CN1804588A - Self-calibrating atmosphere visibility measuring method and measuring system thereof - Google Patents

Abstract

The invention discloses a method and system for measuring the self-aligning atmosphere visual degree. It takes photo of the image of all the target and uses the mode near to human eyes character to process the image to auto compute the normalizing diversity of the target light brightness and the visual degree value and transmits the data to the monitoring center and the LED large screen display of the high speed road inlet and outlet port by GPRS wireless mode.

Description

Self-aligning atmosphere visual degree measuring method and system

Technical field

The present invention relates to a kind of atmospheric visibility measuring method and system, particularly relate to a kind of self-aligning atmosphere visual degree measuring method and system.

Technical background

Along with developing rapidly of Chinese national economy, road traffic particularly freeway traffic has obtained develop rapidly, also in surge at a high speed, interlocal contact is more frequent for motor vehicle quantity, and thing followed traffic safety problem becomes increasingly conspicuous and caused social extensive concern.Visibility is the key factor that directly influences expressway traffic safety, and inferior visibility weather conditions cause large-scale a chain of traffic accident often, cause great casualties and property loss.Therefore, measuring and report visibility quickly and accurately, all is crucial to numerous driver and passenger and vehicle supervision department.

Before more than 50 years, just begun research and development in the world to visibility measurement technical research and instrument.Most visibility measurement instruments of past are based on the transmittance of measuring atmosphere or attenuation coefficient or scattering coefficient and design, under pure mist or the uniform condition of atmosphere, the measurement result of this quasi-instrument also relatively accurately, but rain, snow and the airborne dust weather condition under, their accuracy has just descended greatly.This external atmosphere is inhomogeneous, under the bigger situation of spatial variations, because the spatial dimension (volume) of tested scattered light is very little, adds the non-visible again wavelength of used measurement wavelength, the visibility value of apparatus measures usually with differing greatly that eye-observation obtains.After nineteen ninety, because the appearance of video camera makes people enough methods that is in close proximity to human visual system to obtain and to handle image, realization visibility is measured more accurately.Such as, 1998-2004, the intelligent transportation system research institute of Univ Minnesota-Twin Cities USA utilizes a video camera and a plurality of target, on highway, realize the measurement of visibility in the daytime, obtained the nonlinear curve between visibility value and the target contrast value.But their used computing formula is not all considered the increase to the target luminance brightness that causes because of scattering, not consider black, the intrinsic luminance difference of white object yet.Simultaneously, diffuse transmission type visibility measurement device must carry out pre-calibration (calibration) before using, and this is to bother very much and time-consuming thing, to calibrating the place and certain requirement is also arranged season, and the calibration in greasy weather is not suitable for rain, snow, airborne dust weather again.Therefore, the calibration problem of visibility measurement device is perplexing the practical application of this class surveying instrument.

Domestic research about highway visibility at present mainly concentrates on various weather conditions to the influence of visibility, the environmental pollution aspects such as influence to visibility, do not see relevant ripe practical, formally define based on World Meteorological Organization (WMO) (WMO), directly press the atmospheric visibility real-time detecting system report of human visual system evaluation, more do not see relevant ripe practical report with self-alignment atmospheric visibility real-time detecting system aspect.

Summary of the invention

The objective of the invention is to overcome the deficiencies in the prior art, a kind of self-aligning atmosphere visual degree measuring method and system are provided, this method has been considered to cause the increase of luminance brightness and black because of scattering, the influence that white object intrinsic light luminance difference is measured atmospheric visibility, the computing method that make atmospheric visibility are science more, more practical, the notion of visibility measurement system self-calibration has been proposed, designed without pre-calibration, the atmospheric visibility surveying instrument that is applicable to any weather condition that can calibrate automatically, exempted the trouble of pre-calibration, solved pre-calibration and be not suitable for rain, snow, the difficult problem of airborne dust Changes in weather.

Goal of the invention of the present invention is achieved through the following technical solutions: the method that a kind of self-aligning atmosphere visual degree is measured, and its measuring process comprises:

(1) measures special-purpose target along the visual orientation of target image collecting device 5～10 atmospheric visibilities that are crisscross arranged at the scene; The project installation parameter of its target is calculated according to basic parameter (comprising: the target sum of use, use place (expressway or airport), the distance range of installing, used cameral CCD size, total pixel, the light center height that the maximum focal length of camera, camera are installed etc.) by special software;

(2) with the disposable image that comprises all targets that takes of target image collecting device;

(3) with image analysis processing device the target image is handled, calculated the luminance brightness normalization contrast of each target;

(4) normalization contrast equals the distance of that target of threshold value 0.05, is exactly on-the-spot visibility value, then calculates by the measurement curve fitting to the visibility value beyond the target distance range farthest at target recently.

