CN106296818A - A kind of terrestrial space scene simulation method and system based on mobile platform - Google Patents

Abstract

The present invention relates to a kind of terrestrial space scene simulation method and system based on mobile platform, belong to three dimensions visualization technique field.The present invention utilizes mobile platform client to change viewpoint position, according to the position calculation visual range of viewpoint, determines node to be rendered under current view point position and attitude and segmentation degree, sets up new rendering node structure；According to the new scene rendering node structure generated, generate the node listing needing loading data, and send request of data according to the node listing wanting loading data, desired data is loaded into mobile platform client；In mobile platform client, the image of loading, dem data are compiled as respectively texture, vertex cache object, and carry out drawing display by 3 D stereo mapping software, to realize realizing the emulation to three-dimensional digital earth in mobile platform client.The present invention can realize the visualization of spatial environments in mobile platform client, and effect of visualization is satisfactory, and Consumer's Experience is good.

Description

A kind of terrestrial space scene simulation method and system based on mobile platform

Technical field

The present invention relates to a kind of terrestrial space scene simulation method and system based on mobile platform, belonging to three dimensions can Depending on changing technical field.

Background technology

Near earth space environment is the important place of mankind's space science activity, and the productive life of the mankind is had significant shadow Ring.Along with the progress of space science technical research, people the most increasingly pay close attention to spatial environments information.Spatial environments visual simulating Technology, the instrument understood as a kind of spatial knowledge, space science research and daily life are applied significant.Space Environment refers to around the earth, with the earth as core, and a spatial dimension relevant to the earth.Space environment simulation technical research Receiving more and more attention, under the support of National 863 plan, information engineering university of PLA is blue towards the scholar such as hardwood, Wang Peng Proposing Near-earth Space Environment Elements modeling and visualization method, Space Sci. & Application Research Center, Chinese Academy of Sciences is to pin Spatial environments data field visualization has been carried out correlational study, and the Feng Yukang of Chinese Marine University mainly have studied aerospace craft Visualization simulation technology.On the whole, spatial environments data have reference frame multiformity, ambiguity, dynamic and magnanimity The spies such as data.It is extremely complex that Institute For Space Science relates to spatial environments, and the key element comprised is the most.In productive life, The environmental key-element that people are concerned about mainly includes the relevant factors such as the earth, Celestial Background, spacecraft, is the visual master of spatial environments Want object of study.In analogue system, spatial object mainly includes title, position, time attribute, generally with point-like, wire, face The entities such as shape and body shape represent.For spatial environments, most of objects are all to have strict space-time corresponding relation, so Space-time reference system is indispensable in analogue system.

In recent years, mobile technology fast development, equipment performance particularly graphics performance is continuously available lifting, smart mobile phone etc. Mobile platform equipment has become as a part for the productive life interwoveness of people.Existing scholar visualizes skill to moving three dimension Art has carried out correlational study, is concentrated mainly on moving three dimension geographic information services field.At present, spatial environments visualizes field Technical research has been achieved for a large amount of achievement, but the visualization simulation technology for intelligent family moving platform is studied the most fewer. Study spatial environments visualization simulation technology based on mobile device, space science research combined with people's productive life, Popularize spatial environments relevant knowledge to people to have important practical significance.

Summary of the invention

It is an object of the invention to provide a kind of terrestrial space scene simulation method and system based on mobile platform,

To solve the problem that terrestrial space scene emulates on the mobile apparatus.

The present invention solves that above-mentioned technical problem provides a kind of terrestrial space scene simulation method based on mobile platform, This emulation mode comprises the following steps:

1) utilize mobile platform client to change viewpoint position, according to the position calculation visual range of viewpoint, determine and working as Node to be rendered and segmentation degree under front viewpoint position and attitude, set up new rendering node structure；

2) according to step 1) the new scene rendering node structure that generates, delete from mobile platform client internal memory and become Sightless node, generates simultaneously and needs the node listing of loading data, and sends number according to the node listing wanting loading data According to request, desired data is loaded into mobile platform client；

3) in mobile platform client, the image of loading, dem data are compiled as respectively texture, vertex cache object, and Carry out drawing display by 3 D stereo mapping software, to realize realizing three-dimensional digital earth in mobile platform client Emulation.

