visible light image of the area to be photographed using stitching software. Third, hyperspectral image registration: In the hyperspectral image registration software, numbered digital feature points of the registration plate on the hyperspectral image are selected, and these feature points are registered to the corresponding image feature points in the visible light image. The registration board features digital stroke feature points that are easily identifiable in visible and spectral images. To a certain extent, these feature points can improve the accuracy and precision of registration, eliminating the need to blindly search for control points for correction in related images (natural feature points are often not obvious, and blindly searching for control points may increase geometric correction errors). Furthermore, the registration board is marked with sequential numbers (1, 2, 3, ..., N), allowing for point-by-point image registration and stitching during spectral image registration, significantly improving work efficiency. Because images acquired by a UAV-mounted hyperspectral imager have relatively low geolocation accuracy, a visible orthophoto with higher geolocation accuracy is required as a base map for calibration to ensure a complete hyperspectral image with high geolocation accuracy. See example. Figure 1 Therefore, hyperspectral images need to be registered. The specific steps are as follows.

[0006] Preferably, the registration plate includes a water tank and a float that can be placed in the water tank. The number is set on the upper surface of the float, and the upper surface of the float is horizontal when the float is floated. The method to adjust the upper surface of the registration plate to be horizontal is to inject liquid into the water tank to float the float. Since the water surface is flat, the float is manufactured to ensure that the upper surface is horizontal when floating. Therefore, when using it, only water needs to be introduced into the water tank, and the float is floated in the water to ensure that the upper surface is horizontal, i.e., the upper surface of the registration plate is horizontal. This makes leveling convenient, and if the product meets the requirements, it will be horizontal every time it is used. It eliminates the need to measure with a level and adjust the height in different directions every time it is used, as is the case with existing methods, thus saving measurement time.

[0007] Preferably, the float includes a buoy and a lens covering the buoy. The lens is a convex lens with a raised lower surface and a flat upper surface. An LED bead is installed inside the buoy and is located at the focal point of the lens. The number is set on the upper surface of the lens and is a light-shielding structure. This allows for clear imaging of the markings on the registration plate, especially in low visibility conditions.

[0008] Preferably, the lens is vertically and flexibly mounted inside the float. The upper end of the float has an inwardly flanged edge to prevent the lens from detaching from the float. A permanent magnet is mounted on the inwardly flanged edge, and a ferromagnetic material is provided on the edge of the lens. The permanent magnet attracts the ferromagnetic material, suspending the lens on the inwardly flanged edge. When the lens is suspended on the inwardly flanged edge, the LED beads are located at the focal point of the lens. The water tank has an inflatable airbag structure; when the lens descends to its lowest point, the deflated water tank can be accommodated inside the float. This allows for convenient storage and transport. It also allows for easy repositioning for use.

[0009] Preferably, the LED protrudes from the inner surface of the bottom wall of the float, and the LED is provided with a support block for holding the lens. When the support block holds the lens, there is a surface-fit contact between the support block and the lens. This can prevent collision damage between the LED and the lens.

[0010] The invention also includes a left lens protective film and a right lens protective film, wherein the lens is rectangular; the lower end of the left lens protective film is connected to the lower end of the left side wall of the float, and the upper end is provided with a left retaining strip extending in the front-rear direction. The left retaining strip is located above the lens, and the left lens protective film passes between the lens and the left side wall of the float. The left retaining strip is used to prevent the upper end of the left lens protective film from falling below the lens from between the lens and the left side wall of the float. The left retaining strip is a ferromagnetic structure; the lower end of the right lens protective film is connected to the lower end of the right side wall of the float, and the upper end is provided with... A right locking strip extends in the front-to-back direction and is located above the lens. A right lens protective film passes between the lens and the right side wall of the float. The right locking strip prevents the upper end of the protective film from falling below the lens from between the lens and the right side wall of the float. The right locking strip is a permanent magnet structure. When the lens descends to its lowest point, the left locking strip attracts the right locking strip, causing them to abut together. The left and right lens protective films then cover the upper surface of the lens. When the lens is suspended on the inner flange, both the left and right locking strips are directly below the inner flange. When the lens is lowered and not in use, the protective film automatically covers the lens to prevent dirt and damage from objects stored in the float. When the lens is raised and reset for use, the protective film automatically removes.

