Earth surface classification method based on single-photon laser radar ambient noise rate
阅读说明：本技术 基于单光子激光雷达背景噪声率的地表分类方法 (Earth surface classification method based on single-photon laser radar ambient noise rate ) 是由 李松 刘欣缘 马跃 张智宇 张文豪 周辉 于 2019-07-29 设计创作，主要内容包括：本发明公开了一种基于单光子激光雷达背景噪声率的地表分类方法,首先根据镜面反射理论提出了水面光子反射噪声率的表达式,随后结合系统参数、环境参数与目标特性参数,建立了背景噪声率模型,分别给出了陆地背景噪声率与水体背景噪声率的数学表达式,最后计算得到地表分类噪声率阈值。根据陆地与水体背景噪声率的显著差异,可通过代入激光雷达原始点云数据的统计噪声率与噪声率阈值进行比较,判断地表类型。该分类方法不依赖于传统方法中需要用到的数字地形图或高分辨率遥感影像,采用的辅助数据易于获取,具有快速、高效的优点,可在沿海地区实现高精度的地表类型分类。将该方法应用于MABLE原始点云数据中,分类效果优异。(The invention discloses a kind of earth surface classification methods based on single-photon laser radar ambient noise rate, the expression formula of water surface photon reflecting background rate is proposed according to mirror-reflection theory first, later in conjunction with system parameter, environmental parameter and target property parameter, establish ambient noise rate model, the mathematic(al) representation of land ambient noise rate Yu water body ambient noise rate is set forth, Surface classification noise rate threshold value is finally calculated.According to the significant difference on land and water body ambient noise rate, it can be compared by substituting into the statistical noise rate of laser radar original point cloud data with noise rate threshold value, judge ground surface type.The classification method is easily obtained independent of the digital topography map or high-resolution remote sensing image for needing to use in conventional method, the auxiliary data of use, is had the advantages that fast and efficiently, can realize high-precision ground surface type classification in coastal area.This method is applied in MABLE original point cloud data, classifying quality is excellent.)
1. the earth surface classification method based on single-photon laser radar ambient noise rate characterized by comprising
Step S1: the environmental parameter and target property parameter when system parameter, the measurement of single-photon laser radar are obtained；
Step S2: according to system parameter, environmental parameter and target property parameter, ground photon reflecting background rate f is calculatedL, the water surface Photon reflecting background rate fWWith atmospheric backscatter noise rate fA；
Step S3: according to ground photon reflecting background rate fLWith atmospheric backscatter noise rate fA, calculate land ambient noise rate fnL, according to water surface photon reflecting background rate fWWith atmospheric backscatter noise rate fA, calculate water body ambient noise rate fnW；
Step S4: according to land ambient noise rate fnLWith water body ambient noise rate fnW, calculate the noise rate on ground and water surface classification Threshold value P；
Step S5: reading the point cloud data of airborne laser ceilometer, and statistics contains only within the scope of the default elevation of noise photon event Ambient noise rate fnS；
Step S6: the ambient noise rate f within the scope of default elevation is calculatednSWith water body ambient noise rate fnWRatio；
Step S7: according to ambient noise rate fnSWith water body ambient noise rate fnWRatio and noise rate threshold value P relationship, judgement should Ground surface type corresponding to point cloud data.
2. the method as described in claim 1, which is characterized in that system parameter includes optical maser wavelength, receiving telescope significant surface Product, telescope receive angle of half field-of view, narrow band filter bandwidth, electro-optical system overall efficiency, environmental parameter include the brightness of sun spoke, One way atmospheric transmittance, solar zenith angle and wind speed；Target property parameter includes ground line gradient, ground surface reflectance, the stormy waves gradient With water-reflected rate, step S2 is specifically included:
Ground photon reflecting background rate f is calculated according to formula (1) and (2) respectivelyL, atmospheric backscatter noise rate fA, formula (1) (2) concrete form are as follows:
In formula (1) and (2), Nλ 0For sun spoke brightness, Δ λ is narrow band filter bandwidth, and h is Planck's constant, and v is photon frequency Rate is the light velocity divided by photon wavelength λ, θrAngle of half field-of view is received for telescope, η is electro-optical system overall efficiency, ArIt looks in the distance to receive Mirror effective area, βLFor ground surface reflectance, TaFor one way atmospheric transmittance, θsFor solar zenith angle, ψ is sunray and earth's surface The angle of normal can be expressed as formula (3),
In formula (3), σLFor ground line gradient,For the azimuth of laser ceilometer heading and line of slope；
Water surface photon reflecting background rate f is calculated according to formula (4)W, the concrete form of formula (4) are as follows:
In formula (4), ρ is mirror point at a distance from optical axis, and z is laser ceilometer flying height, βwFor water-reflected rate, βwBecome Expression formula β about ρW(ρ):
In formula (5), the probability density function of stormy waves slope is Gaussian function, s2For its Mean Square Slope, s2=0.003+ 0.00512w, w are mean wind speed.
