CN103218812A - Method for rapidly acquiring tree morphological model parameters based on photogrammetry - Google Patents

Abstract

The invention relates to the tree morphological visual model simulation model and image correction of close range photography measurement, in particular to a method for rapidly acquiring tree morphological model parameters based on photogrammetry, and belongs to the technical field of a computer. The method comprises the following steps of selecting a tree morphological model in form of a power function, shooting and carrying out auxiliary measurement of tree images, correcting the tree images, and matching the model with the images. Compared with the prior art, the method is specially formulated aiming at the requirements of exactly acquiring peripheral contour information of two-dimensional trees; the method has low requirements to the equipment; and the auxiliary measurement is simple and easy to implement. Thus, the method is good for acquiring field data and popularizing; the selected tree morphological model comprises key indexes, namely crown indexes in the tree morphology; and the method is very good for describing the tree morphology and unifying different tree models.

Description

Based on photogrammetric trees appearance model parameter fast acquiring method

Technical field

The present invention relates to the image rectification of simulation of trees form Visualization Model and close-range photogrammetry, particularly, belong to field of computer technology based on photogrammetric trees appearance model parameter fast acquiring method.

Background technology

The simulation of trees form Visualization Model is to finish by modeling method and visualization technique to the trees form.It is mainly used in the visual Simulation application of trees and forest.Trees form modeling technique mainly concentrates on the acquisition methods of the selection of model and parameter.Close-range photogrammetry is a technology of obtaining the reference object relevant information by the analytical analysis to photographic images.When being reference object with trees, during known trees appearance model, its method of obtaining model parameter becomes the focus of research.Usually adopted owing to take individual trees photograph and have simple and effective, help overcoming characteristics such as complicated field operation condition restriction by people.But, make image correcting become to obtain the indispensable technological means of the correlation parameter of tree modelling because there is serious projection problem in single-sheet photo.

Along with the development of virtual reality technology, the three-dimensional visualization analogue technique is applied to every field.Can use general method for the trees visual Simulation of only paying attention to the 3D vision effect (as the tree simulation in the recreation), but for the forestry of paying attention to the trees morphosis more is visual, the authenticity of trees form and Visualization Model analogue technique then are technical skill of field of forestry, and many general methods can't be indiscriminately imitated use.Therefore, the modelling of trees form is to realize the important foundation of trees visual Simulation.On the other hand, the support of obtaining field study data that need be a large amount of of model parameter.For the investigation of the tree morphology index of large sample, and the arduous characteristics of field study circumstance complication, need a kind of in operation simple and fast, the practical and reliable technology is obtained the appearance model parameter of every strain trees fast on effect.The correction of up short image provides quick and the most appropriate technological means for this reason.That is to say that the ortho-rectification of the selection of trees appearance model and trees image is the major technique content of this invention.

Trees appearance model technology is to describe the mathematical method of the peripheral profile of trees.The exterior contour information that in simulation, needs trees, and this profile information is the two-dimentional modality curves model of trees orthograph picture.Adopted triangle (or cone) model and ellipse (or spheroid) model in the past.These models generally are used for the calculating of tree crown volume and tree crown surface area.Triangle model is applicable to the simulation of some coniferous specieses, and oval model is applicable to the simulation of some deciduous species.But common shortcoming is not accurate enough to the description of trees profile.That is to say that more trees form promptly is not that triangle neither be oval completely completely.This invention adopts a kind of model form of power function to replace triangle or oval model, has overcome the shortcoming and the laterally zygomorphic shortcoming of oval model of the strict linear profile of triangle model.

