CN107862743A - A kind of regular grid landform visible range computational methods based on projection - Google Patents
A kind of regular grid landform visible range computational methods based on projection Download PDFInfo
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- CN107862743A CN107862743A CN201710863903.6A CN201710863903A CN107862743A CN 107862743 A CN107862743 A CN 107862743A CN 201710863903 A CN201710863903 A CN 201710863903A CN 107862743 A CN107862743 A CN 107862743A
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- G—PHYSICS
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- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T17/00—Three dimensional [3D] modelling, e.g. data description of 3D objects
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- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
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Abstract
The invention discloses a kind of regular grid landform visible range computational methods based on projection, including it is following rapid：（1）Q-RING and sector division are carried out to terrain mesh；（2）Each mesh point of initial ring is projected to vertical plane to calculate initial skyline, and the second ring is set to work as front ring；（3）Observability when each mesh point of front ring is judged according to a upper skyline；（4）A upper skyline is updated according to the projection elevation when each mesh point of front ring；（5）The skyline after renewal is regarded as when the skyline corresponding to front ring, for the visibility judge of follow-up looped network lattice point, repeat step（2）To step（4）Untill all rings are processed.The block information of the above method each mesh point in any ring is embodied on newest skyline, visual judgement based on the skyline reflects the sight circumstance of occlusion between target point and viewpoint strictly according to the facts, it is as a result relatively reliable, time efficiency is higher compared with existing approximate calculation method or Method for Accurate Calculation.
Description
Technical field
Patent of the present invention is related to recallable amounts technical field, and in particular to a kind of regular grid landform based on projection can
View-shed computing method.
Background technology
The scope that visible range can be seen for a certain specific observation station to atural object around, in facility addressing, landscape road line gauge
Draw and the practical problem such as safety monitoring in there is significant application value.During practical problem solves, atural object around is often abstracted as one
Individual unified surface（Such as topographical surface or urban surface）, and this is abstracted surface common rule grid to represent.Therefore, can
View-shed computing is usually to find relative to a certain viewpoint（That is observation station）All visible mesh points.Lv Pin et al. is in its monograph
《Analysis of Terrain Visibility and application》The middle induction and conclusion computational methods of part common topographical visible range, can be divided into following several
Class：
（1）Without multiplexing point-by-point method：Typical Representative is R3 algorithms.General principle be from viewpoint position into observation scope
Each mesh point draw a light（Referred to as sight）；If current gaze is blocked by other mesh points, current grid point is not
It can be seen that；Otherwise to be visible.Whether block, need according to visual elevation and the further multilevel iudge of slope.The advantages of this method is essence
Degree is very high, it is considered to be a kind of Method for Accurate Calculation；Shortcoming is that efficiency of algorithm is very low, for n × n terrain mesh its
Time complexity is up to O (n3)。
（2）It is multiplexed inside closest approach method：Typical Representative is R2 algorithms.General principle is only accurate calculating visual field boundary point
Observability, then approached for the point inside bounds using boundary point sight with grid lines crosspoint.The advantages of this method
It is that efficiency of algorithm is higher, the terrain mesh its time complexity for n × n is O (n2), shortcoming is that accuracy is poor, there is one
The point of a little erroneous calculations, is a kind of approximation method.
（3）It is multiplexed export-oriented point-by-point method：Typical Representative is xDraw algorithms and plane of reference algorithm.General principle be with regarding
Centered on point, field range is divided into multiple concentric square rings, then outwards records on each ring every lowest visible from inner
Elevation；The observability of outer shroud certain point is determined by inner ring adjacent to 2 points of lowest visible elevation.This method is inside most with multiplexing
Proximal method is similar, and efficiency of algorithm is higher, forn×nTerrain mesh its time complexity for O (n 2), but accuracy is poor,
It is a kind of approximation method.
Above-mentioned optimization method improves the time efficiency of visible range calculating using loss of significance as cost.Should in many reality
In, the accuracy that visible range calculates is also an important measurement factor.Therefore, the computational methods of existing visible range need
Further improve so that the accuracy that visible range can be kept to calculate can also greatly improve the time efficiency of visible range calculating.
