CN105741352A - Display control method and apparatus for three-dimensional terrain model - Google Patents
Display control method and apparatus for three-dimensional terrain model Download PDFInfo
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Abstract
Embodiments of the invention disclose a display control method and apparatus for a three-dimensional terrain model. The method comprises the steps of obtaining DEM data and generating a first three-dimensional terrain model according to the DEM data; calculating the DEM data to obtain a relative terrain height; obtaining an observation height corresponding to a current vision field; according to the observation height and the relative terrain height, calculating a height ratio; according to the height ratio, adjusting a spatial polygon sampling span corresponding to the current vision field; and finally sampling spatial polygons in the current vision field according to the sampling span, and after sampling, displaying a second three-dimensional terrain model. In an actual working process, when the number of the spatial polygons in the vision field is increased, the sampling span is increased to neutralize the increment of the number of the spatial polygons so as to balance a calculation load; when the vision field is reduced, the sampling span is reduced, so that more three-dimensional terrain details are displayed without increasing the calculation amount, and the visual effect is enhanced; and the adjustment effectively balances the conflict between the computer speed and the visual effect, thereby enhancing the user experience.
Description
Technical field
The present invention relates to technical field of forestry, particularly relate to display control method and the device of a kind of three-dimensional terrain model.
Background technology
Virtual forest technology be directly perceived, accurately, the technology of alternatively simulation information such as the on-site landform of extensive forest, composition, the height of tree, source of the gas, distribution.By the relief map built by three-dimensional terrain model and the digital forest form map comprising forest information being synthesized, and carry out the generation Virtual forests such as seeds outward appearance process.Described Virtual forest is the concentration of whole forest form information, have that information is accurate, image directly perceived, performance area is big and the feature of high information integrity, not only comprise the data of whole bottom class data base, can conveniently inquire about whole attributes of bottom class, and the on-site various forest phase information of wide forest can be represented with the formal intuition of virtual image.
Wherein, set up in process at relief map, be usually infinitely to be approached by space polygon (mainly triangle) and obtain, namely construct three-dimensional land map by approaching the space polygon of curved surface.In use, user draws high visual angle, then the space polygon included in the ken increases, it is necessary to a large amount of calculating resource supports could obtain relief map；And user is when reducing visual angle, the space polygon amount in the ken reduces, then can lose the detailed information of three-dimensional land map, affect visual effect.
Therefore, when relief map shows, how the conflict of EQUILIBRIUM CALCULATION FOR PROCESS resource and visual effect is that those skilled in the art need badly and solve the technical problem that.
Summary of the invention
The embodiment of the present invention provides display control method and the device of a kind of three-dimensional terrain model, with the problem solving prior art Virtual forest generation process neutral body topography calculating resource and visual effect conflict.
In order to solve above-mentioned technical problem, the embodiment of the invention discloses following technical scheme:
The embodiment of the invention discloses the display control method of a kind of three-dimensional terrain model, comprise the following steps:
Obtain DEM model data, and generate the first three-dimensional terrain model according to described DEM model data；
Utilize described DEM model data to calculate and obtain landform relative altitude；
Obtain the height of observation that the current ken is corresponding；
According to described height of observation and described landform relative altitude, computed altitude ratio；
According to described aspect ratio, adjust the sampling span of space polygon corresponding to the current ken；
According to the space polygon in the described sampling span current ken of sampling, and show the second three-dimensional terrain model according to sampling rear space polygon.
Preferably, described according to described height of observation with described landform relative altitude, computed altitude ratio includes formula calculated below:
X0=h/Hmax, wherein, X0 is aspect ratio, and h is height of observation, and Hmax is landform relative altitude.
Preferably, described adjust the sampling span of space polygon corresponding to the current ken according to described aspect ratio, including:
Preset base altitude ratio；
Judge that whether described aspect ratio is more than described base altitude ratio；
If it is, increase described sampling span；Or,
If it does not, reduce described sampling span, and minimum sampling span is 1.
Preferably, according to the described aspect ratio of the current ken and described base altitude ratio, calculate and determine the described sampling span that the current ken is corresponding.
Preferably, described according to described aspect ratio, before adjusting the sampling span of space polygon corresponding to the current ken, also include:
According to space polygon number in the current ken, it may be judged whether carry out sampling span adjustment.
Preferably, described display control method also includes:
It is distributed according to the space polygon in the current ken, the current ken is divided into multiple ken block；
Judge whether described ken block carries out sampling span adjustment, carry out sampling span adjustment respectively to needing the one or more ken blocks adjusted.
The embodiment of the invention also discloses the display control unit of a kind of three-dimensional terrain model, including:
First three-dimensional terrain model generation module, is used for obtaining DEM model data, and generates the first three-dimensional terrain model according to described DEM model data；
Landform relative altitude computing module, is used for utilizing described DEM model data to calculate and obtains landform relative altitude；
Height of observation acquisition module, for obtaining the height of observation that the current ken is corresponding；
Aspect ratio computing module, for according to described height of observation and described landform relative altitude, computed altitude ratio；
Sampling span adjusting module, for according to described aspect ratio, adjusting the sampling span of space polygon corresponding to the current ken；
Sampling display module, is used for according to the space polygon in the described sampling span current ken of sampling, and according to sampling rear space polygon display three-dimensional terrain model.
