CN102331402A - Chemical gas detection and identification method by hyperspectral imaging - Google Patents

Abstract

The invention discloses a chemical gas detection and identification method by hyperspectral imaging and relates to the chemical gas detection and identification method. By the chemical gas detection and identification method, the technical problems that on-site sampling is required and the detection speed is low in the conventional chemical gas detection and identification method based on a chemical method can be solved. The chemical gas detection and identification method comprises the following steps of: shooting a spectral image of a detected place when any chemical gas does not exist in the detected place so as to acquire a pixel vector of a background; acquiring a spectral vector of a detected chemical gas from a chemical gas spectrum library; shooting another spectral image of the detected place and filtering the second spectral image by using a filter; sequencing output values of the filter from large to small; setting a threshold of the chemical gas; inputting the output values of the filter and the threshold of the chemical gas into a judger; recording the output values, greater than the threshold, of the filter so as to acquire a chemical gas-containing pixel set; and judging pixels containing the chemical gas by using a minimum markov distance method so as to identify the type of the gas. The chemical gas detection and identification method can be used in the fields of detection for pollution gas emission of chemical factories and environment monitoring.

Description

A kind of high light spectrum image-forming chemical gas detects recognition methods

Technical field

The invention belongs to chemical gas and detect recognition methods.

Background technology

High light spectrum image-forming is a process of obtaining the image information of high spectral resolution at the spectral band of electromagnetic spectrum.High spectrum image has comprised spatial information and the spectral information in the observation scene simultaneously, has the characteristic of " collection of illustrative plates unification ".Each pixel in the image all is a high dimension vector, and each dimension of vector is illustrated in a spectral band.Because the high spectrum image advantage that has the spectral resolution height, contain much information, can improve in the target detection process ability of target being carried out qualitative and quantitative analysis greatly, aspect civilian and military field many, embodied huge using value.The chemical gas incident of leakage happens occasionally all over the world; Existing based on the method for chemical method to the detection and Identification of chemical gas, all to arrive leak scene sampling, staff's health is damaged; And detection speed is slow, is unfavorable for the timely processing to accident.

Summary of the invention

The present invention will solve existingly need arrive on-site sampling and the slow technical matters of detection speed based on chemical method to the method for the detection and Identification of chemical gas, and provides a kind of high light spectrum image-forming chemical gas to detect recognition methods.

A kind of high light spectrum image-forming chemical gas of the present invention detects recognition methods to carry out according to the following steps:

Step 1: in area to be detected during no chemical gas; Using the infrared pick-up device to adopt wavelength is at least three images that the different-wavebands shooting has K pixel in 8 μ m～13 μ m; Each wave band is taken an image, is obtained K pixel vectors x of background by the pixel of the correspondence of these images _k, k=1 wherein, 2,3 ..., K; K is the number of pixels of entire image;

Step 2: use

Calculate the pixel vectors x of background _kThe maximum likelihood estimated value of average Use again

Calculate the pixel vectors x of background _kThe maximum likelihood estimated matrix of variance

, wherein

Be pixel vectors x _kTransposed vector;

Step 3: the target chemical gas for N kind needs detect according to the data in the chemical gas library of spectra, obtains chemical gas spectrum vector s in the gaseous spectrum storehouse _i, i=1 wherein, 2,3 ..., N;

Step 4: in area to be detected; Using the infrared pick-up device to adopt wavelength is at least three images that the different-wavebands shooting has K pixel in 8 μ m～13 μ m; Each wave band is taken an image, is obtained K the pixel vectors z in area to be detected by the pixel of the correspondence of these images _j, j=1 wherein, 2,3 ..., K;

Step 5: shilling i=1;

Step 6: utilize $y_{i,j}=\frac{s_i^T{\widehat{\mathrm{\Σ}}}_b^{-1}(z_j-{\widehat{\mathrm{\μ}}}_b)}{s_i^T{\widehat{\mathrm{\Σ}}}_b^{-1}{s}_i}$ K the pixel vectors z that step 4 is obtained _jThe output valve y of calculating filter _{I, 1}, y _{I, 2}, y _{I, 3}... Y _{I, j-1}, y _{I, j}, y _{I, j+1}..., y _{I, k}And pressing series arrangement from big to small, the maximum likelihood estimated value E [Y] of the average of [α K] individual output valve and the maximum likelihood estimated value Var [Y] of variance are designated as u with [α K] individual output valve simultaneously before calculating again _iWherein

