Image correction method for geographic information display

Abstract

The invention provides an image correction method for geographic information display. Relates to the technical field of geography. The method comprises the following steps: S1, acquiring geographic image data, and simultaneously acquiring corresponding geographic control point data, digital elevation model (DEM) data and atmospheric parameter data; s2, performing preprocessing such as noise removal and contrast enhancement on the acquired geographic image data; s3, carrying out geometric correction on the obtained geographic control point data and digital elevation model data; s4, performing radiation correction on the acquired atmospheric parameter data; and S5, fusing the geographic image data preprocessed in the S2 with the pattern subjected to geometric correction in the S3 and radiation correction in the S4, and carrying out further optimization processing on the fused image. The image correction method for geographic information display provided by the invention has the advantages of being convenient to use and improving the accuracy and reliability of the geographic image.

Description

TECHNICAL FIELD

[0001] The present application relates to the geographic technical field, and in particular to an image correction method for geographic information display. BACKGROUND

[0002] Geographic information is the geographic meaning contained and expressed by geographic data, which is identified by data, so as to realize the systematic collection and quantitative expression of geographic features. With the continuous development of big data visualization application, geographic information visualization has also been paid more and more attention. As the terminal link of geographic data application, the visualization of geographic information not only aims to achieve better presentation, but also aims to more simply and intuitively display the rules in spatial distribution, and to mine deeper information. In the geographic information system, image data is an important basis for geographic information display and analysis. However, due to the influence of many factors such as imaging characteristics of sensors, atmospheric conditions, terrain undulations, and flight attitude of satellites or planes, the obtained geographic images often have problems such as geometric distortion and radiation error. These problems will cause the position of geographic features in the image to be inaccurate, the shape to be distorted, and the color and brightness to be abnormal, which seriously affects the accuracy and reliability of geographic information display, and makes the geographic analysis, monitoring, planning and other applications based on images unable to obtain accurate results.

[0003] At present, although the common image correction method can improve the image quality to a certain extent, it still has some limitations. The existing geometric correction method has poor correction effect for images under complex terrain conditions, and it is difficult to accurately correct the geometric distortion caused by terrain undulations. The radiation correction method has poor adaptability to changes in atmospheric conditions, and cannot accurately eliminate the influence of atmospheric scattering and absorption on the radiation characteristics of the image, thereby reducing the accuracy and reliability of the geographic image.

[0004] Practical invention content

[0005] The technical problem solved by the present application is to provide an image correction method for geographic information display which is convenient to use and improves the accuracy and reliability of geographic images.

[0006] To solve the above technical problems, the image correction method for geographic information display provided by the present application comprises the following steps: S1, acquiring geographic image data, and simultaneously acquiring corresponding geographic control point data, digital elevation model (DEM) data and atmospheric parameter data;

[0007] S2, pre-processing the acquired geographic image data by removing noise and enhancing contrast;

[0008] S3, geometrically correcting the acquired geographic control point data and digital elevation model data;

[0009] S4, performing radiation correction on the acquired atmospheric parameter data;

[0010] S5, the pre-processed geographic image data in S2 is fused with the pattern corrected in S3 and S4, and the fused image is further optimized to improve the information quantity and definition of the image;

[0011] S6, the optimized image in S5 is evaluated by using a quantitative and qualitative combination method.

[0012] Preferably, the geographic image data is obtained by using satellite remote sensing equipment.

[0013] Preferably, the digital elevation model is downloaded from a geographic information data center, and the resolution is 5 meters.

[0014] Preferably, the atmospheric parameter data is obtained from a local meteorological monitoring station, and the atmospheric parameter data includes atmospheric visibility, aerosol concentration, atmospheric temperature, and humidity.

[0015] Preferably, the geographic control point data is obtained by field measurement or using a high-precision geographic information database.

[0016] Preferably, the geographic image data is processed by a median filter algorithm to remove noise, and a histogram equalization method is used to enhance the contrast of the image and improve the visual quality of the image.

[0017] Preferably, the image is geometrically corrected by using a combination of polynomial transformation and collinear equation.

[0018] Preferably, the atmospheric parameter data is radiometrically corrected by using a method based on a radiative transfer model.

[0019] Preferably, the optimization process includes color adjustment, sharpening, etc., so that the image is more consistent with the requirements of geographic information display, and the visual effect and readability of the image are improved.