The content of the invention
The technical problem to be solved in the present invention is overcome the deficiencies in the prior art, there is provided a kind of rule mesh based on projection
Lattice landform visible range computational methods, are a kind of Method for Accurate Calculation, and the block information of each mesh point is embodied in most in any ring
On new skyline, the visual judgement based on the skyline reflects the sight circumstance of occlusion between target point and viewpoint strictly according to the facts；
Established in the renewal of current skyline on the basis of a upper skyline result of calculation, without traveling through each mesh point again, no
By be compared with existing approximate calculation method or Method for Accurate Calculation, its result it is relatively reliable or, time efficiency it is higher.
To reach above-mentioned purpose, the technical solution adopted by the present invention is：A kind of regular grid landform based on projection is visual
Domain computational methods, it is characterised in that including following rapid：
（1）Q-RING and sector division are carried out to terrain mesh；
（2）Vertical plane is established, projects each mesh point of initial ring to vertical plane to calculate initial skyline, and set
Second ring is to work as front ring；
（3）Observability when each mesh point of front ring is judged according to a upper skyline；
（4）A upper skyline is updated according to the projection elevation when each mesh point of front ring；
（5）The skyline after renewal is regarded when the skyline corresponding to front ring, for the visibility judge of follow-up looped network lattice point, to weigh
Multiple step（2）To step（4）Untill all rings are processed.
The step（1）Concretely comprise the following steps：
First be divided into 4 Q-RINGs centered on vision point to terrain mesh, and from inner outwards number consecutively be 1 ~ 4；Then, use
All rings are divided into A, B, C, D totally 4 sector regions by the diagonal of most outer shroud.
The step（2）Concretely comprise the following steps：
A vertical plane is respectively holded up on the side of most outer shroud so that each sector region corresponds to a vertical plane；
8 mesh points of the 1st ring are made to project respectively to 4 vertical planes, then by the projection on 4 vertical planes
Point is sequentially connected, and draws initial skyline, finally according to Similar Principle of Triangle, draws the abscissa on each summit of initial skyline
And projection elevation.
The step（3）Concretely comprise the following steps：
According to similar triangle theory, the projection coordinate when each mesh point of front ring is calculated；
The information on each summit of skyline is stored with balanced binary tree, wherein, the abscissa value on each summit of leaf node storage skyline
And projection height value, the interval range of the abscissa value of nonleaf node storage subordinate's child node；
If positioned at the top of a upper skyline, output current grid point is visible point for the projection of current grid point；
If positioned at the bottom of a upper skyline, output current grid point is invisible point for the projection of current grid point.
The step（4）Concretely comprise the following steps：
If the abscissa of the projection of current grid point is identical with the abscissa on the upper a certain summit of a skyline, current grid is used
The projection elevation of point replaces the projection height value of a upper skyline respective vertices；
If current grid point projection positioned at a upper skyline top, and its abscissa not with upper each summit of a skyline
Abscissa it is identical, then the projection summit new as one of current grid point is inserted into a upper skyline；
If when line and the upper skyline of the projection of each mesh point of front ring have an intersection point, and the abscissa of intersection point is not with upper one
The abscissa on each summit of bar skyline is identical, then the intersection point summit new as one is inserted into a upper skyline；
If a certain summit of a upper skyline be located at when each grid spot projection of front ring line bottom, and its abscissa not with
When the abscissa of each grid spot projection of front ring is identical, then the summit is deleted from a upper skyline.
The beneficial effects of the invention are as follows：
（1）The block information of each mesh point is embodied on newest skyline in any ring, the visuality based on the skyline
Judge to reflect the sight circumstance of occlusion between target point and viewpoint strictly according to the facts, compared with existing approximate calculation method, as a result more may be used
Lean on, be a kind of Method for Accurate Calculation.
(2) renewal of current skyline is established on the basis of a upper skyline result of calculation, each without traveling through again
Mesh point.Early stage, the multiplexing of result of calculation substantially increased the time efficiency that visible range calculates, with existing Method for Accurate Calculation phase
Than, time efficiency is higher, forn×nTerrain mesh its time complexity be reduced to O (n 2log n)。
Brief description of the drawings
The visible range calculation flow chart that accompanying drawing 1 carries for the present invention；
Accompanying drawing 2 is that terrain mesh of the present invention carries out Q-RING and the schematic diagram of sector division；
Accompanying drawing 3 is the schematic diagram that vertical plane of the present invention is set and initial skyline generates；
Accompanying drawing 4 is the schematic diagram of skyline storage mode of the present invention；
Accompanying drawing 5 is the visual schematic diagram judged of each mesh point of the present invention；
Accompanying drawing 6 is the schematic diagram of skyline of the present invention renewal.