3. the method as described in claim 1, which is characterized in that step S3 is specifically included:
By ground photon reflecting background rate fLWith atmospheric backscatter noise rate fASum as land ambient noise rate fnL, by water Face photon reflecting background rate fWWith atmospheric backscatter noise rate fASum as water body ambient noise rate fnW。
4. the method as described in claim 1, which is characterized in that step S4, which is specifically included, calculates ground and water according to formula (6) The noise rate threshold value P of face classification:
5. the method as described in claim 1, which is characterized in that presetting elevation range in step S5 is 400~900m.
6. the method as described in claim 1, which is characterized in that step S7 is specifically included:
As statistical noise rate fnSWith water body ambient noise rate fnLRatio be less than noise rate threshold value P when, determine the type in the region For water body；As statistical noise rate fnSWith water body ambient noise rate fnLRatio be greater than noise rate threshold value P when, determine the region Type is land.
Technical field
The present invention relates to Surface classification technical fields, and in particular to a kind of based on single-photon laser radar ambient noise rate Earth surface classification method.
Background technique
Since photon counter and micropulse laser device are respectively provided with higher detection sensitivity and higher repetition, photon The photon point cloud data more more dense than traditional Full wave shape radar can be obtained by counting radar.Therefore, in order to be carried out to earth surface More accurate observation, US National Aeronautics and Space Administration will transmit ICESat-2 (Ice, Cloud, and land in the end of the year 2018 Elevation Satellite-2), and a photon counting radar is equipped with for it.However since photon counting radar is to letter Number photon and the noise photon for the reflection for being mainly derived from sun bias light are very sensitive, this makes single photon original point cloud number According to a large amount of noise, therefore, how to distinguish signal photon from original point cloud data is the key that photon counting radar.
Accurate ground surface type information is for selecting suitable method to extract signal photon very from original point cloud data It is important, especially in coastal area, since the surface characteristics of different ground surface types is different, distribution of the signal photon on the water surface There is larger difference with the distribution on ground.In the prior art, NCLD (National Center for Learning is utilized Disabilities), laser ceilometer is obtained from satellite optical image along the ground surface type of track.
At least there is following technology in implementing the present invention, it may, the method for finding the prior art in present inventor Problem:
Existing method, which needs to extract to compare with high resolution image after signal photon, classifies, NLCD auxiliary data It is essential；It and is based on warp according to the noise rate threshold value that ambient noise rate in original point cloud data carries out water-ice classification Formula is tested, meanwhile, it be at present based on earth surface for the theoretical formula of earth's surface photon reflecting background rate is a Lang Baiti It is assumed that however the hypothesis is not suitable for the water surface, the theoretical formula about water surface photon reflecting background rate also have no complete data to Out.
It follows that the not high and inefficient technical problem of accuracy exists in the prior art.
Summary of the invention
The present invention mainly analyzes expression formula using the water surface photon reflecting background rate newly derived, in conjunction with system parameter, environment Parameter and target property parameter establish ambient noise rate model, accurately calculate to obtain the noise rate threshold value for Surface classification, Provide a kind of ground surface type classification method based on single-photon laser radar ambient noise rate.