[0020] Compared with the related art, the image correction method for geographic information display provided by the present application has the following beneficial effects:

[0021] The geometric correction method combining polynomial transformation and collinear equation reduces the influence of factors such as terrain undulations on image geometric distortion, effectively improves the geometric correction accuracy of geographic images under complex terrain conditions, and makes the position and shape of geographic features in the image more accurate.

[0022] The radiometric correction method based on the radiative transfer model can accurately calculate the radiometric correction coefficient according to the actual atmospheric parameter data, effectively eliminate the influence of atmospheric condition changes on the radiation characteristics of the image, improve the radiation accuracy of the image, and make the color and brightness of the image more realistically reflect the actual situation of the ground surface.

[0023] Through image fusion and optimization processing, various geographic information data are fused, and the image is further optimized, which not only improves the information quantity and definition of the image, but also makes the image more meet the requirements of geographic information display, and provides more intuitive and accurate geographic information display effect for users.

[0024] By adopting the quantitative and qualitative combined correction result evaluation method, the quality of the corrected image can be comprehensively and accurately evaluated, and the correction effect is ensured to meet the requirements of geographic information display and application. If the requirements are not met, re-correction can be performed in time, thereby ensuring the reliability and practicality of the correction method. DETAILED DESCRIPTION

[0025] The present application will be further described below in combination with embodiments.

[0026] In the present application, the image correction method for geographic information display comprises:

[0027] S1, acquiring geographic image data by a satellite remote sensing device, and simultaneously acquiring digital elevation model (DEM) data corresponding to the geographic image from a geographic information data center, and the resolution is 5 meters, the digital elevation model data reflects the relief of the terrain, and provides a basis for correcting the geometric deformation caused by the terrain, and acquiring geographic control point data by field measurement or using a high-precision geographic information database, which is used for subsequent geometric correction; acquiring atmospheric parameter data from a local meteorological monitoring station; the atmospheric parameter data includes atmospheric visibility of 15km, aerosol concentration of 0.15mg / m 3 , atmospheric temperature of 25℃, and humidity of 60%, which is used for radiation correction

[0028] S2, pre-processing the acquired geographic image data, including removing noise in the image by a median filter algorithm; and enhancing the contrast of the image by a histogram equalization method, and improving the visual quality of the image, thereby providing a better basis for subsequent correction processing.

[0029] S3, using a method combining polynomial transformation and collinearity equation to perform geometric correction on the geographic control point data and the digital elevation model data acquired by the image, first, using the geographic control point data to establish a polynomial transformation model, and performing preliminary geometric correction on the image to eliminate general geometric deformation caused by changes in sensor imaging posture, flight height, etc.; then, combining the digital elevation model data, and performing accurate correction on the geometric deformation in the image caused by terrain relief based on the collinearity equation, and calculating the correct position under ideal imaging conditions for each pixel point in the image according to its corresponding elevation value according to the collinearity equation, thereby realizing effective correction of the geometric deformation of the image under complex terrain conditions.

[0030] S4, the acquired atmospheric parameter data is radiometrically corrected, and a method based on a radiation transmission model is used to perform radiometric correction on the acquired atmospheric parameter data. Through the 6S model, the transmission process of solar radiation in the atmosphere and the interaction with the ground are accurately described. Then, the acquired atmospheric parameter data is input into the radiation transmission model, the scattering, absorption and other effects of the atmosphere on solar radiation are calculated, and then the required radiometric correction coefficient is obtained. Finally, the radiometric correction coefficient is used to correct the radiometric brightness value of each pixel point of the image, eliminate the influence of atmospheric condition changes on the radiometric characteristics of the image, and make the radiometric brightness of the image more truly reflect the actual reflection or emission characteristics of the ground.

[0031] S5, the preprocessed geographic image data is fused with the image after geometric correction and radiometric correction, a wavelet transform-based image fusion method is used to fully retain the useful information of each data and improve the information quantity and clarity of the image. After fusion, the image is further optimized, including color adjustment, sharpening and the like, so that the image is more in line with the requirements of geographic information display and the visual effect and readability of the image are improved.