Node segmentation degree is to choose the tile data of different LOD rank according to viewpoint position, according to screen ranges watt Sheet algorithm of subdivision carries out tile segmentation, using tile drop shadow spread's size on screen as the Rule of judgment of segmentation tile.

This emulation mode also includes the emulation to Celestial Background, and step is as follows:

A. according to azimuth and the elevation angle of current gaze, the scope of the starry sky data being in visual range, and root are calculated According to the Celestial Background data needed for the magnitude rank request loading that user sets；

B. mobile platform client is after the data receiving request, differs in size according to the position drafting of fixed star Point, the size of point represents the brightness of fixed star, and the size of the point that the high fixed star of brightness is corresponding is bigger.

The star place data in moment epoch that starry sky data during Celestial Background emulation are provided by hipparcos catalogue By the data that correction, precession of the equinoxes correction and nutating correction obtain voluntarily.

This emulation mode also includes the emulation to spacecraft, when carrying out spacecraft simulation, and need to be according to its orbital elements meter Calculating orbital position and the attitude of spacecraft under current time, described orbital elements include semi-major axis of orbit α, eccentric ratio e, the nearest Angle ψ, orbit inclination angle i, ascending node precision Ω and argument of pericenter ω, according to the locus γ of above-mentioned orbital elements spacecraft and The computing formula of speed v is:

$\mathrm{\γ}=\mathrm{\α}(cos\mathrm{\ψ}-e)e_0+\mathrm{\α}\sqrt{1-e^2}{\mathrm{sin\ψ\ρ}}_0$

$v=-\frac{{\mathrm{\α}}^{2}n}{\mathrm{\γ}}{\mathrm{sin\ψe}}_0+\frac{{\mathrm{\α}}^{2}n}{\mathrm{\γ}}\sqrt{1-e^2}{\mathrm{cos\ψ\ρ}}_0$

Wherein:

$e_0={\left[\begin{array}{c}cos\mathrm{\Ω}cos\mathrm{\ω}-sin\mathrm{\Ω}sin\mathrm{\ω}\cos i\\ sin\mathrm{\Ω}cos\mathrm{\ω}+cos\mathrm{\Ω}sin\mathrm{\ω}\cos i\\ sin\mathrm{\ω}\sin i\end{array}\right]}^T\left[\begin{array}{c}i\\ j\\ k\end{array}\right]$

${\mathrm{\ρ}}_0={\left[\begin{array}{c}-cos\mathrm{\Ω}\sin \mathrm{\ω}-sin\mathrm{\Ω}\cos \mathrm{\ω}\cos i\\ -sin\mathrm{\Ω}\sin \mathrm{\ω}+cos\mathrm{\Ω}\cos \mathrm{\ω}\cos i\\ sin\mathrm{\ω}\sin i\end{array}\right]}^T\left[\begin{array}{c}i\\ j\\ k\end{array}\right].$

Step 2) in the data that load come from WMS and the WFS server of standard map service access interface can be provided, WMS and the WFS standard map service access interface that mobile platform client accesses this server by network carrys out request data, adds The three-dimensional digital earth data acquisition pyramid data storage model being downloaded to mobile platform client is stored in this server.

Present invention also offers a kind of terrestrial space scene simulating system based on mobile platform, this analogue system includes using In operating in the upper three-dimensional digital earth simulation unit of mobile client, this simulation unit includes scene update module, data Load-on module, compiling drafting module,

Described scene update module is used for utilizing mobile platform client to change viewpoint position, counts according to the position of viewpoint Calculate visual range, determine node to be rendered under current view point position and attitude and segmentation degree, set up new rendering node knot Structure；

Described data load-on module is for according to new scene rendering node structure, from mobile platform client internal memory Deletion becomes sightless node, generates simultaneously and needs the node listing of loading data, and arranges according to the node wanting loading data Table sends request of data, and desired data is loaded into mobile platform client；

Described compiling drafting module is for compiling the image of loading, dem data respectively in mobile platform client For texture, vertex cache object, and carry out drawing display by 3 D stereo mapping software, to realize in mobile platform client The upper realization emulation to three-dimensional digital earth.

