A method of locating the position of a star in a star map

Abstract

The application relates to a method for positioning the position of a star point in a star map, relates to the technical field of computer image processing, and solves the problems of low efficiency of the existing star map processing method and low output frequency of a star sensor, etc. The method uses a histogram mode function of a detector, firstly collects a star map, obtains a row of data containing the mean values of all columns of the histogram and carries out searching on the data, obtains the column corresponding to the peak value data, then configures the detector into a normal output mode, collects a star map again, carries out accumulation and processing on the data of all rows, obtains a column of data containing the accumulation sum of all rows of data and carries out searching on the data, obtains the row corresponding to the peak value data, and finally, according to all column and row data, the data are taken as the center points of star point coordinates, the star point pixels in the stored star map are searched in sequence, and relevant information such as the star point centroid is obtained. The method does not need to search the whole star map, greatly improves the star point searching efficiency, and shortens the star point extraction time.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of computer image processing, in particular to a method for locating the position of a star point in a star map. BACKGROUND

[0002] Star point extraction of a star sensor is a prerequisite for star map recognition, and the rapidity of star point extraction has an important influence on the attitude update rate of the star sensor. In the traditional method, star points are searched by searching each pixel of the stored star map. Generally, the resolution of the star map is relatively high, and it takes hundreds of milliseconds or even seconds to search the entire star map and locate the position of the star point. This reduces the attitude output frequency of the star sensor. In the star map captured by the star sensor, the size of the star point is generally about 5*5 pixels, and the maximum star point is about 12*12 pixels, which is relatively small compared to the total pixels of the detector (such as 1024*1024). The number of star points in a star map is several to twenty or so, and the star map is relatively uniform Gaussian white noise except for the star points. The star points are relatively sparse in the entire star map.

[0003] Based on this, the present application uses the histogram function provided by the detector hardware and the row pixel accumulation and function in the process of reading and storing the star map to quickly locate the position of the star point in the captured star map. In the traditional method, the pixels in the star map are scanned from left to right and from top to bottom, and the star map is binarized, and then the connected domain method is used to scan the star map to find all the star points and their positions. This two-scan method is low in efficiency and time-consuming, which is not conducive to improving the output frame frequency of the star sensor.

[0004] The present application is based on the characteristics of the existing detector, and uses the processing of two consecutive star maps to quickly locate the star points and retrieve the corresponding star points to obtain the star point related information. SUMMARY

[0005] The present application provides a method for locating the position of a star point in a star map to solve the problems of low efficiency of the existing star map processing method and low output frequency of the star sensor.

[0006] A method for locating the position of a star point in a star map, the method comprising the following steps:

[0007] Step 1: set the output mode of the detector to histogram mode, capture a star map, output a row of histogram mean data containing the corresponding columns of each column, retrieve the data and find the peak position corresponding to each star point cluster;

[0008] Step two, set the output mode of the detector to normal mode, take another picture of the star map, and during the storage of the star map reading, accumulate the pixel values of each row to obtain a column of data containing the sum of the pixel values of each row, search for the data and find the row corresponding to the peak position in each star cluster.

[0009] Step three, according to the coordinates of all peak columns obtained in step one and all peak rows obtained in step two, search for star pixels in the range of 5 pixels above, below, left and right of the coordinate point in the stored star map, and find the star points according to the connected domain method, finally calculate and save the star point data information, and all coordinate points are searched, that is, the positions of the star points in the star map are located.

[0010] The method of the present application does not need to search the entire star map, and the column positions of all star points are obtained through the histogram data of the first star map, the row positions of all star points are obtained through the output accumulation sum result of the second star map, and small-range star point search is performed for the coordinate points of all column and row positions to locate the positions of all star points. This method greatly improves the star point search efficiency and shortens the star point extraction time. BRIEF DESCRIPTION OF DRAWINGS

[0011] In order to more clearly illustrate the technical solutions in the embodiments or the prior art, the drawings needed in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0012] Figure 1 FIG. 1 is a schematic diagram of a star cluster containing one peak data in the method for locating the positions of star points in a star map according to the present application;

[0013] Figure 2 FIG. 2 is a schematic diagram of a star cluster containing two peak data in the method for locating the positions of star points in a star map according to the present application. DETAILED DESCRIPTION

[0014] Embodiment one, combined with Figure 1 and Figure 2 The present embodiment is a method for locating the positions of star points in a star map. The method first uses the histogram function configuration of the detector to take a picture of a star map, outputs a row containing histogram mean data corresponding to each column, searches for the data and finds the column corresponding to the peak position in each star cluster.

[0015] Then the detector is set to normal mode, and a star map is taken. In the process of reading and storing the star map, the pixel values of each row are added respectively, and a column of data containing the sum of the pixel values of each row is obtained. The data is searched and the row corresponding to the peak value position in each star cluster is found.

[0016] Finally, according to the coordinates of all peak columns and peak rows, the star point pixels around the coordinate points in the stored star map are searched, and the star points are found according to the connected domain method. Finally, the star point data information is calculated and saved, and all coordinate points are searched, so that the positions of the star points in the star map can be quickly located.

