CN101236086B - Ultraviolet moon sensor output data evaluation and judging method - Google Patents

Abstract

A method for assessing and judging data output by an ultraviolet lunar sensor comprises judging brightness of lunar images output by an ultraviolet lunar sensor, comparing proportion of darkness grey scale pixel in images with preset proportion threshold value, if the former is larger than the latter, image is considered excessively dark, setting data quality grade to the lowest grade, otherwise judging whether image produces intensive flare, if intensive flare appears, setting data quality grade to the lowest grade, otherwise judging lunar efficient edge length in image, if efficient edge length is smaller than preset value, arc is considered too short, setting data quality grade to the lowest grade, otherwise using data quality step calculation according to lunar edge arc and fitting error, the data judgment method selects effective data for data with set grades according to threshold value, and sets application weighting coefficient for effecitive data according to quality grades. The method for assessing and judging data output by an ultraviolet lunar sensor carries out quantification assessment to current target condition and calculation, and effectively avoids influence of incorrect data of ultraviolet lunar sensor to the system.

Description

Ultraviolet moon sensor output data evaluation and determination methods

Technical field

The present invention relates to a kind of evaluation method of the data to ultraviolet moon sensor output, belong to optical imagery attitude sensor field.

Background technology

Along with the quick progress of imaging detection device and processor technology, the spacecraft attitude sensor is developed to imaging type by the unit scan formula gradually, and ultraviolet moon sensor is exactly a kind of big view field imaging formula attitude sensor that is different from traditional horizon instrument.The output of ultraviolet moon sensor is subjected to the restriction of following factor: 1. ultraviolet moon image quality; 2. the phases of the moon comprises full moon, gibbous moon, crescent or half moon, crescent moon; 3. moon face of land landform radiation difference and fluctuating; 4. information processing method adaptability such as edge extracting.Above factor makes the data of ultraviolet moon sensor export the output that has the different pieces of information quality in the different segmental arcs of track, and this just proposes the technical background of ultraviolet moon sensor output data quality evaluation.

The evaluation of data quality grade has realized the mathematical description of correctness, accuracy and the confidence level of attitude information, orbit altitude information, carrying out different data according to the quality grade size for spacecraft navigational guidance control system (GNC) uses, for example reject low-quality level data, high-quality data are used in weighting, so the design of data quality grade has important engineering for the sensor of satellite and GNC system and is worth.

Ultraviolet moon sensor is the sensor of first big visual field expansion target of China.

Jiang Yu, Wang Weitao, Zhang Jiangao, what radiance, data quality problem and excavation thereof in the data mining, computer science [J], 2002 the 12nd phases.Mentioned the data quality notion during database is set up in the document, but main deficiency is to optical attitude sensor field and product quality and the not argumentation of method for building up problem.

U.S. Pat 5319969, introduce a kind of three-axis attitude of ultraviolet spectral coverage attitude sensor that utilizes in the title " Method for determining 3-axis spacecraftattitude " and determined method, wherein do not related to the quality evaluation and the judgement of output data.

Summary of the invention

Technology of the present invention is dealt with problems and is: a kind of ultraviolet moon sensor output data evaluation and determination methods are provided, this data evaluation method realizes the data confidence level of ultraviolet moon sensor output to quantize, this determination methods is further determined the data that quantize to use weight coefficient, effectively avoids the influence of the wrong output data of ultraviolet moon sensor to satellite system.

Technical solution of the present invention is: the ultraviolet moon sensor output data evaluation method comprises the following steps:

(1) moon view data of ultraviolet moon sensor output is carried out brightness analysis, judge that described lunar map disturbs and the bright dark degree of image as veiling glare, the size of dark gray pixel proportion and preset ratio threshold value in the movement images, if the dark gray pixel ratio of image thinks then that greater than the preset ratio threshold value image is dark excessively, change step (5), otherwise change step (2);

(2) judge whether image strong veiling glare occurs,, otherwise change step (3) if step (5) occurs changeing;

(3) the efficient frontier length of the moon in the interpretation image if efficient frontier length less than preset value, thinks that then segmental arc is too short, is changeed step (5), otherwise changes step (4);

(4) according to moon edge arc length with fit error and carry out the data quality classification and calculate;

(5) the output data quality grade is set to lowermost level.