The method that a kind of self-aligning atmosphere visual degree of the present invention is measured, when calculating the luminance brightness normalization contrast of target, comprise the influence that reduces and increase by two parts of the target luminance brightness that causes because of scattering, and comprised influence black, white object intrinsic light luminance difference.Its computing method are as follows:

1. visibility definition

Press World Meteorological Organization (WMO) (WMO), formally being defined as follows of meteorological optical range (Meteorological Visibility) in the daytime: observe in the face of the sky background of scattering, can see and recognize the ultimate range of the black object of subaerial suitable size.So-called " can recognize " is meant the threshold values contrast of the observed luminance contrast C of people (contrast) greater than agreement, and the computing formula of its contrast is as follows:

$C=\frac{L_w-L_b}{L_w}---\left(1\right)$

Wherein, L _W,, L _BBe respectively the luminance brightness of observed white object and black objects.

At aviation field, International Civil Aviation Organization (ICAO) is to visibility and night visibility also have its special definition in the daytime.These definition are originally all based on the independent observation of human eye.Though these definition are uncomplicated,, many difficulties have been brought to scientific measurement because they itself still have many indefinite factors.For example how many luminous reflectances (having determined their luminance brightness) of white, black object is actually; How are the size of its area, shape; Again how, the lighting condition of white, black object is that the skylight illumination is only arranged, and the automobile front illumination is still only arranged, or both haves both at the same time; Under the situation of optical illumination, the light brightness distribution in illumination sky and background sky zone how about on high; Observer's angle and height or the like all do not have clear and definite definition, and they influence measurement result significantly, that is to say that visibility is the function of a plurality of parameter complexity.

After W.E.K.Middleton proposed term " look see scope (Visual Range, VR) ", these indefinite factors had reduced.It is defined as: be the subjective visual evaluation of atmosphere to the decay of luminance contrast in the daytime.In his VR definition, the pigtail of visibility is recognized part and has been omitted, and also further VR is made referrals to other specific field, as aviation VR, inclination VR, meteorological VR etc.Today, the almost indiscriminative interchangeably use of term " visibility " and " look and see scope ".

Visibility measurement of the present invention system is mainly used in the traffic above-ground transportation, so we are interested in control-tower visibility VR, rather than the measurement of atmospheric parameter, can recognize vehicle and road boundary this interior driver of distance.

2. the luminance brightness contrast of target

In order to measure the visibility of atmosphere, specialized designs measurement target drone, its white portion is made of the very high diffuse-reflective material of luminous reflectance, the black part is made of the very low diffuse-reflective material of luminous reflectance, as Fig. 1 and shown in Figure 6.

Target is by the skylight of diffusion and the indirect lighting on ground, and the average equivalent luminance brightness of establishing the illumination sky is L ₀, the average equivalent luminance brightness that ground return produces is Lg, if the target face is a diffuse surface, the luminous reflectance of its white, black target surface is respectively ρ _W,, ρ _B,, their luminance brightness (x=0 place) on hand is respectively L _B0, L _W0, by the photometry theory, have:

$\left.\begin{array}{c}{L}_{w0}={\mathrm{<figure-callout\; id="1"\; label="b"\; filenames="A20061002011500181.png,A20061002011500192.png"\; state="\{\{state\}\}">b</figure-callout>}}_1{\mathrm{\&rho;}}_W{L}_0+{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="A20061002011500181.png,A20061002011500192.png"\; state="\{\{state\}\}">b</figure-callout>}}_2{\mathrm{\&rho;}}_W{L}_g={\mathrm{b\&rho;}}_w{L}_0\\ L_{B0}={\mathrm{<figure-callout\; id="1"\; label="b"\; filenames="A20061002011500181.png,A20061002011500192.png"\; state="\{\{state\}\}">b</figure-callout>}}_1{\mathrm{\&rho;}}_B{L}_0+{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="A20061002011500181.png,A20061002011500192.png"\; state="\{\{state\}\}">b</figure-callout>}}_2{\mathrm{\&rho;}}_B{L}_g={\mathrm{b\&rho;}}_B{L}_0\end{array}\right\}---\left(2\right)$

