CN102568032A - Method for generation of reality surface deformation model - Google Patents

Abstract

The invention, which belongs to the computer graphics field, provides a method for generation of a reality surface deformation model. The method comprises the following steps: (1), determining surface ranges that are influenced by various deformation; (2), determining deformation amounts of the various deformation; (3), fusing the surface deformation amount and original landform data to generate landform elevation values of areas influenced by the deformation; (4), adjusting resolution ratios of landform meshes of the areas influenced by the deformation; (5), adjusting texture and illumination information of the landform meshes of the areas influenced by the deformation; and (6), re-rendering mesh models of areas influenced by the landform so as to generate a reality surface deformation model. According to the invention, the provided surface deformation model generation method can be applied to the landform visualization simulation field; and great help can be provided for improvement of calculation efficiency and reality.

Description

Sense of reality face of land deformation model generation method

Technical field

The invention belongs to field of Computer Graphics, relate to sense of reality face of land deformation model generation method, specifically comprised crater model, rut model and footprint model.

Background technology

Dynamically the face of land deformation model in the landform visualization system is meant the abstractdesription of the face of land being made owing to the deformation that produces with ground object interaction of the method for mathematics or physics.In dynamic landform visualization system, face of land deformation model commonly used comprises crater, rut, footprint etc.Face of land deformation model generating algorithm is through sampling, means such as approximate, and generation can be by dynamic landform visualization system showed and real crater, rut, footprint etc. have the model of similar shape and attribute.Sense of reality face of land deformation model generating algorithm is as the key modules (see figure 1) in the dynamic landform visualization system, to the rendering effect and the performance generation material impact of system.

In real scene, because ground is not rigid surface, the object that contacts with ground neither rigid body, so in the process of object and ground interaction, ground and object all deformation can take place; The ground and the size and Orientation of acting force between the object and reacting force that take place after the deformation determine by deformation position, deformation degree and deformation direction, and these acting forces and reaction force acts can cause new deformation after on ground and object.This process is very complicated, relates to the content in field such as mechanics, kinematics in the physics, is not suitable for the simulation modeling of having relatively high expectations for real-time.

At present, mostly the emulation of face of land deformation model is to be conceived to the physical characteristics of the phenomenon that model simulates, adopts the multiple theoretical expression formula of creating face of land deformation model such as Newton's law, fluid mechanics, particIe system, law of conservation.The principal feature of these face of land deformation models has:

1, calculated amount is big, and computation process is complicated.Because the most models generating algorithm is all paid close attention to the matching degree of the model and the physical characteristics between the phenomenon of simulating, often need a plurality of input parameters when calculating the Terrain Elevation deformation quantity, and expression formula is very complicated usually;

2, coverage is wider, but specific aim is not strong.In the face of land of current popular deformation modeling method, the landing process when the algorithm concern soil particle that has on the face of land deformation takes place; The algorithm that has is paid close attention to the different shape that soil is appeared under various operations such as the excavation of excavator, promotion, extruding; The algorithm that has is paid close attention to the various operations of the object (like dozer) that causes face of land deformation, thereby obtains the various stresses and the motion state of soil particle.Because dynamically the emphasis of landform visualization system is that the form height number of passes if in system, add too much and the factor landform altitude data independence, can reduce the operational efficiency of system on the contrary according to carrying out modeling over the ground;

3, the coverage of face of land deformation model is not clearly proposed.The face of land deformation modeling method of current popular has been used multiple theories such as mechanics, kinematics, particIe system, law of conservation in modeling process, as far as possible accurately calculating the deformation quantity on the face of land, thereby set up the model and the simulation process of the very strong sense of reality.But; The scope on the face of land that is had influence on when seldom having algorithm to pay close attention to object and ground interaction; That is to say that most of algorithm often only relates to the deformation quantity that calculates stress point place, the face of land, but do not have clear and definite method to confirm the particular location of stress point according to characteristics such as the shape on the object and the face of land, physical characteristics, kinetic characteristics; Therefore, the coverage of confirming face of land deformation model is a committed step of face of land deformation being carried out modeling.

To sum up can know, in the process that makes up face of land deformation model, need confirm the deformation quantity of affected zone of topographical surface and height value that should the zone in real time according to less input parameter.Simultaneously, require face of land deformation model to have the stronger sense of reality.

