CN101770656A - Stereo orthophoto pair-based large-scene stereo model generating method and measuring method thereof - Google Patents

Abstract

The invention belongs to the technical field of surveying and mapping science, relating to a stereo orthophoto pair-based large-scene stereo model generating method and a measuring method thereof. The prior model generating and measuring methods have low measurement precision, or complicated calculation and low efficiency. The method provides the stereo orthophoto pair-based large-scene stereo model generating and measuring methods, embeds and establishes a large-scene stereo model by using the stereo orthophoto pair, and can quickly and accurately calculate three-dimensional coordinates of a terrain point. When the method is used for measuring, a parallax acquisition method in accordant direction is adopted, image points corresponding to the terrain points can be found at high speed, coordinates can be directly calculated through plane displacement without reversely thrusting three dimensional coordinates of an original image to carry out forward intersection, and the calculation precision of the method is very close to the stereo measurement precision of the original image pair.

Description

A kind of based on stereo normal incidence image right generation of large scene stereoscopic model and method for measurement

Technical field:

The invention belongs to the mapping science and technology field, relate to a kind of based on stereo normal incidence image right large scene stereoscopic model generation method and method for measurement thereof, this method utilizes stereo normal incidence image to inlaying the stereoscopic model of setting up large scene, adopt the optical parallax acquiring method and the planimetric coordinates displacement of direction unanimity to calculate simultaneously, can calculate the ground point three-dimensional coordinate quickly and accurately, realize the accurate rapid measuring of stereoscopic model.

Background technology:

Known stereo normal incidence image model is the model that is made of orthography and three-dimensional coupling image (or claiming auxiliary stereopsis).This model has kept a large amount of faces of land detailed information that is rich in the aviation image, and under the help of stereoscopic display device, human eye can be seen real ground landscape.On this stereoscopic model, by simple method for measurement, the layman also can easily measure own needed spatial information.This method is commonly employed at aspects such as mapping, geology, traffic, forest, irrigations and water conservancys.Simultaneously, but all possess mosaic splicing, can make and stride picture the large scene stereoscopic model because orthography and solid are mated image; But also there are some problems in the stereo normal incidence image model method of splicing at present, as application number is the 200310111231.1 disclosed method for measuring formation of seamless space stereomodels of inlaying based on the digital three-dimensional orthography, the inconsistent reduction that will cause the elevation measurement accuracy of its parallax directions can not guarantee the plane measurement accuracy simultaneously; Application number is 200310111230.7 disclosed a kind of high precision method for measurement of assisting the seamless stereoscopic model of image based on digital orthoimage and solid, for guaranteeing that precision needs the anti-image coordinates of point in original photo of inferring, calculate with forward intersection, process is loaded down with trivial details again, and counting yield is not high.

Summary of the invention:

The technical problem to be solved in the present invention provides a kind of efficient, succinct generating and method for measurement based on the right large scene stereoscopic model of stereo normal incidence image, can generate large scene stereo normal incidence image model and be implemented in accurate measurement on this model, energy is coordinates computed directly, need not instead to push away original photo coordinate and carry out forward intersection again, reduced operand, improved counting yield, improved the measurement account form, and simultaneously computational accuracy very near original image to stereoacuity.

For solving the problems of the technologies described above, the technology that the present invention adopts is that scheme is:

A kind of method that generates based on the right large scene stereoscopic model of stereo normal incidence image comprises the steps:

(1) ground coordinate that covers the polygonal region on ground with model constitutes polygon, determines that orthography makes the zone; Left sheet at each stereoscopic model in the zone carries out orthorectify, and all orthographies are inlayed, and generates the orthography in whole zone; With gridle shear model overlay area, write down each model area, and with left sheet projection centre coordinate, base length, azimuth of director from the gun as attribute record in section object;

(2) the three-dimensional coupling of the right sheet analogue formation image that uses a model, and merge into the solid coupling image in whole zone, the solid coupling image with each model merges the model that generates whole zone by the zone at last.

In the above-mentioned steps (2), three-dimensional coupling making video comprises the steps:

1. at first determine the border of the three-dimensional coupling of this model image, then each picture point in the bounds is calculated its projection line equation by the polygonal region of model;

2. projection line is put corresponding ground point with the intersection point of DEM as this, utilize the raw video directional data to determine relation between topocentric coordinates and the right sheet image planes point coordinate by collinearity equation, thereby obtain the right sheet image planes of the model point coordinate of three-dimensional each picture point correspondence of coupling image;

3. on right sheet, carry out gray scale by this coordinate and resample, and this gray-scale value is composed the solid coupling image image point position of correspondence;

4. obtain the solid coupling image of model after points all in the border being sampled.

Above-mentioned steps 1. in, need carry out rotation of coordinate in the computation process of projection line equation projected disparity direction and this model base direction are consistent.