Described scene update module determined node segmentation degree is to choose the tile of different LOD rank according to viewpoint position Data, carry out tile segmentation according to the tile algorithm of subdivision of screen ranges, using tile drop shadow spread's size on screen as The Rule of judgment of segmentation tile.

Described analogue system also includes the simulation unit to Celestial Background, and this simulation unit includes:

For the azimuth according to current gaze and the elevation angle, calculate the scope of the starry sky data being in visual range, and Module according to the Celestial Background data needed for the magnitude rank request loading that user sets；

After in mobile platform client in the data receiving request, draw according to the position of fixed star and differ in size The module of point.

Described analogue system also includes the emulation of spacecraft, when carrying out spacecraft simulation, and need to be according to its orbital elements Calculating orbital position and the attitude of spacecraft under current time, described orbital elements include semi-major axis of orbit α, eccentric ratio e, true Nearly angle ψ, orbit inclination angle i, ascending node precision Ω and argument of pericenter ω, according to the locus γ of above-mentioned orbital elements spacecraft With the computing formula of speed v it is:

$\mathrm{\γ}=\mathrm{\α}(cos\mathrm{\ψ}-e)e_0+\mathrm{\α}\sqrt{1-e^2}{\mathrm{sin\ψ\ρ}}_0$

$v=-\frac{{\mathrm{\α}}^{2}n}{\mathrm{\γ}}{\mathrm{sin\ψe}}_0+\frac{{\mathrm{\α}}^{2}n}{\mathrm{\γ}}\sqrt{1-e^2}{\mathrm{cos\ψ\ρ}}_0$

Wherein:

$e_0={\left[\begin{array}{c}cos\mathrm{\Ω}cos\mathrm{\ω}-sin\mathrm{\Ω}sin\mathrm{\ω}\cos i\\ sin\mathrm{\Ω}cos\mathrm{\ω}+cos\mathrm{\Ω}sin\mathrm{\ω}\cos i\\ sin\mathrm{\ω}\sin i\end{array}\right]}^T\left[\begin{array}{c}i\\ j\\ k\end{array}\right]$

${\mathrm{\ρ}}_0={\left[\begin{array}{c}-cos\mathrm{\Ω}\sin \mathrm{\ω}-sin\mathrm{\Ω}\cos \mathrm{\ω}\cos i\\ -sin\mathrm{\Ω}\sin \mathrm{\ω}+cos\mathrm{\Ω}\cos \mathrm{\ω}\cos i\\ sin\mathrm{\ω}\sin i\end{array}\right]}^T\left[\begin{array}{c}i\\ j\\ k\end{array}\right].$

The perseverance in moment epoch that starry sky data when the simulation unit of Celestial Background emulates are provided by hipparcos catalogue Star position data is by the data revised voluntarily, precession of the equinoxes correction and nutating correction obtain.

The data loaded in described data load-on module come from can provide WMS and WFS standard map service access The server of interface, mobile platform client accesses WMS and the WFS standard map service access interface of this server by network Carrying out request data, the three-dimensional digital earth data acquisition pyramid data storage model being loaded into mobile platform client is stored in In this server.

The invention has the beneficial effects as follows: the present invention utilizes mobile platform client to change viewpoint position, according to the position of viewpoint Put calculating visual range, determine node to be rendered under current view point position and attitude and segmentation degree, set up and new render joint Dot structure；According to the new scene rendering node structure generated, generate the node listing needing loading data, and according to load The node listing of data sends request of data, and desired data is loaded into mobile platform client；Will in mobile platform client The image, the dem data that load are compiled as texture, vertex cache object respectively, and draw by 3 D stereo mapping software Display, to realize realizing the emulation to three-dimensional digital earth in mobile platform client.The present invention can be mobile platform visitor Realizing the visualization of spatial environments on the end of family, and effect of visualization is satisfactory, Consumer's Experience is good.

Accompanying drawing explanation

Fig. 1 is environmental simulation system design principle figure based on mobile Framework Model；

Fig. 2 is Quadtree Spatial Index principle schematic；

Fig. 3 is spacecraft orbit position view；

Tu4Shi tile drop shadow spread schematic diagram；

The image pyramid principle schematic of Fig. 5 different resolution hierarchy；

Fig. 6-a is the Celestial Background in experimental example of the present invention, spacecraft simulation schematic diagram；

Fig. 6-b is three-dimensional earth simulated effect figure in experimental example of the present invention；

Fig. 7 is that in experimental example of the present invention, refresh frame deadbeat under different scenes is intended to.

