CN103049931A - Cloud cluster fast three-dimension simulation algorithm based on particle system - Google Patents

Abstract

The invention discloses a cloud cluster fast three-dimension simulation algorithm based on a particle system. The algorithm comprises the following steps of giving profiles of multiple-sphere simulation cloud, solving a rectangular bounding box used for producing particles according to the given spheres, randomly producing particles in the bounding box, giving physical property for the particles according to the particle system principle, comparing the position relationships of the particles and the spheres, if the particles are included in the spheres, the particles are cloud particles, otherwise, canceling the particles which are not cloud particles; rendering and drawing the cloud particles, thereby realizing three-dimensional simulation of the cloud; updating the property of the particles at intervals, and drawing cloud again, thereby realizing dynamic simulation of the cloud. The algorithm designed by the invention can be used for greatly improving the reality and drawing speed of the cloud cluster simulation.

Description

Cloud cluster quick three-dimensional simulation algorithm based on particIe system

Technical field

The invention belongs to the three-dimensional visualization field of weather information, it mainly utilizes three-dimensional visualization technique to realize the three-dimensional modeling of cloud, and utilizes particIe system to realize the three dimension dynamic simulation of cloud cluster.

Background technology

Cloud is a kind of common meteor, and its formation condition is different, and shape and color are also ever-changing with the variation of meteorological element.The irregular smeared out boundary of cloud and complicated light characteristics have increased and utilize computing machine to the difficulty of its analog simulation, but because cloud has important application in fields such as meteorological research, Virtual Battlefield, flight simulation, game animations, in recent years, the researchist has proposed many new methods in the sense of reality simulation field of cloud, has obtained larger progress at aspects such as simulation precision, the sense of reality and real-times.

Mainly being divided three classes for the method for the profile modeling of cloud is method for numerical simulation, heuristic and hybrid method, wherein representative cloud modeling algorithm has following several: the cumulus convection model of employing, by the less cloud of yardstick of having found the solution simple atmospheric fluid dynamics equation simulation; Utilize the spectrum composite function to generate the texture of cloud, it is mapped to the static images of 2D ellipsoid Surface Creation cloud; Cellular automaton (cellular automata, CA) is used for the generation of cloud; CA is improved the coupling reflection grid (Coupled Map Lattice, CML) of rear proposition; Adopt the basic profile of first ball (metaball) method construct cloud; With fuzzy objectives such as particIe system simulation clouds.

In recent years, many scholars have proposed a lot of improved algorithms on the basis of these algorithms, based on the three-dimensional cloud modeling algorithm that improves the Gardenr algorithm; Realized the emulation of the natural landscapes such as cloud in conjunction with Vega Prime and particIe system; Based on the drafting update strategy of Cell, in conjunction with the three-dimensional cloud of the automatic blend rendering of Impostor technology and Impostor, realized the real time modelling of extensive three-dimensional cloud; More there are some scholars that GPU is introduced to accelerate the generation of cloud and drafting etc.

The cloud modeling algorithm of comprehensive above-mentioned all propositions, mainly there is the problem of two aspects in it: the first, owing to introduce various numerical models in the algorithm, it will increase complexity and the calculated amount of cloud modeling widely; The second, the three-dimensional artificial effect of cloud layer is bad, and the sense of reality of cloud is relatively poor.

Summary of the invention

Technical matters to be solved by this invention provides and a kind ofly can improve significantly the authenticity of cloud cluster simulation and the cloud cluster quick three-dimensional simulation algorithm based on particIe system of render speed.