In the obtaining of trees appearance model parameter, can adopt the 3 D laser scanning method to obtain the accurate 3-D view of trees, and, will obtain trees appearance model parameter by its parallel views image and trees appearance model curve registration.But, utilize the condition of this method to be: expensive scanning device; Open-air topographic condition will allow the setting of a plurality of scanning websites; In the scanning process of the long period that every strain trees are carried out, wind-force is unlikely to cause waving of leaf, branch; Need special software analysis or the like for the huge three-dimensional lattice data of obtaining.Therefore in the tree morphology investigation of reality, be very limited.Another kind method is the stereogram method, and this method need be taken at two diverse locations, needs to measure two distances between the shooting point simultaneously, needs the camera inside and outside parameter to demarcate, and post-processed work is also very complicated.The third method is to take individual photo, generally needs to make the pattern that is specifically designed to camera calibration, to carry out the demarcation of complicated camera inside and outside parameter.

Comprehensive above technical background situation can be summarized as follows, and the first, adopt power function model more to help the simulation of trees form than triangle model and oval model.The second, laser scanning method, time cost and equipment cost height, field condition is difficult to satisfy.The 3rd, stereogram method and individual photo method all need complicated camera calibration.

Summary of the invention

The objective of the invention is to propose the wide contrary projective transformation method of a kind of two dimensional trees wooden wheel, on the basis of trees form modeling, provide individual photo is carried out the simple technical method of ortho-rectification fast, and directly obtain the numerical value of trees appearance model parameter by the visual matching process of proofreading and correct back photo and appearance model curve.

The technical solution adopted for the present invention to solve the technical problems is: based on photogrammetric trees appearance model parameter fast acquiring method, it is characterized in that comprising following steps:

Step 1) is selected the trees appearance model of power function form, determines the evaluation method of its model parameter;

Step 2) taking pictures and subsidiary of trees image, and image is carried out ortho-rectification and image resampling, effect is to obtain to comprise the trees profile of trees morphological parameters and proofread and correct auxiliary data;

The correction of step 3) trees image, effect are that the central projection image restoring is become two-dimentional orthograph picture;

The coupling of step 4) model and image, effect are to obtain the numerical value of the crown index of trees.

Described step 1) further comprises: first, trees are carried out expiring up and down take pictures (promptly the setting the last lower limb that point and tree root occupy shooting picture) of width of cloth mode, and with the centre position of the corresponding photo level of trees trunk, the camera heights h0(during records photographing only need write down once when photographer does not change); The second, measure shooting distance L and elevation angle gamma 2 with the Trupulse200 laser measuring apparatus; Arrive this, the field investigation of one tree wood morphological parameters finishes.Compare with other investigation method and to have characteristics very efficiently.

Described step 2) further comprise: the orthography of trees profile is the two dimension copy of real-world object in certain horizontal direction; The actual size of each pixel representative is identical on the image; The image that camera is taken is the result of object central projection, when the shot object height is the twice of camera heights, and camera optical axis and subject profile plane (two dimension copy plane) quadrature, the subject profile is similar to photographic images; When subject is higher than the camera heights twice when above (most of shooting situation), camera optical axis and the formed plane of subject profile be quadrature no longer, and principal point does not overlap with the subject central point; Make the trees photo of shooting have projection error, captured photo can't be used for measuring; If with the reverse plane that projects to trees profile place of each pixel on the photo, then can obtain the true profile of trees; Below divide several steps to finish this correction:

The first step, ask the virtual representation plane equation:

Suppose to exist a plane in the space, the optical axis of its normal vector when taking, and the plane crosses the trunk root, as the S plane among the figure; Because the picture plane parallel of this plane and shooting, there is point correspondence completely in its pixel, so is the enlarged drawing of virtual photographic images, is called the virtual representation plane;

1) the principal point coordinate on virtual representation plane be P (x0, y0, z0):

