Hierarchical simulation foggy day image acquisition system based on cloud chamber

Abstract

The invention discloses a hierarchical simulation foggy day image acquisition system based on a cloud chamber. The system comprises the cloud chamber, a controller, a fog making machine, a camera, a light shield, a light transmittance instrument, a parallel light source, a picture support and an exhaust fan. The cloud chamber is of a rectangular structure and comprises a top panel, a bottom panel and four side panels; a panel on one side of the cloud chamber is provided with an opening allowing a camera lens to freely move and pass through, and the panel is called as a camera panel; a movable panel is arranged on the opposite side of the camera side panel and is connected with the bottom panel in a hinge manner; the picture support is located on the inner side of the cloud room movable panel. The other two side panels of the cloud chamber are respectively called a front side panel and a rear side panel, the fog making machine is positioned on the outer side of the front side panel, and a nozzle of the fog making machine is connected with the front side panel of the cloud chamber box body through a check valve; the exhaust fan is located at the position of a rear side panel of the cloud chamber and used for adjusting the mist concentration in the cloud chamber box. And a sensor part of the light transmittance instrument is positioned in the cloud chamber and is connected with the controller. The invention also provides a foggy day image acquisition method.

Description

Technical Field

[0001] The present invention relates to the field of computer vision, and in particular to a hierarchical simulated foggy image acquisition system based on a cloud chamber. Background Art

[0002] In foggy conditions, the image quality obtained by the imaging system is poor due to the scattering and refraction of light by suspended particles in the atmosphere. Foggy images usually have problems such as low contrast, color distortion, and blurred edges. These image degradation problems bring great challenges to computer vision tasks. Therefore, it is of great research significance and great application prospects to study image processing methods for foggy images, explore simulated foggy image acquisition systems, and construct simulated foggy image datasets with controllable parameters. Foggy image processing is an important technology in the field of computer vision. Its purpose is to enable computers to complete scene understanding tasks such as target detection, semantic segmentation, and instance segmentation in foggy environments. However, in the era of rapid development of deep learning technology, insufficient foggy data has become an important factor restricting the development of this field. Foggy image data has problems such as difficulty in acquisition, labeling, and quantification. Its acquisition process is greatly affected by weather factors, especially image acquisition under different fog concentrations is extremely difficult.

[0003] There are some real foggy scene data sets in existing research, but most of these data are only collected once for the same scene and cannot reflect the impact of changes in fog concentration. Although multiple images of different concentrations of the same scene can be obtained by computer data synthesis, the effectiveness of such methods is limited by the synthesis algorithm used. From an intuitive observation, there is still a big difference between the foggy images synthesized by such methods and the real foggy images. In addition, the foggy images obtained by such methods ignore the physical characteristics of light propagating in the foggy atmosphere and cannot fully reflect the characteristics of foggy images. In addition, the concentration of the foggy images obtained by the synthesis algorithm cannot be mapped and quantified with the fog concentration of the real scene, which limits the practicality of the methods obtained based on such data research.

[0004] In summary, the existing foggy image datasets are difficult to satisfy further in-depth research on foggy image processing algorithms. Therefore, the present invention proposes a hierarchical simulated foggy image acquisition system based on a cloud chamber. Summary of the invention

[0005] In response to the problems of insufficient sample size, difficulty in quantification, and difficulty in pairing in foggy image data, the present invention proposes a hierarchical simulated foggy image acquisition system based on a cloud chamber. The purpose is to collect image data of different fog concentrations under real physical conditions, and it can be independent of natural variables such as weather, light, and scene, thereby achieving better foggy image learning effects and solving the problems of the shortcomings of existing foggy image datasets and the difficulty in labeling dense fog scenes.