Image dark pixel ratio value rate computing formula in the described step (1) is:

$\mathrm{Rate}=\frac{{\mathrm{Num}}_{\mathrm{PT}}}{M\×N}$

Wherein, Num _PTFor gray scale in the image less than dark gray threshold value P _TAmount of pixels sum total;

P _TEqual the maximum background gray levels in the ground experiment;

M, N are the length of image and wide.

A kind of method of judging ultraviolet moon sensor output data: at first,, the result and the Evaluation threshold of claim 1 compared, think valid data greater than the data of threshold value, otherwise cast out according to the fixed Evaluation threshold of emulation and test situation; Then, described valid data are used weight coefficient according to its quality grade size design, the high more application weight coefficient of quality grade is big more, and it is as follows to use the weight coefficient computing formula:

Coef＝Q0*W

W＝QD/max(QD)

Wherein, Coef is the system applies coefficient;

Q0 is default maximum coefficient value;

W is a weighted value;

Max (QD) represents maximum quality grade.

The present invention compared with prior art beneficial effect is:

(1) the present invention is by analyzing the image light and shade, veiling glare situation, moon arc length and the error of calculation that influence the ultraviolet moon sensor attitude measurement, realize the quality grade quantification, mainly rely on front and back data comparing method contrast with existing sensor, realized output data in the rail Real-Time Evaluation, independence, real-time; And because the present invention takes combined factors such as image light and shade, veiling glare into account the accuracy height.

(2) quality computing formula of the present invention is created novelly, comprehensively, has both considered that moon segmental arc length had also comprised the error that fits calculating, complete reflection the attitude degree of accuracy.

(3) picture quality is considered comprehensively, and existing bright dark judgement has veiling glare to disturb judgement again.

(4) the present invention judges the data that quality grade quantizes by establishing threshold value earlier, the data output of poor image quality or moon marginal arc length can be effectively prevented and the data output that the error of calculation is big can be prevented, the present invention can more efficientlyly utilize sensor output data by setting weight coefficient, uses carry out different weights greater than the height qualitative data of threshold value.

Description of drawings

Fig. 1 is a ultraviolet moon sensor output data evaluation calculation flow chart of the present invention;

Fig. 2 is the strong veiling glare decision flow chart of the present invention;

Fig. 3 is a decision flow chart of the present invention;

Fig. 4 is the lunar map picture of the present invention's input;

Fig. 5 is an efficient frontier image of the present invention.

Embodiment

It is disclosed a kind of three-axis attitude sensor that utilizes the ultraviolet spectral coverage in the US5837894 title " Wide Field of View Sensor with diffractive OpticalCorrector " that the ultraviolet moon sensor that relates among the present invention can adopt the patent No. of Honeywell company application.Can also adopt disclosed a kind of three-axis attitude sensor that utilizes the ultraviolet spectral coverage in U.S. Pat 5319969 titles " Method for determining 3-axis spacecraft attitude ".

As shown in Figure 1, be the inventive method process flow diagram, the specific implementation process is as follows:

(1) moon view data of ultraviolet moon sensor output is carried out brightness analysis, judge that described lunar map disturbs and the bright dark degree of image as veiling glare, in the movement images dark pixel ratio rate with set in advance the proportion threshold value size, if ratio value is greater than described proportion threshold value, think that then image is dark excessively, change step (5), otherwise change step (2);

Dark pixel ratio rate value computing formula is in the image:

$\mathrm{Rate}=\frac{{\mathrm{Num}}_{\mathrm{PT}}}{M\×N}$

Wherein, Num _PTFor gray scale in the image less than gray threshold P _TAmount of pixels sum total, P _TEqual the maximum background gray levels in the ground experiment, for 0～255 image P _TCan select [1～10]; M, N are the length of image and wide.