$x_0=\cos (\mathrm{\&beta;}-{\mathrm{\&gamma;}}_1)\cos \left(\mathrm{\&beta;}\right)\sqrt{{\mathrm{<figure-callout\; id="0"\; label="h"\; filenames="HDA00003000904200021.png"\; state="\{\{state\}\}">h</figure-callout>}}_0^2+{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="HDA00003000904200021.png"\; state="\{\{state\}\}">L</figure-callout>}}^2}$

y ₀＝0

${\mathrm{<figure-callout\; id="0"\; label="z"\; filenames="HDA00003000904200021.png"\; state="\{\{state\}\}">z</figure-callout>}}_0=\sin (\mathrm{\&beta;}-{\mathrm{\&gamma;}}_1)\cos \left(\mathrm{\&beta;}\right)\sqrt{{\mathrm{<figure-callout\; id="0"\; label="h"\; filenames="HDA00003000904200021.png"\; state="\{\{state\}\}">h</figure-callout>}}_0^2+{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="HDA00003000904200021.png"\; state="\{\{state\}\}">L</figure-callout>}}^2}$

Wherein, L is a shooting distance, and h0 is a camera heights, and γ 1 is the angle of depression down, and γ 1=arctg (h0/L), β are camera half of field angle up and down, and γ 2 is the elevation angle, β=0.5 (γ 1+ γ 2);

2) equation of virtual representation planar S

The virtual representation planar S be principal point P (x0, y0 z0), are the plane of normal vector with the optical axis, and its equation is:

$x_{0}x+z_{0}z-x_0^2-z_0^2=0$

3) calculate the coordinate of putting P on the virtual representation planar S

If (x, y z) are OP ' (x ', y ', z ') ray and the S intersection point as the plane to the coordinate P on the virtual representation planar S; Wherein, P ' (x ', y ', z ') is a trees profile planar S ' on any point coordinate; Separating its intersection point is:

x＝x't

y＝y't

z＝z't

Wherein, $t=\frac{x_0^2+{\mathrm{<figure-callout\; id="0"\; label="z"\; filenames="HDA00003000904200021.png"\; state="\{\{state\}\}">z</figure-callout>}}_0^2}{x_0{x}^{,}+z_0{z}^{,}}$

By the coordinate points on the S ' plane, obtain corresponding intersection point P on the S plane;

4) ask the scope on virtual representation plane

The height on virtual representation plane

When taking with the ranks ratio of 3:2, the following width on virtual representation plane

Therefore, 4 apex coordinate P11(x11 on virtual representation plane, y11, z11), and P12(x12, y12, z12), and P21(x21, y21, z21), and P22(x22, y22 z22) is

$x_{11}=x_{12}=\cos \left({\mathrm{\&gamma;}}_2\right)\sqrt{{\mathrm{<figure-callout\; id="0"\; label="h"\; filenames="HDA00003000904200021.png"\; state="\{\{state\}\}">h</figure-callout>}}_0^2+{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="HDA00003000904200021.png"\; state="\{\{state\}\}">L</figure-callout>}}^2},$ x21=x22=L；

y11=0.5Ws，y12=-0.5Ws；y21=0.5Ws，y12=y22=-0.5Ws;

$z_{11}=z_{12}=\sin \left({\mathrm{\&gamma;}}_2\right)\sqrt{{\mathrm{<figure-callout\; id="0"\; label="h"\; filenames="HDA00003000904200021.png"\; state="\{\{state\}\}">h</figure-callout>}}_0^2+{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="HDA00003000904200021.png"\; state="\{\{state\}\}">L</figure-callout>}}^2},$ z21=z22=-h0；

Form the border and the scope on virtual representation plane by 4 summits;

In second step, ask trees profile plane:

1) gridding trees profile planar S '

If perpendicular to ground and the plane by the trees trunk is trees profile planar S ', its level is height of tree H, and width is the width W=Ws gridding trees profile plane on virtual representation plane, and sizing grid is made as d=Ws/C, and wherein, C is the photo columns;