In the formula: b ₁, b ₂, b is a scale factor, after being l through light path, the brightness of its target becomes:

$L_W\left(l\right)=L_{W0}\exp (-{\&Integral;}_0^l\mathrm{\&gamma;}\left(x\right)\mathrm{dx})+L_D\left(l\right)$

$L_B\left(l\right)=L_{B0}\exp (-{\&Integral;}_0^l\mathrm{\&gamma;}\left(x\right)\mathrm{dx})+L_D\left(l\right)---\left(3\right)$

Wherein, γ (x) is the atmospheric attenuation coefficient, and the right first expression brightness is because of the decay that absorbs and scattering (going out light path) causes, second L _D(l) then represent the increase that causes because of scattering (going into light path), its expression formula is:

$L_D\left(l\right)={\&Integral;}_0^l{L}_d\&CenterDot;\mathrm{\&sigma;}\left(x\right)g\left(\mathrm{\&phi;}\right)\mathrm{\&Delta;\&Omega;}\&CenterDot;\left[\exp (-{\&Integral;}_x^l\mathrm{\&gamma;}\left(y\right)\mathrm{dy})\right]\&CenterDot;\mathrm{dx}---\left(4\right)$

In the formula: L _dBe the luminance brightness of the back atmosphere column section that thrown light on by sky, obviously it is proportional to the average light brightness L of sky ₀, can be expressed as: L _d=p ₁L ₀, its p ₁Be proportionality constant; G (φ) is the normalization scattering function under the 4 π direction incident conditions:

$g\left(\mathrm{\&phi;}\right)=\frac{{\&Integral;}_0^{4\mathrm{\&pi;}}I\left(\mathrm{\&theta;}\right)f(\mathrm{\&phi;}-\mathrm{\&theta;})d{\mathrm{\&Omega;}}_{\mathrm{\&theta;}}}{{\&Integral;}_0^{4\mathrm{\&pi;}}I\left(\mathrm{\&theta;}\right)d{\mathrm{\&Omega;}}_{\mathrm{\&theta;}}}---\left(5\right)$

When σ (x) g (φ) Δ Ω was 4 π direction incidents, the unit scattering volume scattered to the share that photometry direction (φ) goes up the scattering coefficient in the Δ Ω of solid angle unit in the light path, and the pass of it and scattering coefficient σ (x) is:

${\&Integral;}_0^{4\mathrm{\&pi;}}\mathrm{\&sigma;}\&CenterDot;g\left(\mathrm{\&phi;}\right)\mathrm{d\&Omega;}=\mathrm{\&sigma;}$

$\&CenterDot;{\&Integral;}_0^{4\mathrm{\&pi;}}g\left(\mathrm{\&phi;}\right)\mathrm{d\&Omega;}=1,---\left(6\right)$

Usually: σ (x) g (0) Δ Ω=p ₂σ (x) ... (0＜p ₂＜1)

In the formula: p ₂Be proportionality constant, approximate and aerosol particle concentration has nothing to do.If what consider is horizontal visibility, can think that atmosphere is uniformly, γ (x), σ (x) do not change with distance x, and then (9) formula becomes:

$L_D\left(l\right)=\frac{p_1{L}_0{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="A20061002011500181.png,A20061002011500192.png"\; state="\{\{state\}\}">p</figure-callout>}}_2\mathrm{\&sigma;}}{\mathrm{\&gamma;}}\&CenterDot;(1-e^{-\mathrm{\&gamma;l}})=\mathrm{\&alpha;}{L}_0(1-e^{-\mathrm{\&gamma;l}})---\left(7\right)$

α＝p ₁p ₂σ/γ＝p·σ/γ≈0.95p，………(λ＝514.5nm)

In the formula: (8)

p＝p ₁·p ₂

α-be a proportionality constant, relevant with wavelength, relevant slightly with the state (promptly with target terrain and its features on every side) of ground return optical illumination with target by sky.So (3) formula becomes:

L _W(l)＝bρ _WL ₀·e ^-γl+αL ₀·[1-e ^-γl)]

(9)

L _B(l)＝bρ _BL ₀·e ^-γl+αL ₀·[1-e ^-γl)]