Summary of the invention

Based on the problem that exists in the prior art, the invention provides a kind of sense of reality face of land deformation model generation method.

In order to realize the object of the invention, the technical scheme of employing is summarized as follows:

A kind of sense of reality face of land deformation model generation method may further comprise the steps:

1) face of land scope of confirming various deformation and being influenced, the coordinate of initial landform surface each point be (x, y, z),

2) confirm the deformation quantity of various deformation;

3) merge face of land deformation quantity and original terrain data, generate the landform altitude value of deformation institute range of influence;

4) resolution of the terrain mesh of deformation institute range of influence takes place in adjustment;

5) texture, the illumination information of the terrain mesh of deformation institute range of influence takes place in adjustment;

6) play up the grid model of landform institute range of influence again, generate the face of land deformation model of the sense of reality.

The deformation of said step 1) is spheroid deformation or spheroid deformation.

The expression formula of said spheroid is: The expression formula of said spheroid is:

Wherein the central point of spheroid is (x ₀, y ₀, z ₀), the coordinate of the arbitrfary point on the sphere is (x _e, y _e, z _e); A, b and c are respectively and are the semiaxis length of spheroid at change in coordinate axis direction, are spheroid when a=c.

The coverage of said spheroid deformation is expressed as:

Wherein the central point of spheroid is (x ₀, y ₀, z ₀), the coordinate of the arbitrfary point on the sphere is (x _e, y _e, z _e).

The deformation quantity of said spheroid deformation is expressed as

Spheroid or spheroid surface are carried out the random perturbation based on the Random Mid-point Displacement algorithm.

Deformation in the said step 1) is the banded curve deformation that moving object causes.

If the speed of object is 0, it is 0 that the banded curve deformation that object causes influences face of land scope; If the speed of object is v _i=(x _i, z _i), v so _{⊥ i}For on the surface level perpendicular to v _iVector, n _{⊥ i}For with v _iVertical and x axle component is the vector of unit length of nonnegative value, and the mid point that line segment is intersected on object and ground is P _i, end points is respectively A _iAnd B _i, influence face of land scope and be expressed as:

$A_i(x_{\mathrm{Ai}},z_{\mathrm{Ai}})=P(-l/2)=P_i(x_i,z_i)-\frac{l}{2}\·n_{\⊥i}$

$B_i(x_{\mathrm{Bi}},z_{\mathrm{Bi}})=P(l/2)=P_i(x_i,z_i)+\frac{l}{2}\·n_{\⊥i}.$

Said object is a tire, and the deformation quantity of generation does

W is the dead weight capacity of tire, and l is the width of tire, and D is the diameter of tire, and n ∈ (0,1) is the deformation index, k _φBe friction coefficient.

Deformation in the said step 1) is the deformation that closed curve produces.

The footprint that said closed curve is behaved adopts oval basic configuration as the footprint profile, and part on the lower side adds hyp shape at oval middle part, generates final footprint profile.The deformation quantity that people's footprint produces is Δ y=α m, and α is the deformation coefficient, and m is the people's of generation footprint quality.

Compared with prior art, method of the present invention only needs less input parameter in the process that makes up face of land deformation model, and can confirm the deformation quantity of affected zone of topographical surface and height value that should the zone in real time.Simultaneously, the face of land deformation model that obtains has the stronger sense of reality.

Description of drawings

Fig. 1 is the frame diagram of the dynamic landform visualization system of prior art;

Fig. 2 is the inventive method process flow diagram;

Fig. 3 is a crater model synoptic diagram;

Fig. 4 is a wheel coverage synoptic diagram;

Fig. 5 is a footprint model silhouette synoptic diagram.

Embodiment

Below in conjunction with accompanying drawing and embodiment method of the present invention is described further.

As shown in Figure 1, method of the present invention may further comprise the steps:

Step 1: confirm the face of land scope that deformation influences;

Step 2: confirm deformation quantity;

Step 3: merge face of land deformation and original terrain data;

Step 4: the resolution of the terrain mesh of deformation region takes place in adjustment;

Step 5: information such as the texture of the terrain mesh of adjustment generation deformation region, illumination;

Step 6: play up the grid model of landform again, performance face of land deformation model is to the influence of initial landform topological structure.