Detailed description of the invention

Below in conjunction with the accompanying drawings the detailed description of the invention of the present invention is described further.

Present invention embodiment based on mobile platform terrestrial space scene simulation method

Terrestrial space scene simulation in the present embodiment is directed to the emulation of three-dimensional digital earth, utilizes mobile platform visitor Family end change viewpoint position, according to the position calculation visual range of viewpoint, determines under current view point position and attitude to be rendered Node and segmentation degree, set up new rendering node structure；According to the new scene rendering node structure generated, from mobile platform Deleting in client internal memory and become sightless node, generate needs the node listing of loading data simultaneously, and according to load The node listing of data sends request of data, and desired data is loaded into mobile platform client；Will in mobile platform client The image, the dem data that load are compiled as texture, vertex cache object respectively, and draw by 3 D stereo mapping software Display, to realize realizing the emulation to three-dimensional digital earth in mobile platform client.

The present embodiment uses LOD technology to carry out mass data and renders, and tile algorithm of subdivision is key therein, LOD principle It is finely to represent apart from the object that viewpoint is near, and the coarse expression of object that distance viewpoint is remote.According to perspective projection principle, the most greatly Little object, after projection, seems bigger than apart from remote object apart near object.Same principle is drawing terrestrial time, away from The coordinate range that tile close to viewpoint occupies on screen is big, and the screen coordinate scope occupied apart from remote tile is little, as Shown in Fig. 4.Therefore the screen ranges that tile occupies can be as the standard of selection tile LOD level, and specific algorithm is expressed as:

1) calculate the projection coordinate of four angle points of this tile, obtain the smallest enclosing box of tile drop shadow spread.

2) judge whether tile is in visual range.In OpenGL, depending on the projection coordinate within vertebral body all-1.0, Between 1.0}.If if therefore the coordinate range of the smallest enclosing box of tile { outside-1.0,1.0}, is illustrating that this tile can not See.

3) rectangular extent of screen coordinate corresponding to smallest enclosing box is calculated according to viewing matrix.If the width of this rectangle or Tall and big in the pixel value of tile image, then need this tile is finely divided.The screen coordinate rectangle width of such as certain tile is high For 312*300, and image size is 256*256, then need to be finely divided this tile, i.e. select more fine-resolution watt Sheet.

In the present embodiment, the scene tissue of three-dimensional digital earth usually uses quad-tree structure, as in figure 2 it is shown, user exists When carrying out environment viewing, first according to the position calculation visual range of viewpoint, and then determine scene quadtree's node to be rendered And the segmentation degree of each node.Remove the most sightless node in internal memory, the newest to server request asynchronously The data of visible node, after receiving the data that server returns, are incorporated in scene compiling display.Concrete steps For:

A. scene quad-tree structure updates.User triggers screen on the mobile apparatus, changes viewpoint position, now uses deep The method traversal scenario node of degree first traversal, determines node to be rendered under current view point position and attitude and segmentation degree, Set up and new render quaternary tree.Node segmentation degree i.e. chooses the tile data of different LOD rank according to viewpoint position, is this step Rapid key, the present invention uses tile algorithm of subdivision based on screen ranges to carry out tile segmentation.

B. the new scene rendering node structure that existing scene rendering node structure and step A generate is contrasted, from internal memory Middle deletion becomes sightless node, generates simultaneously and needs the node listing of loading data.

C. node listing is sorted with view distance according to tile, make the tile near with view distance first be loaded.

D. basis wants the node listing of loading data, sends request to server.

E., after mobile client receives data, shadow, dem data are compiled as respectively texture, vertex cache object, by OpenGL ES technology carries out drawing display.

In order to increase the degree true to nature of emulation further, the present invention, on the basis of above-described embodiment, also add star The emulation of empty background.The starry sky data that the present embodiment is used are general hipparcos catalogue data, and this star catalogue includes fixed star Exact position, voluntarily, the data such as trigonometric parallax and parallactic error, star catalogue epoch time used is on January 1st, 2000, its Initial point and basic side are the J2000.0 first point of Aries and J2000.0 mean equator face, and being equivalent to an observer being positioned at the earth's core is not having The star place seen when 1 day 0 January in 2000 in the case of air.Due to the present invention when emulation it is desirable that arbitrarily The position of moment fixed star, so to carry out Coordinate Conversion to catalogue data.The perseverance in moment epoch provided by star catalogue is provided Star position data, by correction, precession of the equinoxes correction and nutating correction voluntarily, is transformed into the position in Current observation moment.