When γ=0, when promptly not having mist, or the l=0 light path very in short-term, second additional brightness L that causes because of scattering _D=0; When γ ↑, during l ↑ very big, i.e. mistiness, during optical length, L _D→ maximum value (≈ 0.95pL ₀).The observed target in x=l place white/contrast C (l) of black surface luminance brightness is:

$C\left(l\right)=\frac{({\mathrm{\&rho;}}_W-{\mathrm{\&rho;}}_B)}{{\mathrm{\&rho;}}_W+\frac{\mathrm{\&alpha;}}{b}\&CenterDot;[e^{\mathrm{\&gamma;l}}-1]}=({\mathrm{\&rho;}}_W-{\mathrm{\&rho;}}_B)\&CenterDot;{[{\mathrm{\&rho;}}_W+\mathrm{\&beta;}(e^{\mathrm{\&gamma;l}}-1)]}^{-1}---\left(10\right)$

By (10) formula as can be known, the contrast that records with concentration of aerosol, light path is relevant and (ρ _W-ρ _B) be directly proportional, and and sky average effective luminance brightness L ₀It is irrelevant that (yes in certain variation range! ), this is our desired result just.In actual measurement, should select target face near desirable diffuse reflection white and desirable diffuse reflection black as far as possible.Again from (10) formula, contrast also with target around terrain and its features slightly (by parameter beta=α/b) relevant, so identical when the terrain and its features shape around the target should be as far as possible with use during calibration.

Must notice that luminance brightness is a radiant quantity by the visible wavelength region of human visual system evaluation, but, by INTEGRAL THEOREM OF MEAN, from (3) to (10) are as long as formula is interpreted as a certain equivalent monochromatic light in the visible wavelength region.(10) the constant b in the formula, ρ _W, ρ _B, α, and then β can be by measurings.Their span is approximately:

b≈(0.1∽0.8)，ρ _W≈(0.8∽0.90)，ρ _B≈(0.02∽0.05)，

p＝(0.01∽0.2)，α≈0.95p，β＝α/b≈(0.01∽0.1∽0.2∽0.9)，

γ≈(0.1∽100)[km ^-1]。

As γ one timing, luminance brightness L _W(l), L _B(l) and contrast C (l) with change curve such as Fig. 2 of distance.

The L that marks in Fig. 2 must be noted _W(l), L _B(l) curve is by maximal value L _W0Curve after the normalization, when distance increases, white target surface brightness L _W(l) descend black target surface brightness L _B(l) rise, be tending towards a constant brightness value α L at last ₀, contrast C (l) then drops to zero from maximal value always.

When γ=0, when promptly not having mist, or the l=0 light path very in short-term, second additional brightness L that causes because of scattering _D=0; Transparent fully, contrast reaches maximal value C ₀

$C=C_0=\frac{{\mathrm{\&rho;}}_w-{\mathrm{\&rho;}}_B}{{\mathrm{\&rho;}}_w}---\left(11\right)$

When concentration of aerosol increases, when distance strengthens, promptly γ ↑, in l ↑ time, (10) formula value is tending towards 0, promptly contrast C → 0 has not again seen target.Obviously, along with distance strengthens, the C value reduces gradually, and object will fog gradually; When C less than a certain critical value ε, human eye can't distinguish object from background, this critical value ε is called liminal contrast, C=ε determines the condition of visibility apart from V.ε is an amount relevant with visual characteristics of human eyes, and the ε value that World Meteorological Organization (WMO) (WMO) is recommended is 0.02, and International Civil Aviation Organization (ICAO) recommendation is 0.05.

Certain when concentration of aerosol, promptly γ is certain, lengthening light path l, as the C that satisfies condition (l)=ε, the time distance, just just equaled visibility value V by the definition of World Meteorological Organization (WMO) (WMO).Get by (10) formula:

$V=\frac{1n({\mathrm{\&rho;}}_W-{\mathrm{\&epsiv;\&rho;}}_W+\mathrm{\&epsiv;\&beta;}-{\mathrm{\&rho;}}_B)-1n\left(\mathrm{\&epsiv;\&beta;}\right)}{\mathrm{\&gamma;}}---\left(12\right)$

3. the variation relation of the luminance brightness normalization contrast of visibility and target

3.1 luminance brightness normalization contrast

About the original definition of visibility, the luminous reflectance of its visibility value and black object and the luminance brightness in background sky zone are closely related by World Meteorological Organization (WMO), also can find out from (10) formula, and its value is subjected to obviously that target is white, the black region luminous reflectance _W,, ρ _B, influence.For reducing the uncertain factor that influences it, press the term " VR " of W.E.K.Middleton, be defined as the subjective assessment of atmosphere to the luminance contrast decay.Therefore we introduce the indignant thought of normalization contrast below, and the variation of contrast value rather than contrast value is own emphatically.