Simultaneously, the present invention also provides this stereoscopic model method for measurement, comprises the steps:

(1) subpoint of selected gauge point on orthography at first judges which model area this point falls in; On solid coupling image, seek the same place of gauge point then along this regional base direction; At orthography and the three-dimensional parallax that mates on the image, calculate the elevation Z ρ of this gauge point according to gauge point by the parallax formula;

(2) directly obtain the planimetric coordinates value of the orthography subpoint of gauge point by the Geographic Reference of orthography, and interpolation goes out the height value of this subpoint in DEM;

(3) by the subpoint coordinate (X, Y, Z), gauge point elevation Z _p, and model left side sheet projection centre (X ₀, Y ₀, Z ₀) between collinear relationship, calculate the in-plane displancement of this gauge point with respect to subpoint;

(4) subpoint planimetric coordinates and planimetric coordinates displacement sum are the accurate planimetric coordinates of gauge point; So far the three-dimensional coordinate of Chosen Point calculates and finishes.

The present invention has following advantage and effect with respect to prior art:

1, in the modelling process, the model area baseline is equidirectional adds by each for the artificial parallax of three-dimensional coupling image, guaranteed the direction consistance of same place parallax, guaranteed that with this corresponding image points coupling is the one dimension coupling, also guaranteed the vertical accuracy in the quick short steps measurement with artificial parallax;

2, because the measurement elevation of stereo normal incidence image model has anti-preferably difference property, therefore, this elevation can be used as the measurement elevation of gauge point; By the collinear relationship between left sheet projected centre point, gauge point and the orthography subpoint thereof, the planimetric coordinates of calculated amount measuring point fast need not instead to push away original photo coordinate and carry out forward intersection, its computational accuracy very near original image to stereoacuity.

3, the measurement accuracy of this method can satisfy mapping and general requirement of using fully very near the measurement accuracy of full digital photogrammetric workstation; And this method computing velocity is very fast, is applicable to the measurement system that needs real-time coordinates computed.

Description of drawings:

Fig. 1 is stereoscopic model product process figure of the present invention.

Fig. 2 is that stereoscopic model of the present invention measures process flow diagram.

Embodiment:

Describe the present invention below in conjunction with accompanying drawing.

Referring to Fig. 1, the generation of continuous stereo orthography model, carry out according to following steps:

1, calculates the quadrilateral area that every boat sheet projects to the dispersed elevation face.The quadrilateral area of the adjacent photo in same air strips is intersected the initial polygonal region that obtains stereoscopic model in twos;

2, utilize the left sheet of each model and digital elevation model in the initial polygonal region of this model, to generate orthography.The numerical differentiation correct algorithm is adopted in the generation of orthography, and algorithm principle and flow process are seen " digital photogrammetry " (Zhang Zuxun, publishing house of Zhang Jianqing Wuhan University 1997);

3,, inlay orthography for whole zone with the orthography of all models.In the manufacturing process, require the gridle between model will avoid atural object, as far as possible ground proximity.Inlay and cut the initial polygonal region of each model with gridle after finishing, obtain the final polygonal region of each model;

4, with the projection centre coordinate (X of model left side sheet ₀, Y ₀, Z ₀) together with model-based line length B and azimuth of director from the gun α, carry out record as the parameter of changeable shape;

5, the right sheet of each model is carried out the making of three-dimensional coupling image by base direction, manufacturing process is used the indirect method sampling, and principle and process are referring to " digital photogrammetry " (Zhang Zuxun, publishing house of Zhang Jianqing Wuhan University 1997):

A) at first the polygonal region of computation model mates polygonal region corresponding in the image in solid, as the sampled targets zone;

B) then in the target area, the topocentric coordinates of this spot projection to DEM calculated in pointwise, and projection is calculated can adopt oblique parallel projection method or logarithm sciagraphy; Introduced the standard projection formula that baseline is parallel to X-axis in " analytical photogrammetry " (Li Deren, Zheng Zhao Bao Mapping Press 1992), this method parallax is a base direction, and the point on the therefore three-dimensional coupling image has following transformational relation with corresponding DEM point:

$\left\{\begin{array}{c}X=X_t-P\·\cos \mathrm{\α}\\ Y=Y_t-P\·\sin \mathrm{\α}\end{array}\right.---\left(1\right)$

(1) parallax of P for calculating by the standard projection formula in the formula, α is an azimuth of director from the gun, (X _t, Y _t) be the planimetric coordinates of three-dimensional coupling image picture point, (X Y) is corresponding with it DEM model points planimetric coordinates.

C) the ground coordinate interpolation by these corresponding point goes out elevation in DEM, and calculate the coordinate of this impact point corresponding point in former right sheet with collinearity equation, collinearity equation computation process is referring to " analytical photogrammetry " (Li Deren, Zheng Zhao Bao Mapping Press 1992).