The deformation that when object that deformation can comprise the curve deformation that spherical weight produces when impacting the recessed sphere deformation, ellipsoid deformation or the moving object that cause on the face of land through the face of land or have weight falls the face of land is produced with closed curve.Enumerating a concrete example respectively describes

Embodiment 1

Spherical weight impacts the sphere deformation that causes on the face of land, is example with shell in the crater that the topographical surface blast forms, and is elaborated.

1. sense of reality crater generating algorithm

A) specific algorithm

Input: the depth d epth in crater and radius r adius.

The algorithm false code:

Generate_crater(int?depth，int?radius)

{

According to the degree of depth in crater and master pattern surface, the crater F of radius parameter establishment semielliptical shape ₁

Utilize the Random Mid-point Displacement algorithm to generate to master pattern surface F ₁Disturbance surface F ₂

According to weight parameter ω with two surperficial F ₁And F ₂Merge each other, produce the effect of random perturbation at original crater model surface;

Smoothing processing is carried out, the excessive fluctuating that elimination possibly occur in surface to after merging;

}

B) generative process on surface, basic crater

The basic configuration of crater model is as shown in Figure 3, because the shape approximation in crater is a semielliptical shape, therefore can use oval-shaped ball as the basic model as the crater modeling.Wherein, the semiaxis length of ellipsoid is by attribute (comprising rigidity, cohesion coefficient, friction coefficient and the deformation index) decision on the bursting strength and the face of land, location, crater.If the central point of the spheroid at place, crater is (x ₀, y ₀, z ₀), the coordinate of lip-deep arbitrfary point, crater is (x _e, y _e, z _e), then the expression formula of the oval sphere at place, crater is:

$\frac{{(x_e-x_0)}^2}{a^2}+\frac{{(y_e-y_0)}^2}{b^2}+\frac{{(z_e-z_0)}^2}{c^2}=1---\left(1\right)$

A wherein, b and c are respectively and are the semiaxis length of oval-shaped ball at change in coordinate axis direction.

Because the formed figure of tangent plane on most of crater and ground is approximate and circular, therefore, can establish a=c and calculate to simplify, therefore, equality (1) can be reduced to:

$\frac{{(x_e-x_0)}^2+{(z_e-z_0)}^2}{a^2}+\frac{{(y_e-y_0)}^2}{b^2}=1---\left(2\right)$

Wherein, a is the radius in crater, and b is the degree of depth in crater.

Can obtain being positioned at every bit (x on the surface in smooth crater through equality (2) _e, z _e) the degree of depth be:

$y_e=\frac{b}{a}\·\sqrt{a^2-{(x_e-x_0)}^2-{(z_e-z_0)}^2}+y_0---\left(3\right)$

Because a and b are constants, therefore can establish k=b/a as constant factor.According to equality (3), can be with point (x in landform ₀, z ₀) be the center, behind given parameter (degree of depth in crater and radius) generation crater, the Level Change amount of each point is in the landform:

$\mathrm{\Δy}=\left\{\begin{array}{cc}k\·\sqrt{a^2-{(x-x_0)}^2-{(z-z_0)}^2}+y_0,& {(x-x_0)}^2+{(z-z_0)}^2\≤a^2\\ 0,& \mathrm{else}\end{array}\right.---\left(4\right)$

By equality (4), can get in the landform each point and generate later height value y ' in the crater and be:

y′＝y-Δy (5)

In equality (5), y is the original height value of each sampled point in the landform.

According to equality (5), the square section radius in given crater and the degree of depth in crater can construct the surface, basic crater that meets actual rule.

C) random perturbation process

Generate after the semiellipse sphere, the basic configuration in crater is confirmed.But because ellipsoidal surface is pure mathematical model, its surface is perfectly smooth, only carries out emulation with the semiellipse sphere as the face of land deformation model of simulating the crater, and the result who obtains performs poor aspect the sense of reality.

In order to strengthen the sense of reality of crater model; After generating basic crater model; The random perturbation based on the Random Mid-point Displacement algorithm is carried out on its smooth surface, and the crater mold surface that makes final generation is not perfectly smooth, has increased the sense of reality of actual rendering result greatly.

The detailed process of random perturbation is following:

In two-dimensional random neutral displacement algorithm, establish in the Random Mid-point Displacement surface more arbitrarily (x, height value z) be expressed as Z (x, z), then this height value can be expressed as:

Z(x，z)＝f(x，z)+D(x，z) (6)

Wherein D (x, z) be point (x, z) locating average is 0, variance is σ ²Gaussian random variable; (x z) is point (x, z) average height of four neighborhood points on every side to f.