[0006] In order to overcome the deficiencies of the prior art, the technical solution adopted by the present invention is:

[0007] 8. A hierarchical simulated foggy image acquisition system based on a cloud chamber, comprising a cloud chamber, a controller, a fog machine, a camera, a light shield, a light transmittance meter, a parallel light source, a picture bracket, and an exhaust fan, wherein:

[0008] The cloud chamber is a rectangular structure, including a top panel, a bottom panel and four side panels. The top panel of the cloud chamber is transparent, and the other panels are covered with light-shielding materials.

[0009] One side panel of the cloud chamber is provided with an opening that allows the camera lens to move freely and pass through, and this side panel is called the camera side panel, and the lens hood is located between the camera lens and the camera side panel of the cloud chamber;

[0010] The opposite side of the camera side panel is a movable panel, which is hinged to the bottom panel;

[0011] The picture holder is located inside the movable panel of the cloud chamber, with the bottom edge parallel to the bottom panel of the cloud chamber. It is used to limit and fix the position of the paper picture and ensure the flatness of the picture so that the picture remains perpendicular to the axis of the lens.

[0012] The other two side panels of the cloud chamber are called the front side panel and the rear side panel respectively. The fog machine is located outside the front side panel, and the nozzle of the fog machine is connected to the front side panel of the cloud chamber box through a check valve.

[0013] The exhaust fan is located at the rear panel of the cloud chamber and is used to adjust the fog density inside the cloud chamber. A check valve is installed at the connection between the exhaust fan and the cloud chamber, which can keep the fog density inside the cloud chamber relatively stable.

[0014] The sensor part of the transmittance meter is located inside the cloud chamber and connected to the controller. The host computer software can be used to control the transmittance meter to collect environmental parameters;

[0015] The parallel light source is arranged above the cloud chamber, and the light emitting surface thereof is parallel to the top panel of the cloud chamber system, so as to provide lighting for the cloud chamber.

[0016] 9. The hierarchical simulated foggy image acquisition system based on a cloud chamber according to claim 1, characterized in that the light shield is coaxial with the lens and is threadedly connected.

[0017] 10. According to the cloud chamber-based hierarchical simulated foggy image acquisition system of claim 1, it is characterized in that locking and limiting devices are symmetrically installed on the outside of the cloud chamber box and the cloud chamber movable panel, and the single-side components are connected by flexible materials, which are used for locking and opening angle limiting of the cloud chamber movable cover. The locking method is magnetic locking, which is used to ensure the airtightness inside the cloud chamber box when the movable panel is closed.

[0018] 11. The hierarchical simulated foggy weather image acquisition system based on the cloud chamber according to claim 1 is characterized in that the top of the picture bracket adopts an open design to facilitate the taking and placing of pictures, and rulers are provided on the left and right sides and the bottom.

[0019] 12. The hierarchical simulated foggy image acquisition system based on a cloud chamber according to claim 1, characterized in that the spectral distribution of the parallel light source simulates daylight.

[0020] 13. The hierarchical simulated foggy image acquisition system based on the cloud chamber according to claim 1 is characterized in that the axis of the camera lens coincides with the axis of the light shield and is perpendicular to the plane where the movable panel of the cloud chamber is located when it is in a closed state, and the axis coincides with the center of the picture.

[0021] 14. A hierarchical simulated foggy image acquisition method implemented by the system of claims 1 to 6, comprising the following steps:

[0022] Step 1: Adjust the positions of various components, turn on the power of the parallel light source, transmittance meter, camera, fog machine, and exhaust fan, and enter the standby state;

[0023] Step 2: Open the controller's host computer software, and when the cloud chamber is in a fog-free state, calibrate the transmittance meter and set the camera shooting parameters;

[0024] Step 3: Place the picture to be taken on the picture holder and close the active panel;

[0025] Step 4: Observe the transmittance value, fill the cloud chamber with fog-making gas, make the transmittance of the gas in the cloud chamber reach the specified value, and use the host computer software to control the camera to take pictures;

[0026] Step 5: Use the fog machine and exhaust fan to adjust the fog density in the cloud chamber and take multiple sets of photos;

[0027] Step 6: Open the movable side panel, take out the picture, and use the exhaust fan to adjust the inside of the cloud chamber to a fog-free state;

[0028] Step 7: Repeat steps 3 to 6 until all the prepared paper pictures have been taken.

