A method and system for three-dimensional visualization simulation of the response of adjacent trees in a stand to collision
By combining the GJK iterative algorithm and the Lambert illumination model with the collision response function of adjacent trees in the forest stand, the growth pattern of tree branches is simulated, which solves the problem that the cross growth of adjacent trees affects the realism of the virtual forest scene and improves the realism of the three-dimensional visualization of the dynamic growth of trees.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- RES INST OF FOREST RESOURCE INFORMATION TECHN CHINESE ACADEMY OF FORESTRY
- Filing Date
- 2022-12-06
- Publication Date
- 2026-06-09
Smart Images
Figure CN115937419B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of forestry scientific research technology, and in particular to a three-dimensional visualization simulation method and system for the collision response of adjacent trees in a forest stand. Background Technology
[0002] In the process of conducting three-dimensional visualization simulation of forest growth dynamics, the phenomenon of cross-growth between adjacent trees is detrimental to the realistic simulation of the canopy growth dynamics of adjacent trees, thus affecting the realism of the three-dimensional visualization simulation of the virtual forest scene and the scientific validity of the growth prediction results. Currently, forest collision response models only consider collision self-elimination or use rotation matrix simulation, without considering the interaction mechanism with environmental factors, which significantly reduces the realism of the three-dimensional visualization simulation of forest dynamic growth. Summary of the Invention
[0003] The purpose of this invention is to provide a three-dimensional visualization simulation method and system for the collision response of adjacent trees in a forest stand, so as to improve the realism of the three-dimensional visualization simulation of the dynamic growth of trees.
[0004] To achieve the above objectives, the present invention provides the following solution:
[0005] A three-dimensional visualization simulation method for collision response between adjacent trees in a forest stand, the method comprising:
[0006] Obtain the outline point location information of two adjacent trees; the outline point location information includes: the outline point location information of the first tree and the outline point location information of the second tree.
[0007] The collision detection model using the GJK iterative algorithm is adopted to determine the collision point when the two adjacent trees first collide based on the contour point position information, thus obtaining the collision point position information;
[0008] Using the Lambert lighting model, the illumination intensity of potential offset points of the collision point is determined based on the collision point location information; the potential offset points include: the potential offset points of the first tree and the potential offset points of the second tree;
[0009] The collision response function of adjacent trees in a forest stand is used to determine the response mode of the collision between the branches of two adjacent trees based on the light intensity at the potential offset point. The response mode includes: unidirectional growth mode, antidirectional growth mode and cross growth mode. The response mode is used to perform three-dimensional visualization simulation of the dynamic growth of trees.
[0010] Optionally, the collision detection model employing the GJK iterative algorithm determines the collision point when the two adjacent trees first collide based on the contour point position information, thereby obtaining the collision point position information. Specifically, this includes:
[0011] A collision detection model based on the GJK iterative algorithm is used to determine the Minkowski sum of two adjacent trees based on the contour point position information, and to determine the collision point when the two adjacent trees first collide based on the Minkowski sum, thus obtaining the collision point position information; the collision point is the point where the contour points of the first tree and the second tree coincide when the two adjacent trees first collide.
[0012] Optionally, the step of using the Lambert lighting model to determine the lighting intensity of the potential offset point of the collision point based on the collision point location information specifically includes:
[0013] Based on the collision point location information, the circles containing the first potential offset point and the second potential offset point are determined respectively. The circle containing the first potential offset point is drawn perpendicularly to the x-axis with a center at a point located on the negative x-axis and a predetermined distance from the collision point, and with the predetermined distance as the radius. The circle containing the second potential offset point is drawn perpendicularly to the x-axis with a center at a point located on the positive x-axis and a predetermined distance from the collision point, and with the predetermined distance as the radius. The x-axis is the horizontal line where the collision point is located, and the collision point is the origin of the x-axis.
[0014] The points located on the circle containing the first potential offset point, in the four directions above, below, left, and right of the center of the circle, are determined as the potential offset points of the first tree;
[0015] The points located on the circle containing the second potential offset point, in the four directions above, below, left, and right of the center of the circle, are determined as the potential offset points of the second tree;
[0016] The Lambert illumination model was used to determine the illumination intensity at the potential offset points of the first tree and the second tree, respectively.
[0017] Optionally, the step of employing the collision response function of adjacent trees in a forest stand to determine the response mode of branch collision between two adjacent trees based on the light intensity at the potential offset point specifically includes:
[0018] The point with the highest light intensity among the potential offset points of the first tree is determined as the first offset point;
[0019] The point with the highest light intensity among the potential offset points of the second tree is determined as the second offset point;
[0020] The collision response function of adjacent trees in a forest stand is used to determine the response mode of the collision between the branches of the two adjacent trees based on the positional relationship between the first offset point and the collision point and the positional relationship between the second offset point and the collision point.