If surface, basic crater is Y, then (x, height z) can be by Y (x, z) expression arbitrfary point on the surface, crater.For the point that has same coordinate on the surface level, the lip-deep height value Y in its basic crater (x, z) with the lip-deep height value Z of Random Mid-point Displacement disturbance (there is a difference in x between z), and establishing this difference is e, then:

e＝Y(x，z)-Z(x，z) (7)

The height value X of the model that therefore, finally generates (x z) can be expressed as:

X(x，z)＝Z(x，z)+ω·e (8)

Wherein, ω is a weight coefficient.Can know that by following formula ω has determined surface, basic crater and Random Mid-point Displacement disturbance surface to size that results model exerted an influence.

When ω=0, and X (x, z)=Z (x, z), results model is determined by disturbance curved surface Z fully; When ω=1, and X (x, z)=Y (x, z), results model is determined by basic surface, crater Y fully; When ω ∈ (0,1), if ω → 0, then X (x, z) → Z (x, z), i.e. the suffered disturbance of results model is bigger, if ω → 1, then X (x, z) → (x, z), i.e. the suffered disturbance of results model is less for Y.

Value through adjustment weight coefficient ω ∈ [0,1] can generate the different crater model of surface undulation degree.

Embodiment 2

The curve deformation that moving object produces during through the face of land, the rut that forms during through ground with the tire of vehicle is that example is elaborated.

1. sense of reality rut generating algorithm

In the landform scene, the outward appearance of rut is a continuous arbitrary curve that certain width is arranged.The width of the width of rut, the degree of depth and position and wheel, direction, position, dead weight capacity and physical property (like elasticity, friction force etc.) and soil physical (like soft degree, viscous degree etc.) have substantial connection.

In order to generate realistic rut model, at first according to kinematic principle, according to the kinematic parameter of wheel, the character of utilization vector and the parameter expression of straight line are confirmed the scope on the face of land that wheel has influence on; According to mechanics principle, calculate the deformation quantity of the face of land in the zone that influenced by wheel then, finally generate rut model.

A) face of land scope that tire influenced

The face of land scope synoptic diagram of tire influence is as shown in Figure 4.If sampling time interval is Δ t, the mid point of the crossing line segment in tire and ground is P when sampling at every turn _i, end points is respectively A _iAnd B _i, the speed of tire is v when sampling at every turn _iIf the width of tire is l, can know by Fig. 3 that then the face of land scope that tire influenced can be by quadrilateral A _iB _iB _I+1A _I+1(i=0,1,2 ...) face formed determines.Therefore, as long as confirmed the end points of tire and ground intersection section, can confirm the coverage of tire to the face of land.

Known the i time when sampling tire speed be v _i=(x _i, z _i), establish v _{⊥ i}For on the surface level perpendicular to v _iVector, then:

I) if v _i=0, stationary vehicle then, the coverage area is 0;

Ii) if v _i≠ 0, then

Satisfy v _iV _{⊥ i}=0, i.e. v _i⊥ v _{⊥ i}

According to v _{⊥ i}Can in the hope of with v _iVertical and x axle component is the vector of unit length n of nonnegative value _{⊥ i}For:

$n_{\⊥i}=k\·(\frac{z_i}{\sqrt{{x_i}^2+{z_i}^2}},-\frac{x_i}{\sqrt{{x_i}^2+{z_i}^2}})---\left(9\right)$

According to equality (9), can know the straight line at the crossing line segment of tire and ground place when the i time sampling, promptly cross a some A _iAnd B _iThe parameter expression of straight line be:

P(t)＝P _i+t·n _⊥i，(t∈R) (10)

P in the formula _iBe line segment A _iB _iMid point.According to equality (10), can obtain two terminal A of the crossing line segment on tire and ground _iAnd B _iCoordinate:

$A_i(x_{\mathrm{Ai}},z_{\mathrm{Ai}})=P(-l/2)=P_i(x_i,z_i)-\frac{l}{2}\·n_{\⊥i}---\left(11\right)$

$B_i(x_{\mathrm{Bi}},z_{\mathrm{Bi}})=P(l/2)=P_i(x_i,z_i)+\frac{l}{2}\·n_{\⊥i}---\left(12\right)$

Wherein, l is the width of tire.