[0029] Experimental results show that the present invention effectively improves the realism of simulated foggy images, and this method combines transmittance to measure the concentration of fog, which can be aligned with the visibility in the real world. This solves the problem that existing methods rely on natural weather or synthetic algorithms and are difficult to align with real fog, and further improves the quality of reconstructed images.

[0030] The characteristics and beneficial effects of the present invention are:

[0031] 1) It greatly expands the number of foggy image data samples with pixel-level annotation information, and enables the annotation of distant image data in foggy scenes;

[0032] 2) We constructed a concentration-progressive paired image for specific scenes, which effectively reduced the annotation cost by reusing the annotation information;

[0033] 3) With the help of the cloud chamber system, a hierarchical simulated foggy scene that meets real physical conditions and has controllable multiple parameters was built;

[0034] 4) Achieved quantification of simulated fog concentration that can be aligned with real-world fog concentration. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a schematic diagram of the structure of the hierarchical simulated foggy image acquisition system based on the cloud chamber.

[0036] Figure 2 This is the operation flow chart of the hierarchical simulated foggy image acquisition system based on the cloud chamber.

[0037] Figure 3 Schematic diagram of the hierarchical simulation of foggy image imaging process.

[0038] Figure 4 Schematic diagram of simulated foggy images under different fog concentrations. DETAILED DESCRIPTION

[0039] The hierarchical simulated foggy day image acquisition system based on the cloud chamber of the present invention is realized by the following technical scheme. The system mainly includes a cloud chamber 101, a controller 102, a fog machine 103, a camera 104, a light shield 105, a camera bracket 106, a light transmittance meter 107, a parallel light source 108, a picture 109, a picture bracket 110, a locking and limiting device 111, and an exhaust fan 112. Figure 1 The overall structure of the hierarchical simulated foggy image acquisition system based on the cloud chamber is demonstrated.

[0040] The cloud chamber 101 is similar in shape to a cuboid, and its right panel is a movable panel connected to the bottom panel in a hinged manner. The top panel of the cloud chamber is transparent, and the other panels are covered with dark shading materials.

[0041] The controller 102 is wiredly connected to the camera, fog machine, and light transmittance meter, and the communication mode is serial communication. The controller includes a processor, a memory, a hardware interface, a display screen, and an input device connected through a system bus, as well as an operating system and a computer program that can control other electronic devices.

[0042] The fog machine 103 is placed in front of the cloud chamber, and the fog machine nozzle is connected with the cloud chamber casing front panel via a non-return valve. In addition, the fog machine contains a movable liquid storage tank to store the fogging solution.

[0043] The camera 104 is located on the left side of the cloud chamber body. A circular opening is set on the left panel of the cloud chamber. The opening is slightly larger than the diameter of the lens to allow the lens to move freely. The axis of the lens and the center of the circular hole are on the same straight line, and the axis of the lens is perpendicular to the left panel of the cloud chamber.

[0044] The light shield 105 is located between the camera lens and the cloud chamber body. The light shield is coaxial with the lens and is threadedly connected. The light shield mainly plays the role of light shielding and sealing.

[0045] The camera bracket 106 is used to fix the camera. The camera bracket is threadedly connected to the universal connecting port at the bottom of the camera. The camera bracket has a telescopic and rotating structure, and the position can be freely adjusted front and back, left and right, up and down. In addition, the camera bracket includes a gimbal, which can support the fixing of the camera at any angle. The bottom plate of the camera bracket and the bottom panel of the gimbal are on the same horizontal plane.