[0021] Optionally, the same-direction growth pattern includes: the branches of the two adjacent trees growing upwards in the same direction, the branches of the two adjacent trees growing downwards in the same direction, the branches of the two adjacent trees growing to the left in the same direction, and the branches of the two adjacent trees growing to the right in the same direction.
[0022] The anisotropic growth pattern includes: the branches of the two adjacent trees growing in an up-down direction and the branches of the two adjacent trees growing in a left-right direction.
[0023] The cross-growth patterns include: the branches of the two adjacent trees growing in an upward and leftward direction, the branches of the two adjacent trees growing in an upward and rightward direction, the branches of the two adjacent trees growing in a downward and leftward direction, and the branches of the two adjacent trees growing in a downward and rightward direction.
[0024] Optionally, the step of employing a collision response function of adjacent trees in a forest stand to determine the response mode of branch collision between two adjacent trees based on the positional relationship between the first offset point and the collision point and the positional relationship between the second offset point and the collision point specifically includes:
[0025] If the first offset point is located above the collision point and the second offset point is located above the collision point, then the response mode is that the branches of the two adjacent trees both grow upwards.
[0026] If the first offset point is located below the collision point, and the second offset point is located below the collision point, then the response mode is that the branches of the two adjacent trees both grow downwards.
[0027] If the first offset point is located to the left of the collision point, and the second offset point is located to the left of the collision point, then the response mode is that the branches of the two adjacent trees both grow to the left.
[0028] If the first offset point is located to the right of the collision point, and the second offset point is located to the right of the collision point, then the response mode is that the branches of the two adjacent trees both grow to the right.
[0029] If the first offset point is above the collision point and the second offset point is below the collision point, or if the first offset point is below the collision point and the second offset point is above the collision point, then the response mode is that the branches of the two adjacent trees grow in an up-down direction.
[0030] If the first offset point is located to the left of the collision point and the second offset point is located to the right of the collision point, or if the first offset point is located to the right of the collision point and the second offset point is located to the left of the collision point, then the response mode is that the branches of the two adjacent trees grow in a left-right direction.
[0031] If the first offset point is above the collision point and the second offset point is to the left of the collision point, or if the first offset point is to the left of the collision point and the second offset point is above the collision point, then the response mode is that the branches of the two adjacent trees grow in an upward and leftward direction.
[0032] If the first offset point is above the collision point and the second offset point is to the right of the collision point, or if the first offset point is to the right of the collision point and the second offset point is above the collision point, then the response mode is that the branches of the two adjacent trees grow in an upward and rightward direction.
[0033] If the first offset point is located below the collision point and the second offset point is located to the left of the collision point, or if the first offset point is located to the left of the collision point and the second offset point is located below the collision point, then the response mode is that the branches of the two adjacent trees grow in a downward and leftward direction.
[0034] If the first offset point is located below the collision point and the second offset point is located to the right of the collision point, or if the first offset point is located to the right of the collision point and the second offset point is located below the collision point, then the response mode is that the branches of the two adjacent trees grow in a downward and rightward direction.
[0035] Optionally, the set length is the average annual growth of the crown width of the two adjacent trees.
[0036] A three-dimensional visualization simulation system for collision response between adjacent trees in a forest stand, the system comprising:
[0037] The outline information acquisition module is used to acquire the outline point position information of two adjacent trees; the outline point position information includes: the outline point position information of the first tree and the outline point position information of the second tree.
[0038] The collision point detection module is used to determine the collision point when the two adjacent trees first collide based on the contour point position information using the GJK iterative algorithm collision detection model, thereby obtaining the collision point position information.
[0039] The illumination intensity determination module is used to determine the illumination intensity of the potential offset points of the collision point based on the collision point location information using the Lambert illumination model; the potential offset points include: the potential offset points of the first tree and the potential offset points of the second tree;
[0040] The response mode determination module is used to determine the response mode of the collision between the branches of two adjacent trees based on the light intensity of the potential offset point using the collision response function of adjacent trees in the forest stand; the response modes include: unidirectional growth mode, antidirectional growth mode and cross growth mode; the response modes are used for three-dimensional visualization simulation of the dynamic growth of trees.
