CN105741352B - A kind of display control method and device of three-dimensional terrain model - Google Patents
A kind of display control method and device of three-dimensional terrain model Download PDFInfo
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- G06F3/04815—Interaction with a metaphor-based environment or interaction object displayed as three-dimensional, e.g. changing the user viewpoint with respect to the environment or object
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Abstract
The embodiment of the invention discloses a kind of display control method of three-dimensional terrain model and devices, and the first three-dimensional terrain model is generated by obtaining DEM model datas, and according to DEM model datas；It is calculated from DEM model datas and obtains landform relative altitude；Obtain the corresponding height of observation of the current ken；Height and landform relative altitude according to the observation, computed altitude ratio；According to height ratio, the corresponding space polygon sampling span of the current ken is adjusted；It is last to sample space polygon in the current ken according to sampling span, the second three-dimensional terrain model is shown after sampling.In practical work process, space polygon number increases in the ken, increases sampling span to neutralize increasing for space polygon number, balancing algorithms load；The ken reduces, then reduces sampling span, in the case where not increasing operand, shows more dimensional topography details, enhances visual effect；The conflict of above-mentioned adjustment active balance computer speed and visual effect enhances user experience.
Description
Technical field
The present invention relates to technical field of forestry, more particularly to the display control method and dress of a kind of three-dimensional terrain model
It sets.
Background technology
Virtual forest technology is intuitive, accurate, interaction simulation extensive forest location landform, composition, tree
The technology of the information such as height, air source, distribution.By the relief map that will be built by three-dimensional terrain model and comprising forest information
The synthesis of digital forest form map, and carry out seeds appearance processing etc. and generate Virtual forest.The Virtual forest is whole forest form information
Concentration has the characteristics that information is accurate, image is intuitive, performance area is big and high information integrity, includes not only whole bottom classes
The data of database, can facilitate whole attributes of inquiry bottom class, and can be showed with the formal intuition of virtual image wide
The various forest phase informations in forest location.
Wherein, it during the foundation of relief map, is usually infinitely forced by space polygon (mainly triangle)
It closely obtains, i.e., constructs three-dimensional land map by approaching the space polygon of curved surface.In use, user draws high visual angle,
The space polygon for including in the ken then increases, and needs a large amount of computing resource supports that could obtain relief map；And user
When reducing visual angle, the space polygon amount in the ken is reduced, then can lose the detailed information of three-dimensional land map, influences vision effect
Fruit.
Therefore, when relief map is shown, how the conflict of EQUILIBRIUM CALCULATION FOR PROCESS resource and visual effect is people in the art
The technical issues of member's urgent need to resolve.
Invention content
A kind of display control method and device of three-dimensional terrain model are provided in the embodiment of the present invention, to solve existing skill
The problem of art Virtual forest generating process neutral body topographic map computing resource and visual effect conflict.
In order to solve the above-mentioned technical problem, the embodiment of the invention discloses following technical solutions：
The embodiment of the invention discloses a kind of display control methods of three-dimensional terrain model, include the following steps：
DEM model datas are obtained, and the first three-dimensional terrain model is generated according to the DEM model datas；
It is calculated using the DEM model datas and obtains landform relative altitude；
Obtain the corresponding height of observation of the current ken；
According to the height of observation and the landform relative altitude, computed altitude ratio；
According to the height ratio, the sampling span of the corresponding space polygon of the current ken is adjusted；
The space polygon in the current ken is sampled according to the sampling span, and is shown according to space polygon after sampling
Second three-dimensional terrain model.
Preferably, described according to the height of observation and the landform relative altitude, computed altitude ratio includes following calculating
Formula：
X0=h/Hmax, wherein X0 is height ratio, and h is height of observation, and Hmax is landform relative altitude.
Preferably, described that the sampling span of the corresponding space polygon of the current ken is adjusted according to the height ratio, packet
It includes：
Default base altitude ratio；
Judge the height than whether being more than the base altitude ratio；
If so, increasing the sampling span；Alternatively,
If not, reduce the sampling span, and minimum sampling span is 1.
Preferably, according to the height of the current ken than with the base altitude ratio, calculate and determine that the current ken corresponds to
The sampling span.
Preferably, described according to the height ratio, before the sampling span for adjusting the corresponding space polygon of the current ken,
Further include：
According to space polygon number in the current ken, sampling span adjustment is judged whether to.