The present invention adopts following technical scheme to solve the problems of the technologies described above: the present invention has designed a kind of cloud cluster quick three-dimensional simulation algorithm based on particIe system, comprises following concrete steps:

Step (1): in space coordinates, set out some spheroids, be used for the profile of simulation cloud;

Step (2): find out all spherome surfaces in the step (1) minute be clipped to maximal projection distance and minimum projection's distance of each coordinate axis in having a few, with to the maximal projection of each coordinate axis apart from forming an end points, with to the minimum projection of each coordinate axis apart from forming another end points, and with the line between these two points as diameter, draw another spheroid, construct this spheroid in connect rectangular parallelepiped, this rectangular parallelepiped namely is defined as the cloud cluster bounding box;

Step (3): according to the ultimate principle of particIe system, produce randomly particle in the bounding box in step (2), and give initial attribute for described particle;

Step (4): judge whether this particle is included in any spheroid of setting in the step (1), if comprise, then this particle is cloud particle; If do not comprise, then delete and do not consider;

Step (5): the cloud particle in the step (4) is carried out texture draw and play up, realize the three-dimensional simulation of cloud cluster;

Step (6): the judgement particle at interval and the position relationship of spheroid, if Particles Moving goes out spheroid, then this particle will not be cloud particle, need its deletion.

As a kind of optimization method of the present invention: described step (1) comprises following concrete processing:

Set three spheroids in volume coordinate, the coordinate of the centre of sphere is respectively (x ₁, y ₁, z ₁), (x ₂, y ₂, z ₂), (x ₃, y ₃, z ₃), radius is respectively R ₁, R ₂, R ₃

As a kind of optimization method of the present invention: described step (2) comprises following concrete processing:

Step (21): utilize following formula find out three spherome surfaces minute be clipped to the maximal projection distance of each coordinate axis in having a few:

$\left\{\begin{array}{c}\mathrm{xMin}=\min \{x_1-R_1,x_2-R_2,x_3-R_3\}\\ \mathrm{yMin}=\min \{y_1-R_1,y_2-R_2,y_3-R_3\}\\ \mathrm{zMin}=\min \{z_1-R_1,z_2-R_2,z_3-R_3\}\end{array}\right.,$

$\left\{\begin{array}{c}\mathrm{xMax}=\max \{x_1+R_1,x_2+R_2,x_3+R_3\}\\ \mathrm{yMax}=\max \{y_1+R_1,y_2+R_2,y_3+R_3\}\\ \mathrm{zMax}=\max \{z_1+R_1,z_2+R_2,z_3+R_3\}\end{array}\right.,$

With to the maximal projection of each coordinate axis apart from forming an end points, coordinate be (xMax, yMax, zMax), with to the minimum projection of each coordinate axis apart from another end points of formation, coordinate is (xMin, yMin, zMin);

Step (22): utilize the line between above-mentioned 2 to draw another spheroid as diameter, sphere centre coordinate is:

((xMax-xMin)/2,(yMax-yMin)/2,(zMax-zMin)/2)，

Radius $R=\sqrt{{(\mathrm{xMax}-\mathrm{xMin})}^2+{(\mathrm{yMax}-\mathrm{yMin})}^2+{(\mathrm{zMax}-\mathrm{zMin})}^2}/2;$

Step (23): according to following formula, obtain this spheroid in connect rectangular parallelepiped:

$\left\{\begin{array}{c}V=\mathrm{length}*\mathrm{width}*\mathrm{height}\\ 2R=\sqrt{{\mathrm{length}}^2+{\mathrm{width}}^2+{\mathrm{height}}^2}\end{array}\right.$

Wherein V is defined as the volume of rectangular parallelepiped, and length, width and height are defined as respectively length and width and the height of rectangular parallelepiped, thereby obtains the cloud cluster bounding box.

As a kind of optimization method of the present invention: described step (3) comprises following concrete processing:

Step (31): the coordinate of establishing the particle that produces at random is (a, b, c), then

$\left\{\begin{array}{c}a=\mathrm{rand}\left(\right)\%(\mathrm{aMax}-\mathrm{bMin}+1)+\mathrm{aMin}\\ b=\mathrm{rand}\left(\right)\%(\mathrm{bMax}-\mathrm{bMin}+1)+\mathrm{bMin}\\ c=\mathrm{rand}\left(\right)\%(\mathrm{cMax}-\mathrm{cMin}+1)+\mathrm{cMin}\end{array}\right.,$

Wherein % is for rounding operator,

Step (32): the above-mentioned particle that produces is at random defined along x axle and the axial speed of z, as its initial attribute.