Revising voluntarily is by standard moment epoch t₀Equator apparent place coordinate (α₀,δ₀) it is transformed into appointment moment t₁Seat Mark (α₁,δ₁), the formula used is as follows

α₁=α₀+μ_α(t₁-t₀) (1)

δ₁=δ₀+μ_δ(t₁-t₀) (2)

Wherein μ_αAnd μ_δBe respectively red footpath voluntarily and proper motion in declination.

Precession of the equinoxes correction is to revise the most unfixing coordinate figure deviation caused of earth rotation, by t₀Moment star place γ₀Warp Cross precession of the equinoxes correction and obtain t₁Moment star place γ₁

${\mathrm{\γ}}_1=\left[\begin{array}{c}{x}_0\\ y_0\\ z_0\end{array}\right]=\left[\begin{array}{c}{\mathrm{cos\α}}_0{\mathrm{cos\δ}}_0\\ {\mathrm{cos\α}}_0{\mathrm{sin\δ}}_0\\ {\mathrm{sin\α}}_0\end{array}\right]---\left(3\right)$

${\mathrm{\γ}}_1=\left[\begin{array}{c}{x}_1\\ y_1\\ z_1\end{array}\right]=R_z(-z)R_y\left(\mathrm{\θ}\right)R_z(-\mathrm{\ζ}){\mathrm{\γ}}_0---\left(4\right)$

Wherein z, θ, ζ are respectively equator precession of the equinoxes parameter, R_zAnd R_yIt is respectively the spin matrix of precession of the equinoxes parameter.

In the slow rotary course of the earth, due to material nonunf ormity and the moon and the perturbation of other planet on the earth Power causes slight jitter, referred to as nutating.Nutating correction obtains the equator apparent place coordinate (α of fixed star₂,δ₂), concrete formula is:

${\mathrm{\γ}}_2=\left[\begin{array}{c}{\mathrm{cos\α}}_2{\mathrm{cos\δ}}_2\\ {\mathrm{cos\α}}_2{\mathrm{sin\δ}}_2\\ {\mathrm{sin\α}}_2\end{array}\right]=R_x(-{\mathrm{\ϵ}}_0-\mathrm{\Δ}\mathrm{\ϵ})R_z(-\mathrm{\Δ}\mathrm{\ψ})R_x\left({\mathrm{\ϵ}}_0\right){\mathrm{\γ}}_1---\left(5\right)$

(-ε in formula₀-Δ ε) it is ecliptic obliquity ,-Δ ψ is nutation of longitude, ε₀For the nutation of obliquity, R_x、R_zIt is respectively nutating ginseng The spin matrix of number.

Mobile device storage capacity is limited, should not complete starry sky data be all deposited in mobile device, and on the scene In scape navigation process, the only fixed star of part is in visual range, if in addition scheduling strategy, only draws the number in visual range According to, it is possible not only to reduce taking of internal memory, moreover it is possible to be greatly improved the rendering efficiency of program.The present invention introduces by setting up Spatial Cable Row data store, and spatial index refers to, according to the spatial relationship between position and shape or the spatial object of spatial object, press Certain tactic a kind of data structure, by the data got rid of outside AOI thus reach reduce internal memory and improve The purpose of efficiency, conventional spatial index type has B-tree, R tree, quaternary tree, Octree and Grid Index etc..

The present invention uses the mode of quaternary tree to organize starry sky data, according to fixed star orientation, starry sky data is carried out sky Between deduct marks storage, set up quaternary tree index.In scene navigation process, according to azimuth and the elevation angle of current gaze, at calculating The scope of the starry sky data in visual range, and the magnitude grade set according to user, dynamically to server request data； Mobile client, after the data receiving request, draws, according to the position of fixed star, the point differed in size, and the size of point represents The brightness of fixed star, the size of the point that the high fixed star of brightness is corresponding is bigger.