In figure：Crunode is each summit of a upper skyline；Triangle point is when front ring each point projects；Round dot is upper one
The intersection point of skyline and the line when the projection of front ring each point.
Embodiment
With reference to specific embodiment, the present invention is described in further detail.
A kind of regular grid landform visible range computational methods based on projection as shown in Figures 1 to 6, specific implementation step
It is as follows：The first step（Referring to the drawings 2）, be first divided into 4 Q-RINGs centered on vision point to terrain mesh, and from it is inner outwards according to
Secondary numbering is 1~4；Then, all rings are divided into A, B, C, D totally 4 sector regions with the diagonal of most outer shroud；Finally, exist
A vertical plane is respectively holded up on the side of most outer shroud so that each sector region corresponds to a vertical plane.
Second step（Referring to the drawings 3）, first 8 mesh points of the 1st ring are projected to 4 vertical planes respectively, so
The subpoint on 4 vertical planes is sequentially connected afterwards, draws initial skyline, finally according to Similar Principle of Triangle, is obtained
Go out the abscissa and projection elevation on each summit of skyline.
3rd step（Referring to the drawings 4）, 4 vertical planes of accompanying drawing 3 are deployed successively, first establish a plane coordinates
System, transverse axis is x-axis, and for representing position of the subpoint in circumferential direction, the longitudinal axis is h axles, for representing the projection of subpoint
Elevation；Then, with each summit of a balanced binary tree storing initial skyline, wherein, leaf node storage skyline respectively pushes up
(x, h) coordinate of point, nonleaf node store the x coordinate scope of subordinate's child node.Finally, the 2nd ring is set to work as front ring, so as to
Following cycle calculates the visible point of each ring.
4th step（Referring to the drawings 5）, the abscissa and projection elevation projected when each summit of front ring is first calculated, is then sentenced again
The disconnected projection on each summit and the position relationship of a upper skyline when front ring.If current vertex is located at the top of a upper skyline
Portion, then it is visible point to export current vertex；Otherwise, it is invisible point to export current vertex.
5th step（Referring to the drawings 6）, operation is updated to a upper skyline using the projection when each mesh point of front ring,
It is specific as follows：
If the x coordinate of the projection of current grid point is identical with the abscissa on some summit of a upper skyline（Accompanying drawing 6 is identified as
1 summit）, then the projection height value of a upper skyline respective vertices is replaced with the projection elevation of current grid point；
If the projection of current grid point is positioned at the top of a upper skyline, and its not horizontal seat with upper each summit of a skyline
Mark identical（Accompanying drawing 6 is identified as 4 summit）, then the projection of the current grid point summit new as one is inserted into a upper day
In the line of border；
If when line and the upper skyline of each grid spot projection of front ring have intersection point, and intersection point is not each with a upper skyline
The abscissa on summit is identical（Accompanying drawing 6 is identified as 2 summit）, then the intersection point summit new as one is inserted into a upper horizon
In line；
If a certain summit of a upper skyline be located at when each mesh point of front ring projection line bottom, and its not with currently
The abscissa of each mesh point of ring is identical（Accompanying drawing 6 is identified as 3 summit）, then the summit is deleted from upper a set of skyline.
6th step：Skyline after renewal is when the skyline corresponding to front ring；Order is new when next ring of front ring
Work as front ring, repeat the 4th step and the 5th step until all rings are processed.
It the above is only the concrete application example of the present invention, protection scope of the present invention be not limited in any way.All uses
Equivalent transformation or equivalent replacement and the technical scheme formed, all fall within rights protection scope of the present invention.
