JP2004361094A - Method for modeling tree - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a modeling method of trees for modeling the trees accurately. <P>SOLUTION: A contour line C is generated, based on a stereo pair image wherein a group of trees 1 is imaged from the sky, or laser altitude data, and a unit tree 3 separated from the group of trees 1 by the generated contour line C is extracted as a modeling unit. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a tree modeling method.
[0002]
[Prior art]
The thing described in patent document 1 is known as what performs forestry phase analysis using the technique of aerial surveying. In this conventional example, the highest elevation point of the laser original data is selected as a tree representative point, and tree extraction processing is performed assuming that a trunk exists immediately below the tree representative point.
[0003]
[Patent Document 1]
JP-A-11-23263
[Problems to be solved by the invention]
However, in the above-described conventional example, there is a problem that it is necessary to know in advance the range of the tree crown when determining the tree representative point. That is, if the region for determining the highest elevation point that is the tree representative point does not accurately correspond to the tree crown, the highest elevation point of a plurality of adjacent trees is determined as one tree representative point, or A plurality of tree representative points may be extracted from a single tree and specified as a single tree, resulting in a problem that reliability is reduced.
[0005]
The present invention has been made in order to solve the above-described drawbacks, and an object of the present invention is to provide a tree modeling method capable of accurately modeling a tree.
[0006]
[Means for Solving the Problems]
According to the invention, the object is
A contour pair C is generated based on a stereo pair image of the tree group 1 from the sky or laser elevation data,
This is achieved by providing a tree modeling method for extracting a unit tree 3 separated from the tree group 1 by the generated contour line C as a modeling unit.
[0007]
In order to model each tree from the tree group 1 including a plurality of trees, it is necessary to accurately extract a tree to be modeled from the tree group 1, and therefore, a stereo pair image obtained from the tree group 1, Alternatively, a contour line C is generated based on the laser elevation data (original data 2).
[0008]
The obtained contour line C is for the crown portion 3a of the tree, and the unit tree 3 is extracted by dividing it from the crown of another adjacent tree. In the present invention in which the unit tree 3 is identified based on the contour line C, the judgment of the unit tree 3 may be performed in consideration of the highest point (vertex) in the predetermined area and the arrangement of the contour line C surrounding the vertex. Because it is possible, the unit tree 3 can be separated and extracted from the tree group 1 with higher accuracy than in the conventional example in which the unit tree 3 is determined only by the vertex information.
[0009]
For example, if the elevation difference between the contour lines C is sufficiently small, as shown in FIG. 2A, when a contour line C having three vertices T1, T2, and T3 is obtained, the relationship between the vertices T1 and T2 is If the area surrounded by the outermost contour line C1 including only the vertices T1 and T2 is equal to or smaller than the area assumed to be the area of the crown portion 3a of a normal tree, it is considered that the area belongs to the same tree, and the contour line C1 is enclosed. If the area is too large to be the same tree, it can be estimated as a separate tree.
[0010]
Similarly, when the area surrounding the contour C2 including the vertices T1, T2, and T3 is about the area of the crown of a normal tree, it is determined that these are the same tree whose top is branched into three. it can.
[0011]
The above-described generation of the contour line C and separation of the unit tree 3 can be performed manually or by a visual check operation, but it is also possible to automate the entire process or a part thereof, and to automate the entire process. In
A contour line generating unit 4 for generating a contour line C from a stereo pair image of the tree group 1 from the sky or the laser elevation data 2;
Unit tree separating means 5 for separating the tree group 1 into tree units from the contour line C
A tree modeling program for making a computer function as a computer is available.
[0012]
In this case, a known method can be adopted as the contour line generating means 4. For example, a method of directly connecting the elevation measurement points while performing curve interpolation such as spline interpolation or bezier interpolation can be used.
[0013]
A program for functioning as the unit tree separating means 5 can be obtained by, for example, describing the above-described unit tree 3 determination method as a procedure.