[0011] Preferably, the left clip has a left cleaning strip extending along its extension direction. When the left clip moves on the lens, it contacts the lens through the left cleaning strip. Similarly, the right clip has a right cleaning strip extending along its extension direction. When the right clip moves on the lens, it contacts the lens through the right cleaning strip. This allows for simultaneous and automatic cleaning of the lens during the application and removal of the protective film.

[0012] Preferably, the upper surface of the lens is provided with a drain groove extending in the front-to-back direction. When the left and right retaining strips are abutted together, the left and right wiping cloths are aligned with the drain groove. This allows for easy removal of dirt wiped off the lens.

[0013] Preferably, the float is provided with a drain outlet, and when the lens is suspended on the inner flange, the drain outlet is aligned with the drain trough. This prevents secondary contamination of the lens when pollutants are discharged from the drain trough.

[0014] Preferably, the inner surface of the left side wall of the float has a horizontal hole, within which a horizontal conductive rod and a spring for driving the horizontal conductive rod out of the horizontal hole are installed. The lower surface of the portion of the inner flange located above the left side wall of the float has a vertical hole, within which a vertical conductive rod and a spring for driving the vertical conductive rod out of the vertical hole are installed. The left retaining bar is a conductor. When the lens is suspended on the inner flange, the left retaining bar abuts against both the horizontal and vertical conductive rods. When the left retaining bar abuts against both the horizontal and vertical conductive rods, the LED is connected to the power supply. The light source can only be illuminated when the lens is reset to the focal point of the lens, preventing accidental ignition. The switch can also hold the lens, ensuring it will not fall off reliably for the user.

[0015] This invention has the following advantages: A registration plate with a pre-fabricated spacing distribution within the target area is used; the image of the registration plate is used as a reference point for registration in the visible light image, making the selection of registration points convenient, fast, and accurate; the upper surface of the registration plate can be easily adjusted to be level; the registration plate emits parallel light rays next to the marker, making it easy to photograph the marker; the registration plates can be collected and stored together, facilitating storage and transportation; a protective film is automatically applied during retraction to prevent lens damage; the outer surface of the lens is automatically cleaned each time it is used and retracted; and the lens can only conduct light reflection after it is moved into position. Attached Figure Description

[0016] Figure 1 A schematic diagram showing the registration plate in use;

[0017] Figure 2 for Figure 1 A magnified view of a portion of point A;

[0018] Figure 3This is a top view of the lens;

[0019] Figure 4 A schematic diagram showing the registration plates when they are folded together;

[0020] Figure 5 for Figure 4 A magnified view of part B.

[0021] In the diagram: 1. Water tank; 2. Float; 3. Float cylinder; 4. Lens; 5. LED light bead; 6. Inward flange; 7. Permanent magnet; 8. Ferromagnetic body; 21. Support block; 9. Left lens protective film; 10. Right lens protective film; 11. Left retaining strip; 12. Right retaining strip; 13. Right retaining strip; 14. Drainage trough; 15. Drainage outlet; 16. Horizontal conductive rod; 17. Horizontal hole spring; 18. Vertical conductive rod; 19. Vertical hole spring; 20. Water; 22. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] See Figures 1 to 5 A hyperspectral image registration method is characterized by the following steps: First, acquiring visible light and hyperspectral images: Numbered registration plates are evenly distributed in the area to be photographed, each with a unique number marked on its upper surface (i.e., the numbers on each registration plate are different). The numbers are Arabic numerals. The upper surfaces of the registration plates are leveled, and local visible light images of various parts of the area to be photographed are acquired using a drone. Hyperspectral images of the area to be photographed are also acquired using a hyperspectral imager mounted on the drone. Second, image stitching: The local visible light images are stitched together to form a global visible light image of the area to be photographed using stitching software. Third, hyperspectral image registration: In the hyperspectral image registration software, feature points from 1 to +1 are selected and registered to the corresponding points in the visible light images.