According to equality (11) and (12), obtaining speed v _iWith a P _iPrerequisite under, can obtain the terminal A of the crossing line segment on tire and ground _iAnd B _iCoordinate, can confirm the scope of the topographical surface that tire influences then.

This method has been avoided complicated trigonometric function operation, the non-existent situation of straight slope that possibly occur when also having avoided adopting analytic geometry method.Through simple and clear vector operation and coordinate computation, can obtain in order to confirming the key point of tire coverage according to two simple input parameters, thereby obtain in the terrain data set that influence owing to tire needs to change the sampled point of height value.

B) the regional high deformation amount of influenced landform

The soft face of land receives after the extruding of vehicle tyre, and its deformation mainly receives the influence of two kinds of power: perpendicular to the force of compression of horizontal direction and the extension power of horizontal direction.

Force of compression, relevant with the weight of vehicle, direction is downward perpendicular to stress surface;

Extension power is made up of friction force and cohesion.Wherein friction force is not only relevant with the weight of vehicle, and and tire

With the physical property on the face of land (like the surface of contact smooth degree on the tire and the face of land etc.) relation is arranged also; Cohesion and soil

Character such as glutinousness relevant.

When rut is carried out modeling; Main consider that terrain sampling point is perpendicular to the deformation quantity on the surface level direction; According to the Bekker soil deformation model that Bekker [1] proposes, can know with the interaction of tire after, the deformation quantity of topographical surface can be represented as follows:

$Y={\left[\frac{3W}{(3-n)(\frac{k_c}{l}+k_{\mathrm{\φ}})l\sqrt{D}}\right]}^{\frac{2}{2n+1}}---\left(13\right)$

Wherein, W is the dead weight capacity of tire, and l is the width of tire, and D is the diameter of tire, and n ∈ (0,1) is the deformation index, k _cBe the cohesion coefficient of soil, k _φBe friction coefficient.

In the interaction process of tire and topographical surface, the cohesion coefficient k _cBe 0, therefore, equality (13) can be simplified as follows:

$Y={\left[\frac{3W}{(3-n)k_{\mathrm{\φ}}l\sqrt{D}}\right]}^{\frac{2}{2n+1}}---\left(14\right)$

Can know from equality (14), be directly proportional with the dead weight capacity of tire by the deformation quantity of tire range of influence landform altitude value, be inversely proportional to the width of tire and the square root of diameter of tyres.

According to equality (11) (12) and (14), can generate realistic rut model.

Embodiment 3

The deformation with closed curve that when weight falls the face of land is caused is that example is elaborated with people's footprint.

1. sense of reality footprint generating algorithm

Footprint in the landform scene is relatively independent each other, and footprint is in the influence of topographical surface among the curve of a closure, and the position of model and size are only relevant with the size of the people's who produces footprint position and pin.Therefore, when footprint was carried out modeling, emphasis was a realistic profile of confirming the footprint model, still, does not have document clearly to propose the generation method of footprint profile at present.

In order to use less parameter, generate the footprint model through fairly simple process, adopt the basic configuration of the ellipse similar as simulation footprint profile with the footprint outward appearance; Afterwards, in order to make the footprint model realistic, part on the lower side adds hyp shape at oval middle part, generates final footprint profile.When calculating receives the high deformation amount in the landform zone that footprint influences, guarantee that according to the people's who produces footprint weight and the coefficient relevant the final footprint model that generates meets universal law with soil physical properties, realistic.

A) profile of footprint model

The profile synoptic diagram of footprint model is as shown in Figure 5.Adopt local coordinate system when generating the footprint profile, with people's current location initial point, with people's working direction y axle positive dirction as the footprint local coordinate system as the footprint local coordinate system.

The main operation of confirming the footprint profile comprises:

I) the confirming of elliptic focus position in the local coordinate system

Because the y axle positive dirction of local coordinate system is consistent with people's working direction, so the focus of ellipse is positioned on the y axle and about the x rotational symmetry.Oval equation is:

$\frac{x^2}{b^2}+\frac{y^2}{a^2}=1,\left(\right|x|\≤b,|y|\≤a)---\left(15\right)$

In equality (15), a and b are respectively oval major semi-axis and minor semi-axis.