Preferably, the display control method further includes：
According to the space polygon distribution in the current ken, the current ken is divided into multiple ken blocks；
Judge whether the ken block carries out sampling span adjustment, to one or more ken blocks for adjusting of needs respectively into
Row sampling span adjustment.
The embodiment of the invention also discloses a kind of display control units of three-dimensional terrain model, including：
First three-dimensional terrain model generation module is given birth to for obtaining DEM model datas, and according to the DEM model datas
At the first three-dimensional terrain model；
Landform relative altitude computing module obtains landform relative altitude for being calculated using the DEM model datas；
Height of observation acquisition module, for obtaining the corresponding height of observation of the current ken；
Height is than computing module, for according to the height of observation and the landform relative altitude, computed altitude ratio；
It samples span and adjusts module, for according to the height ratio, adjusting adopting for the corresponding space polygon of the current ken
Spline span；
Display module is sampled, for sampling the space polygon in the current ken according to the sampling span, and according to adopting
Space polygon shows three-dimensional terrain model after sample.
Preferably, the height than computing module according to following formula computed altitude ratio：
X0=h/Hmax, wherein X0 is height ratio, and h is height of observation, and Hmax is landform relative altitude.
Preferably, the sampling span adjustment module further includes：
Base altitude is than presetting module, for presetting base altitude ratio；
Height is than judgment module, for judging the height than whether being more than the base altitude ratio；
Sample span management module, for according to the height than judgment module as a result, being more than if the height compares
The base altitude ratio, increases the sampling span；If the height is than less than or equal to the base altitude ratio, reduction is adopted
Spline span, and minimum sampling span is 1.
Preferably, the sampling span management module, according to the height than with the base altitude ratio, calculate determination works as
The sampling span of the preceding ken.
Preferably, the display control unit further includes：
It samples span and adjusts judgment module, for according to space polygon number in the current ken, judging whether to adopt
Spline span adjusts.
Preferably, the display control unit further includes：
The current ken is divided into multiple regard by ken piecemeal module for being distributed according to the space polygon in the current ken
Domain block；
Ken block samples span management module, for judging whether the ken block carries out sampling span adjustment, to needing
One or more ken blocks of adjustment carry out sampling span adjustment respectively.
By above technical scheme as it can be seen that a kind of display control method of three-dimensional terrain model provided in an embodiment of the present invention and
Device generates the first three-dimensional terrain model by obtaining DEM model datas, and according to DEM model datas；Utilize the DEM moulds
Type data, which calculate, obtains landform relative altitude；Obtain the corresponding height of observation of the current ken；According to the height of observation and described
Landform relative altitude, computed altitude ratio；According to the height ratio, adjust the sampling of the corresponding space polygon of the current ken across
Degree；The space polygon in the current ken finally is sampled according to the sampling span, and is shown according to space polygon after sampling
Second three-dimensional terrain model.In practical work process, when the space polygon number in the ken increases, increase the sampling across
Degree neutralizes increasing for space polygon number, to balancing algorithms load；When ken diminution, by reducing the sampling span,
In the case where not increasing operand, the details of more dimensional topographies is shown, enhance visual effect；By above-mentioned adjustment, effectively
The conflict of computer speed and visual effect is balanced, user experience is enhanced.
Description of the drawings
In order to more clearly explain the embodiment of the invention or the technical proposal in the existing technology, to embodiment or will show below
There is attached drawing needed in technology description to be briefly described, it should be apparent that, for those of ordinary skill in the art
Speech, without creative efforts, other drawings may also be obtained based on these drawings.
Fig. 1 is a kind of flow diagram of the display control method of three-dimensional terrain model provided in an embodiment of the present invention；
Fig. 2 is a kind of flow diagram of sampling span method of adjustment provided in an embodiment of the present invention；
Fig. 3 is simulation dimensional topography scene graph when height of observation provided in an embodiment of the present invention is higher；
Fig. 4 is simulation dimensional topography scene graph when height of observation provided in an embodiment of the present invention is relatively low；
Fig. 5 is the flow diagram of the display control method of another three-dimensional terrain model provided in an embodiment of the present invention；
Fig. 6 is a kind of structural schematic diagram of the display control unit of three-dimensional terrain model provided in an embodiment of the present invention；
Fig. 7 is the structural schematic diagram that a kind of sampling span provided in an embodiment of the present invention adjusts module；
Fig. 8 is the structural schematic diagram of the display control unit of another three-dimensional terrain model provided in an embodiment of the present invention.