[0046] The transmittance meter 107 includes components such as a sensor, a manual controller and a serial port control line, wherein the sensor part of the transmittance meter is located at the center of the bottom of the cloud chamber box, and the measuring light beam is perpendicular to the long side of the box; the manual controller is placed at the bottom of the angle between the front panel of the box and the right side panel, which is powered by an alkaline dry battery, and is provided with a liquid crystal display and buttons to support manual debugging and measurement; the serial port control line of the transmittance meter passes through the front panel of the cloud chamber box and is connected to the corresponding interface on the controller, and the upper computer software can be used to control the transmittance meter to collect environmental parameters. There is a sealing plug at the junction of the serial port control line and the panel to ensure the stability of the gas environment in the cloud chamber.

[0047] The parallel light source 108 is arranged directly above the cloud chamber system, and its light emitting surface is parallel to the top panel of the cloud chamber system, and is used to provide lighting for the cloud chamber system. The spectral distribution is similar to daylight during the day, and the color rendering index CRI>80.

[0048] Picture 109 is used to display specific scene information. The paper used is 130g white matte coated paper, the paper size is 210mm×297mm, and the picture content is printed in color. It can be freely placed and extracted in the picture holder.

[0049] The picture holder 110 is located in the middle of the inner side of the right side panel of the cloud chamber, with the bottom edge parallel to the bottom panel of the cloud chamber. It is used to limit and fix the position of the paper picture and ensure the flatness of the picture so that the picture remains perpendicular to the axis of the lens. The top of the picture holder adopts an open design to facilitate the placement of the picture, and is equipped with rulers on the left and right sides and the bottom.

[0050] The locking and limiting device 111 is located on the outside of the cloud chamber box and the right side panel of the cloud chamber, and is installed symmetrically. The single-side components are connected by flexible materials and are used for locking and opening angle limiting of the right side cover of the cloud chamber. The locking method is magnetic locking, which is used to ensure the airtightness inside the cloud chamber box when the right side panel is closed.

[0051] The exhaust fan 112 is located in the lower middle position of the rear panel of the cloud chamber and is used to adjust the fog density inside the cloud chamber. A check valve is installed at the connection between the exhaust fan and the box to keep the fog density inside the cloud chamber relatively stable.

[0052] The controller 102 and the fog machine 103 are located in front of the cloud chamber 101, the camera 104, the light shield 105 and the camera bracket 106 are located on the left side of the cloud chamber 101, the light transmittance meter 107 is located inside the cloud chamber 101, the parallel light source 108 is located directly above the cloud chamber 101, the picture 109 is located inside the cloud chamber 101 when in working state, and can be replaced by opening the right side panel of the cloud chamber 101, the picture bracket 110 is located on the inside of the right side panel of the cloud chamber 101, the sub-components of the locking and limiting device 111 are respectively located on the outside of the box body and the right side panel of the cloud chamber 101, and the exhaust fan 112 is located in the middle of the rear side panel of the cloud chamber 101. The camera bracket 106 is located on the same plane as the bottom panel of the cloud chamber 101. The lens axis of the camera 104 coincides with the axis of the light shield 105, and is perpendicular to the plane where the right side panel of the cloud chamber 101 is located when it is in the closed state, and the axis coincides with the center of the picture 109.

[0053] Those skilled in the art should understand that the described embodiments are only used to explain the present invention and are not used to limit the scope of the present invention. A specific device may include more or fewer components than the described embodiments, or combine certain components, or have a different arrangement of components.

[0054] In the embodiment of the present invention, the shape of the cloud chamber box is a rectangular parallelepiped, and similar channel structures such as cubes and cylinders can be used to build the cloud chamber system, which does not affect the performance of the hierarchical simulated foggy image acquisition system based on the cloud chamber. Although the pictures in this embodiment are printed with paper materials, they can also be replaced with thin wood chips, plastic boards, etc., or replaced with a three-dimensional model that does not exceed the size of the cloud chamber box during actual operation. In addition, the camera in the present invention is not limited to a visible light camera, and other unmodified imaging devices should be considered to be within the recording scope of this application. Figure 1 The overall structure of the system shown does not constitute a limitation on the structure and equipment of the present invention. As long as its technical features do not deviate from the concept of the present invention, they all belong to the protection scope of this application.