As a kind of optimization method of the present invention: described step (4) comprises following concrete processing:

The particle of at random generation and each spheroid in the bounding box are compared, and the formula of utilization is as follows:

$\left\{\begin{array}{c}{(a-x_1)}^2+{(b-y_1)}^2+{(c-z_1)}^2\≤{R_1}^2\\ {(a-x_2)}^2+{(b-y_2)}^2+{(c-z_2)}^2\≤{R_2}^2\\ {(a-x_3)}^2+{(b-y_3)}^2+{(c-z_3)}^2\≤{R_3}^2\end{array}\right.,$

If particle is included in the spheroid, then this particle is cloud particle; If this particle is not contained in the spheroid, then deletes and do not consider.

The present invention compared with prior art has following advantage:

1. the designed cloud cluster quick three-dimensional simulation algorithm based on particIe system of the present invention, owing to consider the unpredictability of cloud profile and motion state, introduce spheroid and simulate the profile of cloud, by changing the number of spheroid, can realize the three-dimensional visualization of difformity and pattern, in conjunction with particIe system, simulate the dynamic effect of cloud by the motion of each particle in the system simultaneously;

2. the designed cloud cluster quick three-dimensional simulation algorithm based on particIe system of the present invention has preferably cloud three-dimensional artificial effect, and compares with already present algorithm, and its render speed also is greatly improved.

Description of drawings

Fig. 1 is schematic flow sheet of the present invention;

Fig. 2 is the bounding box of the cloud cluster that solves of the present invention;

Fig. 3 is for using particIe system to carry out design sketch after particle-filled;

Fig. 4 is the texture of the texture mapping used of the present invention;

Fig. 5 a is that the present invention carries out the design sketch after particle is played up rear drafting;

Fig. 5 b is that the present invention carries out the design sketch after particle is played up rear drafting;

Fig. 6 a is cloud cluster dynamic mode graphoid during Particles Moving 1s in the situation of using two spheroids simulation cloud cluster profiles;

Fig. 6 b is cloud cluster dynamic mode graphoid during Particles Moving 10s in the situation of using two spheroids simulation cloud cluster profiles;

Fig. 6 c is cloud cluster dynamic mode graphoid during Particles Moving 20s in the situation of using two spheroids simulation cloud cluster profiles;

Fig. 7 a is cloud cluster dynamic mode graphoid during Particles Moving 1s in the situation of using three spheroids simulation cloud cluster profiles;

Fig. 7 b is cloud cluster dynamic mode graphoid during Particles Moving 10s in the situation of using three spheroids simulation cloud cluster profiles;

Fig. 7 c is cloud cluster dynamic mode graphoid during Particles Moving 20s in the situation of using three spheroids simulation cloud cluster profiles.

Embodiment

The present invention is described in further detail below in conjunction with accompanying drawing:

As shown in Figure 1, the present invention has designed a kind of cloud cluster quick three-dimensional simulation algorithm based on particIe system, comprises following concrete steps:

Step (1): in space coordinates, set out some spheroids, be used for the profile of simulation cloud;

Step (2): find out all spherome surfaces in the step (1) minute be clipped to maximal projection distance and minimum projection's distance of each coordinate axis in having a few, obtain minute being clipped to the x axle, the y axle, 3 maximal projection distances of z axle are clipped to the x axle with dividing, the y axle, 3 minimum projection's distances of z axle, with to 3 maximal projections of each coordinate axis apart from end points of the crossing formation of place straight line, with to 3 minimum projections of each coordinate axis apart from another end points of the crossing formation of place straight line, and with the line between these two end points as diameter, draw another spheroid, construct this spheroid in connect rectangular parallelepiped, this rectangular parallelepiped namely is defined as the cloud cluster bounding box, in specific embodiment, we comprise following concrete processing take three balls as example:

Step (21): utilize following formula find out three spherome surfaces minute be clipped to the maximal projection distance of each coordinate axis in having a few:

$\left\{\begin{array}{c}\mathrm{xMin}=\min \{x_1-R_1,x_2-R_2,x_3-R_3\}\\ \mathrm{yMin}=\min \{y_1-R_1,y_2-R_2,y_3-R_3\}\\ \mathrm{zMin}=\min \{z_1-R_1,z_2-R_2,z_3-R_3\}\end{array}\right.,$

$\left\{\begin{array}{c}\mathrm{xMax}=\max \{x_1+R_1,x_2+R_2,x_3+R_3\}\\ \mathrm{yMax}=\max \{y_1+R_1,y_2+R_2,y_3+R_3\}\\ \mathrm{zMax}=\max \{z_1+R_1,z_2+R_2,z_3+R_3\}\end{array}\right.,$

With to the maximal projection of each coordinate axis apart from forming an end points, coordinate be (xMax, yMax, zMax), with to the minimum projection of each coordinate axis apart from another end points of formation, coordinate is (xMin, yMin, zMin);

Step (22): utilize the line between above-mentioned 2 to draw another spheroid as diameter, sphere centre coordinate is:

((xMax-xMin)/2,(yMax-yMin)/2,(zMax-zMin)/2)，

Radius $R=\sqrt{{(\mathrm{xMax}-\mathrm{xMin})}^2+{(\mathrm{yMax}-\mathrm{yMin})}^2+{(\mathrm{zMax}-\mathrm{zMin})}^2}/2;$

Step (23): according to following formula, obtain this spheroid in connect rectangular parallelepiped:

$\left\{\begin{array}{c}V=\mathrm{length}*\mathrm{width}*\mathrm{height}\\ 2R=\sqrt{{\mathrm{length}}^2+{\mathrm{width}}^2+{\mathrm{height}}^2}\end{array}\right.$

Wherein V is defined as the volume of rectangular parallelepiped, and length, width and height are defined as respectively length and width and the height of rectangular parallelepiped, thereby obtains the cloud cluster bounding box.

Step (3): according to the ultimate principle of particIe system, as shown in Figure 3, produce randomly particle in the bounding box in step (2), concrete steps are as follows:

Step (31): the coordinate of establishing the particle that produces at random is (a, b, c), then

$\left\{\begin{array}{c}a=\mathrm{rand}\left(\right)\%(\mathrm{aMax}-\mathrm{bMin}+1)+\mathrm{aMin}\\ b=\mathrm{rand}\left(\right)\%(\mathrm{bMax}-\mathrm{bMin}+1)+\mathrm{bMin}\\ c=\mathrm{rand}\left(\right)\%(\mathrm{cMax}-\mathrm{cMin}+1)+\mathrm{cMin}\end{array}\right.,$

Wherein % is for rounding operator,

Step (32): the generation of particle is realized by random function that mainly because mass particle is very little, so can ignore action of gravitation, namely particle only has along x axle and the axial speed of y.

Step (4): the coordinate of particle and the centre of sphere of each spheroid in the step (1) are compared, and concrete steps are as follows:

The particle of at random generation and each spheroid in the bounding box are compared, and the formula of utilization is as follows:

$\left\{\begin{array}{c}{(a-x_1)}^2+{(b-y_1)}^2+{(c-z_1)}^2\≤{R_1}^2\\ {(a-x_2)}^2+{(b-y_2)}^2+{(c-z_2)}^2\≤{R_2}^2\\ {(a-x_3)}^2+{(b-y_3)}^2+{(c-z_3)}^2\≤{R_3}^2\end{array}\right.,$

If particle is included in the spheroid, then this particle is cloud particle; If this particle is not contained in the spheroid, then deletes and do not consider.

