CN104376601B - Terrain deformation processing method applied to dynamic terrains based on triangular irregular network - Google Patents
Terrain deformation processing method applied to dynamic terrains based on triangular irregular network Download PDFInfo
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Abstract
The invention discloses a terrain deformation processing method applied to dynamic terrains based on a triangular irregular network. The terrain deformation processing method includes the steps of (1) determining a terrain deformation region based on a specific physical model; (2) inserting new peaks into the terrain deformation region; (3) achieving deformation region triangulation network reconstitution through the adoption of a point-by-point insertion algorithm; (4) calculating change values of deformation peak elevation values based on the specific physical model, substituting all peaks in the deformation region into the specific physical model for calculation, and obtaining the elevation change values of the peaks; (5) after the elevation change values of the peaks are obtained, modifying the elevation values of the peaks in the deformation region, obtaining the elevation values of the peaks in the deformation region after terrain deformation processing is carried out, and achieving local terrain deformation. By means of the terrain deformation processing method, the method that the new peaks are inserted into the deformation region is adopted, the number of triangles in the deformation region is increased, the problem that the resolution ratio of the deformation region in insufficient in the past is solved, and the reality sense is strengthened.
Description
Technical field
The present invention relates to a kind of landform deformation processing method applied in the dynamic landform based on TIN, belong to
In virtual reality, computer simulation technique field.
Background technology
Dynamic landform refers to when drawing landform, the operation according to user or needs, by artificial physical (as vehicle, big gun
Bullet, pedestrian etc.) with interacting of landform and the geometric attribute of real time modifying landform or non-geometric attribute.Dynamic terrain rendering belongs to real
When field of drawing problem, so the drafting of dynamic landform must use the correlation technique of real-time rendering, solve real-time rendering
Required common problem.But dynamic landform has its particularity, landform needs operation or artificial physical and landform according to user
Interaction and occur physically to update in real time, different from the interaction of real-time rendering, this change not only occurs on the drafting stage,
And the terrain data structure that system is safeguarded in bottom also will be changed based on specific physical model in real time.
The generation of landform is mainly based upon regular triangular net and TIN：(1) regular triangular network method, the method
Advantage be to be easily achieved quick topographic structure ergodic algorithm, but it does not consider relief model complexity change, without exception
Using the triangular representation of uniform density, the disadvantage of this method is, simply local in topographic structure, and wave in resource
Take, and baroque place, careful degree not, cannot accomplish distributing rationally of resource again.(2) TIN side
Method, the method can approach geometric height field with less sealene triangle, and resolution is adjustable, improves rendering speed.Due to
The features such as regular triangular net has quick, simple, so the dynamic landform of great majority all selects the rule-based triangulation network to generate, does not advise
Then application in dynamic landform for the triangulation network is more rare.
Landform deformation process is the important content that dynamic real-time terrain rendering needs complete, and this mainly includes terrain data
The relevant issues changed in real time and caused due to deformation are processed.Wherein, the change of terrain data is mainly included to deformed area height
The modification of journey value；And the problem being caused by landform deformation mainly includes the resolution extension of landform and the seriality of deformed region
Keep two aspects.The landform deformation processing method of traditional dynamic landform based on TIN is based on specific thing
Reason model is directly inquired about to terrain data and is changed.If applied in large-scale terrain, due to not to querying method
It is optimized, the resolution of deformed region is not also extended, then the real-time of dynamic landform and sense of reality all can not meet
Require.
Content of the invention
The invention aims to solving the problems, such as real-time and the sense of reality of the dynamic landform based on TIN,
Propose a kind of landform deformation processing method applied in the dynamic landform based on TIN.
A kind of landform deformation processing method applied in the dynamic landform based on TIN of the present invention, including
Following step：
Step one：Process the deformation of deformed article as needed, select its corresponding specific physical model, based on specific thing
Reason model definitely deformation region；
Step 2：New summit is inserted in deformed region；
Step 3：Using incremental inserting algorithm, realize the reconstruct of the deformed region triangulation network；
Step 4：Based on specific physical model calculating deformation summit height value changing value, by summits all in deformed region
Substitute into specific physical model to be calculated, obtain the elevation changing value on summit；
Step 5：After obtaining the elevation changing value on summit, the height value on modification deformed region summit, that is, obtain deformed area
Height value after landform deformation process for the domain Zhong Ge summit, makes whole deformation region present the effect of landform deformation, realizes
The deformation of local landform.
It is an advantage of the current invention that：
(1) using the method inserting new summit in deformed region, improve the number of triangles in deformed region, solve
The problem of conventional deformed region lack of resolution, enhances sense of reality；
(2) method combining is searched using grid positioning and straight line and carry out the triangle lookup of new summit place, significantly carry
The high efficiency searched, improves the real-time of dynamic landform；
(3) incremental inserting algorithm realizes the reconstruct of the deformed region triangulation network, quickly achieves the seriality of deformed region.