Be matrix

Inverse matrix; α=5%～10%;

Step 7: utilize $E\left[Y\right]=\frac{\mathrm{\σ}}{1-\mathrm{\ξ}}$ With $\mathrm{Var}\left[Y\right]=\frac{{\mathrm{\σ}}^2}{{(1-\mathrm{\ξ})}^2(1-2\mathrm{\ξ})}$ Calculate parameter σ and ξ; Be used further to detect the thresholding of i kind chemical gas ${\mathrm{\η}}_i=u_i+\frac{\mathrm{\σ}}{\mathrm{\ξ}}[{\left(\frac{\mathrm{\α}}{P_{\mathrm{FA}}}\right)}^2-1];$ P wherein _FABe false-alarm probability, P _FA=10 ^-3～10 ^-5

Step 8: the output valve y of each wave filter that step 6 is calculated _{I, 1}, y _{I, 2}, y _{I, 3}... Y _{I, j-1}, y _{I, j}, y _{I, j+1}..., y _{I, k}The thresholding of the i kind chemical gas that calculates with step 7 ${\mathrm{\η}}_i=u_i+\frac{\mathrm{\σ}}{\mathrm{\ξ}}[{\left(\frac{\mathrm{\α}}{P_{\mathrm{FA}}}\right)}^2-1]$ Together import decision device and compare, judge whether output valve, if not, then make i add 1, execution in step six greater than the wave filter of thresholding; If, execution in step nine;

Step 9: record is greater than the corresponding pixel vectors z of the output valve of thresholding _iAnd corresponding i kind chemical gas;

Step 10: judge then whether i equals N, if not, make i add 1, execution in step six; If then execution in step 11;

Step 11: that writes down in the step 8 uses z greater than the corresponding pixel vectors of the output valve of thresholding _cExpression, c=1,2 ..., C; The corresponding spectrum vector of chemical gas in the gaseous spectrum storehouse used s _dExpression, d=1 wherein, 2,3 ..., D; Make c=1, d=1; Wherein C representes that D representes the maximal value of corresponding chemical gas kind greater than the maximal value of the number of the corresponding pixel vectors of the output valve of thresholding;

Step 12: calculate ${\mathrm{\Δ}}_{c,d}=\sqrt{{(z_c-{\widehat{\mathrm{\μ}}}_b-{\hat{a}}_d{S}_d)}^T{\widehat{\mathrm{\Σ}}}_b^{-1}(z_c-{\widehat{\mathrm{\μ}}}_b-{\hat{a}}_d{s}_d)}$ Calculate horse formula distance, delta _{C, d}, wherein, ${\hat{a}}_d=\frac{s_d^T{\widehat{\mathrm{\Σ}}}_b^{-1}(z_c-{\widehat{\mathrm{\μ}}}_b)}{s_d^T{\widehat{\mathrm{\Σ}}}_b^{-1}{s}_d},$

Be the maximum likelihood estimated value of the average of background,

The maximum likelihood estimated matrix of the variance of background

Inverse matrix,

The transposition of the spectrum vector of d kind chemical gas in the gaseous spectrum storehouse;

Step 13: judge whether d is 1, if make d add 1, execution in step 12; If not, execution in step 14 then;

Step 14: judge Δ _{C, d}≤Δ _{C, d-1}If,, record d gas; If not, execution in step 15;

Step 15: judge whether d equals D, if not, then make d add 1, return step 12; If, execution in step 16;

Step 10 six: c gas that monitors threat is judged into the chemical gas of last record and made c add 1;

Step 10 seven: judge whether c equals C, if not, make c add 1, execution in step 12; If then execution in step 18;

Step 10 eight: calculate the pairing volume coordinate of each pixel that detects chemical gas, accomplish the detection identification of chemical gas.