Above-mentioned technical problem of the invention is mainly to be addressed by following technical proposals:
The present invention provides a kind of earth surface classification methods based on single-photon laser radar ambient noise rate, comprising:
Step S1: the environmental parameter and target property parameter when system parameter, the measurement of single-photon laser radar are obtained；
Step S2: according to system parameter, environmental parameter and target property parameter, ground photon reflecting background rate is calculated fL, water surface photon reflecting background rate fWWith atmospheric backscatter noise rate fA；
Step S3: according to ground photon reflecting background rate fLWith atmospheric backscatter noise rate fA, calculate land ambient noise Rate fnL, according to water surface photon reflecting background rate fWWith atmospheric backscatter noise rate fA, calculate water body ambient noise rate fnW；
Step S4: according to land ambient noise rate fnLWith water body ambient noise rate fnW, calculate ground and the water surface classification make an uproar Sound rate threshold value P；
Step S5: reading the point cloud data of airborne laser ceilometer, and statistics contains only the default elevation model of noise photon event Enclose interior ambient noise rate fnS；
Step S6: the ambient noise rate f within the scope of default elevation is calculatednSWith water body ambient noise rate fnWRatio；
Step S7: according to ambient noise rate fnSWith water body ambient noise rate fnWRatio and noise rate threshold value P relationship, Judge ground surface type corresponding to the point cloud data.
In one embodiment, system parameter includes optical maser wavelength, receiving telescope effective area, telescope reception half Field angle, narrow band filter bandwidth, electro-optical system overall efficiency, environmental parameter include the brightness of sun spoke, one way atmospheric transmittance, Solar zenith angle and wind speed；Target property parameter includes ground line gradient, ground surface reflectance, the stormy waves gradient and water-reflected rate, step Rapid S2 is specifically included:
Ground photon reflecting background rate f is calculated according to formula (1) and (2) respectivelyL, atmospheric backscatter noise rate fA, formula (1) and the concrete form of (2) are as follows:
In formula (1) and (2), Nλ 0For sun spoke brightness, Δ λ is narrow band filter bandwidth, and h is Planck's constant, and v is light Sub- frequency is the light velocity divided by photon wavelength λ, θrAngle of half field-of view is received for telescope, η is electro-optical system overall efficiency, ArTo receive Telescope effective area, βLFor ground surface reflectance, TaFor one way atmospheric transmittance, θsFor solar zenith angle, ψ be sunray with The angle of earth's surface normal can be expressed as formula (3),
In formula (3), σLFor ground line gradient,For the azimuth of laser ceilometer heading and line of slope；
Water surface photon reflecting background rate f is calculated according to formula (4)W, the concrete form of formula (4) are as follows:
In formula (4), ρ is mirror point at a distance from optical axis, and z is laser ceilometer flying height, βwFor water-reflected rate, βw Become the expression formula β about ρW(ρ):
In formula (5), the probability density function of stormy waves slope is Gaussian function, s2For its Mean Square Slope, s2=0.003+ 0.00512w, w are mean wind speed.
In one embodiment, step S3 is specifically included:
By ground photon reflecting background rate fLWith atmospheric backscatter noise rate fASum as land ambient noise rate fnL, By water surface photon reflecting background rate fWWith atmospheric backscatter noise rate fASum as water body ambient noise rate fnW。
In one embodiment, step S4 is specifically included according to formula (6)
Calculate the noise rate threshold value P on ground and water surface classification:
In one embodiment, it is 400~900m that elevation range is preset in step S5.
In one embodiment, step S7 is specifically included:
As statistical noise rate fnSWith water body ambient noise rate fnLRatio be less than noise rate threshold value P when, determine the region Type is water body；As statistical noise rate fnSWith water body ambient noise rate fnLRatio be greater than noise rate threshold value P when, determine the area The type in domain is land.