By (10) formula as can be known, when γ=0, promptly desirable fine day, atmosphere are transparent fully, and contrast reaches maximal value C ₀, we claim that the contrast of this moment is the intrinsic contrast of target, C is the target apparent contrast that observes, and then defines C _N=C/C ₀Normalization contrast for target:

$C_N\left(l\right)=\frac{C\left(l\right)}{C_0}=\frac{{\mathrm{\&rho;}}_W}{{\mathrm{\&rho;}}_W+\mathrm{\&beta;}\&CenterDot;[e^{\mathrm{\&gamma;l}}-1]}---\left(13\right)$

Its maximal value is 1, and minimum value is 0.Certain when concentration of aerosol, promptly γ is certain, and lengthening light path l is when satisfying condition: C _N(l)=and distance during ε, promptly by behind the big gas column of level of certain distance, when the contrast of target decays to ε times of intrinsic contrast, be exactly the visibility V of Middleton definition _RBe worth, that is:

$V_R=\frac{1n({\mathrm{\&rho;}}_W-{\mathrm{\&epsiv;\&rho;}}_W+\mathrm{\&epsiv;\&beta;})-1n\left(\mathrm{\&epsiv;\&beta;}\right)}{\mathrm{\&gamma;}}---\left(14\right)$

Actual conditions to visibility measurement, formula (13), (14) considered additional brightness and the intrinsic light luminance difference black, white object that causes because of scattering, thereby the visibility of Koschmieder law than before and Duntley law is calculated more science, more practical of formula.

By (13) formula as can be known, the luminous reflectance of white, the black region of target is to V _RInfluence just much smaller.

3.2 the luminance brightness normalization contrast of target is with the variation of distance under the different visibility conditions

Under normalizing condition, we will ask: " under different visibility conditions, how target normalization contrast changes with distance? "Suppose target just like preceding simple shape shown in Figure 1, the intrinsic contrast of normalization that is obtained by black/white area pixel value average computation is 1.Suppose that the distance that target is laid moves from the near to the remote, and the linear distance that increases, under different visibility conditions, measure the normalization contrast of this target, will how to change? the following formula that we at first utilize (14) formula to derive calculates attenuation coefficient γ corresponding under the different visibility conditions and comes:

$\mathrm{\&gamma;}=\frac{1n({\mathrm{\&rho;}}_W-{\mathrm{\&epsiv;\&rho;}}_W+\mathrm{\&epsiv;\&beta;})-1n\left(\mathrm{\&epsiv;\&beta;}\right)}{V_R}---\left(15\right)$

If choose ρ _W≈ 0.8, ρ _B≈ 0.03, b ≈ 0.2, p=0.17, β=0.95p/b ≈ 0.81, ε=0.05 item;

γ≈2.98/V _R (16)

We are as if choosing following visibility value: V _R=(50,100,200,300,400,500,700,1000) m, then corresponding respectively attenuation coefficient γ [km ^-1] be about: (59.6,29.8,14.8,9.95,7.46,5.96,4.26,2.98).This (16) formula not only considered because of absorbing and scattering causes the decay of object brightness, and considered the increase that causes because of scattering (going into light path).With γ value substitution (13) formula, just can calculate the variation relation of normalization contrast, as the curve among Fig. 3 with distance.

Transverse axis is represented the distance of target.The normalization contrast is the visibility value that the pairing distance of intersection point of the horizontal line of ε and certain curve just equals this curve.The contrast of any target drops to below the threshold value, just is considered to invisible.From Fig. 3 as seen, when low visibility, contrast descends very fast with the increase of distance.Clearly, distance will not have contribution greater than the target of visibility when measuring visibility.For example, visibility event is 100m, and then all positions target of being distal to 100m can not be used to calculate visibility.