[0055] The present invention should be placed in a dark room for data collection to reduce the influence of stray light. Figure 2The operation process of the hierarchical simulated foggy image acquisition system based on the cloud chamber is demonstrated. The specific implementation steps for image acquisition are as follows:

[0056] Step 201: adjust the position of the device, add solution into the liquid storage barrel of the fog machine, turn on the power of the parallel light source, transmittance meter, camera, fog machine, and exhaust fan, and enter the standby state.

[0057] Step 202: Open the host computer software on the controller, and when the cloud chamber system is in a fog-free state, calibrate the transmittance meter and set the camera shooting parameters.

[0058] Step 203: Place the picture to be taken on the picture holder and close the right panel.

[0059] Step 204: observe the transmittance value, fill the cloud chamber box with fog-making gas, make the transmittance of the gas in the cloud chamber reach a specified value, and use the host computer software to control the camera to take pictures.

[0060] Step 205: Use a fog machine and an exhaust fan to adjust the fog density in the cloud chamber and perform multiple sets of shooting.

[0061] Step 206: Open the right side panel, take out the picture, and use the exhaust fan to adjust the inside of the cloud chamber to a fog-free state.

[0062] Step 207: Repeat steps 203 to 206 until all prepared paper pictures are taken.

[0063] It should be understood that although Figure 2 The steps in the process are shown in sequence as indicated by the arrows, but the steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of the steps, and the steps can be executed in other orders. Figure 2 At least part of the steps may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least part of the sub-steps or stages of other steps.

[0064] The hierarchical simulation foggy image imaging process of the present invention is as follows: Figure 3As shown, it mainly includes two imagings, "primary imaging" mainly refers to the process of capturing images from natural scenes; "secondary imaging" refers to the process of collecting simulated foggy images through the present invention using the results of primary imaging. Due to the invariance of the image structure, the simulated foggy image obtained by the secondary imaging has the same annotation information as the original image obtained by the primary imaging. Object boundaries and distant targets in real foggy images are usually difficult to be effectively annotated, while primary imaging images often have good brightness, clarity and dynamic range, and can obtain high-quality annotation information. Therefore, the annotation results of the simulated foggy images obtained by the embodiments of the present invention can be better than the annotation results of real foggy images.

[0065] In addition, through the embodiment of the present invention, multiple groups of foggy images with different fog concentrations under the same exposure conditions can be obtained. Since the position of the image remains unchanged during acquisition, a group of simulated foggy images can share the same annotation results, greatly reducing the time and labor costs of annotation.

[0066] The fog in natural scenes is usually composed of tiny water droplets suspended in the air. The fog machine in the embodiment of the present invention uses liquid raw materials and atomizes the solution through high-frequency vibration of the internal components of the fog machine. The simulated fog formed is close to the composition and cause of real fog and has highly consistent physical properties. According to the atmospheric scattering model, the total light intensity of the image collected by the imaging device can be decoupled into two parts: one part is the target reflected light directly reflected by the target in the scene; the other part is the atmospheric scattered light caused by scattering of suspended particles in the air. The one-time imaging process of the hierarchical simulation of foggy images of the present invention can be expressed as formula (1).

[0067] I1(x1)=D1(x1)+A1(x1) (1)

[0068] Among them, I1 represents the image obtained by one imaging, D1 represents the direct reflected light of the scenery in the natural scene, A1 represents the atmospheric scattered light in the natural environment, and x1 represents the position of the pixel point in the one-shot imaging image.

[0069] D1(x1)=R1(x1)·t1(x1) (2)

[0070] A1(x1)=A ∞ ·(1-t1(x1)) (3)

[0071] Among them, R1 represents the fog-free image corresponding to the natural scene, t1 represents the atmospheric environment transmittance, and A ∞ Represents the atmospheric scattered light at infinite distance in natural scenes.