2) trees profile planar S is set ' on the point coordinate position

If trees profile planar S ' on the point coordinate position be that P ' (x ', y ', z ') gets its position

x'＝L,

Be changed to y'=0.5 * W-(i+0.5) * d i=0,1,2,3 ..., 0.5C (6)

z'＝H-h0-(j+0.5)×d j＝0,1,2,3,...,R

According to i, the value of j obtains the capable C row of a R coordinate points, H=Ltg (γ 2) on S ' plane;

In the 3rd step, photo resamples:

1) the transfer point coordinate is the ranks number

There is a Pij ' in the institute of getting on the trees profile plane, corresponding virtual is arranged as the some Pij(xij on the plane, yij, zij); Get its line number r=Rdh/Hs; Columns c=Cdw/Ws; Wherein, dh is the distance of P point to virtual representation plane upper border line, and dw is the horizontal range of P point to boundary line, the left side; Dh, dw is calculated as follows:

$\mathrm{dh}=\sqrt{{\mathrm{<figure-callout\; id="2"\; label="dx"\; filenames="HDA00003000904200021.png"\; state="\{\{state\}\}">dx</figure-callout>}}^2+{\mathrm{<figure-callout\; id="2"\; label="dz"\; filenames="HDA00003000904200021.png"\; state="\{\{state\}\}">dz</figure-callout>}}^2}$

$\mathrm{dw}=\frac{2}{3}\sin \left(\mathrm{\&beta;}\right)\sqrt{h_0^2+L^2}-y_{\mathrm{ij}}$

Wherein, $\mathrm{dx}=x_{\mathrm{ij}}-\cos \left({\mathrm{\&gamma;}}_2\right)\sqrt{{\mathrm{<figure-callout\; id="0"\; label="h"\; filenames="HDA00003000904200021.png"\; state="\{\{state\}\}">h</figure-callout>}}_0^2+{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="HDA00003000904200021.png"\; state="\{\{state\}\}">L</figure-callout>}}^2}$

$\mathrm{dz}=z_{\mathrm{ij}}-\sin \left({\mathrm{\&gamma;}}_2\right)\sqrt{{\mathrm{<figure-callout\; id="0"\; label="h"\; filenames="HDA00003000904200021.png"\; state="\{\{state\}\}">h</figure-callout>}}_0^2+{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="HDA00003000904200021.png"\; state="\{\{state\}\}">L</figure-callout>}}^2}$

2) photo resamples:

(r c) is calculated by bilinear interpolation the image picture elements numerical value f of the capable c row of the r that resamples, and establishes r1, r2, c1, c2 are the ranks number of four neighbor points around the capable c row of r, and its pixel value is respectively f(r1, c1), f(r1, c2), f(r2, c1), f(r2, c2), the pixel value f(r of the capable c of r row then, c) as follows:

f(r ₁)＝(c ₂-c)f(r ₁,c1)+(c-c ₁)f(r ₁,c ₂)

f(r ₂)＝(c ₂-c)f(r ₂,c1)+(c-c ₁)f(r ₂,c ₂)

f(r,c)＝(r ₂-r)f(r ₁)+(r-r ₁)f(r ₂)

To the capable c row of all r of image image resampling, obtain the orthograph picture by following formula.

Described step 3) further comprises: the coupling of model and image, set up as drag:

$y=H-a_1{x}^{b_1}$ Wherein: $a_1=\frac{H-H_c}{{\left(0.5C_r\right)}^{b_1}}---\left(1\right)$

$y=H_b+a_2{\mathrm{<figure-callout\; id="2"\; label="x\; b"\; filenames="HDA00003000904200021.png"\; state="\{\{state\}\}">x</figure-callout>}}^{b_{}}$ Wherein: $a_2=\frac{H_c-H_b}{{\left(0.5C_r\right)}^{b_2}}---\left(2\right)$

(1) formula is the crown model in tree crown top;

(2) formula is the crown model in tree crown bottom, and two formula simultaneous constitute the trees appearance model; Wherein, y is the height of arbitrfary point on the crown curve; Hc is the crown height at maximum hat width of cloth place; H is the height of tree; Hb is a clear bole height; B1, b2 are crown index under the last crown exponential sum; X is the distance that trunk is arrived in the arbitrfary point on the horizontal direction; Cr is x, gets the hat amplitude, and figure is about the y rotational symmetry; The effect of model is mainly used in the calculating of trees morphological Simulation.