The proportion threshold value that sets in advance determines that according to the ratio that the nominal size of target accounts for entire image scope is [0.9～0.99].

(2) judge whether image strong veiling glare occurs,, otherwise change step (3) if step (5) occurs changeing; Wherein, the high light interference phenomenon is judged flow process as shown in Figure 2, and concrete grammar is as follows:

The first step is determined the target surface analyzed area that the strong veiling glare of image that ultraviolet moon sensor is taken the photograph is judged, analyzed area is lower images certain delegation in partly ultraviolet moon sensor apparent field outside.

Second step, the pixel in the described analyzed area is carried out Horizon Search, if continuous two pixels of appearance greater than the bright pixel threshold value, then stop search and changeed for the 3rd step, otherwise continue search; The bright pixel threshold value is slightly less than in the ground experiment the brightest gray-scale value of determining, generally is not less than 95% of the brightest gray-scale value.

The 3rd step, pixel in second step is begun in vertically search and the statistics search contiguous pixels greater than the number of described bright pixel threshold value greater than any one pixel in two pixels of high light threshold value, when the number of statistics during greater than the number threshold value, there is strong veiling glare in the representative image, stop search; Otherwise, the one other pixel point is vertically searched for and adds up in the search contiguous pixels greater than the number of described bright pixel threshold value, when the number of statistics during, there is strong veiling glare in the representative image greater than number threshold value (the number threshold value is generally greater than 10), stop search; Otherwise, finish until the whole search of analyzed area from the continuation search of second step.

(3) length of interpretation moon image border if edge length less than preset value, thinks that then segmental arc is too short, is changeed step (5), otherwise changes step (4); The span of preset value [1/4～1/8] * 360.

(4) lunar map is looked like to carry out the quality classification and calculate, computing formula is as follows:

$\mathrm{QD}=[\frac{\mathrm{Vnum}}{\mathrm{dPixel}}/K]$

Wherein, Vnum is an efficient frontier length;

DPixel fits error for circle;

K is a constant;

[] is rounding operation;

The quality grade of QD for quantizing.

(5) lunar map is set to 0 as quality grade.

By top method to moon picture appraisal after, current sensor data and corresponding quality grade are exported to spacecraft GNC system, GNC gives up low-quality level data, then uses and just adds different weights with high-quality data if quality grade is higher than threshold value, and wherein threshold value can be made as 6.

As shown in Figure 3, be application process process flow diagram of the present invention, at first,, the result and the Evaluation threshold of claim 1 compared, think valid data greater than the data of threshold value, otherwise cast out according to the fixed Evaluation threshold of emulation and test situation; Then, described valid data are used weight coefficient according to its quality grade size design, the high more application weight coefficient of quality grade is big more, and it is as follows to use the weight coefficient computing formula:

Coef＝Q0*W

W＝QD/max(QD)

Wherein, Coef is the system applies coefficient;

Q0 is default maximum coefficient value;

W is a weighted value;

Max (QD) represents maximum quality grade.

Evaluation threshold span recited above [3～7].

Embodiment:

With image input ultraviolet moon sensor internal memory shown in Figure 4, sensor equivalent focal length 1.8758mm (137.2 pixel), target surface pixel 1024*1024 length 14mm, choosing the dark pixel gray threshold is 15, the dark pixel proportion threshold value is 90%, calculates the dark pixel sum:

Num＝931907

The dark pixel ratio:

Rate＝Num/(1024*1024)＝88.87％

Judge dark pixel ratio Rate＜90%, change strong veiling glare over to and judge.

Set strong veiling glare threshold value 250, G in selection area (x, y) last several capable pixel grey scale is all less than the high light threshold value, so the computed image edge length, selecting edge arc length threshold value is 60 ° of equal value of 1/6 circular arc, handle marginal arc segment length 172 ° of (see figure 5)s, edge length so through edge fitting: Vnum=172＞preset value 45, therefore carry out quality grade and calculate, set the total progression of quality [0～15], scale-up factor K is 20, and the round error of fitting during substitution is calculated is 0.95, so quality grade:

Qd＝[(172/0.95/20)]＝9

Setting sensor quality threshold value is that Qt is 4, so: Qd＞Qt, this time sensor result of calculation output data is effective; System is 0.2 to the default maximum coefficient value Q0 of sensor data, uses weights W: W=Qd/max (QD)=9/15 so

The application factor of weighting: Coef=W*Q0=0.12.