[0041] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:
[0042] This invention employs the GJK (Gilbert-Johnson-Keerthi) iterative collision detection model to obtain accurate location information of collision points. It determines the response mode of collisions between branches of adjacent trees by using the Lambert illumination model and the collision response function of adjacent trees in the forest stand. It considers the influence of light factors on tree growth, which can make up for the deficiency of current three-dimensional visualization simulation of tree dynamic growth in failing to represent the phototropic characteristics of tree branch growth. It solves the problem of cross-growth of adjacent trees in virtual forest scenes and provides support for the realistic simulation of continuous dynamic growth of trees. Attached Figure Description
[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0044] Figure 1 A flowchart of the three-dimensional visualization simulation method for the collision response of adjacent trees in a forest stand provided by the present invention;
[0045] Figure 2 This is a schematic diagram showing the location of the potential offset point in the collision response provided in an embodiment of the present invention;
[0046] Figure 3 A schematic diagram illustrating ten possible scenarios of collision response provided in an embodiment of the present invention;
[0047] Figure 4 A flowchart illustrating the three-dimensional visualization simulation method for collision response between adjacent trees in a forest stand, provided in this embodiment of the invention.
[0048] Figure 5A schematic diagram illustrating the changes in adjacent trees before and after the collision response, provided in an embodiment of the present invention;
[0049] Figure 6 This is a block diagram of the three-dimensional visualization simulation system for the collision response of adjacent trees in a forest stand provided by the present invention. Detailed Implementation
[0050] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0051] The purpose of this invention is to provide a method and system for three-dimensional visualization simulation of collision response between adjacent trees in a forest stand, so as to improve the realism of three-dimensional visualization simulation of dynamic tree growth.
[0052] Specifically, this invention is based on the Unity3D platform and uses the GJK iterative algorithm to obtain accurate information on collision locations. It determines the response mode of collisions between adjacent trees by using the Lambert illumination model and the collision response function f(B1,B2) of adjacent trees in the forest stand. It proposes a three-dimensional visualization simulation method and system for collision response between adjacent trees in a forest stand that considers illumination factors. This invention belongs to the field of three-dimensional visualization simulation technology for tree growth in forestry scientific research, and mainly involves the theory of tree growth in forest management and the three-dimensional visualization simulation technology in computer science.
[0053] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0054] Example 1
[0055] like Figure 1 As shown, this invention provides a three-dimensional visualization simulation method for the collision response of adjacent trees in a forest stand, the method comprising:
[0056] Step 101: Obtain the outline point location information of two adjacent trees; the outline point location information includes: the outline point location information of the first tree and the outline point location information of the second tree.
[0057] Step 102: Using the GJK iterative algorithm collision detection model, determine the collision point when the two adjacent trees first collide based on the contour point position information, and obtain the collision point position information.
[0058] Step 103: Using the Lambert lighting model, determine the illumination intensity of the potential offset points of the collision point based on the collision point location information; the potential offset points include: the potential offset points of the first tree and the potential offset points of the second tree.
[0059] Step 104: Using the collision response function of adjacent trees in the forest stand, determine the response mode of the collision between the branches of the two adjacent trees based on the light intensity of the potential offset point; the response mode includes: unidirectional growth mode, antidirectional growth mode and cross growth mode; the response mode is used to perform three-dimensional visualization simulation of the dynamic growth of the trees.
[0060] The unidirectional growth pattern includes: branches of two adjacent trees growing upwards in the same direction; branches of two adjacent trees growing downwards in the same direction; branches of two adjacent trees growing to the left in the same direction; and branches of two adjacent trees growing to the right in the same direction. The anisotropic growth pattern includes: branches of two adjacent trees growing in a one-up-one-down direction; and branches of two adjacent trees growing in a one-left-one-right direction. The intersecting growth pattern includes: branches of two adjacent trees growing in a one-up-one-left direction; branches of two adjacent trees growing in a one-up-one-right direction; branches of two adjacent trees growing in a one-down-one-left direction; and branches of two adjacent trees growing in a one-down-one-right direction.
[0061] The above methods will be discussed in detail below from three aspects: the GJK iterative algorithm collision detection model for obtaining collision points, the Lambert lighting model, and the collision response algorithm between tree models.
[0062] (1) GJK iterative algorithm collision detection model for obtaining collision points
[0063] To address the issue of adjacent trees growing intersecting in virtual forest scenarios, an iterative collision detection model based on the GJK algorithm (first proposed by Gilbert, Johnson, and Keerthi) is used to obtain the location information of collision points between adjacent tree models. This information is then output to the Lambert lighting model to calculate the light intensity around the collision point.