Because atmosphere is transparent relatively in LONG WAVE INFRARED zone (8-13 μ m), utilize the high spectrum image of this wave band to carry out remote detection and Identification to the chemical gas of leakage or discharge in violation of regulations.Gas detection with based on chemical method is compared, and utilizes the high light spectrum image-forming technology that gas is detected and has more real-time and more secure to personal safety.In long wave infrared region, the imaging model of chemical gas can be constructed as x=as+v, and wherein x is a pixel vectors in the high spectrum image, and s is the spectrum vector of chemical gas, and v is the background vector, and a is the coefficient relevant with thickness with the concentration of this gas.Therefore,, design a matched filter and evade this interference, and whether the output of wave filter can cooperate decision threshold to detect chemical gas to exist in order to detect the influence that the pixel that contains chemical gas just must be removed background clutter.But need making up a rational statistical model, this make the output of wave filter to meet; Theory according to Manolakis; The background clutter that no chemical gas covers is at high spectrum image that long wave infrared region became; Through behind the matched filter, its output valve meets broad sense Pareto and distributes, and obtains a CFAR decision threshold through the mode of setting false-alarm probability.The detection of chemical gas is to accomplish with relevant with it decision threshold through designing a matched filter.Mahalanobis distance utilizes the similarity that the statistical property of data can two samples of fine measurement, and therefore on the problem of chemical gas identification, the pixel that detected chemical gas in the image is existed is judged to the minimum chemical gas of mahalanobis distance with it.Find P the minimum value in the mahalanobis distance, pairing gaseous species promptly is the chemical gas that this location of pixels is revealed or discharged.The design concept synoptic diagram of the inventive method is as shown in Figure 1, and above various piece is integrated, and is exactly the system of automatic chemical gas detection and Identification.

High light spectrum image-forming chemical gas of the present invention detects the recognition methods area of monitoring chemical gaseous emission or leakage at a distance, has avoided arriving on-site sampling, and has worked by computer operation, and detection speed is fast.

The present invention can be used for detection and the environmental monitoring field to the discharging of chemical plant dusty gas.

Description of drawings

The design concept synoptic diagram of Fig. 1 the inventive method; Fig. 2 is the process flow diagram that high light spectrum image-forming chemical gas of the present invention detects recognition methods.

Embodiment

Embodiment one: a kind of high light spectrum image-forming chemical gas of this embodiment detects recognition methods to carry out according to the following steps:

Step 1: in area to be detected during no chemical gas; Using the infrared pick-up device to adopt wavelength is at least three images that the different-wavebands shooting has K pixel in 8 μ m～13 μ m; Each wave band is taken an image, is obtained K pixel vectors x of background by the pixel of the correspondence of these images _k, k=1 wherein, 2,3 ..., K; K is the number of pixels of entire image;

Step 2: use

Calculate the pixel vectors x of background _kThe maximum likelihood estimated value of average

Use again

Calculate the pixel vectors x of background _kThe maximum likelihood estimated matrix of variance

Wherein

Be pixel vectors x _kTransposed vector;

Step 3: the target chemical gas for N kind needs detect according to the data in the chemical gas library of spectra, obtains chemical gas spectrum vector s in the gaseous spectrum storehouse _i, i=1 wherein, 2,3 ..., N;

Step 4: in area to be detected; Using the infrared pick-up device to adopt wavelength is at least three images that the different-wavebands shooting has K pixel in 8 μ m～13 μ m; Each wave band is taken an image, is obtained K the pixel vectors z in area to be detected by the pixel of the correspondence of these images _j, j=1 wherein, 2,3 ..., K;

Step 5: shilling i=1;

Step 6: utilize $y_{i,j}=\frac{s_i^T{\widehat{\mathrm{\Σ}}}_b^{-1}(z_j-{\widehat{\mathrm{\μ}}}_b)}{s_i^T{\widehat{\mathrm{\Σ}}}_b^{-1}{s}_i}$ K the pixel vectors z that step 4 is obtained _jThe output valve y of calculating filter _{I, 1}, y _{I, 2}, y _{I, 3}... Y _{I, j-1}, y _{I, j}, y _{I, j+1}..., y _{I, k}And pressing series arrangement from big to small, the maximum likelihood estimated value E [Y] of the average of [α K] individual output valve and the maximum likelihood estimated value Var [Y] of variance are designated as u with [α K] individual output valve simultaneously before calculating again _iWherein

Be matrix

Inverse matrix; α=5%～10%;

Step 7: utilize $E\left[Y\right]=\frac{\mathrm{\σ}}{1-\mathrm{\ξ}}$ With $\mathrm{Var}\left[Y\right]=\frac{{\mathrm{\σ}}^2}{{(1-\mathrm{\ξ})}^2(1-2\mathrm{\ξ})}$ Calculate parameter σ and ξ; Be used further to detect the thresholding of i kind chemical gas ${\mathrm{\η}}_i=u_i+\frac{\mathrm{\σ}}{\mathrm{\ξ}}[{\left(\frac{\mathrm{\α}}{P_{\mathrm{FA}}}\right)}^2-1];$ P wherein _FABe false-alarm probability, P _FA=10 ^-3～10 ^-5