Described step 4) further comprises:

Carrying out the visual coupling of figure (establishment VBA software platform under the Excel environment) under the Excel by orthograph picture and trees appearance model, adjust the trees morphological parameters, make it adapt to the trees profile, this moment the trees appearance model parameter that obtains, as the height of tree, crown height, clear bole height, the hat width of cloth, crown index etc. is the model parameter of this image up and down; Obtain the trees appearance model simultaneously.

The present invention be directed to the requirement of accurately obtaining the peripheral profile information of two-dimentional trees and tailor-make, not high to equipment requirements, subsidiary is simple, realize easily, therefore, help obtaining and promoting the use of of field data, on the other hand, the critical index that has comprised the trees forms in the trees appearance model of selecting, promptly crown index.Be very beneficial for the description of trees form and the unification of different seeds models.In terms of existing technologies, this invention is owing to only pay close attention to the peripheral profile of trees, though also adopt individual photography photo, but do not need to make the pattern that is used for camera calibration, do not need to carry out the demarcation of complicated camera inside and outside parameter yet, only need the several simple data of subsidiary just can realize photo is carried out the ortho-rectification of image.Image after the correction can satisfy trees appearance model CALCULATION OF PARAMETERS.

Description of drawings

Fig. 1 is a flow chart of steps of the present invention;

Fig. 2 is trees form of the present invention and parameter thereof;

Fig. 3 is a trees photographic projection synoptic diagram of the present invention;

Fig. 4 is that the image before and after the present invention resamples compares.

Embodiment

When considered in conjunction with the accompanying drawings, by the reference following detailed, can more completely understand the present invention better and learn wherein many attendant advantages easily, but accompanying drawing described herein is used to provide further understanding of the present invention, constitute a part of the present invention.

For above-mentioned purpose of the present invention, feature can be become apparent more, the present invention is further detailed explanation below in conjunction with the drawings and specific embodiments.

May further comprise the steps as shown in Figure 1:

Step 1) is selected the trees appearance model of power function form, obtains the mathematic(al) representation of trees form by model.

Select captured trees, its tree crown does not preferably overlap mutually with peripheral trees, and spot for photography and trees ' root take full width up and down on a surface level, is the trees photo of axis with the trunk, and the records photographing height.

The parameter of effect is (unit: rice): 8.4 meters of shooting distances, 1.6 meters of camera heights, the elevation angle 38.6 degree relatively.Data are calculated by the mean distance of each pixel representative before proofreading and correct.Proofreading and correct back pixel sample size is 0.0019567058*0.0019567058 rice 2, and picture altitude is 4246 pixels.Proofreading and correct the back true altitude is 4246*0.0019567058=8.3081728268 rice.

Data are obtained	The height of tree	Crown height	Clear bole height	The hat width of cloth	a up	Go up crown index	a down	Following crown index	Principal point horizontal line height
										Numerical value before proofreading and correct	8.31	4.34	1.98	3.47	1.914	1.324	0.984	1.588	Height 4.05
Numerical value is opened in correction	8.31	3.80	1.69	3.33	2.296	1.324	0.939	1.588	Actual respective heights 3.61
										Laser scanning numerical value	8.42	3.82	1.68	3.28	2.389	1.324	0.976	1.588	Actual respective heights 3.77

The trees appearance model is before proofreading and correct: go up tree crown: y=8.31-1.914|x|1.324

Following tree crown: y=1.98+0.984|x|1.588

Proofreading and correct back trees appearance model is: go up tree crown: y=8.31-2.296|x|1.324

Following tree crown: y=1.69+0.939|x|1.588

Laser scanning trees appearance model: go up tree crown: y=8.42-2.389|x|1.324

Following tree crown: y=1.68+0.976|x|1.588

The graph curve of accompanying drawing 2 has identified the trees form, and all parameters wherein are the trees morphological parameters, the mathematic(al) representation of trees appearance model for concerning between these parameters.The parameter value difference, the trees form of expression is also inequality.