Brief description
Fig. 1 is the flow chart in the present invention based on the landform deformation processing method in the dynamic landform of TIN；
Fig. 2 is the flow chart of deformed region triangulation network reconstruct in the present invention；
Fig. 3 is the schematic diagram of grid positioning mode in the present invention；
Fig. 4 is the schematic diagram that cathetus of the present invention searches method；
Fig. 5 is the schematic diagram of summit position in the triangles in the present invention
Fig. 6 is schematic diagram in triangle edges for the summit in the present invention
Fig. 7 is the schematic diagram of Local Optimization Algorithm in the present invention.
Specific embodiment
Below in conjunction with drawings and Examples, the present invention is described in further detail.
The method using inserting new summit in deformed region for the present invention, improves the number of triangles in deformed region,
Solve the problems, such as conventional deformed region lack of resolution, enhance sense of reality；Searched using grid positioning and straight line and combine
Method carry out new summit place triangle and search, the efficiency of lookup is greatly improved, improves the real-time of dynamic landform；By
Point insertion algorithm realizes the reconstruct of the deformed region triangulation network, quickly achieves the seriality of deformed region.
A kind of landform deformation processing method applied in the dynamic landform based on TIN of the present invention, flow process
As shown in figure 1, including following step：
Step one：Process the deformation of deformed article as needed, (such as bomb draws to select its corresponding specific physical model
The crater deformation rising is to calculate deformation based on crater model, and the rut that automobile presses through meadow appearance is the physical model based on rut
Calculate deformation), based on specific physical model definitely deformation region.
Dynamic landform is modified to landform in simulation process, so that local landform is deformed, assumes new landform
The crater that in landforms, such as Campaign Process, projectile impacts ground produces, vehicle crosses the rut that soft soil is formed, natural or
The phenomenons such as the landslide in the mountain region that artificial origin is formed caves in, bridge collapse, route denial, the deformation of these landform is required for depending on
Its specific physical model.After known landform deformation position, by landform becomes be can determine to the calculating of physical model
The precise region of shape.
Step 2：New summit is inserted in deformed region.
Because deformed region there occurs that landform deforms, if going to describe with the resolution of pre-existing topography, can seem very coarse,
Not true, so needing to insert new summit in deformed region, complete the extension of deformed region resolution.Concrete insertion top
The quantity of point and distribution density, can determine adjustment according to actual simulated effect.(determine deformed region, that is, determine top
The insertion scope of point, the method for insertion has many kinds, typically adopts radom insertion, and the quantity of insertion is certainly more, and effect is got over
Exquisiteness, but the excessive real-time that again can affect program of quantity, need between this repeatedly to debug one best numerical value of selection, institute
Adjustment is determined according to actual simulated effect with the quantity on summit.)
Step 3：Using incremental inserting algorithm, realize the reconstruct of the deformed region triangulation network；
Flow process is as shown in Fig. 2 specifically include：
Step 3.1：Take any one summit from the point concentration of the new insertion of deformed region.
Step 3.2：The method combining is searched using grid positioning and straight line and carries out this summit place triangle lookup, tool
Body is：
(3.2a) grid positioning mode, as shown in Figure 3：
As insertion point P in the structure triangulation network, it was usually that in advance discrete point is pressed with x coordinate sequence in the past, so adjacent
Point place triangle also relative close, but when the y-coordinate of point differs greatly although adjacent after 2 points of sequences, but they are located
Triangle but wide apart, at this moment the efficiency of anchor point place triangle is very low.Can be greatly improved using grid positioning mode
Navigate to the efficiency of point P place triangle.
All discrete point x, the maximin x of y-coordinate can be obtained first after discrete point is processedmax、xmin、ymax、
ymin, then can build a grid and all discrete points are included.Because each grid is represented with an integer data,
So the quantity of grid is less than discrete point quantity, but if grid quantity is very little, in each grid, have a large amount of trianglees, from
Even and if point cocked hat in this grid is searched according to straight line and still will be searched a large amount of trianglees, do not play quick positioning
Effect, through repetition test, grid number is the 1/10th about proper of discrete points.Assume substantially uniform point of discrete point
Cloth, so make line number and columns be directly proportional to the span of y-coordinate and x coordinate respectively.Then
In formula
lx- discrete point zone transverse width
lyThe vertical width of-discrete point zone
NP- discrete point quantity
N-grid number
The row and column position of point P place grid is then judged by its coordinate figure：
In formula
The transverse and longitudinal coordinate of x, y-discrete point
xmin,yminHorizontal, vertical coordinate minima in-all discrete points
lx,ly- discrete point zone is horizontal, vertical width
Nrow,NCOL- grid line number and columns
When often inserting a point, calculate the corresponding position (row, col) in grid of this point, if this grid is the
Insertion point, then do not record triangle numbering, at this moment can appoint and take a triangle or from last in the case that point is ranked
One triangle begins look for；The triangle numbering otherwise being recorded from this grid begins look for, and at this moment only need to search few three
Angular can navigate to point P place triangle.