In order to increase the degree true to nature of emulation further, the present invention, on the basis of above-described embodiment, also add boat The emulation of it device.

Spacecraft is the important component part of spatial environments key element, spacecraft simulation it is crucial that calculate and navigate under current time The orbital position of it device and attitude.When spacecraft orbits, its position and attitude receives non-homogeneous terrestrial gravitation, the 3rd body The impact of the perturbation such as gravitation, solar radiation pressure and atmospheric drag, the present invention calculates its position according to the orbital elements of spacecraft. Orbital elements are also called orbital tracking, may determine that the orbit plane orientation in space by them, and track is in orbit plane Orientation, the shape of track and the spacecraft position in track.Orbital elements have six, as it is shown on figure 3, i.e. track half is long Axle α, eccentric ratio e, very near angle ψ, orbit inclination angle i, ascending node precision Ω, argument of pericenter ω, i, j and k refer to coordinate axes list Bit vector.Six orbital trackings of known certain moment t, can calculate spacecraft locus γ in corresponding coordinate system and Speed v, i.e. Calculation for Ephemerides, its computing formula is:

$\mathrm{\γ}=\mathrm{\α}(cos\mathrm{\ψ}-e)e_0+\mathrm{\α}\sqrt{1-e^2}{\mathrm{sin\ψ\ρ}}_0---\left(6\right)$

$v=-\frac{{\mathrm{\α}}^{2}n}{\mathrm{\γ}}{\mathrm{sin\ψe}}_0+\frac{{\mathrm{\α}}^{2}n}{\mathrm{\γ}}\sqrt{1-e^2}{\mathrm{cos\ψ\ρ}}_0---\left(7\right)$

Wherein:

$e_0={\left[\begin{array}{c}cos\mathrm{\Ω}cos\mathrm{\ω}-sin\mathrm{\Ω}sin\mathrm{\ω}\cos i\\ sin\mathrm{\Ω}cos\mathrm{\ω}+cos\mathrm{\Ω}sin\mathrm{\ω}\cos i\\ sin\mathrm{\ω}\sin i\end{array}\right]}^T\left[\begin{array}{c}i\\ j\\ k\end{array}\right]---\left(8\right)$

${\mathrm{\ρ}}_0={\left[\begin{array}{c}-cos\mathrm{\Ω}sin\mathrm{\ω}-sin\mathrm{\Ω}cos\mathrm{\ω}\cos i\\ -sin\mathrm{\Ω}sin\mathrm{\ω}+cos\mathrm{\Ω}cos\mathrm{\ω}\cos i\\ sin\mathrm{\ω}\sin i\end{array}\right]}^T\left[\begin{array}{c}i\\ j\\ k\end{array}\right]---\left(9\right)$

The present embodiment data required for terrestrial space scene simulation process include starry sky, spacecraft, earth surface ring The multiple types of datas such as border, and quantity is far beyond the storage computing capability of current mobile device, therefore institute in the present invention The data needed all are obtained by load mode.

(1) the starry sky data being loaded into mobile client store according to quad-tree structure.

According to spatial dimension and magnitude grade, starry sky data are stored according to quad-tree structure.Magnitude the lowest grade, its number The biggest according to amount, node represents that spatial dimension is the least, and the degree of depth in quaternary tree is the deepest.When mutual with client end AP P, according to visitor Visible range that family end passes over and magnitude class parameter, in server will be in visible range and magnitude grade is more than ginseng All node datas of number return to client, client-side program be updated rendering.

(2) the spacecraft data acquisition Mysql database purchase of mobile client it is loaded into.

Spacecraft data mainly include spacecraft mark and orbit parameter etc., and its simple in construction is clear and definite, can directly make Store with ripe relational database.Use Mysql database purchase spacecraft data herein, by all of spacecraft number According to existing in a table.When receiving the request of data of client, perform corresponding SQL statement and carry out query and search.

(3) storage of the three-dimensional earth data being loaded into mobile client uses pyramid data storage model.