[0024] The registration plate includes a water tank 1 and a float 2 that can be placed inside the water tank. Numbers are set on the upper surface of the float. When the float is raised, the upper surface of the registration plate is horizontal. The method to level the upper surface of the registration plate is to inject liquid into the water tank to raise the float. The float includes a buoy 3 and a lens 4 covering the buoy. The lens is a convex lens with a raised lower surface and a flat upper surface. Numbers are set at the center of the upper surface of the lens and are Arabic numerals written in a dark color, specifically black. An LED bead 5 is installed inside the buoy. The LED bead is located at the focal point of the lens and is numbered as a light-shielding structure. The lens is vertically adjustable inside the buoy. The upper end of the buoy has an inner flange 6 to prevent the lens from detaching from the buoy. A permanent magnet 7 is installed on the inner flange, and a ferromagnetic body 8 is located on the edge of the lens. The permanent magnet attracts the ferromagnetic body, suspending the lens on the inner flange. When the lens is suspended on the inner flange, the LED bead is located at the focal point of the lens. The water tank is an inflatable airbag structure; when the lens descends to its lowest point, the deflated water tank can accommodate the float. The LED protrudes from the inner surface of the float's bottom wall, and a lens-supporting block 21 is provided on the LED. When the block supports the lens, there is a surface-fitting contact between the block and the lens. It also includes a left lens protective film 9 and a right lens protective film 10. The lens is rectangular; the raised portion of its lower surface is circular. The lower end of the left lens protective film is connected to the lower end of the left side wall of the float, and the upper end has a left retaining strip 11 extending in the front-back direction. The left retaining strip is located above the lens, and the left lens protective film passes between the lens and the left side wall of the float. The left retaining strip prevents the upper end of the left lens protective film from falling below the lens from between the lens and the left side wall of the float. The left retaining strip has a ferromagnetic structure and is a conductor. The left retaining strip has a left wiping strip 12 extending along its extension direction. When the left retaining strip moves on the lens, it contacts the lens through the left wiping strip. The lower end of the right lens protective film is connected to the lower end of the right side wall of the float, and the upper end is provided with a right retaining strip 13 extending in the front-to-back direction. The right retaining strip is located above the lens, and the right lens protective film passes between the lens and the right side wall of the float. The right retaining strip is used to prevent the upper end of the right lens protective film from falling below the lens from between the lens and the right side wall of the float. The right retaining strip is a permanent magnet structure. The right retaining strip is provided with a right wiping strip 14 extending in the extension direction of the right retaining strip. When the right retaining strip moves on the lens, it contacts the lens through the right wiping strip. When the lens descends to the lowest point, the left retaining strip attracts the right retaining strip, so that the left retaining strip and the right retaining strip abut together, and the left lens protective film and the left lens protective film block the upper surface of the lens; when the lens is suspended on the inner flange, the left retaining strip and the right retaining strip are both located directly below the inner flange. The upper surface of the lens is provided with a drain groove 15 extending in the front-to-back direction. When the left retaining strip and the right retaining strip abut together, the left wiping strip and the right wiping strip are aligned with the drain groove. The pontoon is equipped with a drain outlet 16, and when the lens is suspended on the inner flange, the drain outlet is aligned with the drain trough.A horizontal hole is provided on the inner surface of the left side wall of the float. A horizontal conductive rod 17 and a spring 18 for driving the horizontal conductive rod to extend out of the horizontal hole are provided in the horizontal hole. A vertical hole is provided on the lower surface of the portion of the inner flange located above the left side wall of the float. A vertical conductive rod 19 and a spring 20 for driving the vertical conductive rod to extend out of the vertical hole are provided in the vertical hole. When the lens is suspended on the inner flange, the left retaining bar abuts against both the horizontal and vertical conductive rods. When the left retaining bar abuts against both the horizontal and vertical conductive rods, the LED is connected to the power supply and can be lit.

[0025] When using the registration plate, inflate the water tank and fill it with water (22). The lens rises and abuts against the inner flange. At this time, the vertical and horizontal conductive rods are connected by the left locking strip, and the power supply is connected to the LED, causing the LED to reflect light. When the registration plate is not in use, deflate the water tank and retract it. The lens moves down to be supported on the support block, and the water tank is stored in the float.