Step (5): the particle that will be in marginal position carries out texture as polygonal summit to be drawn and plays up, thereby realizes the three-dimensional simulation of cloud cluster; If using the 3D rendering intent of the particIe system of Reeves proposition plays up each particle, can greatly reduce rendering speed, it is very low drawing frame per second when number of particles is many, the present invention proposes a kind of new particle rendering intent, by analysis, the particle that produces at random has a lot of laps, can carry out a plurality of particles as polygonal summit the drafting of texture, the present invention uses texture shown in Figure 4, carries out the drafting effect of cloud particle after the texture mapping shown in Fig. 5 a and Fig. 5 b.

Step (6): the judgement particle at interval and the position relationship of spheroid, if Particles Moving goes out spheroid, then this particle will not be cloud particle, need its deletion, the present invention mainly uses VC++ to realize the Three Dimensional Dynamic Simulation of cloud in conjunction with OpenGL, operation result as shown in Figure 6 and Figure 7, wherein Fig. 6 is the bounding box of simulating cloud cluster profile and definite cloud particle with two balls, Fig. 7 then simulates the bounding box of cloud cluster profile and definite cloud particle with three spheroids, to two figure contrast as can be known, the spheroid of use varying number can be realized the simulation of various shape cloud.

Fig. 6 a, Fig. 6 b, the operation result when this three width of cloth of Fig. 6 c figure is respectively Particles Moving 1s, 10s and 20s, when this three width of cloth figure is analyzed as can be known, because cloud particle is in the continuous motion, so the profile of cloud is also constantly changing, has namely realized the dynamic similation of cloud.

In like manner, Fig. 7 a, Fig. 7 b, the operation result when Fig. 7 c is respectively Particles Moving 1s, 10s and 20s, the profile of cloud is also constantly changing, and has realized equally the dynamic similation of cloud.

By experiment as can be known, the algorithm of this paper can be realized the Three Dimensional Dynamic Simulation of the cloud that the sense of reality is stronger, and can realize the three-dimensional simulation of the cloud of various shapes by the quantity that changes simulation cloud profile spheroid.

Claims (5)

1. the cloud cluster quick three-dimensional simulation algorithm based on particIe system is characterized in that, comprises following concrete steps:

Step (1): in space coordinates, set out some spheroids, be used for the profile of simulation cloud;

Step (2): find out all spherome surfaces in the step (1) minute be clipped to maximal projection distance and minimum projection's distance of each coordinate axis in having a few, with to the maximal projection of each coordinate axis apart from forming an end points, with to the minimum projection of each coordinate axis apart from forming another end points, and with the line between these two end points as diameter, draw another spheroid, construct this spheroid in connect rectangular parallelepiped, this rectangular parallelepiped namely is defined as the cloud cluster bounding box;

Step (3): according to the ultimate principle of particIe system, produce randomly particle in the bounding box in step (2), and give initial attribute for described particle;

Step (4): judge whether this particle is included in any spheroid of setting in the step (1), if comprise, then this particle is cloud particle; If do not comprise, then delete and do not consider;

Step (5): the cloud particle in the step (4) is carried out texture draw and play up, realize the three-dimensional simulation of cloud cluster;

Step (6): the judgement particle at interval and the position relationship of spheroid, if Particles Moving goes out spheroid, then this particle will not be cloud particle, need its deletion.