Specific implementation mode
In order to make those skilled in the art more fully understand the technical solution in the present invention, below in conjunction with of the invention real
The attached drawing in example is applied, technical scheme in the embodiment of the invention is clearly and completely described, it is clear that described implementation
Example is only a part of the embodiment of the present invention, instead of all the embodiments.Based on the embodiments of the present invention, this field is common
The every other embodiment that technical staff is obtained without making creative work, should all belong to protection of the present invention
Range.
Referring to Fig. 1, for a kind of flow signal of the display control method of three-dimensional terrain model provided in an embodiment of the present invention
Figure, the display control method include the following steps：
Step S101：DEM model datas are obtained, and the first three-dimensional terrain model is generated according to the DEM model datas.
The DEM model datas include mainly Rule acquisition and irregular three according to the difference of data organization form
Angular pessimistic concurrency control；Regional space cutting is the grid unit of rule by the Rule acquisition, each grid unit pair
It is typically the regular grids such as square, rectangle, triangle to answer a height value, the grid unit；The sealene triangle
The point acquired by features of terrain is connected into the triangle of covering whole region and non-overlapping copies by pessimistic concurrency control according to certain rule,
Constitute a triangular irregular net.The DEM model datas can obtain in the following manner：Use the devices such as total powerstation, GPS
Material carries out field measurement；Based on remote sensing images, aerophotograph, DEM model datas are obtained using photogrammetric means；By having
Data map, converted and obtained after being handled.The file format for storing DEM model datas can be shp or dbf formats,
It is used with facilitating to read for tools such as ArcGIS.By reading the DEM model data files, the DEM model datas are obtained；
Certainly, in the specific implementation, technical staff can also be to the DEM model datas into the work such as edlin, correction, the above process
For those skilled in the art's common method, details are not described herein.
According to the DEM model datas, Three-dimensional Terrain Visualization is carried out to obtain the described 1st using three-dimensional software
Tie up relief model.In specific generating process, generally joined with displays such as the height of observation of acquiescence, resolution ratio and display areas
Number, is shown, wherein the height of observation is in the height of observation for analog subscriber observes the DEM model datas pair
The visual results when three-dimensional terrain model answered；The display parameters such as certain height of observation, resolution ratio and display area can
To carry out personalized customization before first three-dimensional terrain model is shown, and shown with corresponding display parameters.
Step S102：It is calculated using the DEM model datas and obtains landform relative altitude.
According to the DEM model datas that step S101 is obtained, the corresponding elevation of highest height above sea level in the DEM model datas is calculated
The difference of value height value corresponding with minimum height above sea level, obtains the landform relative altitude.The landform relative altitude can pass through
All height values in the DEM model datas are traversed, and therefrom the mode of acquisition minimum and peak obtains.
Step S103：Obtain the corresponding height of observation of the current ken.
When user needs to check greater area of three-dimensional terrain model, to understand the overall picture of entire three-dimensional terrain model, then
It needs to adjust the display area that the ken includes the three-dimensional terrain model of bigger, the ken corresponds to larger height of observation at this time；When with
Family needs the three-dimensional terrain model for checking more small area, to understand the details of partial 3 d relief model, then adjustment is needed to observe
Display area including smaller three-dimensional terrain model, at this time the ken correspond to smaller height of observation.In the specific implementation, user
The mode for generally using mouse or keyboard operation, carries out real-time ken adjustment, and user is facilitated to consult three-dimensional terrain model.Work as user
The ken is adjusted to the ken of appropriate observation, changing for height of observation can be carried out according to mouse or the variable quantity of keyboard operation
It calculates, to obtain the height of observation of the current ken, the height of observation determines specific according to mouse or the variable quantity of keyboard operation
Calculating process is those skilled in the art's common technology, and details are not described herein.
Step S104：According to the height of observation and the landform relative altitude, computed altitude ratio.
Obtain the landform relative altitude by step S102 and step S103 obtain the height of observation, according to
Lower formula, which calculates, determines the height ratio：
X0=h/Hmax, wherein X0 is height ratio, and h is height of observation, and Hmax is landform relative altitude.
Step S105：According to the height ratio, the sampling span of the corresponding space polygon of the current ken is adjusted.