[0064] Step 102 specifically includes: using the GJK iterative algorithm collision detection model, determining the Minkowski sum of the two adjacent trees based on the contour point position information, and determining the collision point when the two adjacent trees first collide based on the Minkowski sum, thereby obtaining the collision point position information; the collision point is the point where the contour points of the first tree and the second tree coincide when the two adjacent trees first collide.
[0065] The principle of the GJK iterative algorithm collision detection model is as follows:
[0066] Assuming two adjacent trees are A and B, and d(A, B) represents the distance between A and B, then the distance between two adjacent trees can be expressed as:
[0067] d(A,B)=min{||xy||:x∈A,y∈B}
[0068] The algorithm returns the two closest points a and b between two adjacent trees that satisfy the formula:
[0069] ||ab||=d(A,B)a∈A and b∈B
[0070] Define v(C) as the point in the configuration space C that is closest to the origin, and satisfy the formula:
[0071] v(C)∈C and||v(C)||=min{||x||:x∈C}
[0072] The distance between A and B can be expressed in the form of Minkowski sum (i.e., Minkowski sum) AB as:
[0073] d(A,B)=v(AB)
[0074] Using the above formula, the intersection detection between adjacent trees A and B can be transformed into finding the point closest to the origin on the simplex (AB).
[0075] The problem of collision detection between adjacent trees can be described as follows:
[0076]
[0077] The zero vector represents the origin of the configuration space. That is, when two adjacent trees collide, the origin zero vector lies within (AB). Therefore, the distance d(A, B) between A and B can be expressed as:
[0078] d(A,B)=min{||x||:x∈AB}
[0079] When adjacent trees A and B just collide, i.e. d(A,B)=0, the position information of the collision point a or b is returned (at this time, the outline point a on the first tree and the outline point b on the second tree coincide, and both can be used as the collision point).
[0080] (2) Lambert lighting model
[0081] Based on the Unity3D development platform, the Lambert lighting model is introduced. According to the position information of the collision point a or b of adjacent trees A and B output by the GJK iterative algorithm in (1), the light intensity of the four positions around the collision point of each tree is calculated.
[0082] Step 103 specifically includes: determining the circles containing the first potential offset point and the second potential offset point based on the collision point location information; wherein, the circle containing the first potential offset point is drawn perpendicularly to the x-axis with a point located on the negative x-axis and a set distance from the collision point as its center and the set distance as its radius; the circle containing the second potential offset point is drawn perpendicularly to the x-axis with a point located on the positive x-axis and a set distance from the collision point as its center and the set distance as its radius; the x-axis is the horizontal line where the collision point is located, and the collision point is the origin of the x-axis; determining the points on the circle containing the first potential offset point located above, below, left, and right of the center as the potential offset points of the first tree; determining the points on the circle containing the second potential offset point located above, below, left, and right of the center as the potential offset points of the second tree; and using the Lambert lighting model to determine the light intensity of the potential offset points of the first tree and the potential offset points of the second tree. Preferably, the set length is the average annual growth of the crown width of the two adjacent trees.
[0083] (i) Calculation of illumination intensity at a point. Actual illumination intensity I = (Ambient light + Diffuse light + Ispecular light) * Attenuation factor (F) att The attenuation factor is generally related to the distance from the light source, and it decreases with increasing distance. For example, given that the sunlight intensity at a certain moment is I0, and the distance from a point P to the light source is d, the sunlight intensity at point P is:
[0084]
[0085] In the formula, I P P represents the light intensity, and F represents the light intensity. att K represents the attenuation factor. c K l K q These represent the distance decay constant, linear decay constant, and quadratic decay constant, respectively, and their values are typically set to 1.0, 0.09, and 0.032.
[0086] (ii) Calculation of illumination intensity at potential offset points around the collision point. After obtaining the location information of the collision point, the Lambert illumination model is used to calculate the illumination intensity at potential offset points around the collision point. For example, see... Figure 2 Assuming the known collision point is P(x,y,z) and the average annual crown growth is r meters (m), calculate the locations of four potential offset points for each collision object (i.e., the first tree and the second tree) within a circle r meters in front of point P. The center of the circle containing the potential offset point of the first tree is P. r = (x+r,y,z), the four potential offset points are P_up=(x+r,y+r,z), P_down=(x+r,yr,z), P_left=(x+r,y,zr), P_right=(x+r,y,z+r); the center of the circle containing the potential offset point of the second tree is P. r The light intensity at each of the four potential offset points is P_up = (xr, y, z), P_down = (xr, yr, z), P_left = (xr, y, zr), and P_right = (xr, y, z+ r). The light intensity at these points is then calculated using Lambertmodel. This allows for a comparison of the light intensity at each of the four potential offset points for each tree, revealing the maximum light intensity values B1 and B2 for the two colliding branches.