Step 2) taking pictures and subsidiary of trees image, and image is carried out ortho-rectification and image resampling, effect is to obtain to comprise the trees profile of trees morphological parameters and proofread and correct auxiliary data.

Utilize the Trupulse200 laser measuring apparatus, measure shooting distance and take the elevation angle.

It is the optical axis side plan view that Fig. 3 makes left side figure.The blue wire frame representation virtual representation of right figure plane; Blue OP is an optical axis, and S ' is the physical plane, i.e. trees profile plane, and S is the virtual representation plane.P is a principal point.P ' is the real space position of principal point correspondence.

The correction of step 3) trees image, effect are that the central projection image restoring is become two-dimentional orthograph picture.

According to above algorithm image is proofreaied and correct, and preserved and proofread and correct the back image.

As shown in Figure 4, the left side is image before proofreading and correct, and the right is for proofreading and correct the back image, principal point height and the clear bole height height true altitude after proofread and correct before proofreading and correct.Proofread and correct back trees form because principal point obtains stretching with top, slightly narrow partially before proofreading and correct, principal point obtains compression with the lower part, and is slightly wider before proofreading and correct.Acquisition parameters: 12.4 meters of distances, the elevation angle 30.8 degree, 1.6 meters of camera heights.

The coupling of step 4) model and image, effect are to obtain the numerical value of the crown index of trees.

On trees morphological Simulation software platform, read and proofread and correct the back image, adjust the trees morphological parameters trees modality curves and trees image outline are complementary.The trees morphological parameters that obtains is exactly the parameter values of the appearance model behind the captured trees image rectification.

Used specific embodiment herein principle of the present invention and embodiment are set forth, the explanation of above embodiment just is used for helping to understand method of the present invention and core concept thereof; Simultaneously, for one of ordinary skill in the art, according to thought of the present invention, part in specific embodiments and applications all can change.In sum, this description should not be construed as limitation of the present invention.

[1]Min Liu，HuaiQing Zhang，“Research on Three-dimensional Simulation of Tree’s Morphology Based on Tree-crown Growth model”,CiSE2010 .

Claims (5)

1. based on photogrammetric trees appearance model parameter fast acquiring method, it is characterized in that comprising following steps:

Step 1) is selected the trees appearance model of power function form, determines the evaluation method of its model parameter;

Step 2) taking pictures and subsidiary of trees image, and image is carried out ortho-rectification and image resampling, effect is to obtain to comprise the trees profile of trees morphological parameters and proofread and correct auxiliary data;

The correction of step 3) trees image, effect are that the central projection image restoring is become two-dimentional orthograph picture;

The coupling of step 4) model and image, effect are to obtain the numerical value of the crown index of trees.

2. according to claim 1 based on photogrammetric trees appearance model parameter fast acquiring method, it is characterized in that, described step 1) further comprises: first, trees are carried out expiring up and down take pictures (promptly the setting the last lower limb that point and tree root occupy shooting picture) of width of cloth mode, and with the centre position of the corresponding photo level of trees trunk, the camera heights h0(during records photographing only need write down once when photographer does not change); The second, measure shooting distance L and elevation angle gamma 2 with the Trupulse200 laser measuring apparatus; Arrive this, the field investigation of one tree wood morphological parameters finishes.Compare with other investigation method and to have characteristics very efficiently.