[0026] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the invention. Although the invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A hyperspectral image registration method, characterized in that, Step 1: Acquiring Visible and Hyperspectral Images: Numbered registration plates are evenly distributed across the area to be photographed. Each registration plate has a unique number marked on its upper surface. The upper surfaces of the registration plates are leveled. A drone is used to acquire local visible light images of various parts of the area to be photographed. A hyperspectral image of the area is acquired using a drone equipped with a hyperspectral imager. Step 2: Image Stitching: The local visible light images are stitched together using stitching software to create a global visible light image of the area to be photographed. Step 3: Hyperspectral Image Registration: In hyperspectral image registration software, numbered digital feature points on the hyperspectral images are selected and registered to their corresponding points in the visible light images. The registration plate, which includes a water tank and a float that can be placed inside the water tank, is positioned at the location of the feature points. The numbering is set on the upper surface of the float. When the float is floated, the upper surface of the registration plate is horizontal. The method for leveling the upper surface of the registration plate is to inject liquid into the water tank to float the float. The float includes a buoyancy tube and a lens covering the buoyancy tube. The lens is a convex lens with a raised lower surface and a flat upper surface. An LED bead is installed inside the buoyancy tube, located at the focal point of the lens. The numbering is set on the upper surface of the lens and serves as a light-shielding structure. The lens is vertically and vertically mounted inside the buoyancy tube. The upper end of the buoyancy tube has an inward-facing flange to prevent the lens from detaching from the buoyancy tube. A permanent magnet is installed on the inward-facing flange. The lens is made of iron, and its edge is provided with a ferromagnetic material. A permanent magnet attracts the ferromagnetic material, suspending the lens on the inner flange. When the lens is suspended on the inner flange, the LED bead is located at the focal point of the lens. The water tank is an inflatable airbag structure; when the lens descends to its lowest point, the deflated water tank can be accommodated in the float. The LED bead protrudes from the inner surface of the bottom wall of the float, and the LED bead is provided with a support block to hold the lens. When the support block holds the lens, there is a surface-fit contact between the support block and the lens. It also includes a left lens protective film and a right lens protective film. The lens is rectangular. The lower end of the left lens protective film is connected to the lower end of the left side wall of the float, and the upper end is provided with a left retaining strip extending in the front-back direction. The left retaining strip is located above the lens. The left lens protective film passes between the lens and the left side wall of the float. The left retaining strip is used to prevent the upper end of the left lens protective film from falling below the lens from between the lens and the left side wall of the float. The left retaining strip is a ferromagnetic structure. The lower end of the right lens protective film is connected to the lower end of the right side wall of the float. The upper end is provided with a right retaining strip extending in the front-back direction. The right retaining strip is located above the lens. The right lens protective film passes between the lens and the right side wall of the float. The right retaining strip is used to prevent the upper end of the right lens protective film from falling below the lens from between the lens and the right side wall of the float. The right retaining strip is a permanent magnet structure. When the lens descends to the lowest point, the left retaining strip attracts the right retaining strip, causing the left retaining strip and the right retaining strip to abut together. The left lens protective film and the left lens protective film block the upper surface of the lens. When the lens is suspended on the inner flange, both the left and right locking strips are located directly below the inner flange.

2. The hyperspectral image registration method according to claim 1, characterized in that, The left card bar has a left wiping strip extending along the left card bar extension direction. When the left card bar moves on the lens, it contacts the lens through the left wiping strip. The right card bar has a right wiping strip extending along the right card bar extension direction. When the right card bar moves on the lens, it contacts the lens through the right wiping strip.

3. The hyperspectral image registration method according to claim 2, characterized in that, The upper surface of the lens is provided with a drain groove extending in the front-to-back direction. When the left and right locking strips abut together, the left and right wiping cloths are aligned with the drain groove.

4. The hyperspectral image registration method according to claim 3, characterized in that, The pontoon is provided with a drain outlet, and when the lens is suspended on the inner flange, the drain outlet is aligned with the drain trough.

5. The hyperspectral image registration method according to claim 4, characterized in that, A horizontal hole is provided on the inner surface of the left side wall of the float. A horizontal conductive rod and a horizontal hole spring for driving the horizontal conductive rod to extend out of the horizontal hole are provided in the horizontal hole. A vertical hole is provided on the lower surface of the part of the inner flange located above the left side wall of the float. A vertical conductive rod and a vertical hole spring for driving the vertical conductive rod to extend out of the vertical hole are provided in the vertical hole. The left locking bar is a conductor. When the lens is suspended on the inner flange, the left locking strip abuts against both the horizontal and vertical conductive rods. When the left locking strip abuts against both the horizontal and vertical conductive rods, the LED is connected to the power supply.

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