3.3 the luminance brightness normalization contrast of target is with the variation of visibility under the different distance

If target is placed under the distance of (25,50,75,100,125,150,175,200,250,300,400,500) m, we will ask: " how the normalization contrast of target changes with visibility under the different distance? "This means that the variable l in (13) formula fixes visibility V to each target _RThereby attenuation coefficient γ is (≈ 2.98/V _R) change.To each target, we change visibility, its result of calculation such as Fig. 4 in (0-1000) m scope.The normalization contrast is the distance that horizontal line and the pairing visibility value of the intersection point of certain curve of ε just equals the corresponding target of this curve.Notice that visibility event is less than the target distance, this target just is considered to cannot see so.For example, visibility event is lower than 300m, the target at l=300m place because of contrast less than threshold value, will be invisible.Visibility event is big more a lot of than target distance, the contrast of this target will become rapidly and be tending towards saturated greatly, this means, this target can not provide can be for measuring the difference of enough big contrast.For example, visibility event is bigger than 100m, and the target at the 25m place can not provide measurable enough big contrast difference so.By the curve of Fig. 3 and Fig. 4, when using the target of fixed number, we can obtain some the important restricted conclusions about visibility measurement:

If we only allow to use a target to measure the visibility of (25-500) m, target must be placed in the 25m place.Because of when visibility is 25m, the target of any 25m of being distal to will be invisible.Among Fig. 3, with regard to susceptible of proof, it will cross all visibility lines at the standardized perpendicular line in 25m place.On the other hand, the variation of this target (25m) contrast shows that under the high-visibility condition, use closely target, accuracy will be low-down.For instance, when visibility when 400 change to 500m, the contrast of this target changes very little.

By top analysis as can be known, the method that self-aligning atmosphere visual degree of the present invention is measured has been considered the additional brightness and black, the intrinsic luminance difference of white object that cause because of scattering.In order in wide scope, to measure visibility, will in wide distance range, settle the identical target of intrinsic contrast, under different distance, settle more target will increase the scope and the accuracy of measuring visibility.Use single target will seriously limit accuracy of measurement and measurement range.

A kind of self-aligning atmosphere visual degree measuring system, it is made up of atmospheric visibility measurement mechanism, Surveillance center and visibility display device.

The atmospheric visibility measurement mechanism comprises the special-purpose target of 5～10 visibility measurements, target image collecting device, meteorologic parameter surveying instrument, image analysis processing device and measure field GPRS equipment; Special-purpose target places measure field, target image collecting device bornb sight photographic images, image analysis processing device will clap image recognition, the normalization contrast that localization process obtains each target, together with the on-the-spot meteorologic parameter that records, by on-the-spot GPRS equipment, be sent back to Surveillance center through mobile radio communication, internet.

Surveillance center comprises supervisory control comuter, data server; Supervisory control comuter receives the data that measure field GPRS equipment is beamed back from the internet, calculate the visibility value by the normalization contrast of a plurality of targets, then together with on-the-spot meteorologic parameter, again through the internet, mobile radio communication is sent back to and shows on-the-spot GPRS equipment.

The visibility display device: comprise that one shows on-the-spot GPRS equipment, a big screen LED display, GPRS equipment directly is connected with the big screen LED display by the interface data transmission line.

The special-purpose target of visibility measurement of the present invention comprises target bar, base plate, base plate is fixed on the top of target bar, the target bar is fixed on the stilt of basis, ground, base plate is divided into four blocks, wherein two of the diagonal angle blocks are black diffusion reflective surface, and two other diagonal angle block is white diffusion reflective surface.

Base plate be shaped as square or circle, four blocks are the impartial square of size or fan-shaped, homochromy block is diagonal line and distributes.

Diffuse transmission type visibility measurement system must carry out pre-calibration (calibration) before using, and this is to bother very much and time-consuming thing, to calibrating the place and certain requirement is also arranged season, and the calibration in greasy weather is not suitable for sleet and airborne dust weather again.

For addressing this problem, self calibration visibility measurement of the present invention system be by following sport technique segment cooperatively interact and specialized designs realizes: suitably design the target number, the target distance, target size and the locus of laying, make once take just can clap simultaneously the image of each target, record the normalization contrast of a plurality of targets, make the target under the different distance just constitute the metering scale that visibility " is never left the post ", " just " can recognize that the distance under target, the visibility value just equals that distance, then calculate to the visibility value beyond the target distance range farthest at nearest target by the measurement curve fitting, distance between target is the length scales of visibility measurement, realized " measuring i.e. calibration ", thereby realized measuring system (mist under any weather conditions, rain, snow, sand) self calibration of real-time online.Trouble when having exempted the system calibration of diffuse transmission type visibility measurement.