[0087] (3) Collision response algorithm between tree models
[0088] Using the Lambert illumination model, the maximum light intensity values B1 and B2 among the four potential offset points of the two colliding branches are obtained. Based on the established forest stand adjacent tree collision response function f(B1,B2), the possible growth scenarios after tree collision are simulated.
[0089] Step 104 specifically includes: determining the point with the highest light intensity among the potential offset points of the first tree as the first offset point; determining the point with the highest light intensity among the potential offset points of the second tree as the second offset point; and using the forest stand adjacent tree collision response function to determine the response mode of the branch collision of the two adjacent trees based on the positional relationship between the first offset point and the collision point and the positional relationship between the second offset point and the collision point.
[0090] (i) Collision Response Patterns of Adjacent Tree Branches. Taking Chinese fir as an example, considering the phototropic growth characteristics of tree branches, the growth patterns of adjacent tree branches potentially colliding are divided into three categories: (i) Same-direction growth pattern: branches of adjacent trees all grow upward, downward, leftward, or rightward in the same direction; (ii) Opposite-direction growth pattern: branches of adjacent trees grow in opposite directions, one upward and one downward, and one leftward and one rightward; (iii) Cross-growth pattern: branches of adjacent trees grow in opposite directions, one upward and one leftward, one upward and one rightward, one downward and one leftward, and one downward and one rightward. See details for specific effects. Figure 3 .
[0091] (ii) Collision response function f(B1,B2) between adjacent trees in a forest stand. Compared with the three possible scenarios after a collision proposed by Xiao B et al. in 2015, which uses a rotation matrix to reflect the collision, the collision response function f(B1,B2) between adjacent trees in this invention fully considers the biological characteristics of phototropic growth of trees and introduces a light factor I to simulate the collision response process in a virtual forest growth scenario. The function is specifically as follows:
[0092]
[0093] In the formula: S1-10 represents the possible response scenarios of collisions between branches (see...) Figure 3 Max1 and Max2 represent the illumination intensities I at the four potential offset positions of the two colliding objects. P The location information of the maximum value.
[0094] like Figure 3 As shown in S1, if the first offset point is located above the collision point and the second offset point is located above the collision point, then the response mode is that the branches of the two adjacent trees both grow upwards.
[0095] like Figure 3 As shown in S2, if the first offset point is located below the collision point and the second offset point is located below the collision point, then the response mode is that the branches of the two adjacent trees both grow downwards.
[0096] like Figure 3 As shown in S3, if the first offset point is located to the left of the collision point and the second offset point is located to the left of the collision point, then the response mode is that the branches of the two adjacent trees both grow to the left.
[0097] like Figure 3 As shown in S4, if the first offset point is located to the right of the collision point and the second offset point is located to the right of the collision point, then the response mode is that the branches of the two adjacent trees both grow to the right.
[0098] like Figure 3 As shown in S5, if the first offset point is above the collision point and the second offset point is below the collision point, or if the first offset point is below the collision point and the second offset point is above the collision point, then the response mode is that the branches of the two adjacent trees grow in an up-down direction.
[0099] like Figure 3As shown in S6, if the first offset point is located to the left of the collision point and the second offset point is located to the right of the collision point, or if the first offset point is located to the right of the collision point and the second offset point is located to the left of the collision point, then the response mode is that the branches of the two adjacent trees grow in a left-right direction.
[0100] like Figure 3 As shown in S7, if the first offset point is located above the collision point and the second offset point is located to the left of the collision point, or if the first offset point is located to the left of the collision point and the second offset point is located above the collision point, then the response mode is that the branches of the two adjacent trees grow in an upward and leftward direction.
[0101] like Figure 3 As shown in S8, if the first offset point is located above the collision point and the second offset point is located to the right of the collision point, or if the first offset point is located to the right of the collision point and the second offset point is located above the collision point, then the response mode is that the branches of the two adjacent trees grow in an upward and rightward direction.
[0102] like Figure 3 As shown in S9, if the first offset point is located below the collision point and the second offset point is located to the left of the collision point, or if the first offset point is located to the left of the collision point and the second offset point is located below the collision point, then the response mode is that the branches of the two adjacent trees grow in a downward and leftward direction.
[0103] like Figure 3 As shown in S10, if the first offset point is located below the collision point and the second offset point is located to the right of the collision point, or if the first offset point is located to the right of the collision point and the second offset point is located below the collision point, then the response mode is that the branches of the two adjacent trees grow in a downward and rightward direction.
