CN102013097A - Yellow River main humping line detection method based on spectrum similarity and space continuity - Google Patents

Abstract

The invention discloses a Yellow River main humping line detection method based on spectrum similarity and space continuity, which is used for solving the technical problem of poor accuracy in the traditional Yellow River main humping line detection method. The method comprises the following steps of: carrying out rough segmentation on the river according to the spectrum characteristics of a water area in a remote sensing image; then extracting a shoreside line by utilizing edge detection, and determining a river area; segmenting the river according to the bending degree and the direction of the river segment and the river distribution between the south flowage line and the north flowage line; and extracting a main humping line of the segmented river by utilizing the spectrum similarity and the space continuity of the main humping line. According to the invention, the accuracy of the Yellow River main humping line detection method is improved.

Description

Based on the main slide line detecting method in the Yellow River of spectral similarity and space continuity

Technical field

The present invention relates to the main slide line detecting method in a kind of the Yellow River, particularly based on the main slide line detecting method in the Yellow River of spectral similarity and space continuity.

Background technology

Being extracted in of the main slide line in the Yellow River all is by artificial drafting traditionally, and this method is not only time-consuming, effort, and is subjected to the influence of natural conditions such as weather easily, the more important thing is, is difficult in time grasp in flood season the main situation of change of slipping.In recent years, remote sensing image has been widely used in fields such as water body identification, river extraction, water quality detection, big flood detection, waters change-detection, and methods that these researchs are adopted are the characteristic that is shown on image according to water body basically and use some traditional sorting techniques to detect.The continuous development that remote sensing technology and remote sensing image are handled, making the utilization remote sensing image carry out the main slide line detection in the Yellow River becomes possibility.The problem that the main slide in river course shows in husky matter river course of the changeable alluvial of river gesture is outstanding, because less to the gesture research of river, heavily silt-carrying river river course in the world, so, also do not report at present about the applied research achievement of main slide in remote sensing image decipher river course and river gesture figure.Domestic, Preliminary Applications has only been carried out in river course main slide remote sensing image decipher at present in the Yellow River, yet, image data is handled and decipher relies on artificial visual, whole process is time-consuming, simultaneously, also has the difficulty that is difficult to accurately extract the main slide in river course according to the visual interpretation of remote sensing image.

Summary of the invention

In order to overcome the deficiency of existing the Yellow River main slide line detecting method poor accuracy, the invention provides the main slide line detecting method in a kind of the Yellow River based on spectral similarity and space continuity, this method is carried out the river coarse segmentation according to the spectrum characteristic in waters in the remote sensing images; Utilize rim detection to extract shoreline again, determine river region; Degree of crook and the distribution of the river between direction and the north and south flowage line according to the section are carried out segmentation to the river; To the river course after the segmentation, utilize main spectral similarity and the space continuity that slips line to extract the main line that slips, can improve the Yellow River main slide line detecting method accuracy.

The technical solution adopted for the present invention to solve the technical problems: the main slide line detecting method in a kind of the Yellow River based on spectral similarity and space continuity is characterized in comprising the steps:

(a) adopt supervised classification and matching process to carry out the river and cut apart, and sorted image is carried out the morphology processing, merge the zonule, eliminate less beach and bridge according to the features of shape of section, the Yellow River;

(b) adopt the Canny operator that the edge is detected, connection is followed the tracks of at detected edge, connect preliminary north and south, the Yellow River bank flowage line, remove and disturb line segment, obtain one group of useful line segment according to the neighborhood method; Again according to statistical property, the number that the point of being judged in every line segment belongs to a certain bank is greater than a certain threshold value, north and south bank image; The line segment of two sides, north and south is stored in the matrix respectively in certain sequence in order, obtain the complete flowage line of north and south bank;

(c) the dam bank that calculates the space by the curvature of windowing transforms to the curvature territory, and the curved place, position of pushing up of bend is represented in the maximum point position of gained curvature sequence; The transition and linkage point position between two continuous river bends is represented in minimum point position between two continuous threshold points, and the Yellow River is divided into typical section and atypia section;

(d) by to artificial field exploring to the master slip into a large amount of study of row, set up the main library of spectra of slipping; Choose bayou place and slip the most similar point in the library of spectra, as initial main slide sample with main;

By the initial main some beginning of slipping, calculate its directional ray, and obtain its length and position:

1. defining directional ray is a series of line segments that pass the center pixel, and its length is estimated with threshold value by the spectral similarity between adjacent picture elements and determined; Similarity measure is:

$\mathrm{SA}(x,y)=\frac{P^{\mathrm{cen}}\·P^{\mathrm{cur}}}{\left|P^{\mathrm{cen}}\right|\left|P^{\mathrm{cur}}\right|}=\frac{\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{P}_i^{\mathrm{cen}}{P}_i^{\mathrm{cur}}}{\sqrt{\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{P}_i^{\mathrm{cen}}{P}_i^{\mathrm{cen}}}\sqrt{\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{P}_i^{\mathrm{cur}}{P}_i^{\mathrm{cur}}}}$

In the formula, SA (x, y) the current neighborhood pixel of expression (x, y) the similarity measure value on this directional ray,

The spectral value of imago on wave band i in the expression, Represent the spectral value of current neighborhood pixel on wave band i, n represents the wave band number;

2. directional ray therefrom imago unit set out towards both sides expansions, the condition of directional ray expansion is that the similarity measure of current pixel is less than spectral similarity degree threshold value T;

3. travel through the whole piece river, 1. 2. follow the tracks of the directional ray that obtains initial pixel, the promptly main line that slips of resulting directional ray with step according to step.

The invention has the beneficial effects as follows: the spectrum characteristic owing to according to waters in the remote sensing images, carry out the river coarse segmentation; Utilize rim detection to extract shoreline again, determine river region; Degree of crook and the distribution of the river between direction and the north and south flowage line according to the section are carried out segmentation to the river; To the river course after the segmentation, utilize main spectral similarity and the space continuity that slips line to extract the main line that slips, improved the Yellow River main slide line detecting method accuracy.

Below in conjunction with the drawings and specific embodiments the present invention is elaborated.

Description of drawings

Accompanying drawing is the Yellow River main slide line detecting method process flow diagram that the present invention is based on spectral similarity and space continuity.

Embodiment

With reference to accompanying drawing.1, the river is cut apart.

Importing a secondary TM multispectral image, at first is the river coarse segmentation.Adopt spectral classification and matching technique, as: spectrum to flux matched, mahalanobis distance is cut apart and method such as Gauss Markov is carried out the spectrum picture classification, and according to the aftertreatment of classifying of the features of shape of section, the Yellow River, merge as: zone etc.Divide time-like to adopt supervised classification method, because image is subjected to the influence of factors such as weather, in the image there be than big-difference the spectrum of the upper reaches of the Yellow River and downstream water body, have very mistake if adopt single sample to carry out the classification of spectrum angle, therefore adopt two kinds of samples respectively image to be classified, then composograph.Because the influence of bridge and beach is arranged in the image, be not easy to the extraction of two sides, north and south flowage line, under the situation that requires to be fit to further study in edge definition image has been carried out the morphology processing, promptly image expands and corrodes operation, has eliminated less beach and bridge.

2, bank line extracts.

Adopt the Canny operator that the edge is detected, and connection is followed the tracks of at detected edge, sort out the flowage line of north and south, river bank, for next step river segmentation is got ready.For the ease of extracting the two sides, north and south, need resulting edge line is carried out connection tracking; According to the neighborhood method, utilize a border following algorithm to arrive and obtain one group of continuous segments, remove some short interference line segments according to length, can remove beach, thereby obtain one group of useful line segment according to the style characteristic of beach simultaneously.According to the distribution characteristics of the Yellow River water body, observe it and have certain horizontal and vertical features, but algorithm for design carries out the judgement of north and south bank to every section line segment in view of the above.Only to need to consider to obtain the information of which bank under this whole section flowage line to the judgement that some representational point in every section carries out the north and south bank based on efficiency of algorithm.According to statistical property, the point of being judged in every section belongs to the number of a certain bank can judge that greater than a certain threshold value this section is to belong to southern bank or northern bank, otherwise, then belong to an other bank, thereby obtain north and south bank image.As required the line segment of two sides, north and south is stored in the matrix respectively in certain sequence in order, thereby obtain the complete flowage line in two sides, be beneficial to next step the main line drawing that slips.

3, river segmentation.

With regard to the Yellow River main slide line problem the Yellow River is divided into typical section and atypia section.The typical case section is divided into straight little curved, the crooked and branch branch of a river three classes again.

The shape of each class section all has very big difference, and the main mode one of describing difference is to utilize tortuosity factor and curvature to describe the degree of crook and the direction of section, and the 2nd, distribute to determine whether to exist by the river between the flowage line of north and south and divide a branch of a river.Space relationship between section and the section also is one of main slide line foundation in the Yellow River of judging, therefore, it also is very important calculating for the relation of the space distribution between the section, the present invention is sections such as Curved Continuous is joined, bend is come over and pledged allegiance to the space distribution contextual definition, utilizes the continuous variation arrangement between the section to be distinguished from the space.Concrete segmentation method is as follows:

A) the dam bank that calculates the space by the curvature of windowing transforms to the curvature territory, and the curved place, position of pushing up of bend has been represented in the maximum point position of gained curvature sequence.

B) the transition and linkage point position between two continuous river bends is represented in the minimum point position between two continuous threshold points.