[0017] Specific implementation two, combined Figure 1 and Figure 2 The present embodiment is an embodiment of the method for locating the positions of star points in a star map as described in the first embodiment. The specific process is as follows:

[0018] First, the detector is set to histogram mode output by mode setting. At this time, the detector (assuming that the pixels are M rows by N columns) will output a row of valid data with only N columns of pixels. Each pixel in the N columns is the histogram mean value of all M rows of pixels in this column. Due to the characteristics of Gaussian diffusion distribution of star point pixel values on a star map, the star point data on the N columns of pixel values output on the histogram also basically obeys normal distribution. The mean value of the N data is calculated. To reduce interference, a certain value (recommended 1 / 3 of the mean value) is added to the mean value as a threshold. The N data is searched based on the threshold, and P star point clusters basically obeying normal distribution can be searched. Then, the P star point clusters are searched separately, the column corresponding to the peak pixel in each star point cluster is searched, and the position value is recorded. In the searching process, it may be found that there are multiple peak pixels in a star point cluster, and the column positions corresponding to the peak pixels are all recorded. Therefore, there are P' columns corresponding to all peak pixels, which are the columns where the star points are located.

[0019] Then, the detector is set to normal mode. In normal mode, the detector takes a star map with M rows by N columns of pixels. After taking a star map, the processor reads the pixels of the star map from left to right and from top to bottom in sequence and stores them in the relevant memory. In the process of reading the pixels, the pixel values of each row are added separately. Therefore, when the image is stored, an M row of data is obtained. The M row of data is the total value of the star point pixel values in the star map projected on the M row. Similarly, by searching the M data, Q star point clusters basically obeying normal distribution can be searched. Then, the Q star point clusters are searched separately, and the row corresponding to the peak pixel in each star point cluster is searched (for example Figure 1As shown, 1 star point cluster contains 1 peak value row, and the position value is recorded. In the retrieval process, it can be found that there are multiple peak value pixels in a star point cluster, and the row positions corresponding to the peak value pixels are all recorded (such as Figure 2 As shown, 1 star point cluster contains 2 peak value rows, and all the peak value pixels correspond to Q' rows, that is, the row where the star point center is located;

[0020] Finally, P' column data and Q' row data are obtained, and P' is taken as the column coordinate and Q' is taken as the row coordinate to form P' × Q' star point center position coordinates. Then, whether there is a star point pixel at each of the P' × Q' coordinate centers is retrieved, and the range of 5 pixels above, below, left and right of the center position is retrieved for less missed probability. If a star point pixel is retrieved, all pixels of the star point are marked by the connected domain method, and the centroid and other information of the star point are calculated. After all the position coordinate positions are retrieved, the information of all the star points is obtained, and the information is stored for future use.

[0021] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, all possible combinations of the technical features in the above-described embodiments are not described, but as long as the combinations of the technical features do not contradict, they should be considered as within the scope of the present disclosure.

[0022] The above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the patent. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of variations and improvements can be made, which are within the scope of the present application. Therefore, the scope of protection of the present application should be subject to the appended claims.

Claims

1. A method of locating the position of a star in a star map, characterized by: The method is realized by the following steps: Step one, set the output mode of the detector to histogram mode, take a star map, output a row of histogram mean data corresponding to each column, search the data and find the column corresponding to the peak position in each star point cluster, and obtain all peak columns; Step two, set the output mode of the detector to normal mode, take another star map, and add up the pixel values of each row during the storage process of the star map, obtain a column of data containing the sum of pixel values corresponding to each row, search the data and find the row corresponding to the peak position in each star point cluster, and obtain all peak rows; Step three, according to the coordinate points corresponding to all peak columns obtained in step one and all peak rows obtained in step two, search for star point pixels in the stored star map within a range of 5 pixels above, below, left and right of the coordinate points, find star points according to the connected domain method, and finally calculate and save the star point data information. All coordinate points are searched, which realizes the positioning of the positions of star points in the star map. In step one, the detector outputs a row of valid data of N columns of pixels, and each pixel in the N columns is the histogram mean value of all M rows of pixels in this column. The mean value of N data is calculated. A certain number of values are added to the mean value as a threshold, and the N data are searched based on the threshold to obtain P star point clusters subject to normal distribution. The P star point clusters are searched to obtain the column position corresponding to the column of the peak pixel in each star point cluster, and finally the column corresponding to all peak pixels is obtained.

2. The method of locating a star position in a star chart according to claim 1, wherein: The certain number of values added as the threshold specifically refers to 1 / 3 of the mean value.

3. The method of claim 1, wherein: In step two, M rows of data are obtained by reading out the pixels of the star map from left to right and from top to bottom in turn. The M rows of data are the total values of the star point pixel values in the star map projected on the M rows. The M rows of data are searched to obtain Q star point clusters, and the Q star point clusters are searched to obtain the row position corresponding to the row of the peak pixel in each star point cluster. Finally, the row corresponding to all peak pixels is obtained.

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