Said one or multiple technical solutions in the embodiment of the present application at least have following one or more technology effects Fruit:
A kind of earth surface classification method based on single-photon laser radar ambient noise rate provided by the invention, firstly, obtaining Environmental parameter and target property parameter when the system parameter of single-photon laser radar, measurement；Then, according to system parameter, Environmental parameter and target property parameter calculate ground photon reflecting background rate fL, water surface photon reflecting background rate fWAfter atmosphere To shot noise rate fA；Then, according to ground photon reflecting background rate fLWith atmospheric backscatter noise rate fA, calculate land back Scape noise rate fnL, according to water surface photon reflecting background rate fWWith atmospheric backscatter noise rate fA, calculate water body ambient noise rate fnW；Next, according to land ambient noise rate fnLWith water body ambient noise rate fnW, calculate the noise rate on ground and water surface classification Threshold value P；Then, the point cloud data of airborne laser ceilometer is read, statistics contains only within the scope of the default elevation of noise photon event Ambient noise rate fnS；The ambient noise rate f within the scope of default elevation is calculated againnSWith water body ambient noise rate fnWRatio；Most Afterwards, according to ambient noise rate fnSWith water body ambient noise rate fnWRatio and noise rate threshold value P relationship, judge this cloud number According to corresponding ground surface type.
Due to method provided by the invention, background can be established in conjunction with system parameter, environmental parameter and target property parameter Noise rate model, and land ambient noise rate and water body ambient noise rate can be calculated, and then Surface classification is calculated Noise rate threshold value, finally by according to ambient noise rate fnSWith water body ambient noise rate fnWRatio and noise rate threshold value P pass System, judges corresponding ground surface type, provides reliable foundation for ground surface type classification；Also, the ground surface type classification method It only needs using the noise photon being easily obtained, and does not need to extract signal photon, while also not dependent on tradition The digital topography map or high-resolution remote sensing image for needing to use in method, therefore may be implemented operand is small, arithmetic speed While fast, complete to classify to the high accuracy of coastal area ground surface type.Meanwhile the classification method is in high latitude sea ice area Ground surface type detection aspect have very big application potential.
Detailed description of the invention
In order to more clearly explain the embodiment of the invention or the technical proposal in the existing technology, to embodiment or will show below There is attached drawing needed in technical description to be briefly described, it should be apparent that, the accompanying drawings in the following description is the present invention Some embodiments for those of ordinary skill in the art without creative efforts, can also basis These attached drawings obtain other attached drawings.
Fig. 1 is a kind of process signal of earth surface classification method based on single-photon laser radar ambient noise rate of the present invention Figure；
Fig. 2 is geometric representation of the water surface stormy waves reflected sunlight to Return Signal for Laser Altimeter visual field；
Fig. 3 is ground photon reflecting background rate fLWith water surface photon reflecting background rate fWThe ratio between P1It makes an uproar with atmospheric backscatter Sound rate fAWith water surface photon reflecting background rate fWThe ratio between P2With solar zenith angle θsThe change curve of increase；
Fig. 4 is different solar zenith angle θs, atmospheric transmittance TaWith ground surface reflectance βLNoise rate threshold value P when combination Distribution map；
Fig. 5 is flow chart of the invention in concrete application；
Fig. 6 is the MABLE track (using solid-line curve) on high-resolution satellite image, (b) original captured for MABLE Beginning point cloud data；
Fig. 7 is specific example middle high-resolution image, (b) original point cloud data to capture.
Specific embodiment
It is an object of the invention to the technical problems not high and inefficient for accuracy existing in the prior art, mention A kind of earth surface classification method based on single-photon laser radar ambient noise rate supplied improves classifying quality and classification standard to reach The technical effect of true property.
In order to achieve the above objectives, central scope of the invention is as follows:
Ambient noise rate the present invention is based on single-photon laser radar in different ground surface types has the characteristics that significant difference, The classification method of ground surface type is judged according to the statistical noise rate in original point cloud data.For the ground characteristic different from the water surface Parameter derives water surface photon reflecting background rate in combination with single-photon laser radar system parameters and measurement environmental parameter Expression formula, and noise rate threshold value is calculated.By the comparison of the statistical noise rate in original point cloud data, earth's surface class is judged Type is a kind of fast and efficiently ground surface type classification method.
In order to make the object, technical scheme and advantages of the embodiment of the invention clearer, below in conjunction with the embodiment of the present invention In attached drawing, technical scheme in the embodiment of the invention is clearly and completely described, it is clear that described embodiment is A part of the embodiment of the present invention, instead of all the embodiments.Based on the embodiments of the present invention, those of ordinary skill in the art Every other embodiment obtained without creative efforts, shall fall within the protection scope of the present invention.
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