In embodiments of the present invention, it is described sampling span can be understood as sampling every line number, generally positive integer and
Minimum value is 1.When the sampling span is 1, the three-dimensional terrain model will be generated with complete DEM model datas, thus
The DEM model data information that the three-dimensional terrain model includes all is generated, there is highest level of detail；When it is described sampling across
When degree is not 1, the corresponding space polygon of DEM model datas will be sampled with the sampling span, and have segment space more
Shape corresponding DEM model datas in side will not be sampled, and generate the dimensional topography according to the space polygon after sampling
Model, the three-dimensional terrain model thus generated has a degree of loss of detail, but can reduce calculation amount rapidly, from
And improve calculating speed.
Referring to Fig. 2, for a kind of flow diagram of sampling span method of adjustment provided in an embodiment of the present invention, this method packet
Include following steps：
Step S1051：Default base altitude ratio.
The base altitude than being determined according to the visual custom of user, generally with the observation of 0.65 times of landform relative altitude away from
Optimal visual effect can be obtained from observation, it is thus determined that base altitude ratio is 0.65；Certainly, in the specific implementation,
User can set the base altitude ratio as any number according to itself custom, and adjust needs according to practical, can be arranged
Any number of base altitude ratios.
Step S1052：Judge the height than whether being more than the base altitude ratio.
According to the height ratio that step S104 is obtained, judge the corresponding height of the current ken than whether being more than the base altitude
Than；When user changes the ken, such as the height of observation is improved, then the height for the current ken being calculated is than increasing；When
User reduces the height of observation, then the height for the current ken being calculated obtains in step S101 certainly than reducing
The acquiescence of first three-dimensional terrain model shows that the corresponding height ratio of the ken can be base altitude ratio.
Step S1053：If the current corresponding height of the ken is than more than the base altitude ratio, increasing sampling span.
If user improves height of observation to facilitate the overall picture for obtaining three-dimensional terrain model, by adjusting the height of observation
Ken adjustment is carried out, when being adjusted to the suitable ken, the corresponding height of the current ken is than more than the base altitude ratio, then increasing
The sampling span.
Preferably, according to the height of the current ken than with the base altitude ratio, calculate and determine that the current ken corresponds to
The sampling span, i.e., according to the height of the current ken than with the base altitude than difference degree, described in adjustment
Sample span.
In the specific implementation, phase step type adjustment is carried out to the sampling span, if the height ratio of the current ken is more than institute
State base altitude ratio, then the sampling span be directly adjusted to a fixed numbers, for example, the fixed numbers be 3 or other
Numerical value etc..Certainly, flexible adjustable strategies can be arranged in user in the specific implementation, such as the first base altitude ratio can be arranged
With the second base altitude ratio, the first base altitude ratio is less than the second base altitude ratio, if the height of the current ken
Than being more than the first base altitude ratio and being less than the second base altitude ratio, the sampling span of the current ken can be set
Value is the first fixed numbers, such as first fixed numbers are 2；If it is basic that the height ratio of the current ken is more than described second
Height ratio, the sampling span value that the current ken can be arranged are the second fixed numbers, and second fixed numbers are 3 etc..
In addition, according to the height of the current ken than with the base altitude ratio, to the sampling span carry out it is progressive
Formula adjusts.Such as it is calculated according to following formula：
Current ken sampling span=current ken height ratio/base altitude ratio+sampling span coefficient, wherein due to adopting
The value of spline span is generally positive integer, can be to preceding ken height ratio divided by base altitude than rear rounding, the sampling span
Coefficient could be provided as the constant values such as the corresponding sampling span of the 0,1 or first three-dimensional terrain model.
Step S1054：If the current corresponding height of the ken is than less than the base altitude ratio, reducing sampling span.
If user reduces height of observation to facilitate the details for obtaining three-dimensional terrain model, by adjusting the height of observation
Ken adjustment is carried out, when being adjusted to the suitable ken, the corresponding height of the current ken is than less than the base altitude ratio, then reducing
The sampling span.
Equally, according to the height of the current ken than with the base altitude ratio, calculate and determine that the current ken is corresponding
The sampling span, i.e., according to the height of the current ken than with the base altitude than difference degree, adopt described in adjustment
Spline span.