[0032] S6, the corrected image is evaluated by combining quantitative and qualitative methods. In the quantitative evaluation, the geometric accuracy index of the image is calculated, the root mean square error RMSE is 0.8 pixels, and the mean error ME is 0.5 pixels. The radiometric accuracy index, the signal-to-noise ratio SNR is 35dB, and the peak signal-to-noise ratio PSNR is 38dB. Compared with the original image, the accuracy indexes are significantly improved. In the qualitative evaluation, it is found through artificial visual interpretation that the position of the geographic elements in the corrected image is accurate, the shape is complete, the color and brightness are reasonable, and the geographic information can be clearly displayed. Through evaluation, the corrected image meets the requirements of geographic information display, and the corrected image is evaluated by combining quantitative and qualitative methods. The quantitative evaluation is performed by calculating the geometric accuracy index (such as root mean square error RMSE, mean error ME, etc.) and the radiometric accuracy index (such as signal-to-noise ratio SNR, peak signal-to-noise ratio PSNR, etc.) of the image, and compared with the original image and the standard reference image to evaluate the correction effect. The qualitative evaluation is performed by artificial visual interpretation to check the position accuracy, shape integrity, color and brightness of the geographic elements in the image, and to judge whether the corrected image meets the requirements of geographic information display. If the evaluation result does not meet the requirements, the corresponding correction step is returned to perform re-correction until the satisfactory correction effect is achieved.

[0033] Compared with the related art, the image correction method for geographic information display provided by the present application has the following beneficial effects:

[0034] The image correction method for geographic information display provided by the application can reduce the influence of factors such as terrain undulation on image geometric deformation by combining a polynomial transformation with a geometric correction method of collinear equation, can effectively improve the geometric correction precision of geographic images under complex terrain conditions, and can make the position and shape of geographic elements in the images more accurate.

[0035] The radiation correction method through a radiation transmission model can accurately calculate a radiation correction coefficient according to actual atmospheric parameter data, effectively eliminates the influence of atmospheric condition changes on the radiation characteristics of images, improves the radiation precision of images, and makes the color and brightness of images more truly reflect the actual situation of the ground.

[0036] Through image fusion and optimization processing, various geographic information data are fused, and the images are further optimized, which not only improves the information quantity and definition of the images, but also makes the images more meet the requirements of geographic information display, and provides more intuitive and accurate geographic information display effect for users.

[0037] By adopting the correction result evaluation method combining quantification and qualification, the quality of the corrected images can be comprehensively and accurately evaluated, and it is ensured that the correction effect meets the requirements of geographic information display and application. If the requirements are not met, re-correction can be performed in time, and the reliability and practicality of the correction method are ensured.

[0038] The above only describes the embodiments of the application, and does not limit the patent range of the application, and any equivalent structure or equivalent process transformation using the content of the specification of the application, or direct or indirect application in other related technical fields, are also included in the patent protection range of the application.

Claims

1. An image correction method for displaying geographic information, characterized in that: The steps include: S1. Acquire geographic image data, and simultaneously acquire corresponding geographic control point data, digital elevation model (DEM) data, and atmospheric parameter data; S2, preprocessing the acquired geographic image data by removing noise, enhancing contrast, etc.; S3, performing geometric correction on the acquired geographic control point data and digital elevation model data; S4. Performing radiation correction on the acquired atmospheric parameter data; S5, fusing the geographic image data pre-processed in S2 with the pattern geometrically corrected in S3 and radiometrically corrected in S4, and further optimizing the fused image to improve the information content and clarity of the image; S6. Evaluate the optimized image in S5 using a combination of quantitative and qualitative methods.

2. The image correction method for geographic information display according to claim 1, characterized in that: The geographic image data is obtained by using satellite remote sensing equipment.

3. The image correction method for geographic information display according to claim 2, characterized in that: The digital elevation model is downloaded from the geographic information data center and has a resolution of 5 meters.

4. The image correction method for geographic information display according to claim 3, characterized in that: The atmospheric parameter data are obtained from a local meteorological monitoring station, and the atmospheric parameter data include atmospheric visibility, aerosol concentration, atmospheric temperature, and humidity.

5. The image correction method for geographic information display according to claim 4, characterized in that: The geographic control point data is obtained by field measurement or by using a high-precision geographic information database.

6. The image correction method for geographic information display according to claim 5, characterized in that: The median filtering algorithm is used to remove noise from geographic image data, and the histogram equalization method is used to enhance the contrast of the image and improve the visual quality of the image.

7. The image correction method for geographic information display according to claim 6, characterized in that: The image is geometrically corrected by combining polynomial transformation with collinearity equation.

8. The image correction method for geographic information display according to claim 7, characterized in that: The atmospheric parameter data are radiated and corrected using a method based on the radiation transfer model.

9. The image correction method for geographic information display according to claim 8, characterized in that: The optimization processing includes color adjustment, sharpening processing, etc., so as to make the image more in line with the requirements of geographic information display and improve the visual effect and readability of the image.