So-called " just " can recognize, is meant that the normalization contrast drops to equal generally acknowledged threshold epsilon=0.05.

By top narration as can be seen: the present invention has taken into full account additional brightness and black, the intrinsic luminance difference of white object that causes because of scattering, computing method and formula have been improved, improved visibility measurement result's accuracy, efficiently solve the self calibration problem simultaneously, described visibility measurement system is applicable to that the self calibration of (mist, rain, snow, sand) real-time online under any weather conditions measures, exempt the trouble of the necessary pre-calibration of diffuse transmission type visibility measurement device, be applicable to the measurement and the demonstration of the atmospheric visibility in places such as highway, airport.

Description of drawings

Fig. 1 takes the light path synoptic diagram of target.

Fig. 2 target luminance brightness L _W(1), L _B(1) and contrast C (1) with the change curve of distance.

Fig. 3 is under several selected visibility conditions, and target normalization contrast is with the change curve of distance.

The normalization contrast of target is with the change curve of visibility under Fig. 4 different distance.

Fig. 5 self-aligning atmosphere visual degree measuring system composition frame chart.

The square atmospheric visibility of Fig. 6 a is measured special-purpose target.

The circular atmospheric visibility of Fig. 6 b is measured special-purpose target.

Embodiment

Further describe technical scheme of the present invention below in conjunction with accompanying drawing.

Embodiment 1:

(1) on-the-spot weather: middle mist

(2) target and parameter:

As Fig. 6 a, the special-purpose target of the visibility measurement that present embodiment adopts comprises target bar 1, base plate 2, base plate 2 is fixed on the top of target bar 1, target bar 1 is fixed on the stilt of basis, ground, base plate 2 is divided into four blocks, wherein two of the diagonal angle blocks are black diffusion reflective surface 3, and two other diagonal angle block is white diffusion reflective surface 4.Base plate 2 be shaped as square, four blocks are the impartial square of size, homochromy block is diagonal line and distributes.

The project installation parameter of target can calculate according to basic parameter (being the maximum focal length of target sum, use place (expressway or airport), the distance range of installing, used cameral CCD size, total pixel, camera, the light center height that camera is installed etc.), now uses parameter as follows:

Existing target number=8

The distance of each target=(25,50,75,100,125,150,175,200) m

The length of side of each target=(0.40,0.65,0.86,1.06,1.23,1.40,1.56,1.72) m

Each target bar is projected in the surface level

Apart from drift angle=(2.42,2.42,1.47,1.47,0.70,0.70,0.0,0.0) of central axis °

Each target bar is projected in the surface level

Offset distance=(1.06,2.11,1.92,2.57,1.53,1.83,0.0,0.0) m apart from central axis

The height of each target bar=(4.59,4.90,3.77,4.55,2.95,4.15,2.13,3.71) m

This group target bar height value to ground basis for level or wait the condition calculating of inclining.

(3) measuring system:

The self-aligning atmosphere visual degree measuring system, it is made up of atmospheric visibility measurement mechanism, Surveillance center and visibility display device.

The atmospheric visibility measurement mechanism comprises the special-purpose target of 8 visibility measurements, target image collecting device, meteorologic parameter surveying instrument, image analysis processing device and measure field GPRS equipment; Special-purpose target places measure field, target image collecting device bornb sight photographic images, image analysis processing device will clap image recognition, the normalization contrast that localization process obtains each target, together with the on-the-spot meteorologic parameter that records, by on-the-spot GPRS equipment, be sent back to Surveillance center through mobile radio communication, internet.

Surveillance center comprises supervisory control comuter, data server; Supervisory control comuter receives the data that measure field GPRS equipment is beamed back from the internet, calculate the visibility value by the normalization contrast of a plurality of targets, then together with on-the-spot meteorologic parameter, again through the internet, mobile radio communication is sent back to and shows on-the-spot GPRS equipment.

The visibility display device comprises that one shows on-the-spot GPRS equipment, a big screen LED display, and GPRS equipment directly is connected with the big screen LED display by the interface data transmission line.

The target image collector is changed to digital camera.