Moreover, the adjustment process of the sampling span can be the phase step type adjustment or gradual as described in step S1053
Adjustment.The phase step type is adjusted, if the height ratio of the current ken is less than the base altitude ratio, will directly work as forward sight
The sampling span in domain is adjusted to a fixed numbers, and the fixed numbers can be 2 or 1, and the sampling span minimum is adjusted to
1, that is, include all dimensional topography details；By the way that multiple base altitudes are arranged than by way of, sampling span adjustment is adjusted flexibly
Specifically the first base altitude ratio and the second base altitude ratio is arranged in strategy, and the second base altitude ratio is less than described first
Base altitude ratio will work as if the height ratio of the current ken is less than the first base altitude ratio, is more than the second base altitude ratio
The sampling span of the preceding ken is adjusted to the first fixed numbers, such as first fixed numbers are 2；If the height of the current ken
Than being less than the second base altitude ratio, the sampling span of the current ken is adjusted to the second fixed numbers, such as described second
Fixed numbers are 1 etc..For the progressive adjustments, according to the height of the current ken than with the base altitude ratio, meter
Calculate the sampling span for determining the current ken.Such as in the specific implementation, the sampling span can be calculated by following formula：
Current ken sampling span=sampling span coefficient-base altitude ratio/current ken height ratio, wherein described to adopt
Spline span coefficient could be provided as arbitrary constant, such as could be provided as any numbers such as 4, and equally can be to base altitude
Than divided by current ken height than obtained numerical value rounding.
It should be noted that currently the gradual calculation formula of the sampling span of the ken can be any other form, this
Field technology personnel can determine as needed sampling span and base altitude ratio and current ken height than mathematical computations
Relationship.
Step S106：The space polygon in the current ken is sampled according to the sampling span, and according to space after sampling
Polygon shows the second three-dimensional terrain model.
According to the sampling span that above-mentioned steps determine, the space polygon in the current ken is sampled.When user carries
When high height of observation, the space polygon in the ken increases, and by way of increasing the sampling span, samples in the current ken
Space polygon, and the second three-dimensional terrain model, the second dimensional topography mould are shown according to the space polygon after sampling
Type is different from first three-dimensional terrain model, is the three-dimensional terrain model that resampling generates later, by the above process phase
It reduces the space polygon for participating in calculating with answering, expands increased space polygon to neutralize the ken, to EQUILIBRIUM CALCULATION FOR PROCESS
Load is simulation dimensional topography scene graph when height of observation provided in an embodiment of the present invention is higher referring to Fig. 3, currently referring to figure
The height ratio of the ken is 1.4396, and base altitude ratio is 0.65, and the height ratio of the current ken divided by the base altitude compare rounding
Numerical value afterwards is 2, thus sets the sampling span of the current ken as 2；When user reduces height of observation, the space in the ken is polygon
Shape is reduced, and in such a way that reduction samples span, in the case where not increasing calculated load, increases three-dimensional terrain model in the ken
Detailed information, and second three-dimensional terrain model is generated according to the space polygon after sampling, to improve dimensional topography
The visual effect of model is simulation dimensional topography scene graph when height of observation provided in an embodiment of the present invention is smaller referring to Fig. 4,
The sampling span, than 0.65, is finally adjusted to 1, with highest level of detail by height of observation at this time much smaller than base altitude
Show the three-dimensional terrain model.
In order to further save computing resource, on the basis of the display control method of three-dimensional terrain model shown in Fig. 1,
Further include step before the sampling span for adjusting the corresponding space polygon of the current ken according to the height ratio：According to current
Space polygon number in the ken judges whether to sampling span adjustment.
In the specific implementation, pre-set space polygon quantity threshold first, the space polygon quantity threshold can root
The data such as hardware such as CPU or memory according to computer determine, to ensure in the space polygon quantity threshold, computer
Computing resource can support the data processing of respective numbers space polygon；After completing ken adjustment, such as institute can be improved
It states height of observation or reduces the height of observation, the number for the space polygon for including in the current ken after statistical adjustment judges
Whether current ken space polygon number is more than the space polygon quantity threshold, if it is greater, then according to step S1051
The adjustment that sampling span is carried out to the process of step S1054, with EQUILIBRIUM CALCULATION FOR PROCESS resource；If it is less, judging without being adopted
The adjustment of spline span carries out resampling and display second to the corresponding sampling span operation of omission and according to sampling span
The processing steps such as three-dimensional terrain model.
Referring to Fig. 5, the flow for the display control method of another three-dimensional terrain model provided in an embodiment of the present invention is shown
It is intended to, on the basis of the display control method of three-dimensional terrain model shown in Fig. 1, in order to increase the spirit of the sampling span adjustment
Activity simultaneously further saves computing resource, and this method is further comprising the steps of：
Step S201：According to the space polygon distribution in the current ken, the current ken is divided into multiple ken blocks.