The three-dimensional earth of the present invention renders employing LOD technology, and when carrying out scene rendering, the distance according to object with viewpoint is selected Selecting the model of different level of detail, distance is the nearest, and the level of detail of object model is the highest, and the data volume used is the biggest.? When scape browses, generally comprising the tile node of multiple resolution in Same Scene, therefore the storage of three-dimensional earth data is also adopted by The hierarchical data mode that this multiresolution of pyramid is multiple dimensioned.Pyramid is the model of a kind of continuous resolution, but in reality In the situation of border, generally use the fixed resolution hierarchical structure that the multiple in 2 amplifies step by step, as shown in Figure 5.Building pyramid Time, first with original whole world landform or image data as pyramidal top layer, carry out dividing formation the according to the grid of M*N 0 layer of tile, then according to the grid partition of 2M*2N forms the 1st layer of tile, the rest may be inferred, and grid size increases by 1 times successively, raw Become each layer tile data.Pyramidal storage can directly utilize simple in construction, it is easy to accomplish, the folder management that stability is strong Mode realize.Owing to the resolution of next layer data is 2 times of last layer, coincideing with quad-tree structure, this method is simultaneously Also the foundation of quaternary tree index is completed.

The emulation of terrestrial space scene can be realized in mobile client by the said process present invention.

The embodiment of present invention terrestrial space based on mobile platform scene simulating system

Analogue system in the present embodiment is as it is shown in figure 1, include the upper 3-dimensional digital for operating in mobile client Earth simulation unit, this simulation unit includes scene update module, data load-on module, compiling drafting module, scene update mould Block is used for utilizing mobile platform client to change viewpoint position, according to the position calculation visual range of viewpoint, determines and is working as forward sight Node to be rendered and segmentation degree under some position and attitude, set up new rendering node structure；Data load-on module is used for basis New scene rendering node structure, deletes from mobile platform client internal memory and becomes sightless node, generate needs simultaneously The node listing of loading data, and send request of data according to the node listing wanting loading data, desired data is loaded into shifting Moving platform client；Compiling drafting module is for being compiled as the image of loading, dem data respectively in mobile platform client Texture, vertex cache object, and carry out drawing display by 3 D stereo mapping software, to realize in mobile platform client Realize the emulation to three-dimensional digital earth.In order to improve systematic function, improve good Consumer's Experience, mobile platform of the present invention visitor Family end uses multi-thread design, and UI thread is responsible for the alternative events of user and is processed and scene rendering；Customer incident triggers and starts number According to more new thread, carry out scene update, request of data, and be incorporated into scene after receiving the data that server returns, by UI thread completes to draw.

In order to prove the feasibility of the present invention, illustrate using a concrete mobile client as experimental example below. This experimental example uses builds Tomcat as the webserver in Windows7 64bit operating system, uses open GIS soft Part GeoServer provides WMS and WFS network geographic information data access interface, utilizes Eclipse to carry out based on GeoServer Regarded as output controlling, issues the geographic information data Map Services such as image.Mobile client design sets based on Android operation system Standby, use Android Studio IDE, develop in conjunction with OpenGL ES 2.0 three dimensional graphics.

Running the analogue system of the present invention in Android operation system mobile device, experimental facilities hardware environment is 8 cores Huawei's honor 6 mobile phone of CPU, 3G internal memory, operating system is Android 4.4.Operational effect as shown in Fig. 6-a and 6-b, Fig. 6- A is Celestial Background, spacecraft simulation schematic diagram；Fig. 6-b is three-dimensional earth simulated effect figure.Screen-refresh frame when system is run Speed is tested, experimental result as shown in Figure 7: Celestial Background, spacecraft screen-refresh frame speed are above 50fs^-1, the three-dimensional earth Drawing frames speed is 27fs^-1, whole scenes are stable at 24fs^-1Left and right.In experimentation, system is run smooth, existing without card As, it is swift in response；Consumer's Experience is good, and visual effect is satisfactory.

Claims (10)

1. a terrestrial space scene simulation method based on mobile platform, it is characterised in that this emulation mode includes following step Rapid:

1) utilize mobile platform client to change viewpoint position, according to the position calculation visual range of viewpoint, determine and working as forward sight Node to be rendered and segmentation degree under some position and attitude, set up new rendering node structure；

2) according to step 1) the new scene rendering node structure that generates, from mobile platform client internal memory, delete that become can not The node seen, generates simultaneously and needs the node listing of loading data, and please according to the node listing transmission data wanting loading data Ask, desired data is loaded into mobile platform client；

3) in mobile platform client, the image of loading, dem data are compiled as respectively texture, vertex cache object, and by 3 D stereo mapping software carries out drawing display, to realize realizing imitating three-dimensional digital earth in mobile platform client Very.