[0072] The secondary imaging process of the hierarchical simulated foggy image of the present invention can be expressed as formula (4).

[0073] I2(x2)=D2(x2)+A2(x2) (4)

[0074] Among them, I2 represents the image obtained by secondary imaging, D2 represents the direct reflected light of the image to be taken in the cloud chamber system, A2 represents the scattered light of the simulated foggy environment in the cloud chamber system, and x2 represents the position of the pixel point in the secondary imaging image.

[0075] D2(x2)=R2(x2)·t2(x2) (5)

[0076]

[0077] R2(x)~I1(x)(7)

[0078] Among them, R2 represents the image to be taken, t2 represents the transmittance inside the cloud chamber system, represents the scattered light at the right panel position of the cloud chamber system, d2 represents the imaging distance of the secondary imaging, and x represents the position of the pixel point. Since the material to be photographed for the secondary imaging is printed from the image obtained by the primary imaging, the image to be photographed is similar to the image obtained by the primary imaging. In addition, since the image structure remains unchanged, the pixel values ​​at the same position of R2 and I1 are similar.

[0079] Therefore, formula (4) can be rewritten as formula (8).

[0080]

[0081] By comparing formula (1) with formula (8), we can obtain the atmospheric scattered light A of the hierarchical simulated foggy image relative to the natural scene, as shown in formula (9).

[0082]

[0083] Since the primary imaging distance is usually much larger than the secondary imaging distance, it can be considered With A ∞ Approximately, formula (9) can be simplified to formula (10).

[0084] A(x)=A ∞ ·(1-t1(x)·t2(x)) (10)

[0085] The embodiment of the present invention can dynamically adjust the concentration of fog in the cloud chamber system through the fog machine, so the transmittance t2 inside the cloud chamber system is a controllable parameter, so formula (10) is rewritten in the form of formula (11).

[0086] A(x,t2)=A ∞ ·(1-t1(x)·t2) (11)

[0087] Since the transmittance of the atmospheric environment and the transmittance inside the cloud chamber system are both positive numbers, the atmospheric scattered light A of the simulated foggy image is inversely proportional to the transmittance t2 inside the cloud chamber system. The atmospheric scattered light A' of the real foggy scene can be expressed as formula (12).

[0088] A'(x)=A ∞ ·(1-t(x)) (12)

[0089] Where t(x) represents the transmittance of the real foggy scene. By comparing formula (10) with formula (12), the functional relationship between the transmittance of the real foggy scene and the transmittance inside the cloud chamber system can be obtained as formula (13).

[0090] t(x)=t1(x)·t2(x) (13)

[0091] According to the provisions of the national standards of the People's Republic of China on horizontal visibility and meteorological visibility, in the embodiment of the present invention, the simulated foggy image is divided into five levels: no fog, light fog, moderate fog, dense fog, and heavy fog. Figure 4 The simulated foggy images under different fog concentrations collected by the embodiment of the present invention are shown. In the figure, (a), (b), (c), (d), and (e) are simulated foggy images corresponding to five fog concentration levels from light to heavy. The first row of images uses a monochrome background as the image to be taken, and the last two rows of images use natural scene images as the images to be taken. The experimental results show that the present invention effectively improves the fidelity of the simulated foggy images, and the method combines transmittance to measure the fog concentration, which can be aligned with the visibility in the real world, solving the problem that the existing methods rely on natural weather or synthesis algorithms and are difficult to align with real fog, and further improves the quality of the reconstructed image.

[0092] It is understandable that the above description of the present invention is exemplary and cannot be construed as a limitation of the present invention. A person skilled in the art can make several modifications, substitutions and improvements without departing from the concept of the present application, all of which fall within the scope of protection of the present application.