[0014]
As described above, according to the present invention, since a single tree can be accurately separated and extracted from a dense tree, the number of trees in a forest or the like can be accurately measured.
[0015]
Further, since the contour line C is data indicating the shape itself, it can be displayed as a three-dimensional shape that can be immediately viewed without needing other additional data, as described later. In the case of estimating or the like, it can be processed as a statistic having a shape characteristic without passing through a viewable state.
[0016]
In this case, the tree type is different only from the planar arrangement of the contour lines C, for example, because the density of the contour lines C is different between the trees having the contour lines C shown in FIGS. Although the degree of tree species discrimination is possible so that the user can easily know what to do, more information can be obtained by performing three-dimensional modeling of the crown portion 3a.
[0017]
That is, by performing three-dimensional modeling of the crown portion 3a, it becomes possible to accumulate three-dimensional shape elements such as the volume of the crown portion 3a as statistics, and for example, the volume and area of the crown portion 3a according to tree species Or a table in which the geometric characteristic values such as the height and the thickness of the trunk portion 3b are associated with each other, it is possible to immediately derive information about the trunk portion 3b of the specific tree such as the timber volume. .
[0018]
It should be noted that the association between the contour line C and the trunk portion 3b with respect to the canopy portion 3a can be performed by focusing on various elements on condition that almost one-to-one correspondence can be obtained statistically.
[0019]
The output by the three-dimensional modeling of the crown portion 3a does not necessarily need to be a three-dimensional display image. As described above, when estimating the volume of the trunk portion 3b from the shape characteristics of the crown portion 3a, the three-dimensional coordinates are used. It suffices if the value of interest in the system can be derived.
[0020]
As described above, according to the present invention, by giving the contour line C to the obtained canopy portion 3a, it becomes possible to accurately grasp the trunk portion 3b. It can be used to increase the height, but can also be used to display trees in three dimensions.
[0021]
In this case, a contour line generating means 4 for generating a contour line C of a crown portion 3a of the tree based on a stereo pair image of the tree taken from the sky or the laser elevation data 2,
Crown modeling means 6 for modeling the shape of the crown portion 3a based on the contour line generating means 4,
Tree modeling programs are available to make a computer function as a computer. In order to obtain the shape of the entire tree, a program obtained by adding a function as the trunk portion estimating means 7 to the above-described modeling program can be used.
[0022]
For the purpose of three-dimensional display of a tree, since the accurate thickness of the trunk portion 3b is not necessarily required, the trunk portion estimating means 7 only needs to be able to depict the position, shape, and the like of the trunk portion 3b. The modeling of the trunk portion 3b is performed by determining a trunk position with respect to the canopy portion 3a, and then linearly extending from the trunk position toward the ground surface, or sequentially connecting representative points such as centroids on each contour plane Cf. It is done by doing.
[0023]
To determine the representative point on each contour plane Cf, MAT (Media Axis Transform) which is an algorithm for obtaining a skeleton of a predetermined planar shape can be applied.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows an embodiment of the present invention. This embodiment is configured to analyze the number, volume, species, and the like of trees vegetated in a forest. A contour line generating unit 4 that generates a contour line C from the original data 2 and a contour line C are used. A unit tree separating unit 5 for separating the unit tree 3 from the dense tree portion, a crown modeling unit 6 for determining the shape of the trunk 3b of the separated unit tree 3, and a trunk part estimating unit for estimating the trunk part 3b from the crown shape. 7 are provided.
[0025]
These means are realized by running a predetermined computer program on a computer.
[0026]
The original data 2 is obtained from a flying object such as an aircraft flying above the target area and uses a stereo pair image that can be viewed stereoscopically, or laser elevation data obtained by laser-scanning the target area from above. .
[0027]
Contour lines C are extracted from the original data 2 by the contour line generating means 4. As shown in FIG. 3, in addition to the smoothing processing by the Bezier interpolation method in the contour plane Cf, the contour line C is also subjected to smoothing processing between contour planes Cf adjacent in the vertical direction (height direction). Optimization is achieved.