Claims (5)
1. a kind of regular grid landform visible range computational methods based on projection, it is characterised in that including following rapid：
（1）Q-RING and sector division are carried out to terrain mesh；
（2）Vertical plane is established, projects each mesh point of initial ring to vertical plane to calculate initial skyline, and set
Second ring is to work as front ring；
（3）Observability when each mesh point of front ring is judged according to a upper skyline；
（4）A upper skyline is updated according to the projection elevation when each mesh point of front ring；
（5）The skyline after renewal is regarded when the skyline corresponding to front ring, for the visibility judge of follow-up looped network lattice point, to weigh
Multiple step（2）To step（4）Untill all rings are processed.
2. the regular grid terrain visualization view-shed computing method according to claim 1 based on projection, it is characterised in that
The step（3）Concretely comprise the following steps：
According to similar triangle theory, the projection coordinate when each mesh point of front ring is calculated；
The information on each summit of skyline is stored with balanced binary tree, wherein, the abscissa value on each summit of leaf node storage skyline
And projection height value, the interval range of the abscissa value of nonleaf node storage subordinate's child node；
If positioned at the top of a upper skyline, output current grid point is visible point for the projection of current grid point；
If positioned at the bottom of a upper skyline, output current grid point is invisible point for the projection of current grid point.
3. the regular grid terrain visualization view-shed computing method according to claim 1 based on projection, it is characterised in that
The step（1）Concretely comprise the following steps：
First be divided into 4 Q-RINGs centered on vision point to terrain mesh, and from inner outwards number consecutively be 1~4；Then, use
All rings are divided into A, B, C, D totally 4 sector regions by the diagonal of most outer shroud.
4. the regular grid terrain visualization view-shed computing method according to claim 1 based on projection, it is characterised in that
The step（2）Concretely comprise the following steps：
A vertical plane is respectively holded up on the side of most outer shroud so that each sector region corresponds to a vertical plane；
8 mesh points of the 1st ring are made to project respectively to 4 vertical planes, then by the projection on 4 vertical planes
Point is sequentially connected, and draws initial skyline, finally according to Similar Principle of Triangle, draws abscissa and the throwing on each summit of skyline
Shadow elevation.
5. the terrain visualization view-shed computing method according to claim 1 based on projection rule grid, it is characterised in that
The step（4）In comprise the following steps：
If the abscissa of the projection of current grid point is identical with the abscissa on the upper a certain summit of a skyline, current grid is used
The projection elevation of point replaces the projection height value of a upper skyline respective vertices；
If current grid point projection positioned at a upper skyline top, and its abscissa not with upper each summit of a skyline
Abscissa it is identical, then the projection summit new as one of current grid point is inserted into a upper skyline；
If when line and the upper skyline of the projection of each mesh point of front ring have an intersection point, and the abscissa of intersection point is not with upper one
The abscissa on each summit of bar skyline is identical, then the intersection point summit new as one is inserted into a upper skyline；
If a certain summit of a upper skyline be located at when each grid spot projection of front ring line bottom, and its abscissa not with
When the abscissa of each grid spot projection of front ring is identical, then the summit is deleted from a upper skyline.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111681313A (en) * | 2020-05-18 | 2020-09-18 | 云南迅测科技有限公司 | Digital topographic map-based space vision field analysis method and electronic equipment |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102074050A (en) * | 2011-03-01 | 2011-05-25 | 哈尔滨工程大学 | Fractal multi-resolution simplified method used for large-scale terrain rendering |
| KR101344649B1 (en) * | 2012-05-22 | 2013-12-26 | 인하대학교 산학협력단 | Hash-based skyline query processing method and apparatus thereof |
| CN106960464A (en) * | 2017-03-28 | 2017-07-18 | 长春理工大学 | Moving three-dimensional scene Virtual Terrain visuality Quick method |
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- 2017-09-22 CN CN201710863903.6A patent/CN107862743B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102074050A (en) * | 2011-03-01 | 2011-05-25 | 哈尔滨工程大学 | Fractal multi-resolution simplified method used for large-scale terrain rendering |
| KR101344649B1 (en) * | 2012-05-22 | 2013-12-26 | 인하대학교 산학협력단 | Hash-based skyline query processing method and apparatus thereof |
| CN106960464A (en) * | 2017-03-28 | 2017-07-18 | 长春理工大学 | Moving three-dimensional scene Virtual Terrain visuality Quick method |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111681313A (en) * | 2020-05-18 | 2020-09-18 | 云南迅测科技有限公司 | Digital topographic map-based space vision field analysis method and electronic equipment |
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