(3.2b) straight line searches method, as shown in Figure 4：
When assuming insertion point P ', begin look for it is clear that searching according to the rectilinear direction of in figure is shortest path from triangle ABC
Footpath.Point P ' place triangle is A ' B ' C ', and general vertex of a triangle presses arranged counterclockwise, and each edge of such triangle is all
One vector, such that it is able to judge that point P ' is on the left side of each edge or right side respectively, if left side is represented with+1, right side uses -1
Represent, straight line represented with 0 thus have the number that value is ± 1 or 0 to represent the position of point P ' certain triangle relatively.If knowing
Three, road value is all+1, then find point P ' place triangle；If only one of which -1, just search along this edge；But work as
When having two -1, how this searches, with regard to having become the key of problem.If the center of gravity of triangle ABC is P, in figure point P ' relatively BC and
The position on CA side is all -1, and at this moment we judge the position of C point relative rectilinear PP ', if left side (+1), then along PP ' right side
(BC) direction is searched；If right side (- 1), then search along PP ' left side (AC) direction；If 0, search along AC or BC direction.
If not cocked hat in this way in practical situations both, the path searching triangle is usually very tortuous, inefficiency,
The method efficiently can quickly navigate to target triangle.
Step 3.3：After finding summit place triangle, using area-judgment method judge summit whether in triangle or
Person is in triangle edges.It is assumed that triangle abc, triangle abv, triangle bcv, the area of triangle acv as shown in Fig. 5 (a)
It is respectively S, S1, S2, S3, do following judgement：
If S1=0, and S1+S2+S3=S, then, on the ab of side, such as Fig. 5 (b) is shown for explanation point v.
If S2=0, and S1+S2+S3=S, then, on the bc of side, such as Fig. 5 (c) is shown for explanation point v.
If S3=0, and S1+S2+S3=S, then, on the ac of side, such as Fig. 5 (d) is shown for explanation point v.
If S1 ≠ 0, S2 ≠ 0, S3 ≠ 0, and S1+S2+S3=S, then explanation point v is inside triangle abc.
Step 3.4：Adjustment triangle topology structure.After the particular location determining insertion summit, by following two situation
Modify：
(1) summit is in triangle, as shown in Fig. 5 (a)：Delete former triangle abc, increase point v, with summit a, b, c shape
Become 3 new trianglees.
(2) summit is on the side of triangle, as shown in Figure 6：Delete side corresponding to two trianglees be triangle abc,
Triangle bcd, is increased point v and is become 4 trianglees with summit a, b, c, D-shaped：I.e. triangle abv, triangle acv, triangle bdv,
Triangle dcv.
Step 3.5：Using Local Optimization Algorithm, update the triangle of all generations one by one.Local optimization procedure such as Fig. 7 institute
Show, comprise the following steps：
(1) two trianglees with common edge are synthesized a polygon.
(2) conducted a survey with largest empty circle criterion, see its 4th summit whether within the circumscribed circle of triangle.
(3) if revising diagonal and will exchange diagonal, that is, completing the process of local optimization procedure.
Step 3.6：Repeat step 3.1 is to step 3.6 until taking all summits of deformed region new insertion point concentration.
Step 4：Based on specific physical model calculating deformation summit height value changing value.By summits all in deformed region
Substitute into specific physical model to be calculated, the elevation changing value on summit can be obtained.
Step 5：After obtaining the elevation changing value on summit, then change the height value on deformed region summit, that is, deformed
Height value after landform deformation process for the region Zhong Ge summit, makes whole deformation region present the effect of landform deformation, from
And realize the deformation of local landform.