Ii) elliptic equation Determination of Parameters in the local coordinate system

Because with the elementary contour of ellipse as footprint, therefore, the ratio of oval length semiaxis should meet the length-width-ratio of normal footprint.Through statistics and debugging; Ratio as the oval length semiaxis of footprint profile is 3: 1 o'clock; The footprint profile that generates is relatively near truth; Therefore, in the equation of ellipse,

Iii) the confirming of hyperbolic focus position in the local coordinate system

In order to generate the footprint model of the sense of reality, on ellipse, merge hyp figure.Hyp focus is positioned on the straight line

and about the y rotational symmetry.Hyp equation is:

$\frac{x^2}{a^{\′2}}-\frac{{(y+\frac{a}{4})}^2}{b^{\′2}}=1,\left(\right|x|\≥b^{\′},|y|\≥0)---\left(16\right)$

Wherein, a ' and b ' are respectively hyp major semi-axis and minor semi-axis.

Iv) Hyperbolic Equation Determination of Parameters in the local coordinate system

Generate the footprint model in order smoothly to merge with ellipse, hyp length semiaxis need be set up appropriate proportionate relationship with the length semiaxis of ellipse.Through statistics and debugging, when the ratio of hyp major semi-axis and the minor semi-axis of ellipse is 3: 4, and the ratio of hyp length semiaxis is 2: 3 o'clock, and the footprint model of acquisition is more true to nature.

Therefore, in Hyperbolic Equation, $\left\{\begin{array}{c}{a}^{\′}=\frac{3}{4}\\ b^{\′}=\frac{9}{8}\end{array}\right..$

The value of v) putting on the footprint profile

Through getting in oval and two conic sections of hyperbolic curve when the y value is identical, can obtain the point set of footprint profile more near the point of y axle.

According to equality (15), the horizontal ordinate expression formula that can get on oval is:

$x^2=b^2\·(1-\frac{y^2}{a^2}),\left(\right|x|\≤b,|y|\≤a)---\left(17\right)$

According to equality (16), the horizontal ordinate expression formula that can get on the hyperbolic curve is:

$x^2=a^{\′2}\·[1+\frac{{(y+\frac{a}{4})}^2}{b^{\′2}}],\left(\right|x|\≥b^{\′},|y|\≥0)---\left(18\right)$

According to equality (17) and equality (18), the algorithm that can obtain generating the footprint profile is following:

Algorithm input: do not have;

Algorithm output: footprint profile point set;

The specific algorithm false code:

Generate_footprint(VertexSet&v_set)

{

float?xe，xh；

for(float?y＝-a；y＜＝a；y+＝Δy)

{

$\mathrm{xe}=\sqrt{b^2\·(1-\frac{y^2}{a^2});}$

$\mathrm{xh}=\sqrt{a^{\′2}\·[1+\frac{{(y+\frac{a}{4})}^2}{b^{\′2}}]};$

if(xe＜＝xh)

{

v_set.insert(<xe，y>)；

v_set.insert(<-xe，y>)；

}

else

{

v_set.insert(<xh，y>)；

v_set.insert(<-xh，y>)；

}

}

}

Vi) local coordinate is tied to the conversion of global coordinate system

Because the profile point set of the footprint model of setting up through above step generates in local coordinate system, need carry out the conversion that local coordinate is tied to global coordinate system in the time of in being applied to terrain sampling point.

The y axle positive dirction of the local coordinate system at footprint model place is people's in the landform scene a working direction; Can convert the footprint model silhouette point set representations in the local coordinate system in the global coordinate system corresponding expression through appropriate rotation and translation according to current position and the working direction in landform of people; In addition, through suitable zoom operations, can show different big or small footprints.

B) receive the high deformation amount of footprint range of influence in the landform

The landform zone stressing conditions that influenced by footprint is similar with the landform zone that influenced by tire, also is to receive perpendicular to the pressure of horizontal direction and the extension power of horizontal direction.

The deformation that receives the landform zone that footprint influences is mainly by the pressure perpendicular to horizontal direction, and promptly people's gravity causes, therefore, the height value deformation quantity of footprint model is relevant with the people's of generation footprint weight, and deformation quantity can be expressed from the next:

Δy＝αm (19)

In equality (19), α is the deformation coefficient, and m is the people's of generation footprint quality (unit: kilogram).Through the value of adjustment α, can show the form of footprint in the soil of different soft degree.