Step 8: the output valve y of each wave filter that step 6 is calculated _{I, 1}, y _{I, 2}, y _{I, 3}... Y _{I, j-1}, y _{I, j}, y _{I, j+1}..., y _{I, k}The thresholding of the i kind chemical gas that calculates with step 7 ${\mathrm{\η}}_i=u_i+\frac{\mathrm{\σ}}{\mathrm{\ξ}}[{\left(\frac{\mathrm{\α}}{P_{\mathrm{FA}}}\right)}^2-1]$ Together import decision device and compare, judge whether output valve, if not, then make i add 1, execution in step six greater than the wave filter of thresholding; If, execution in step nine;

Step 9: record is greater than the corresponding pixel vectors z of the output valve of thresholding _iAnd corresponding i kind chemical gas;

Step 10: judge then whether i equals N, if not, make i add 1, execution in step six; If then execution in step 11;

Step 11: that writes down in the step 8 uses z greater than the corresponding pixel vectors of the output valve of thresholding _cExpression, c=1,2 ..., C; The corresponding spectrum vector of chemical gas in the gaseous spectrum storehouse used s _dExpression, d=1 wherein, 2,3 ..., D; Make c=1, d=1; Wherein C representes that D representes the maximal value of corresponding chemical gas kind greater than the maximal value of the number of the corresponding pixel vectors of the output valve of thresholding;

Step 12: calculate ${\mathrm{\Δ}}_{c,d}=\sqrt{{(z_c-{\widehat{\mathrm{\μ}}}_b-{\hat{a}}_d{s}_d)}^T{\widehat{\mathrm{\Σ}}}_b^{-1}(z_c-{\widehat{\mathrm{\μ}}}_b-{\hat{a}}_d{s}_d)}$ Calculate horse formula distance, delta _{C, d}, wherein, ${\hat{a}}_d=\frac{s_d^T{\widehat{\mathrm{\Σ}}}_b^{-1}(z_c-{\widehat{\mathrm{\μ}}}_b)}{s_d^T{\widehat{\mathrm{\Σ}}}_b^{-1}{s}_d},$

Be the maximum likelihood estimated value of the average of background,

The maximum likelihood estimated matrix of the variance of background

Inverse matrix,

The transposition of the spectrum vector of d kind chemical gas in the gaseous spectrum storehouse;

Step 13: judge whether d is 1, if make d add 1, execution in step 12; If not, execution in step 14 then;

Step 14: judge Δ _{C, d}≤Δ _{C, d-1}If,, record d gas; If not, execution in step 15;

Step 15: judge whether d equals D, if not, then make d add 1, return step 12; If, execution in step 16;

Step 10 six: c gas that monitors threat is judged into the chemical gas of last record and made c add 1;

Step 10 seven: judge whether c equals C, if not, make c add 1, execution in step 12; If then execution in step 18;

Step 10 eight: calculate the pairing volume coordinate of each pixel that detects chemical gas, accomplish the detection identification of chemical gas.

[α K] expression in the step 5 of this embodiment rounds calculating with α K.

In this embodiment,, utilize the high spectrum image of this wave band to carry out remote detection and Identification to the chemical gas of leakage or discharge in violation of regulations because atmosphere is transparent relatively in LONG WAVE INFRARED zone (8-13 μ m).Gas detection with based on chemical method is compared, and utilizes the high light spectrum image-forming technology that gas is detected and has more real-time and more secure to personal safety.In long wave infrared region, the imaging model of chemical gas can be constructed as x=as+v, and wherein x is a pixel vectors in the high spectrum image, and s is the spectrum vector of chemical gas, and v is the background vector, and a is the coefficient relevant with thickness with the concentration of this gas.Therefore,, design a matched filter and evade this interference, and whether the output of wave filter can cooperate decision threshold to detect chemical gas to exist in order to detect the influence that the pixel that contains chemical gas just must be removed background clutter.But need making up a rational statistical model, this make the output of wave filter to meet; Theory according to Manolakis; The background clutter that no chemical gas covers is at high spectrum image that long wave infrared region became; Through behind the matched filter, its output valve meets broad sense Pareto and distributes, and obtains a CFAR decision threshold through the mode of setting false-alarm probability.The detection of chemical gas is to accomplish with relevant with it decision threshold through designing a matched filter.Mahalanobis distance utilizes the similarity that the statistical property of data can two samples of fine measurement, and therefore on the problem of chemical gas identification, the pixel that detected chemical gas in the image is existed is judged to the minimum chemical gas of mahalanobis distance with it.Find P the minimum value in the mahalanobis distance, pairing gaseous species promptly is the chemical gas that this location of pixels is revealed or discharged.This embodiment integrates above various piece, is exactly the system of automatic chemical gas detection and Identification.The monitoring chemical gaseous emission at a distance of this embodiment or the area of leakage, aspects such as the detection of dusty gas discharging and environmental monitoring all have very high practicality in the chemical plant.