[0104] The following is a specific implementation case.
[0105] like Figure 4 As shown, based on real forest resource survey data, two adjacent trees that collided, with r = 0.05m and tree1 coordinates (0,0,0) and tree2 coordinates (3.93,0,0), were selected to verify the proposed collision response strategy. The steps are as follows:
[0106] Step 1: Use the GJK iterative algorithm collision detection model to obtain the location information of the points where adjacent tree models collide.
[0107] Specifically, based on the Unity3D platform, using the GJK iterative algorithm, the collision point coordinates are output from the runtime data as (2.09, 8.55, -0.15).
[0108] Step 2: Using the Lambert lighting model, obtain the maximum light intensity B1 and B2 at the four potential offset positions of the two colliding branches.
[0109] Specifically, the four potential offset points of tree1 are P_up = (2.59, 9.05, -0.15), P_down = (2.59, 8.05, -0.15), P_left = (2.59, 8.55, 0.35), and P_right = (2.59, 8.55, -0.65); the four potential offset points of tree2 are P_up” = (1.59, 9.05, -0.15), P_down” = (1.59, 8.05, -0.15), P_left” = (1.59, 8.55, -0.65), and P_right” = (1.59, 8.55, 0.35).
[0110] The light source is set to a directional light source with an illumination intensity of I0 and coordinates (-52.34, -1.23, -54.36). The illumination intensities of potential offset points P_up, P_down, P_left, and P_right in tree1 are 0.004951, 0.004967, 0.004916, and 0.005003 times that of I0, respectively. The illumination intensities of potential offset points P_up”, P_down”, P_left”, and P_right” in tree2 are 0.005039, 0.005056, 0.005093, and 0.005003 times that of I0, respectively.
[0111] Step 3: Establish the collision response function f(B1,B2) between adjacent trees in the forest stand to simulate the possible growth scenarios after tree collision.
[0112] Specifically, such as Figure 5 As shown, after a collision between adjacent trees, the branch of tree1 that collided with the tree shifts to P_right, and the branch of tree2 that collided with the tree shifts to P_left. The FPS in the response scene reaches 8.6fps, with an accuracy of 100%, which can achieve accurate collision detection and realistic response between adjacent trees.
[0113] Example 2
[0114] To implement the method corresponding to Embodiment 1 above and achieve the corresponding functions and technical effects, a three-dimensional visualization simulation system for the collision response of adjacent trees in a forest stand is provided below. For example... Figure 6 As shown, the system includes:
[0115] The contour information acquisition module 601 is used to acquire the contour point position information of two adjacent trees; the contour point position information includes: the position information of the contour point of the first tree and the position information of the contour point of the second tree.
[0116] The collision point detection module 602 is used to determine the collision point when the two adjacent trees first collide based on the contour point position information using the GJK iterative algorithm collision detection model, thereby obtaining the collision point position information.
[0117] The illumination intensity determination module 603 is used to determine the illumination intensity of the potential offset points of the collision point based on the collision point location information using the Lambert illumination model; the potential offset points include: the potential offset points of the first tree and the potential offset points of the second tree.
[0118] The response mode determination module 604 is used to determine the response mode of the collision between the branches of the two adjacent trees based on the light intensity of the potential offset point using the collision response function of adjacent trees in the forest stand; the response mode includes: unidirectional growth mode, antidirectional growth mode and cross growth mode; the response mode is used to perform three-dimensional visualization simulation of the dynamic growth of the trees.
[0119] In summary, this invention provides a three-dimensional visualization simulation method and system for the collision response of adjacent trees in a forest stand. It overcomes the deficiency of current three-dimensional visualization simulations of dynamic tree growth that cannot represent the phototropic characteristics of tree branch growth, solves the problem of intersecting growth of adjacent trees in virtual forest scenes, improves the realism of three-dimensional visualization simulations of dynamic tree growth, and provides support for the realistic simulation of continuous dynamic tree growth.
[0120] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple; relevant parts can be referred to the method section.
[0121] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.