(4) measuring method:

(i) measure special-purpose target along the visual orientation of target image collecting device 8 atmospheric visibilities that are crisscross arranged at the scene;

(ii) with the disposable image that comprises all targets that takes of target image collecting device;

(iii) the target image is handled, calculated the luminance brightness normalization contrast of each target with image analysis processing device;

(iv) normalization contrast equals the distance of that target of threshold value 0.05, is exactly on-the-spot visibility value, then calculates by the measurement curve fitting to the visibility value beyond the target distance range farthest at target recently.

(5) measurement result: (becoming one of the refined high speed 25km 2005-11-27 of place day example)

In the last table, the value of normalization contrast C n is all greater than threshold value 0.05, and expression visibility should be in target distance (200m) farthest in addition, extrapolate according to curve fitting, the visibility measurement result is 300m, and the normal personnel's visual observation of eyesight is about 310m, coincide with measurement result of the present invention.

Embodiment 2:

(1) on-the-spot weather: dense fog

(2) target and parameter: with embodiment 1

(3) measuring system and measuring method are with embodiment 1

(4) measurement result: (becoming another example of the refined high speed 25km 2005-11-27 of place day)

In the last table, that target of value=0.05 of normalization contrast C n distance be 150m, that is the visibility measurement result is 150m, and the normal personnel's visual observation of eyesight is about 160m, and is identical with measurement result of the present invention.

Claims (6)

1. the method measured of a self-aligning atmosphere visual degree is characterized in that measuring process comprises:

(1) measures special-purpose target along the visual orientation of target image collecting device 5～10 atmospheric visibilities that are crisscross arranged at the scene;

(2) with the disposable image that comprises all targets that takes of target image collecting device;

(3) with image analysis processing device the target image is handled, calculated the luminance brightness normalization contrast of each target;

(4) normalization contrast equals the distance of that target of threshold value 0.05, is exactly on-the-spot visibility value, then calculates by the measurement curve fitting to the visibility value beyond the target distance range farthest at target recently.

2. the method that a kind of self-aligning atmosphere visual degree according to claim 1 is measured, the luminance brightness normalization contrast calculation procedure that it is characterized in that target has comprised the variation that reduces and increase by two parts of the target luminance brightness that causes because of scattering, and has comprised processing black, white object intrinsic light luminance difference.

3. self-aligning atmosphere visual degree measuring system, it is characterized in that: it is made up of atmospheric visibility measurement mechanism, Surveillance center and visibility display device;

The atmospheric visibility measurement mechanism comprises the special-purpose target of 5～10 visibility measurements, target image collecting device, meteorologic parameter surveying instrument, image analysis processing device and measure field GPRS equipment; Special-purpose target places measure field, target image collecting device bornb sight photographic images, image analysis processing device will clap image recognition, the normalization contrast that localization process obtains each target, together with the on-the-spot meteorologic parameter that records, by on-the-spot GPRS equipment, be sent back to Surveillance center through mobile radio communication, internet; Surveillance center comprises supervisory control comuter, data server; Supervisory control comuter receives the data that measure field GPRS equipment is beamed back from the internet, calculate the visibility value by the normalization contrast of a plurality of targets, then together with on-the-spot meteorologic parameter, again through the internet, mobile radio communication is sent back to and shows on-the-spot GPRS equipment;

The visibility display device comprises that one shows on-the-spot GPRS equipment, a big screen LED display, and GPRS equipment directly is connected with the big screen LED display by the interface data transmission line;

4. a kind of self-aligning atmosphere visual degree measuring system according to claim 3, it is characterized in that the special-purpose target of described visibility measurement comprises target bar (1), base plate (2), base plate (2) is fixed on the top of target bar (1), target bar (1) is fixed on the stilt of basis, ground, base plate (2) is divided into four blocks, wherein two of the diagonal angle blocks are black diffusion reflective surface (3), and two other diagonal angle block is a white diffusion reflective surface (4).

5. a kind of self-aligning atmosphere visual degree measuring system according to claim 3, what it is characterized in that described atmospheric visibility measures the base plate of special-purpose target (2) is shaped as square or circle, four blocks are the impartial square of size or fan-shaped, and homochromy block is diagonal line and distributes.

6. a kind of self-aligning atmosphere visual degree measuring system according to claim 3 is characterized in that this system can calibrate like rain, snow, airborne dust weather automatically according to different weather conditions.

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