4, the main line drawing that slips.

Based on the Yellow River of spectral similarity and space continuity main slide line drawing method.

At first by to artificial field exploring to the master slip into a large amount of study of row, set up the main library of spectra of slipping.Choose bayou place and slip the most similar point in the library of spectra, as initial main slide sample with main.

By the initial main some beginning of slipping, calculate its directional ray, and obtain its length and position:

Step1 definition directional ray is a series of line segments that pass the center pixel, and their length has nothing in common with each other, and its length is estimated with threshold value by the spectral similarity between adjacent picture elements and determined.Similarity measure is:

$\mathrm{SA}(x,y)=\frac{P^{\mathrm{cen}}\·P^{\mathrm{cur}}}{\left|P^{\mathrm{cen}}\right|\left|P^{\mathrm{cur}}\right|}=\frac{\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{P}_i^{\mathrm{cen}}{P}_i^{\mathrm{cur}}}{\sqrt{\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{P}_i^{\mathrm{cen}}{P}_i^{\mathrm{cen}}}\sqrt{\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{P}_i^{\mathrm{cur}}{P}_i^{\mathrm{cur}}}}$

In the formula, SA (x, y) the current neighborhood pixel of expression (x, y) the similarity measure value on this directional ray,

The spectral value of imago on wave band i in the expression, Represent the spectral value of current neighborhood pixel on wave band i, n represents the wave band number.

The Step2 directional ray according to specific rule therefrom imago unit set out towards both sides expansions, the condition of directional ray expansion is that the similarity measure of current pixel is less than threshold value T.Here, T is a spectral similarity degree threshold value, and it is relevant with the intensity of variation of pixel gray scale in the same shape area.Because flow has certain directivity, actual directional ray expansion can not be carried out towards all directions, but according to the river direction, will remove with the direction that the river direction deviates from, and expands again.

Step3 travels through the whole piece river, goes on foot according to Step1 and Step2 two and can follow the tracks of the directional ray that obtains initial pixel.

With the directional ray that obtains as the main line that slips, thereby determine its position.

Claims (1)

1. the main slide line detecting method in the Yellow River based on spectral similarity and space continuity is characterized in that comprising the steps:

(a) adopt supervised classification and matching process to carry out the river and cut apart, and sorted image is carried out the morphology processing, merge the zonule, eliminate less beach and bridge according to the features of shape of section, the Yellow River;

(b) adopt the Canny operator that the edge is detected, connection is followed the tracks of at detected edge, connect preliminary north and south, the Yellow River bank flowage line, remove and disturb line segment, obtain one group of useful line segment according to the neighborhood method; Again according to statistical property, the number that the point of being judged in every line segment belongs to a certain bank is greater than a certain threshold value, north and south bank image; The line segment of two sides, north and south is stored in the matrix respectively in certain sequence in order, obtain the complete flowage line of north and south bank;

(c) the dam bank that calculates the space by the curvature of windowing transforms to the curvature territory, and the curved place, position of pushing up of bend is represented in the maximum point position of gained curvature sequence; The transition and linkage point position between two continuous river bends is represented in minimum point position between two continuous threshold points, and the Yellow River is divided into typical section and atypia section;

(d) by to artificial field exploring to the master slip into a large amount of study of row, set up the main library of spectra of slipping; Choose bayou place and slip the most similar point in the library of spectra, as initial main slide sample with main;

By the initial main some beginning of slipping, calculate its directional ray, and obtain its length and position:

1. defining directional ray is a series of line segments that pass the center pixel, and its length is estimated with threshold value by the spectral similarity between adjacent picture elements and determined; Similarity measure is:

$\mathrm{SA}(x,y)=\frac{P^{\mathrm{cen}}\·P^{\mathrm{cur}}}{\left|P^{\mathrm{cen}}\right|\left|P^{\mathrm{cur}}\right|}=\frac{\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{P}_i^{\mathrm{cen}}{P}_i^{\mathrm{cur}}}{\sqrt{\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{P}_i^{\mathrm{cen}}{P}_i^{\mathrm{cen}}}\sqrt{\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{P}_i^{\mathrm{cur}}{P}_i^{\mathrm{cur}}}}$

In the formula, SA (x, y) the current neighborhood pixel of expression (x, y) the similarity measure value on this directional ray,

The spectral value of imago on wave band i in the expression,

Represent the spectral value of current neighborhood pixel on wave band i, n represents the wave band number;

2. directional ray therefrom imago unit set out towards both sides expansions, the condition of directional ray expansion is that the similarity measure of current pixel is less than spectral similarity degree threshold value T;

3. travel through the whole piece river, 1. 2. follow the tracks of the directional ray that obtains initial pixel, the promptly main line that slips of resulting directional ray with step according to step.

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