3. according to claim 1 based on photogrammetric trees appearance model parameter fast acquiring method, it is characterized in that described step 2) further comprising: the orthography of trees profile is the two dimension copy of real-world object in certain horizontal direction; The actual size of each pixel representative is identical on the image; The image that camera is taken is the result of object central projection, when the shot object height is the twice of camera heights, and camera optical axis and subject profile plane (two dimension copy plane) quadrature, the subject profile is similar to photographic images; When subject is higher than the camera heights twice when above (most of shooting situation), camera optical axis and the formed plane of subject profile be quadrature no longer, and principal point does not overlap with the subject central point; Make the trees photo of shooting have projection error, captured photo can't be used for measuring; If with the reverse plane that projects to trees profile place of each pixel on the photo, then can obtain the true profile of trees; Below divide several steps to finish this correction:

The first step, ask the virtual representation plane equation:

Suppose to exist a plane in the space, the optical axis of its normal vector when taking, and the plane crosses the trunk root, as the S plane among the figure; Because the picture plane parallel of this plane and shooting, there is point correspondence completely in its pixel, so is the enlarged drawing of virtual photographic images, is called the virtual representation plane;

1) the principal point coordinate on virtual representation plane be P (x0, y0, z0):

$x_0=\cos (\mathrm{\&beta;}-{\mathrm{\&gamma;}}_1)\cos \left(\mathrm{\&beta;}\right)\sqrt{h_0^2+L^2}$

y ₀＝0

$z_0=\sin (\mathrm{\&beta;}-{\mathrm{\&gamma;}}_1)\cos \left(\mathrm{\&beta;}\right)\sqrt{h_0^2+L^2}$

Wherein, L is a shooting distance, and h0 is a camera heights, and γ 1 is the angle of depression down, and γ 1=arctg (h0/L), β are camera half of field angle up and down, and γ 2 is the elevation angle, β=0.5 (γ 1+ γ 2);

2) equation of virtual representation planar S

The virtual representation planar S be principal point P (x0, y0 z0), are the plane of normal vector with the optical axis, and its equation is:

$x_{0}x+z_{0}z-x_0^2-z_0^2=0$

3) calculate the coordinate of putting P on the virtual representation planar S

If (x, y z) are OP ' (x ', y ', z ') ray and the S intersection point as the plane to the coordinate P on the virtual representation planar S; Wherein, P ' (x ', y ', z ') is a trees profile planar S ' on any point coordinate; Separating its intersection point is:

x＝x't

y＝y't

z＝z't

Wherein, $t=\frac{x_0^2+z_0^2}{x_0{x}^{,}+z_0{z}^{,}}$

By the coordinate points on the S ' plane, obtain corresponding intersection point P on the S plane;

4) ask the scope on virtual representation plane

The height on virtual representation plane When taking with the ranks ratio of 3:2, the following width on virtual representation plane Therefore, 4 apex coordinate P11(x11 on virtual representation plane, y11, z11), and P12(x12, y12, z12), and P21(x21, y21, z21), and P22(x22, y22 z22) is

$x_{11}=x_{12}=\cos \left({\mathrm{\&gamma;}}_2\right)\sqrt{h_0^2+L^2},$ x21=x22=L；

y11=0.5Ws，y12=-0.5Ws；y21=0.5Ws，y12=y22=-0.5Ws;

$z_{11}=z_{12}=\sin \left({\mathrm{\&gamma;}}_2\right)\sqrt{h_0^2+L^2},$ z21=z22=-h0；

Form the border and the scope on virtual representation plane by 4 summits;

In second step, ask trees profile plane:

1) gridding trees profile planar S '

If perpendicular to ground and the plane by the trees trunk is trees profile planar S ', its level is height of tree H, and width is the width W=Ws gridding trees profile plane on virtual representation plane, and sizing grid is made as d=Ws/C, and wherein, C is the photo columns;