D) according to the coordinate of each impact point corresponding point in raw video, interpolation goes out this gray-scale value, gives impact point, and three-dimensional coupling making video finishes;

6, all three-dimensional coupling images are merged into the solid coupling image in whole zone, so far whole regional stereo normal incidence image finishes to modelling.

Referring to Fig. 2, the measurement process of this stereoscopic model, carry out as follows:

1, on the orthography of stereoscopic model, finds, calculate the regional polygon that this point falls into by the subpoint of gauge point;

2,, on solid coupling image, find same place with the given baseline fix angular direction of polygon parameter alpha.Owing to be the one dimension coupling, therefore have fast speeds and easy operability;

3, according to the same place parallax, calculated amount measuring point elevation is referring to " analytical photogrammetry " (Li Deren, Zheng Zhao Bao Mapping Press 1992);

4, with the subpoint ground flat areal coordinate of gauge point on the orthography (X Y), adds coordinate displacement, the ground flat areal coordinate of calculated amount measuring point, formula is as follows:

$\left\{\begin{array}{c}{X}_p=X+\mathrm{\Δx}\\ Y_p=Y+\mathrm{\Δy}\end{array}\right.---\left(2\right)$

(2) (X Y) is subpoint ground flat areal coordinate, and (Δ X, Δ Y) is the planimetric coordinates displacement, (X in the formula _p, Y _p) be gauge point ground flat areal coordinate:

Wherein the coordinate displacement computing formula is as follows:

$\left\{\begin{array}{c}\mathrm{\Δx}=\frac{(Z_p-Z)(X_0-X)}{(Z_0-Z)}\\ \mathrm{\Δy}=\frac{(Z_p-Z)(Y_0-Y)}{(Z_0-Z)}\end{array}\right.---\left(3\right)$

(3) (X Y) is the subpoint coordinate, and Z is the elevation of subpoint interpolation on DEM, (X in the formula ₀, Y ₀, Z ₀) be the projection centre coordinate, Z _pElevation for gauge point; So far, the coordinate measure of gauge point finishes.

Claims (4)

1. a method that generates based on the right large scene stereoscopic model of stereo normal incidence image comprises the steps:

(1) ground coordinate that covers the polygonal region on ground with model constitutes polygon, determines that orthography makes the zone; Left sheet at each stereoscopic model in the zone carries out orthorectify, and all orthographies are inlayed, and generates the orthography in whole zone; With gridle shear model overlay area, write down each model area, and with left sheet projection centre coordinate, base length, azimuth of director from the gun as attribute record in section object;

(2) the three-dimensional coupling of the right sheet analogue formation image that uses a model, and merge into the solid coupling image in whole zone, the solid coupling image with each model merges the model that generates whole zone by the zone at last.

2. according to the described a kind of method that generates based on the right large scene stereoscopic model of stereo normal incidence image of claim, it is characterized in that: in the step (2), three-dimensional coupling making video comprises:

1. at first determine the border of the three-dimensional coupling of this model image, then each picture point in the bounds is calculated its projection line equation by the polygonal region of model;

2. projection line is put corresponding ground point with the intersection point of DEM as this, utilize the raw video directional data to determine relation between topocentric coordinates and the right sheet image planes point coordinate by collinearity equation, thereby obtain the right sheet image planes of the model point coordinate of three-dimensional each picture point correspondence of coupling image;

3. on right sheet, carry out gray scale by this coordinate and resample, and this gray-scale value is composed the solid coupling image image point position of correspondence;

4. obtain the solid coupling image of model after points all in the border being sampled.

3. a kind of method that generates based on the right large scene stereoscopic model of stereo normal incidence image according to claim 2, it is characterized in that: step 1. in, need carry out rotation of coordinate in the computation process of described projection line equation projected disparity direction and this model base direction are consistent.

4. a kind of method for measurement based on the right large scene stereoscopic model of stereo normal incidence image as claimed in claim 1 comprises the steps:

(1) subpoint of selected gauge point on orthography judges which model area this point falls in; On solid coupling image, seek the same place of gauge point then along this regional base direction; At orthography and the three-dimensional parallax that mates on the image, calculate the elevation Zp of this gauge point according to gauge point by the parallax formula;

(2) directly obtain the planimetric coordinates value of the orthography subpoint of gauge point by the Geographic Reference of orthography, and interpolation goes out the height value of this subpoint in DEM;

(3) by the subpoint coordinate (X, Y, Z), gauge point elevation Z _p, and model left side sheet projection centre (X ₀, Y ₀, Z ₀) between collinear relationship, calculate the in-plane displancement of this gauge point with respect to subpoint;

(4) subpoint planimetric coordinates and planimetric coordinates displacement sum are the accurate planimetric coordinates of gauge point.

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