In with a varied topography or gradient big rise and fall shaped area, generally go to approach using more space polygon true
Looks on the spot then can complete landform landform is simple or the shaped area of gentle gradient using less space polygon
Characterization.Therefore, the density degree being distributed according to space polygon, multiple ken blocks are divided by the current ken, and space is polygon
The less region division of shape enters in a ken block, and the more region division of space polygon is entered in another ken block.When
So, in the specific implementation, user can be such that ken block is of the same size with the current ken of decile；Moreover, user can pass through
The operations such as coordinate or mouse sliding are manually entered, the current ken is divided into different ken blocks by selection.
Step S202：Judge whether the ken block carries out sampling span adjustment.
Sampling span is judged whether in through the above steps in the way of space polygon number, of the invention real
It applies in example, ken block space polygon threshold value can be set, to judge that the space polygon number that each ken block includes is
It is no to be more than the ken block space polygon threshold value, if it is greater, then sampling span adjustment is carried out, if it is less, sentencing
It is disconnected to be adjusted without carrying out sampling span.
Step S203：Sampling span adjustment is carried out respectively to one or more ken blocks that needs adjust.
By the judgement of step S202, sampling span adjustment is carried out respectively to one or more ken blocks that needs adjust,
Specific sampling span adjustment process may refer to step S1051 to step S1054, and details are not described herein.
In embodiments of the present invention, by the way that the current ken is divided into multiple ken blocks, each ken block is carried out respectively
Judge whether to need to adjust sampling span, to reject the ken block that need not be adjusted, the part for then only adjusting needs regards
Domain block is adjusted without carrying out global adaptation, is advantageously reduced operand, is improved computational efficiency.
As seen from the above-described embodiment, the display control method of three-dimensional terrain model provided in an embodiment of the present invention, by obtaining
DEM model datas are taken, and the first three-dimensional terrain model is generated according to DEM model datas；It is obtained using DEM model datas calculating
Obtain landform relative altitude；Obtain the corresponding height of observation of the current ken；According to the height of observation and the landform relative altitude,
Computed altitude ratio；According to the height ratio, the sampling span of the corresponding space polygon of the current ken is adjusted；Described in last foundation
Sampling span samples the space polygon in the current ken, and shows the second dimensional topography mould according to space polygon after sampling
Type.In practical work process, when the space polygon number in the ken increases, increases the sampling span, it is more to neutralize space
Side figurate number purpose increases, to balancing algorithms load；When ken diminution is not increasing operation by reducing the sampling span
In the case of amount, the details of more dimensional topographies is shown, enhance visual effect；By above-mentioned adjustment, active balance computer
The conflict of speed and visual effect enhances user experience.
By the description of above embodiment of the method, it is apparent to those skilled in the art that the present invention can
Realized by the mode of software plus required general hardware platform, naturally it is also possible to by hardware, but in many cases the former
It is more preferably embodiment.Based on this understanding, technical scheme of the present invention substantially makes tribute to the prior art in other words
The part offered can be expressed in the form of software products, which is stored in a storage medium, packet
Some instructions are included to use so that a computer equipment (can be personal computer, server or the network equipment etc.) executes
All or part of the steps of the method according to each embodiment of the present invention.And storage medium above-mentioned includes：Read-only memory
(ROM), the various media that can store program code such as random access memory (RAM), magnetic disc or CD.
It is corresponding with a kind of display control method embodiment of three-dimensional terrain model provided by the invention, the present invention also provides
A kind of display control unit of three-dimensional terrain model.
It is a kind of structural representation of the display control unit of three-dimensional terrain model provided in an embodiment of the present invention referring to Fig. 6
Figure, the device include：
First three-dimensional terrain model generation module 11, for obtaining DEM model datas, and according to the DEM model datas
Generate the first three-dimensional terrain model；
Landform relative altitude computing module 12 obtains landform relative altitude for being calculated using the DEM model datas；
Height of observation acquisition module 13, for obtaining the corresponding height of observation of the current ken；When user by the ken adjust to
When needing the ken observed, the corresponding height of observation of the current ken is obtained；
Height is than computing module 14, for according to the height of observation and the landform relative altitude, computed altitude ratio；
It samples span and adjusts module 15, for according to the height ratio, adjusting the corresponding space polygon of the current ken
Sample span；
Display module 16 is sampled, for sampling the space polygon in the current ken according to the sampling span, and according to
Space polygon shows three-dimensional terrain model after sampling.