To sum up, the crater generating algorithm that the present invention relates to has adopted the basic configuration of half ellipsoidal surface as the simulation crater, simultaneously, in order to increase the sense of reality of rendering effect, adds random perturbation on smooth elliposoidal surface; When generating rut model; According to the tire motion characteristic that produces rut and the mechanical characteristic on the tire and the face of land; Adopt the parameter expression method of vector sum straight line to confirm the face of land scope that tire influences, and confirm the height value deformation quantity of involved area according to the physical property on the tire and the face of land; When generating the footprint model, adopt analytic geometry method, utilize oval and Hyperbolic Equation structure footprint profile, through setting the realistic footprint model of parametric configuration of oval and Hyperbolic Equation.More than three kinds of models both had higher formation efficiency, have stronger fidelity again.

Claims (12)

1. sense of reality face of land deformation model generation method may further comprise the steps:

1) face of land scope of confirming various deformation and being influenced, the coordinate of initial landform surface each point be (x, y, z),

2) confirm the deformation quantity of various deformation;

3) merge face of land deformation quantity and original terrain data, generate the landform altitude value of deformation institute range of influence;

4) resolution of the terrain mesh of deformation institute range of influence takes place in adjustment;

5) texture, the illumination information of the terrain mesh of deformation institute range of influence takes place in adjustment;

6) play up the grid model of landform institute range of influence again, generate the face of land deformation model of the sense of reality.

2. the method for claim 1 is characterized in that, the deformation of said step 1) is spheroid deformation or spheroid deformation.

3. method as claimed in claim 2 is characterized in that, the expression formula of said spheroid is:

The expression formula of said spheroid is:

Wherein the central point of spheroid is (x ₀, y ₀, z ₀), the coordinate of the arbitrfary point on the sphere is (x _e, y _e, z _e); A, b and c are respectively and are the semiaxis length of spheroid at change in coordinate axis direction, are spheroid when a=c.

4. method as claimed in claim 3 is characterized in that, the coverage of said spheroid deformation is expressed as:

Wherein the central point of spheroid is (x ₀, y ₀, z ₀), the coordinate of the arbitrfary point on the sphere is (x _e, y _e, z _e).

5. method as claimed in claim 4; It is characterized in that the deformation quantity of said spheroid deformation is expressed as

6. method as claimed in claim 3 is characterized in that, spheroid or spheroid surface are carried out the random perturbation based on the Random Mid-point Displacement algorithm.

7. the method for claim 1 is characterized in that, the deformation in the said step 1) is the banded curve deformation that moving object causes.

8. method as claimed in claim 7 is characterized in that, if the speed of object is 0, it is 0 that the banded curve deformation that object causes influences face of land scope; If the speed of object is v _i=(x _i, z _i), v so _{⊥ i}For on the surface level perpendicular to v _iVector, n _{⊥ i}For with v _iVertical and x axle component is the vector of unit length of nonnegative value, and the mid point that line segment is intersected on object and ground is P _i, end points is respectively A _iAnd B _i, influence face of land scope and be expressed as:

$A_i(x_{\mathrm{Ai}},z_{\mathrm{Ai}})=P(-l/2)=P_i(x_i,z_i)-\frac{l}{2}\&CenterDot;n_{\&perp;i}$

$B_i(x_{\mathrm{Bi}},z_{\mathrm{Bi}})=P(l/2)=P_i(x_i,z_i)+\frac{l}{2}\&CenterDot;n_{\&perp;i}.$

9. method as claimed in claim 8 is characterized in that, said object is a tire, and the deformation quantity of generation does

W is the dead weight capacity of tire, and l is the width of tire, and D is the diameter of tire, and n ∈ (0,1) is the deformation index, k _φBe friction coefficient.

10. the method for claim 1 is characterized in that, the deformation in the said step 1) is the deformation that closed curve produces.

11. method as claimed in claim 10 is characterized in that, the footprint that said closed curve is behaved adopts oval basic configuration as the footprint profile, and part on the lower side adds hyp shape at oval middle part, generates final footprint profile.

12. method as claimed in claim 11 is characterized in that, the deformation quantity that people's footprint produces is Δ y=α m, and α is the deformation coefficient, and m is the people's of generation footprint quality.

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