2. the cloud cluster quick three-dimensional simulation algorithm based on particIe system according to claim 1 is characterized in that described step (1) comprises following concrete processing:

Set three spheroids in volume coordinate, the coordinate of the centre of sphere is respectively (x ₁, y ₁, z ₁), (x ₂, y ₂, z ₂), (x ₃, y ₃, z ₃), radius is respectively R ₁, R ₂, R ₃

3. the cloud cluster quick three-dimensional simulation algorithm based on particIe system according to claim 2 is characterized in that described step (2) comprises following concrete processing:

Step (21): utilize following formula find out three spherome surfaces minute be clipped to the maximal projection distance of each coordinate axis in having a few:

$\left\{\begin{array}{c}\mathrm{xMin}=\min \{x_1-R_1,x_2-R_2,x_3-R_3\}\\ \mathrm{yMin}=\min \{y_1-R_1,y_2-R_2,y_3-R_3\}\\ \mathrm{zMin}=\min \{z_1-R_1,z_2-R_2,z_3-R_3\}\end{array}\right.,$

$\left\{\begin{array}{c}\mathrm{xMax}=\max \{x_1+R_1,x_2+R_2,x_3+R_3\}\\ \mathrm{yMax}=\max \{y_1+R_1,y_2+R_2,y_3+R_3\}\\ \mathrm{zMax}=\max \{z_1+R_1,z_2+R_2,z_3+R_3\}\end{array}\right.,$

With to the maximal projection of each coordinate axis apart from forming an end points, coordinate be (xMax, yMax, zMax), with to the minimum projection of each coordinate axis apart from another end points of formation, coordinate is (xMin, yMin, zMin);

Step (22): utilize the line between above-mentioned 2 to draw another spheroid as diameter, sphere centre coordinate is:

((xMax-xMin)/2,(yMax-yMin)/2,(zMax-zMin)/2)，

Radius $R=\sqrt{{(\mathrm{xMax}-\mathrm{xMin})}^2+{(\mathrm{yMax}-\mathrm{yMin})}^2+{(\mathrm{zMax}-\mathrm{zMin})}^2}/2;$

Step (23): according to following formula, obtain this spheroid in connect rectangular parallelepiped:

$\left\{\begin{array}{c}V=\mathrm{length}*\mathrm{width}*\mathrm{height}\\ 2R=\sqrt{{\mathrm{length}}^2+{\mathrm{width}}^2+{\mathrm{height}}^2}\end{array}\right.$

Wherein V is defined as the volume of rectangular parallelepiped, and length, width and height are defined as respectively length and width and the height of rectangular parallelepiped, thereby obtains the cloud cluster bounding box.

4. the cloud cluster quick three-dimensional simulation algorithm based on particIe system according to claim 3 is characterized in that described step (3) comprises following concrete processing:

Step (31): the coordinate of establishing the particle that produces at random is (a, b, c), then

$\left\{\begin{array}{c}a=\mathrm{rand}\left(\right)\%(\mathrm{aMax}-\mathrm{bMin}+1)+\mathrm{aMin}\\ b=\mathrm{rand}\left(\right)\%(\mathrm{bMax}-\mathrm{bMin}+1)+\mathrm{bMin}\\ c=\mathrm{rand}\left(\right)\%(\mathrm{cMax}-\mathrm{cMin}+1)+\mathrm{cMin}\end{array}\right.,$

Wherein % is for rounding operator,

Step (32): the above-mentioned particle that produces is at random defined along x axle and the axial speed of z, as its initial attribute.

5. the cloud cluster quick three-dimensional simulation algorithm based on particIe system according to claim 4 is characterized in that described step (4) comprises following concrete processing:

The particle of at random generation and each spheroid in the bounding box are compared, and the formula of utilization is as follows:

$\left\{\begin{array}{c}{(a-x_1)}^2+{(b-y_1)}^2+{(c-z_1)}^2\≤{R_1}^2\\ {(a-x_2)}^2+{(b-y_2)}^2+{(c-z_2)}^2\≤{R_2}^2\\ {(a-x_3)}^2+{(b-y_3)}^2+{(c-z_3)}^2\≤{R_3}^2\end{array}\right.,$

If particle is included in the spheroid, then this particle is cloud particle; If this particle is not contained in the spheroid, then deletes and do not consider.

Images