Embodiment two: what this embodiment and embodiment one were different is: calculating each method that detects the pairing volume coordinate of pixel of chemical gas in the step 10 eight is: according to the spatial resolution and the camera site of high spectrum sensor, calculate the pairing volume coordinate of each pixel that detects chemical gas: $\left\{\begin{array}{c}u=u_0+\mathrm{\θ}\·e\\ v=v_0+\mathrm{\θ}\·f^{\′}\end{array}\right.,$ (u ₀, v ₀) be the volume coordinate of a known pixels on the image, be reference point with it, (u v) is the corresponding volume coordinate of pixel, and (e is the horizontal vertical number of pixels coordinate that the pixel that detects chemical gas deviates from benchmark pixel f), and θ is the spatial resolution of sensor.Other is identical with embodiment one.

Embodiment three: the method for a kind of high light spectrum image-forming chemical gas detection and Identification of this embodiment is carried out according to the following steps:

Step 1: in area to be detected during no chemical gas; Using the infrared pick-up device to adopt wavelength is 10 images that the different-wavebands shooting has 10000 pixels in 8 μ m～13 μ m; Each wave band is taken an image; Obtain 10 images altogether, obtain 10000 pixel vectors x of background by the pixel of the correspondence of these 10 images _k, k=1 wherein, 2,3 ..., 10000;

Step 2: use

Calculate the maximum likelihood estimated value of the average of background

Use again

Calculate the maximum likelihood estimated matrix of the variance of background

Wherein

Be pixel vectors x _kTransposed vector;

Step 3: the target chemical gas for 10 kinds of needs detect according to the data in the chemical gas library of spectra, obtains i kind chemical gas spectrum vector s in the gaseous spectrum storehouse _i, i=1 wherein, 2,3 ..., 10;

Step 4: in area to be detected; Using the infrared pick-up device to adopt wavelength is the image that the 10 different-wavebands shooting in 8 μ m～13 μ m has 10000 pixels; Each wave band is taken an image; Obtain 10 images altogether, obtain 10000 pixel vectors z in area to be detected by the pixel of the correspondence of these 10 images _j, j=1 wherein, 2,3 ..., 10000;

Step 5: shilling i=1;

Step 6: utilize $y_{i,j}=\frac{s_i^T{\widehat{\mathrm{\Σ}}}_b^{-1}(z_j-{\widehat{\mathrm{\μ}}}_b)}{s_i^T{\widehat{\mathrm{\Σ}}}_b^{-1}{s}_i}$ 10000 pixel vectors z that step 4 is obtained _jThe output valve y of calculating filter _{I, 1}, y _{I, 2}, y _{I, 3}... Y _{I, j-1}, y _{I, j}, y _{I, j+1}..., y _{I, 10000}And, calculate maximum likelihood estimated value E [Y] and the maximum likelihood estimated value Var [Y] of variance of the average of preceding 500 output valves again by from big to small series arrangement, simultaneously the 500th output valve is designated as u _iWherein

Be matrix

Inverse matrix;

Step 7: utilize $E\left[Y\right]=\frac{\mathrm{\σ}}{1-\mathrm{\ξ}}$ With $\mathrm{Var}\left[Y\right]=\frac{{\mathrm{\σ}}^2}{{(1-\mathrm{\ξ})}^2(1-2\mathrm{\ξ})}$ Calculate parameter σ and ξ; Be used further to detect the thresholding of i kind chemical gas ${\mathrm{\η}}_i=u_i+\frac{\mathrm{\σ}}{\mathrm{\ξ}}[{\left(\frac{\mathrm{\α}}{P_{\mathrm{FA}}}\right)}^2-1];$ P wherein _FABe false-alarm probability, P _FA=10 ^-4