Claims

1. A hierarchical simulated foggy image acquisition system based on a cloud chamber, comprising a cloud chamber, a controller, a fog machine, a camera, a light shield, a light transmittance meter, a parallel light source, a picture bracket, and an exhaust fan, wherein: The cloud chamber is a rectangular structure, including a top panel, a bottom panel and four side panels. The top panel of the cloud chamber is transparent, and the other panels are covered with light-shielding materials. One side panel of the cloud chamber is provided with an opening that allows the camera lens to move freely and pass through, and this side panel is called the camera side panel, and the lens hood is located between the camera lens and the camera side panel of the cloud chamber; The opposite side of the camera side panel is a movable panel, which is hinged to the bottom panel; The picture holder is located inside the movable panel of the cloud chamber, with the bottom edge parallel to the bottom panel of the cloud chamber. It is used to limit and fix the position of the paper picture and ensure the flatness of the picture so that the picture remains perpendicular to the axis of the lens. The other two side panels of the cloud chamber are called the front side panel and the rear side panel respectively. The fog machine is located outside the front side panel, and the nozzle of the fog machine is connected to the front side panel of the cloud chamber box through a check valve. The exhaust fan is located at the rear panel of the cloud chamber and is used to adjust the fog density inside the cloud chamber. A check valve is installed at the connection between the exhaust fan and the cloud chamber, which can keep the fog density inside the cloud chamber relatively stable. The sensor part of the transmittance meter is located inside the cloud chamber and connected to the controller. The host computer software can be used to control the transmittance meter to collect environmental parameters; The parallel light source is arranged above the cloud chamber, and the light emitting surface thereof is parallel to the top panel of the cloud chamber system, so as to provide lighting for the cloud chamber.

2. The hierarchical simulated foggy image acquisition system based on cloud chamber according to claim 1 is characterized in that: The lens hood is coaxial with the lens and is threaded.

3. The hierarchical simulated foggy image acquisition system based on cloud chamber according to claim 1 is characterized in that: Locking and limiting devices are symmetrically installed on the outside of the cloud chamber box and the cloud chamber movable panel. The single-side components are connected by flexible materials and are used for locking and opening angle limiting of the cloud chamber movable cover. The locking method is magnetic locking, which is used to ensure the airtightness inside the cloud chamber box when the movable panel is closed.

4. The hierarchical simulated foggy image acquisition system based on cloud chamber according to claim 1 is characterized in that: The top of the picture holder adopts an open design to facilitate the placement of pictures, and is equipped with rulers on the left and right sides and the bottom.

5. The hierarchical simulated foggy image acquisition system based on cloud chamber according to claim 1 is characterized in that: The spectral distribution of parallel light sources simulates daylight.

6. The hierarchical simulated foggy image acquisition system based on cloud chamber according to claim 1, characterized in that: The axis of the camera lens coincides with the axis of the hood and is perpendicular to the plane in which the movable panel of the cloud chamber is located when it is in the closed state, and the axis coincides with the center of the picture.

7. A hierarchical simulated foggy image acquisition method implemented by the system of claims 1 to 6 comprises the following steps: Step 1: Adjust the positions of various components, turn on the power of the parallel light source, transmittance meter, camera, fog machine, and exhaust fan, and enter the standby state; Step 2: Open the controller's host computer software, and when the cloud chamber is in a fog-free state, calibrate the transmittance meter and set the camera shooting parameters; Step 3: Place the picture to be taken on the picture holder and close the active panel; Step 4: Observe the transmittance value, fill the cloud chamber with fog-making gas, make the transmittance of the gas in the cloud chamber reach the specified value, and use the host computer software to control the camera to take pictures; Step 5: Use the fog machine and exhaust fan to adjust the fog density in the cloud chamber and take multiple sets of photos; Step 6: Open the movable side panel, take out the picture, and use the exhaust fan to adjust the inside of the cloud chamber to a fog-free state; Step 7: Repeat steps 3 to 6 until all the prepared paper pictures have been taken.

Images