2) trees profile planar S is set ' on the point coordinate position

If trees profile planar S ' on the point coordinate position be that P ' (x ', y ', z ') gets its position

x'＝L,

Be changed to y'=0.5 * W-(i+0.5) * d i=0,1,2,3 ..., 0.5C (6)

z'＝H-h0-(j+0.5)×d j＝0,1,2,3,...,R

According to i, the value of j obtains the capable C row of a R coordinate points, H=Ltg (γ 2) on S ' plane;

In the 3rd step, photo resamples:

1) the transfer point coordinate is the ranks number

There is a Pij ' in the institute of getting on the trees profile plane, corresponding virtual is arranged as the some Pij(xij on the plane, yij, zij); Get its line number r=Rdh/Hs; Columns c=Cdw/Ws; Wherein, dh is the distance of P point to virtual representation plane upper border line, and dw is the horizontal range of P point to boundary line, the left side; Dh, dw is calculated as follows:

$\mathrm{dh}=\sqrt{{\mathrm{dx}}^2+{\mathrm{dz}}^2}$

$\mathrm{dw}=\frac{2}{3}\sin \left(\mathrm{\&beta;}\right)\sqrt{h_0^2+L^2}-y_{\mathrm{ij}}$

Wherein, $\mathrm{dx}=x_{\mathrm{ij}}-\cos \left({\mathrm{\&gamma;}}_2\right)\sqrt{h_0^2+L^2}$

$\mathrm{dz}=z_{\mathrm{ij}}-\sin \left({\mathrm{\&gamma;}}_2\right)\sqrt{h_0^2+L^2}$

2) photo resamples:

(r c) is calculated by bilinear interpolation the image picture elements numerical value f of the capable c row of the r that resamples, and establishes r1, r2, c1, c2 are the ranks number of four neighbor points around the capable c row of r, and its pixel value is respectively f(r1, c1), f(r1, c2), f(r2, c1), f(r2, c2), the pixel value f(r of the capable c of r row then, c) as follows:

f(r ₁)＝(c ₂-c)f(r ₁,c1)+(c-c ₁)f(r ₁,c ₂)

f(r ₂)＝(c ₂-c)f(r ₂,c1)+(c-c ₁)f(r ₂,c ₂)

f(r,c)＝(r ₂-r)f(r ₁)+(r-r ₁)f(r ₂)

To the capable c row of all r of image image resampling, obtain the orthograph picture by following formula.

4. according to claim 1 based on photogrammetric trees appearance model parameter fast acquiring method, it is characterized in that described step 3) further comprises: the coupling of model and image, set up as drag:

$y=H-a_1{x}^{b_1}$ Wherein: $a_1=\frac{H-H_c}{{\left(0.5C_r\right)}^{b_1}}---\left(1\right)$

$y=H_b+a_2{x}^{b_2}$ Wherein: $a_2=\frac{H_c-H_b}{{\left(0.5C_r\right)}^{b_2}}---\left(2\right)$

(1) formula is the crown model in tree crown top;

(2) formula is the crown model in tree crown bottom, and two formula simultaneous constitute the trees appearance model; Wherein, y is the height of arbitrfary point on the crown curve; Hc is the crown height at maximum hat width of cloth place; H is the height of tree; Hb is a clear bole height; B1, b2 are crown index under the last crown exponential sum; X is the distance that trunk is arrived in the arbitrfary point on the horizontal direction; Cr is x, gets the hat amplitude, and figure is about the y rotational symmetry; The effect of model is mainly used in the calculating of trees morphological Simulation.

5. according to claim 1 based on photogrammetric trees appearance model parameter fast acquiring method, it is characterized in that described step 4) further comprises:

Carrying out the visual coupling of figure (establishment VBA software platform under the Excel environment) under the Excel by orthograph picture and trees appearance model, adjust the trees morphological parameters, make it adapt to the trees profile, this moment the trees appearance model parameter that obtains, as the height of tree, crown height, clear bole height, the hat width of cloth, crown index etc. is the model parameter of this image up and down; Obtain the trees appearance model simultaneously.

Images