Step 8: the output valve y of each wave filter that step 6 is calculated _{I, 1}, y _{I, 2}, y _{I, 3}... Y _{I, j-1}, y _{I, j}, y _{I, j+1}..., y _{I, k}The thresholding of the i kind chemical gas that calculates with step 7 ${\mathrm{\η}}_i=u_i+\frac{\mathrm{\σ}}{\mathrm{\ξ}}[{\left(\frac{\mathrm{\α}}{P_{\mathrm{FA}}}\right)}^2-1]$ Together import decision device and compare, judge whether output valve, if not, then make i add 1, execution in step six greater than the wave filter of thresholding; If, execution in step nine;

Step 9: record is greater than the corresponding pixel vectors z of the output valve of thresholding _iAnd corresponding i kind chemical gas;

Step 10: judge then whether i equals N, if not, make i add 1, execution in step six; If then execution in step 11;

Step 11: that writes down in the step 8 uses z greater than the corresponding pixel vectors of the output valve of thresholding _cExpression, c=1,2 ..., C; The corresponding spectrum vector of chemical gas in the gaseous spectrum storehouse used s _dExpression, d=1 wherein, 2,3 ..., D; Make c=1, d=1; Wherein C representes that D representes the maximal value of corresponding chemical gas kind greater than the maximal value of the number of the corresponding pixel vectors of the output valve of thresholding;

Step 12: calculate ${\mathrm{\Δ}}_{c.d}=\sqrt{{(z_c-{\widehat{\mathrm{\μ}}}_b-{\hat{a}}_d{s}_d)}^T{\widehat{\mathrm{\Σ}}}_b^{-1}(z_c-{\widehat{\mathrm{\μ}}}_b-{\hat{a}}_d{s}_d)}$ Calculate horse formula distance, delta _{C, d}, wherein, ${\hat{a}}_d=\frac{s_d^T{\widehat{\mathrm{\Σ}}}_b^{-1}(z_c-{\widehat{\mathrm{\μ}}}_b)}{s_d^T{\widehat{\mathrm{\Σ}}}_b^{-1}{s}_d},$ Be the maximum likelihood estimated value of the average of background,

The maximum likelihood estimated matrix of the variance of background Inverse matrix, The transposition of the spectrum vector of d kind chemical gas in the gaseous spectrum storehouse;

Step 13: judge whether d is 1, if make d add 1, execution in step 12; If not, execution in step 14 then;

Step 14: judge Δ _{C, d}≤Δ _{C, d-1}If,, record d gas; If not, execution in step 15;

Step 15: judge whether d equals D, if not, then make d add 1, return step 12; If, execution in step 16;

Step 10 six: c gas that monitors threat is judged into the chemical gas of last record and made c add 1;

Step 10 seven: judge whether c equals C, if not, make c add 1, execution in step 12; If then execution in step 18;

Step 10 eight:, calculate the pairing volume coordinate of each pixel that detects chemical gas according to the spatial resolution and the camera site of high spectrum sensor: $\left\{\begin{array}{c}u=u_0+\mathrm{\θ}\·e\\ v=v_0+\mathrm{\θ}\·f^{\′}\end{array}\right.,$ (u ₀, v ₀) be the volume coordinate of a known pixels on the image, be reference point with it, (u; V) be the corresponding volume coordinate of pixel, (e f) is the horizontal vertical number of pixels coordinate that the pixel that detects chemical gas deviates from benchmark pixel; θ is the spatial resolution of sensor, accomplishes the detection identification of chemical gas.

Wavelength in this embodiment in step 1 and the step 4 is that 10 different-wavebands in 8 μ m～13 μ m are got like this:

8.0μm～8.25μm	8.26μm～8.50μm	8.51μm～8.75μm	8.51μm～8.75μm	8.76μm～9.00μm
					9.05μm～9.25μm	9.26μm～9.50μm	9.51μm～9.75μm	9.76μm～10.00μm	10.01μm～10.25μm

The dimension of pixel vectors is identical with the number of the wave band of being got in the high spectrum image, the pixel vectors x of background in the step 1 of this embodiment _kDimension be 10 the dimension, the pixel vectors z in the step 4 _jDimension also be 10 the dimension.