Terrestrial space scene simulation method based on mobile platform the most according to claim 1, it is characterised in that node is thin Point degree is to choose the tile data of different LOD rank according to viewpoint position, carries out according to the tile algorithm of subdivision of screen ranges Tile segments, using tile drop shadow spread's size on screen as the Rule of judgment of segmentation tile.

Terrestrial space scene simulation method based on mobile platform the most according to claim 1, it is characterised in that this emulation Method also includes the emulation to Celestial Background, and step is as follows:

A. according to azimuth and the elevation angle of current gaze, calculate the scope of starry sky data being in visual range, and according to Celestial Background data needed for the magnitude rank request loading that family sets；

B. mobile platform client is after the data receiving request, draws the point differed in size, point according to the position of fixed star Size represent the brightness of fixed star, the size of the point that the high fixed star of brightness is corresponding is bigger.

Terrestrial space scene simulation method based on mobile platform the most according to claim 3, it is characterised in that starry sky is carried on the back The star place data in moment epoch that starry sky data during scape emulation are provided by hipparcos catalogue by revising voluntarily, year The data that difference is revised and nutating correction obtains.

Terrestrial space scene simulation method based on mobile platform the most according to claim 1, it is characterised in that step 2) The data of middle loading come from can provide WMS and the WFS server of standard map service access interface, mobile platform client WMS and the WFS standard map service access interface being accessed this server by network carrys out request data, is loaded into mobile platform visitor The three-dimensional digital earth data acquisition pyramid data storage model of family end is stored in this server.

6. a terrestrial space scene simulating system based on mobile platform, it is characterised in that this analogue system includes for transporting Row is in the upper three-dimensional digital earth simulation unit of mobile client, and this simulation unit includes that scene update module, data load Module, compiling drafting module,

Described scene update module is used for utilizing mobile platform client to change viewpoint position, and the position calculation according to viewpoint can Depending on scope, determine node to be rendered under current view point position and attitude and segmentation degree, set up new rendering node structure；

Described data load-on module, for according to new scene rendering node structure, is deleted from mobile platform client internal memory Become sightless node, generate simultaneously and need the node listing of loading data, and send out according to the node listing wanting loading data Send request of data, desired data is loaded into mobile platform client；

Described compiling drafting module is for being compiled as stricture of vagina respectively by the image of loading, dem data in mobile platform client Reason, vertex cache object, and carry out drawing display by 3 D stereo mapping software, real to realize in mobile platform client The now emulation to three-dimensional digital earth.

Terrestrial space scene simulating system based on mobile platform the most according to claim 6, it is characterised in that described field Scape more new module determined node segmentation degree is to choose the tile data of different LOD rank according to viewpoint position, according to screen The tile algorithm of subdivision of scope carries out tile segmentation, using tile drop shadow spread's size on screen as the judgement of segmentation tile Condition.

Terrestrial space scene simulating system based on mobile platform the most according to claim 6, it is characterised in that described Analogue system also includes the simulation unit to Celestial Background, and this simulation unit includes:

For the azimuth according to current gaze and the elevation angle, the scope of the starry sky data that calculating is in visual range, and according to The module of the Celestial Background data needed for the magnitude rank request loading that user sets；

After in mobile platform client in the data receiving request, draw, according to the position of fixed star, the point differed in size Module.

Terrestrial space scene simulating system based on mobile platform the most according to claim 8, it is characterised in that starry sky is carried on the back The star place data in moment epoch that starry sky data when the simulation unit of scape emulates are provided by hipparcos catalogue are passed through The data that correction, precession of the equinoxes correction and nutating correction obtain voluntarily.

Terrestrial space scene simulating system based on mobile platform the most according to claim 6, it is characterised in that described Data load-on module in the data that load come from WMS and the WFS server of standard map service access interface can be provided, WMS and the WFS standard map service access interface that mobile platform client accesses this server by network carrys out request data, adds The three-dimensional digital earth data acquisition pyramid data storage model being downloaded to mobile platform client is stored in this server.