Claims
1. A three-dimensional visualization simulation method for the collision response of adjacent trees in a forest stand, characterized in that, The method includes: Obtain the outline point location information of two adjacent trees; the outline point location information includes: the outline point location information of the first tree and the outline point location information of the second tree. The collision detection model using the GJK iterative algorithm is adopted to determine the collision point when the two adjacent trees first collide based on the contour point position information, thus obtaining the collision point position information; Using the Lambert lighting model, the illumination intensity of potential offset points of the collision point is determined based on the collision point location information. The potential offset points include the potential offset points of the first tree and the second tree. Specifically, determining the illumination intensity of potential offset points of the collision point using the Lambert lighting model includes: determining the circles containing the first and second potential offset points based on the collision point location information; the circle containing the first potential offset point is drawn perpendicular to the x-axis, with a center at a point located on the negative x-axis and a predetermined distance from the collision point, and a radius equal to the predetermined distance; the circle containing the second potential offset point is drawn perpendicular to the x-axis, with a center at a point on the negative x-axis and a radius equal to the predetermined distance from the collision point. A circle is drawn perpendicular to the x-axis, with the center at a point a predetermined distance from the collision point and the radius of that predetermined distance. The x-axis is the horizontal line where the collision point is located, and the collision point is the origin of the x-axis. Points on the circle containing the first potential offset point, located above, below, left, and right of the center, are identified as potential offset points for the first tree. Points on the circle containing the second potential offset point, located above, below, left, and right of the center, are identified as potential offset points for the second tree. The Lambert lighting model is used to determine the light intensity at the potential offset points of the first and second trees, respectively. The predetermined distance is the average annual crown growth of the two adjacent trees. The collision response function of adjacent trees in a forest stand is used to determine the response mode of branch collision between two adjacent trees based on the light intensity at the potential offset point. The response modes include: unidirectional growth mode, antidirectional growth mode, and cross-growth mode. These response modes are used for three-dimensional visualization simulation of dynamic tree growth. The specific collision response function of adjacent trees in a forest stand is as follows: ； Where B1 and B2 are the maximum illumination intensities at the four potential offset points of the two colliding branches, respectively; B1 and B2 are obtained through the Lambert illumination model; S1-10 represents the possible response scenarios of the collision between branches; Max1 and Max2 represent the location information of the maximum illumination intensities at the four potential offset positions of the two colliding objects; P up P down P left P right These are the four potential offset points for the first tree; up , down , left , right These are the four potential offset points for the second tree.
2. The three-dimensional visualization simulation method for collision response between adjacent trees in a forest stand according to claim 1, characterized in that, The collision detection model employing the GJK iterative algorithm determines the collision point when the two adjacent trees first collide based on the contour point position information, thus obtaining the collision point position information, specifically including: A collision detection model based on the GJK iterative algorithm is used to determine the Minkowski sum of two adjacent trees based on the contour point position information, and to determine the collision point when the two adjacent trees first collide based on the Minkowski sum, thus obtaining the collision point position information; the collision point is the point where the contour points of the first tree and the second tree coincide when the two adjacent trees first collide.
3. The three-dimensional visualization simulation method for collision response between adjacent trees in a forest stand according to claim 1, characterized in that, The method employs a collision response function between adjacent trees in a forest stand to determine the response mode of branch collisions between two adjacent trees based on the light intensity at the potential offset point. Specifically, this includes: The point with the highest light intensity among the potential offset points of the first tree is determined as the first offset point; The point with the highest light intensity among the potential offset points of the second tree is determined as the second offset point; The collision response function of adjacent trees in a forest stand is used to determine the response mode of the collision between the branches of the two adjacent trees based on the positional relationship between the first offset point and the collision point and the positional relationship between the second offset point and the collision point.
4. The three-dimensional visualization simulation method for collision response between adjacent trees in a forest stand according to claim 3, characterized in that, The same-direction growth pattern includes: the branches of the two adjacent trees growing upwards in the same direction, the branches of the two adjacent trees growing downwards in the same direction, the branches of the two adjacent trees growing to the left in the same direction, and the branches of the two adjacent trees growing to the right in the same direction. The anisotropic growth pattern includes: the branches of the two adjacent trees growing in an up-down direction and the branches of the two adjacent trees growing in a left-right direction. The cross-growth patterns include: the branches of the two adjacent trees growing in an upward and leftward direction, the branches of the two adjacent trees growing in an upward and rightward direction, the branches of the two adjacent trees growing in a downward and leftward direction, and the branches of the two adjacent trees growing in a downward and rightward direction.