In this embodiment,, utilize the high spectrum image of this wave band to carry out remote detection and Identification to the chemical gas of leakage or discharge in violation of regulations because atmosphere is transparent relatively in LONG WAVE INFRARED zone (8-13 μ m).Gas detection with based on chemical method is compared, and utilizes the high light spectrum image-forming technology that gas is detected and has more real-time and more secure to personal safety.In long wave infrared region, the imaging model of chemical gas can be constructed as x=as+v, and wherein x is a pixel vectors in the high spectrum image, and s is the spectrum vector of chemical gas, and v is the background vector, and a is the coefficient relevant with thickness with the concentration of this gas.Therefore,, design a matched filter and evade this interference, and whether the output of wave filter can cooperate decision threshold to detect chemical gas to exist in order to detect the influence that the pixel that contains chemical gas just must be removed background clutter.But need making up a rational statistical model, this make the output of wave filter to meet; Theory according to Manolakis; The background clutter that no chemical gas covers is at high spectrum image that long wave infrared region became; Through behind the matched filter, its output valve meets broad sense Pareto and distributes, and obtains a CFAR decision threshold through the mode of setting false-alarm probability.The detection of chemical gas is to accomplish with relevant with it decision threshold through designing a matched filter.Mahalanobis distance utilizes the similarity that the statistical property of data can two samples of fine measurement, and therefore on the problem of chemical gas identification, the pixel that detected chemical gas in the image is existed is judged to the minimum chemical gas of mahalanobis distance with it.Find P the minimum value in the mahalanobis distance, pairing gaseous species promptly is the chemical gas that this location of pixels is revealed or discharged.This embodiment integrates above various piece, is exactly the system of automatic chemical gas detection and Identification.The monitoring chemical gaseous emission at a distance of this embodiment or the area of leakage, aspects such as the detection of dusty gas discharging and environmental monitoring all have very high practicality in the chemical plant.

Claims (2)

1. a high light spectrum image-forming chemical gas detects recognition methods, it is characterized in that the high light spectrum image-forming chemical gas detects recognition methods and carries out according to the following steps:

Step 1: in area to be detected during no chemical gas; Using the infrared pick-up device to adopt wavelength is at least three images that the different-wavebands shooting has K pixel in 8 μ m～13 μ m; Each wave band is taken an image, is obtained K pixel vectors x of background by the pixel of the correspondence of these images _k, k=1 wherein, 2,3 ..., K; K representes the number of pixels of entire image;

Step 2: use

Calculate the pixel vectors x of background _kThe maximum likelihood estimated value of average

Use again Calculate the pixel vectors x of background _kThe maximum likelihood estimated matrix of variance

Wherein

Be pixel vectors x _kTransposed vector;

Step 3: the target chemical gas for N kind needs detect according to the data in the chemical gas library of spectra, obtains chemical gas spectrum vector s in the gaseous spectrum storehouse _i, i=1 wherein, 2,3 ..., N;

Step 4: in area to be detected; Using the infrared pick-up device to adopt wavelength is at least three images that the different-wavebands shooting has K pixel in 8 μ m～13 μ m; Each wave band is taken an image, is obtained K the pixel vectors z in area to be detected by the pixel of the correspondence of these images _j, j=1 wherein, 2,3 ..., K;

Step 5: shilling i=1;

Step 6: utilize $y_{i,j}=\frac{s_i^T{\widehat{\mathrm{\Σ}}}_b^{-1}(z_j-{\widehat{\mathrm{\μ}}}_b)}{s_i^T{\widehat{\mathrm{\Σ}}}_b^{-1}{s}_i}$ K the pixel vectors z that step 4 is obtained _jThe output valve y of calculating filter _{I, 1}, y _{I, 2}, y _{I, 3}... Y _{I, j-1}, y _{I, j}, y _{I, j+1}..., y _{I, k}And pressing series arrangement from big to small, the maximum likelihood estimated value E [Y] of the average of [α K] individual output valve and the maximum likelihood estimated value Var [Y] of variance are designated as u with [α K] individual output valve simultaneously before calculating again _iWherein

Be matrix

Inverse matrix; α=5%～10%;