[0028]
The tree to be processed is separated and extracted from the tree group 1 by the unit tree separating means 5 based on the contour line C obtained as described above. When the contour C extracted in a forest or the like where trees are densely included includes a plurality of vertices T in a region defined by the same contour C as shown in FIG. As described above, the separating unit 5 identifies the unity of the tree based on the area of the contour line C including the vertex T.
[0029]
When the processing in the contour line generating means 4 and the unit tree separating means 5 is completed, the top height of the tree, the radius of the crown, and the height of the crown are obtained as statistics for the number of trees and each unit tree 3, and The tree height is obtained by referring to the elevation data on the ground surface, and is stored in the tree database.
[0030]
Next, each tree is modeled by the crown modeling means 6 and the trunk partial estimating means 7, and is displayed three-dimensionally. The canopy modeling means 6 models the surface layer of the canopy portion 3a using a NURBS (Non-Uniform Rational B-Spline) surface to give a three-dimensional shape of the canopy portion 3a.
[0031]
On the other hand, the trunk portion estimating means 7 estimates the thickness of the trunk portion 3b and the position of the trunk, and the thickness of the trunk portion 3b is statistically calculated from the radius or volume of the canopy portion 3a. On the other hand, as the trunk position, the median value of the plane position of the representative point such as the centroid of each contour plane Cf is used, and the trunk portion 3b is the plane position given by the median value as shown in FIG. From the top to the upper end of the crown portion 3a.
[0032]
In the above description, for convenience of explanation, a case where a unit tree 3 extracted and separated from a tree dense part such as a forest is modeled to obtain a three-dimensional shape by modeling is described. In the case of a tree, it may be configured without the unit tree separating means 5.
[0033]
【The invention's effect】
As is apparent from the above description, according to the present invention, a tree can be accurately modeled.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating the present invention.
FIGS. 2A and 2B are diagrams illustrating the operation of the present invention, wherein FIG. 2A is a diagram illustrating an operation of a unit tree separating unit, and FIGS. 2B and 2C are diagrams illustrating a tree type identification state.
3A and 3B are diagrams showing contour lines of a crown portion of a unit tree, where FIG. 3A shows a state before smoothing, and FIG. 3B shows a state after smoothing processing.
FIG. 4 is a diagram showing a state where a tree is three-dimensionally modeled.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Tree group 2 Original data 3 Unit tree 3a Crown part 3b Trunk part 4 Contour generating means 5 Unit tree separating means 6 Crown modeling means 7 Trunk estimation means C Contour

Claims (6)

Generate contour lines based on stereo pair images of the trees and the laser elevation data,
A tree modeling method for extracting a unit tree separated from a tree group by a generated contour line as a modeling unit. Generate a contour line of the crown portion of the tree based on a stereo pair image of the tree taken from the sky, or laser elevation data,
A tree modeling method that models the shape of the crown by complementing the generated contours with a free-form surface. Generate a contour line of the crown portion of the tree based on a stereo pair image of the tree taken from the sky, or laser elevation data,
While modeling the shape of the crown based on the generated contours,
A tree modeling method for estimating geometric quantities of a trunk portion from the crown shape and height information. Contour line generating means for generating a contour line from a stereo pair image of a group of trees from the sky, or laser elevation data,
A tree modeling program that causes a computer to function as a unit tree separation unit that separates a group of trees from a contour line into tree units. Contour line generating means for generating a contour line of a tree crown portion based on a stereo pair image of a tree taken from the sky or laser elevation data,
A tree modeling program for causing a computer to function as a crown modeling means for modeling the shape of a crown portion based on contour lines. Contour line generating means for generating a contour line of a tree crown portion based on a stereo pair image of a tree taken from the sky or laser elevation data,
A crown modeling means for modeling the shape of the crown portion based on the contour lines,
A tree modeling program for causing a computer to function as a trunk portion estimating unit that estimates a morphological element of a stem portion from a geometric characteristic of a crown model output from the canopy modeling unit.

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