5. The three-dimensional visualization simulation method for collision response between adjacent trees in a forest stand according to claim 4, characterized in that, The method employs a forest stand adjacent tree collision response function to determine the response mode of branch collision between two adjacent trees based on the positional relationship between the first offset point and the collision point, and the positional relationship between the second offset point and the collision point. Specifically, this includes: If the first offset point is located above the collision point and the second offset point is located above the collision point, then the response mode is that the branches of the two adjacent trees both grow upwards. If the first offset point is located below the collision point, and the second offset point is located below the collision point, then the response mode is that the branches of the two adjacent trees both grow downwards. If the first offset point is located to the left of the collision point, and the second offset point is located to the left of the collision point, then the response mode is that the branches of the two adjacent trees both grow to the left. If the first offset point is located to the right of the collision point, and the second offset point is located to the right of the collision point, then the response mode is that the branches of the two adjacent trees both grow to the right. If the first offset point is above the collision point and the second offset point is below the collision point, or if the first offset point is below the collision point and the second offset point is above the collision point, then the response mode is that the branches of the two adjacent trees grow in an up-down direction. If the first offset point is located to the left of the collision point and the second offset point is located to the right of the collision point, or if the first offset point is located to the right of the collision point and the second offset point is located to the left of the collision point, then the response mode is that the branches of the two adjacent trees grow in a left-right direction. If the first offset point is above the collision point and the second offset point is to the left of the collision point, or if the first offset point is to the left of the collision point and the second offset point is above the collision point, then the response mode is that the branches of the two adjacent trees grow in an upward and leftward direction. If the first offset point is above the collision point and the second offset point is to the right of the collision point, or if the first offset point is to the right of the collision point and the second offset point is above the collision point, then the response mode is that the branches of the two adjacent trees grow in an upward and rightward direction. If the first offset point is located below the collision point and the second offset point is located to the left of the collision point, or if the first offset point is located to the left of the collision point and the second offset point is located below the collision point, then the response mode is that the branches of the two adjacent trees grow in a downward and leftward direction. If the first offset point is located below the collision point and the second offset point is located to the right of the collision point, or if the first offset point is located to the right of the collision point and the second offset point is located below the collision point, then the response mode is that the branches of the two adjacent trees grow in a downward and rightward direction.
6. A three-dimensional visualization simulation system for the collision response of adjacent trees in a forest stand, characterized in that, The system includes: The outline information acquisition module is used to acquire the outline point position information of two adjacent trees; the outline point position information includes: the outline point position information of the first tree and the outline point position information of the second tree. The collision point detection module is used to determine the collision point when the two adjacent trees first collide based on the contour point position information using the GJK iterative algorithm collision detection model, thereby obtaining the collision point position information. The illumination intensity determination module is used to determine the illumination intensity of potential offset points of the collision point based on the collision point location information using the Lambert illumination model. The potential offset points include the potential offset points of the first tree and the second tree. Specifically, determining the illumination intensity of the potential offset points of the collision point using the Lambert illumination model includes: determining the circles containing the first and second potential offset points based on the collision point location information; the circle containing the first potential offset point is drawn perpendicularly to the x-axis, with a point located on the negative x-axis and a predetermined distance from the collision point as its center and the predetermined distance as its radius; the circle containing the second potential offset point is drawn perpendicularly to the x-axis, with a point located on the negative x-axis and a predetermined distance from the collision point as its center; the circle containing the second potential offset point is drawn perpendicularly to the x-axis, with a point located on the negative x-axis and a predetermined distance from the collision point as its center and the predetermined distance as its radius. A circle is drawn perpendicular to the x-axis, with the center at a point on the positive x-axis and a predetermined distance from the collision point, and the predetermined distance as the radius. The x-axis is the horizontal line where the collision point is located, and the collision point is the origin of the x-axis. Points on the circle containing the first potential offset point, located above, below, left, and right of the center, are determined as potential offset points of the first tree. Points on the circle containing the second potential offset point, located above, below, left, and right of the center, are determined as potential offset points of the second tree. The Lambert lighting model is used to determine the light intensity at the potential offset points of the first tree and the second tree, respectively. The predetermined distance is the average annual growth of the crown width of the two adjacent trees. The response mode determination module is used to determine the response mode of branch collision between two adjacent trees based on the light intensity at the potential offset point, using the collision response function of adjacent trees in the forest stand. The response modes include: unidirectional growth mode, antidirectional growth mode, and cross-growth mode. These response modes are used for three-dimensional visualization simulation of dynamic tree growth. The specific collision response function of adjacent trees in the forest stand is as follows: ； Where B1 and B2 are the maximum illumination intensities at the four potential offset points of the two colliding branches, respectively; B1 and B2 are obtained through the Lambert illumination model; S1-10 represents the possible response scenarios of the collision between branches; Max1 and Max2 represent the location information of the maximum illumination intensities at the four potential offset positions of the two colliding objects; P up P down P left P right These are the four potential offset points for the first tree; up , down , left , right These are the four potential offset points for the second tree.