Step 7: utilize $E\left[Y\right]=\frac{\mathrm{\σ}}{1-\mathrm{\ξ}}$ With $\mathrm{Var}\left[Y\right]=\frac{{\mathrm{\σ}}^2}{{(1-\mathrm{\ξ})}^2(1-2\mathrm{\ξ})}$ Calculate parameter σ and ξ; Be used further to detect the thresholding of i kind chemical gas ${\mathrm{\η}}_i=u_i+\frac{\mathrm{\σ}}{\mathrm{\ξ}}[{\left(\frac{\mathrm{\α}}{P_{\mathrm{FA}}}\right)}^2-1];$ P wherein _FABe false-alarm probability, P _FA=10 ^-3～10 ^-5Step 8: the output valve y of each wave filter that step 6 is calculated _{I, 1}, y _{I, 2}, y _{I, 3}... Y _{I, j-1}, y _{I, j}, y _{I, j+1}..., y _{I, k}The thresholding of the i kind chemical gas that calculates with step 7 ${\mathrm{\η}}_i=u_i+\frac{\mathrm{\σ}}{\mathrm{\ξ}}[{\left(\frac{\mathrm{\α}}{P_{\mathrm{FA}}}\right)}^2-1]$ Together import decision device and compare, judge whether output valve, if not, then make i add 1, execution in step six greater than the wave filter of thresholding; If, execution in step nine;

Step 9: record is greater than the corresponding pixel vectors z of the output valve of thresholding _iAnd corresponding i kind chemical gas;

Step 10: judge then whether i equals N, if not, make i add 1, execution in step six; If then execution in step 11;

Step 11: that writes down in the step 8 uses z greater than the corresponding pixel vectors of the output valve of thresholding _cExpression, c=1,2 ..., C; The corresponding spectrum vector of chemical gas in the gaseous spectrum storehouse used s _dExpression, d=1 wherein, 2,3 ..., D; Make c=1, d=1; Wherein C representes that D representes the maximal value of corresponding chemical gas kind greater than the maximal value of the number of the corresponding pixel vectors of the output valve of thresholding;

Step 12: calculate ${\mathrm{\Δ}}_{c,d}=\sqrt{{(Z_c-{\widehat{\mathrm{\μ}}}_b-{\hat{a}}_d{s}_d)}^T{\widehat{\mathrm{\Σ}}}_b^{-1}(Z_c-{\widehat{\mathrm{\μ}}}_b-{\hat{a}}_d{s}_d)}$ Calculate horse formula distance, delta _{C, d}, wherein, ${\hat{a}}_d=\frac{s_d^T{\widehat{\mathrm{\Σ}}}_b^{-1}(z_c-{\widehat{\mathrm{\μ}}}_b)}{s_d^T{\widehat{\mathrm{\Σ}}}_b^{-1}{s}_d},$

Be the maximum likelihood estimated value of the average of background,

The maximum likelihood estimated matrix of the variance of background

Inverse matrix,

The transposition of the spectrum vector of d kind chemical gas in the gaseous spectrum storehouse;

Step 13: judge whether d is 1, if make d add 1, execution in step 12; If not, execution in step 14 then;

Step 14: judge Δ _{C, d}≤Δ _{C, d-1}If,, record d gas; If not, execution in step 15;

Step 15: judge whether d equals D, if not, then make d add 1, execution in step 12; If, execution in step 16;

Step 10 six: c gas that monitors threat is judged into the chemical gas of last record and made c add 1;

Step 10 seven: judge whether c equals C, if not, make c add 1, execution in step 12; If then execution in step 18;

Step 10 eight: calculate the pairing volume coordinate of each pixel that detects chemical gas, accomplish the detection identification of chemical gas.

2. a kind of high light spectrum image-forming chemical gas according to claim 1 detects recognition methods; It is characterized in that calculating in the step 10 eight each method that detects the pairing volume coordinate of pixel of chemical gas is: according to the spatial resolution and the camera site of high spectrum sensor, calculate the pairing volume coordinate of each pixel that detects chemical gas: $\left\{\begin{array}{c}u=u_0+\mathrm{\θ}\·e\\ v=v_0+\mathrm{\θ}\·f^{\′}\end{array}\right.,$ (u ₀, v ₀) be the volume coordinate of a known pixels on the image, be reference point with it, (u v) is the corresponding volume coordinate of pixel, and (e is the horizontal vertical number of pixels coordinate that the pixel that detects chemical gas deviates from benchmark pixel f), and θ is the spatial resolution of sensor.

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