Preferably, the height than computing module 14 according to following formula computed altitude ratio：
X0=h/Hmax, wherein X0 is height ratio, and h is height of observation, and Hmax is landform relative altitude.
Referring to Fig. 7, for a kind of structural schematic diagram of sampling span adjustment module provided in an embodiment of the present invention, the sampling
Span adjusts module 15：
Base altitude is than presetting module 151, for presetting base altitude ratio；
Height is than judgment module 152, for judging the height than whether being more than the base altitude ratio；
Span management module 153 is sampled, is used for according to the height than judgment module 152 as a result, if the height
Than being more than the base altitude ratio, increase the sampling span；If the height than less than or equal to the base altitude ratio,
Reduce sampling span, and minimum sampling span is 1.
Preferably, the sampling span management module 153, according to the height than with the base altitude ratio, calculate true
The sampling span of the settled preceding ken.
In order to save computing resource, the display control unit of the three-dimensional terrain model further includes that sampling span adjustment judges
Module, for according to space polygon number in the current ken, judging whether to sampling span adjustment；When for completing the ken
After adjustment, the judgement of judgment module is adjusted by the sampling span, if without carrying out sampling span adjustment, can be omitted
It samples the calculating of span, according to sampling span resampling and the subsequent step of the second three-dimensional terrain model of generation, saves and calculate
Resource.
Referring to Fig. 8, the structure for the display control unit of another three-dimensional terrain model provided in an embodiment of the present invention is shown
It is intended to, on the basis of device shown in Fig. 6, which further includes：
The current ken is divided into multiple by ken piecemeal module 21 for being distributed according to the space polygon in the current ken
Ken block；
Ken block samples span management module 22, for judging whether the ken block carries out sampling span adjustment, to needing
The one or more ken blocks to be adjusted carry out sampling span adjustment respectively.
In embodiments of the present invention, by the way that the current ken is divided into multiple ken blocks, each ken block is carried out respectively
Judge whether to need to adjust sampling span, to reject the ken block that need not be adjusted, the part for then only adjusting needs regards
Domain block is adjusted without carrying out global adaptation, is advantageously reduced operand, is improved computational efficiency.
As seen from the above-described embodiment, the display control unit of three-dimensional terrain model provided in an embodiment of the present invention, by obtaining
DEM model datas are taken, and the first three-dimensional terrain model is generated according to DEM model datas；It is obtained using DEM model datas calculating
Obtain landform relative altitude；Obtain the corresponding height of observation of the current ken；According to the height of observation and the landform relative altitude,
Computed altitude ratio；According to the height ratio, the sampling span of the corresponding space polygon of the current ken is adjusted；Described in last foundation
Sampling span samples the space polygon in the current ken, and shows the second dimensional topography mould according to space polygon after sampling
Type.In practical work process, when the space polygon number in the ken increases, increases the sampling span, it is more to neutralize space
Side figurate number purpose increases, to balancing algorithms load；When ken diminution is not increasing operation by reducing the sampling span
In the case of amount, the details of more dimensional topographies is shown, enhance visual effect；By above-mentioned adjustment, active balance computer
The conflict of speed and visual effect enhances user experience.
For convenience of description, it is divided into various units when description apparatus above with function to describe respectively.Certainly, implementing this
The function of each unit is realized can in the same or multiple software and or hardware when invention.
Each embodiment in this specification is described in a progressive manner, identical similar portion between each embodiment
Point just to refer each other, and each embodiment focuses on the differences from other embodiments.Especially for device or
For system embodiment, since it is substantially similar to the method embodiment, so describing fairly simple, related place is referring to method
The part of embodiment illustrates.Apparatus and system embodiment described above is only schematical, wherein the conduct
The unit that separating component illustrates may or may not be physically separated, the component shown as unit can be or
Person may not be physical unit, you can be located at a place, or may be distributed over multiple network units.It can root
According to actual need that some or all of module therein is selected to achieve the purpose of the solution of this embodiment.Ordinary skill
Personnel are without creative efforts, you can to understand and implement.
It should be noted that herein, the relational terms of such as " first " and " second " or the like are used merely to one
A entity or operation with another entity or operate distinguish, without necessarily requiring or implying these entities or operation it
Between there are any actual relationship or orders.Moreover, the terms "include", "comprise" or its any other variant are intended to
Cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements includes not only those
Element, but also include other elements that are not explicitly listed, or further include for this process, method, article or setting
Standby intrinsic element.In the absence of more restrictions, the element limited by sentence "including a ...", it is not excluded that
There is also other identical elements in the process, method, article or apparatus that includes the element.