Claims (1)
1. a kind of landform deformation processing method applied in the dynamic landform based on TIN, including following step
Suddenly：
Step one：Process the deformation of deformed article as needed, select its corresponding specific physical model, based on specific physics mould
Type definitely deformation region；
Step 2：New summit is inserted in deformed region；
The quantity of insertion new summit and distribution density, determine adjustment according to actual emulation effect；
Step 3：Using incremental inserting algorithm, realize the reconstruct of the deformed region triangulation network；
Specifically include：
Step 3.1：Take any one summit from the point concentration of the new insertion of deformed region；
Step 3.2：The method combining is searched using grid positioning and straight line and carries out this summit place triangle lookup, specifically
For：
(3.2a) grid positioning mode：
First, carry out discrete point process, obtain all discrete point x, the maximin x of y-coordinatemax、xmin、ymax、ymin, build
One grid is included all discrete points, and grid number is 1/10th of discrete points；Assume that discrete point is uniformly distributed, OK
Number and columns are directly proportional to the span of y-coordinate and x coordinate, then respectively：
In formula：
lx- discrete point zone transverse width
lyThe vertical width of-discrete point zone
NP- discrete point quantity
N-grid number
The row and column position of point P place grid is then judged by its coordinate figure：
In formula
The transverse and longitudinal coordinate of x, y-discrete point
xmin,yminHorizontal, vertical coordinate minima in-all discrete points
lx,ly- discrete point zone is horizontal, vertical width
Nrow,Ncol- grid line number and columns
When often inserting a point, calculate this corresponding position (row, col) in grid of point, if this grid is for the first time
Insertion point, then do not record triangle numbering, appoints and takes a triangle or open from last triangle in the case of a sequence
Begin to search；The triangle numbering otherwise being recorded from this grid begins look for, anchor point P place triangle；
(3.2b) straight line searches method：
When assuming insertion point P ', begin look for from triangle ABC, point P ' place triangle is A ' B ' C ', judge that point P ' is respectively
On the left side of each edge or right side, if left side is represented with+1, right side is represented with -1, is represented with 0 on straight line, passes through ± 1 or 0
The position to represent point P ' relatively certain triangle for the number；If it is known that three values are all+1, then find point P ' place triangle；If only
Have one -1, then search along this edge；When there being two -1, if the center of gravity of triangle ABC is P, the P ' that sets up an office BC and CA relatively
The position on side is all -1, then judge the position of C point relative rectilinear PP ', if left side+1, then searches along PP ' right side BC direction；If
For right side -1, then search along PP ' left side AC direction；If 0, search along AC or BC direction；
Step 3.3：After finding summit place triangle, using area-judgment method judge summit whether in triangle or
In triangle edges；Assume that triangle abc, triangle abv, triangle bcv, the area of triangle acv are respectively S, S1, S2, S3,
Do following judgement：
If S1=0, and S1+S2+S3=S, then explanation point v is on the ab of side；
If S2=0, and S1+S2+S3=S, then explanation point v is on the bc of side；
If S3=0, and S1+S2+S3=S, then explanation point v is on the ac of side；
If S1 ≠ 0, S2 ≠ 0, S3 ≠ 0, and S1+S2+S3=S, then explanation point v is inside triangle abc；
Step 3.4：Adjustment triangle topology structure；After the particular location determining insertion summit, carry out by following two situation
Modification：
(1) former triangle abc, in triangle, is deleted in summit, increases point v, forms 3 new trianglees with summit a, b, c；
(2) summit is on the bc side of triangle, and two trianglees deleted corresponding to bc side are triangle abc, triangle bcd,
Increase point v and become 4 trianglees with summit a, b, c, D-shaped：I.e. triangle abv, triangle acv, triangle bdv, triangle dcv；
Step 3.5：Using Local Optimization Algorithm, update the triangle of all generations one by one, comprise the following steps：
(1) two trianglees with common edge are synthesized a polygon；
(2) conducted a survey with largest empty circle criterion, see its 4th summit whether within the circumscribed circle of triangle；
(3) if revising diagonal and will exchange diagonal, that is, completing the process of local optimization procedure；
Step 3.6：Repeat step 3.1 is to step 3.6 until taking all summits of deformed region new insertion point concentration；
Step 4：Based on specific physical model calculating deformation summit height value changing value, summits all in deformed region are substituted into
Specific physical model is calculated, and obtains the elevation changing value on summit；
Step 5：After obtaining the elevation changing value on summit, the height value on modification deformed region summit, that is, obtain in deformed region
Height value after landform deformation process for each summit, makes whole deformation region present the effect of landform deformation, realizes local
The deformation of landform.
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| CN101441779A (en) * | 2008-12-26 | 2009-05-27 | 南京师范大学 | Rapid dynamic drafting method of magnanimity digital terrain |
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| CN101441779A (en) * | 2008-12-26 | 2009-05-27 | 南京师范大学 | Rapid dynamic drafting method of magnanimity digital terrain |
Non-Patent Citations (2)
| Title |
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| A Modified LOD Terrain Model Based on QuadTree Algorithm;Yuxin Zhao等;《Computational Sciences and Optimization, 2009. CSO 2009. International Joint Conference on》;20090426;第259-263页 * |
| 三角网数字地面模型的动态修改与编辑;刘学军等;《中国公路学报》;20001031;第13卷(第4期);第16-20页 * |
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