Inventive concept and method can be applied on the data evaluation and judgement of other space sensitive device; as long as the method for utilizing thought of the present invention to realize all falls into protection scope of the present invention, the unspecified part of the present invention belongs to general knowledge as well known to those skilled in the art.

Claims (6)

1. the ultraviolet moon sensor output data evaluation method is characterized in that comprising the following steps:

(1) moon view data of ultraviolet moon sensor output is carried out brightness analysis, judge that described lunar map is as bright dark degree, the size of dark gray pixel proportion and preset ratio threshold value in the movement images, if the dark gray pixel ratio of image thinks then that greater than the preset ratio threshold value image is dark excessively, change step (4), otherwise change step (2);

(2) judge whether image strong veiling glare occurs,, otherwise change step (3) if step (4) occurs changeing;

Judge whether image strong veiling glare occurs, and method is as follows in the described step (2):

The first step is determined the target surface analyzed area that the strong veiling glare of image that ultraviolet moon sensor is taken the photograph is judged;

Second step, the pixel in the described analyzed area is carried out Horizon Search, if continuous two pixels of appearance greater than the bright pixel threshold value, then stop search and changeed for the 3rd step, otherwise continue search;

The 3rd step, pixel in second step is begun in vertically search and the statistics search contiguous pixels greater than the number of described bright pixel threshold value greater than any one pixel in two pixels of bright pixel threshold value, when the number of statistics during greater than the number threshold value, there is strong veiling glare in the representative image, stop search; Otherwise, the one other pixel point is vertically searched for and adds up in the search contiguous pixels greater than the number of described bright pixel threshold value, when the number of statistics during, there is strong veiling glare in the representative image greater than the number threshold value, stop search; Otherwise, finish until the whole search of analyzed area from the continuation search of second step;

(3) the efficient frontier length of the moon in the interpretation image if efficient frontier length less than preset value, thinks that then segmental arc is too short, is changeed step (4), otherwise changes step (5);

(4) Shu Chu data quality grade is set to lowermost level;

(5) fit error according to the efficient frontier length of the moon with circle and carry out the data quality rating calculation;

Data quality rating calculation formula in the described step (5) is:

$\mathrm{QD}=[\frac{\mathrm{Vnum}}{\mathrm{dPixel}}/K]$

Wherein, Vnum is an efficient frontier length;

DPixel fits error for circle;

K is a proportionality constant, determines span [20～80] according to emulation and test findings;

[] is rounding operation;

The quality grade of QD for quantizing.

2. ultraviolet moon sensor output data evaluation method according to claim 1 is characterized in that: the dark pixel ratio Rate computing formula of the image in the described step (1) is:

$\mathrm{Rate}=\frac{{\mathrm{Num}}_{\mathrm{PT}}}{M\×N}$

Wherein, Num _PTFor gray scale in the image less than dark gray threshold value P _TAmount of pixels sum total;

P _TEqual the maximum background gray levels in the ground experiment;

M, N are the length of image and wide.

3. ultraviolet moon sensor output data evaluation method according to claim 1 is characterized in that: preset ratio threshold value range of choice is [0.9～0.99] in the described step (1).

4. ultraviolet moon sensor output data evaluation method according to claim 1 is characterized in that: the analyzed area in the described first step is certain delegation in the lower images part outside the ultraviolet moon sensor apparent field.

5. ultraviolet moon sensor output data evaluation method according to claim 1 is characterized in that: described bright pixel threshold value is slightly less than in the ground experiment the brightest gray-scale value of determining, is not less than 95% of the brightest gray-scale value.

6. ultraviolet moon sensor output data evaluation method according to claim 1 is characterized in that: span [1/4～1/8] * 360 of preset value in the described step (3).

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