The above is only the specific implementation mode of the present invention, is made skilled artisans appreciate that or realizing this hair
It is bright.Various modifications to these embodiments will be apparent to one skilled in the art, as defined herein
General Principle can be realized in other embodiments without departing from the spirit or scope of the present invention.Therefore, of the invention
It is not intended to be limited to the embodiments shown herein, and is to fit to and the principles and novel features disclosed herein phase one
The widest range caused.
Claims (6)
1. a kind of display control method of three-dimensional terrain model, which is characterized in that include the following steps：
DEM model datas are obtained, and the first three-dimensional terrain model is generated according to the DEM model datas；
It is calculated using the DEM model datas and obtains landform relative altitude；
Obtain the corresponding height of observation of the current ken；
According to the height of observation and the landform relative altitude, computed altitude ratio；
According to the height ratio, the sampling span of the corresponding space polygon of the current ken is adjusted；The current ken is corresponding
Sampling span is calculated by the height ratio and preset base altitude ratio of the current ken；
The space polygon in the current ken is sampled according to the sampling span, and second is shown according to space polygon after sampling
Three-dimensional terrain model；
It is described according to the height ratio, before the sampling span for adjusting the corresponding space polygon of the current ken, further include：
According to space polygon number in the current ken, sampling span adjustment is judged whether to；
The method further includes：
According to the space polygon distribution in the current ken, the current ken is divided into multiple ken blocks；
Judge whether the ken block carries out sampling span adjustment, the one or more ken blocks adjusted to needs are adopted respectively
Spline span adjusts.
2. the display control method of three-dimensional terrain model according to claim 1, which is characterized in that described according to the sight
Height and the landform relative altitude are examined, computed altitude ratio includes following calculation formula：
X0=h/Hmax, wherein X0 is height ratio, and h is height of observation, and Hmax is landform relative altitude.
3. the display control method of three-dimensional terrain model according to claim 1, which is characterized in that described according to the height
Ratio is spent, the sampling span of the corresponding space polygon of the current ken is adjusted, including：
Default base altitude ratio；
Judge the height than whether being more than the base altitude ratio；
If so, increasing the sampling span；Alternatively,
If not, reduce the sampling span, and minimum sampling span is 1.
4. a kind of display control unit of three-dimensional terrain model, which is characterized in that including：
First three-dimensional terrain model generation module generates for obtaining DEM model datas, and according to the DEM model datas
One three-dimensional terrain model；
Landform relative altitude computing module obtains landform relative altitude for being calculated using the DEM model datas；
Height of observation acquisition module, for obtaining the corresponding height of observation of the current ken；
Height is than computing module, for according to the height of observation and the landform relative altitude, computed altitude ratio；
Sample span and adjust module, for according to the height ratio, adjust the sampling of the corresponding space polygon of the current ken across
Degree；The corresponding sampling span of the current ken is calculated by the height ratio and preset base altitude ratio of the current ken；
Sample display module, for sampling the space polygon in the current ken according to the sampling span, and according to sampling after
Space polygon shows three-dimensional terrain model；
Further include：It samples span and adjusts judgment module, for according to space polygon number in the current ken, judging whether to
Sample span adjustment；
Further include：The current ken is divided into multiple by ken piecemeal module for being distributed according to the space polygon in the current ken
Ken block；
Ken block samples span management module, for judging whether the ken block carries out sampling span adjustment, to needing to adjust
One or more ken blocks carry out respectively sampling span adjustment.
5. the display control unit of three-dimensional terrain model according to claim 4, which is characterized in that the height is than calculating
Module is according to following formula computed altitude ratio：
X0=h/Hmax, wherein X0 is height ratio, and h is height of observation, and Hmax is landform relative altitude.
6. the display control unit of three-dimensional terrain model according to claim 4, which is characterized in that the sampling span tune
Mould preparation block further includes：
Base altitude is than presetting module, for presetting base altitude ratio；
Height is than judgment module, for judging the height than whether being more than the base altitude ratio；
Sample span management module, for according to the height than judgment module as a result, if the height compares more than described
Base altitude ratio increases the sampling span；If the height than less than or equal to the base altitude ratio, reduce sampling across
Degree, and minimum sampling span is 1.
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| 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 |
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| 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 |
| CN104574508A (en) * | 2015-01-14 | 2015-04-29 | 山东大学 | Multi-resolution model simplifying method oriented to virtual reality technology |
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