Preferably, described aspect ratio computing module compares according to below equation computed altitude:
X0=h/Hmax, wherein, X0 is aspect ratio, and h is height of observation, and Hmax is landform relative altitude.
Preferably, described sampling span adjusting module also includes:
Base altitude, than presetting module, is used for presetting base altitude ratio；
Aspect ratio judge module, is used for judging that whether described aspect ratio is more than described base altitude ratio；
Sampling span management module, for the result according to described aspect ratio judge module, if described aspect ratio is more than described base altitude ratio, increases described sampling span；If described aspect ratio is less than or equal to described base altitude ratio, reduce sampling span, and minimum sampling span is 1.
Preferably, described sampling span management module, according to described aspect ratio and described base altitude ratio, calculate the described sampling span determining the current ken.
Preferably, described display control unit also includes:
Sampling span adjusts judge module, for according to space polygon number in the current ken, it may be judged whether carry out sampling span adjustment.
Preferably, described display control unit also includes:
Ken piecemeal module, for being distributed according to the space polygon in the current ken, is divided into multiple ken block by the current ken；
Ken block sampling span management module, is used for judging whether described ken block carries out sampling span adjustment, carries out sampling span adjustment respectively to needing the one or more ken blocks adjusted.
From above technical scheme, the display control method of a kind of three-dimensional terrain model that the embodiment of the present invention provides and device, by obtaining DEM model data, and generate the first three-dimensional terrain model according to DEM model data；Utilize described DEM model data to calculate and obtain landform relative altitude；Obtain the height of observation that the current ken is corresponding；According to described height of observation and described landform relative altitude, computed altitude ratio；According to described aspect ratio, adjust the sampling span of space polygon corresponding to the current ken；Last according to the space polygon in the described sampling span current ken of sampling, and show the second three-dimensional terrain model according to sampling rear space polygon.In practical work process, when the space polygon increased number in the ken, increase described sampling span, neutralize increasing of space polygon number, thus balancing algorithms load；When the ken reduces, by reducing described sampling span, when not increasing operand, show the details of more dimensional topography, strengthen visual effect；By above-mentioned adjustment, the active balance conflict of computer speed and visual effect, strengthen Consumer's Experience.
Accompanying drawing explanation
In order to be illustrated more clearly that the embodiment of the present invention or technical scheme of the prior art, the accompanying drawing used required in embodiment or description of the prior art will be briefly described below, apparently, for those of ordinary skills, under the premise not paying creative work, it is also possible to obtain other accompanying drawing according to these accompanying drawings.
The schematic flow sheet of the display control method of a kind of three-dimensional terrain model that Fig. 1 provides for the embodiment of the present invention；
The schematic flow sheet of a kind of span method of adjustment of sampling that Fig. 2 provides for the embodiment of the present invention；
Simulation dimensional topography scene graph when height of observation that Fig. 3 provides for the embodiment of the present invention is higher；
Simulation dimensional topography scene graph when height of observation that Fig. 4 provides for the embodiment of the present invention is relatively low；
The schematic flow sheet of the display control method of the another kind of three-dimensional terrain model that Fig. 5 provides for the embodiment of the present invention；
The structural representation of the display control unit of a kind of three-dimensional terrain model that Fig. 6 provides for the embodiment of the present invention；
The structural representation of a kind of span adjusting module of sampling that Fig. 7 provides for the embodiment of the present invention；
The structural representation of the display control unit of the another kind of three-dimensional terrain model that Fig. 8 provides for the embodiment of the present invention.
Detailed description of the invention
In order to make those skilled in the art be more fully understood that the technical scheme in the present invention, below in conjunction with the accompanying drawing in the embodiment of the present invention, technical scheme in the embodiment of the present invention is clearly and completely described, obviously, described embodiment is only a part of embodiment of the present invention, rather than whole embodiments.Based on the embodiment in the present invention, the every other embodiment that those of ordinary skill in the art obtain under not making creative work premise, all should belong to the scope of protection of the invention.
Referring to Fig. 1, the schematic flow sheet of the display control method of a kind of three-dimensional terrain model provided for the embodiment of the present invention, described display control method comprises the following steps:
Step S101: obtain DEM model data, and generate the first three-dimensional terrain model according to described DEM model data.
The described DEM model data difference according to data type of organization, mainly includes Rule acquisition and triangular irregular net model；Described Rule acquisition is by the grid unit that regional space cutting is rule, and the corresponding height value of each described grid unit, described grid unit is usually the regular grids such as square, rectangle, triangle；Described triangular irregular net model, by connecting into, by the point of features of terrain collection, the triangle covering whole region and non-overlapping copies according to certain rule, constitutes a triangular irregular net.Described DEM model data can obtain in the following manner: uses the equipment such as total powerstation, GPS to carry out field measurement；Based on remote sensing images, boat sheet, photogrammetric means are used to obtain DEM model data；By existing data map, obtain after carrying out changing and process.The file format of storage DEM model data can be shp or dbf form, reads for instruments such as ArcGIS to facilitate.By reading described DEM model data file, obtain described DEM model data；Certainly, in the specific implementation, the work such as described DEM model data can also be edited by technical staff, correction, said process is those skilled in the art's common method, does not repeat them here.
According to described DEM model data, three-dimensional software is utilized to carry out Three-dimensional Terrain Visualization thus obtaining described first three-dimensional terrain model.In concrete generation process, general with display parameters such as the height of observation of acquiescence, resolution and display areas, displaying, wherein said height of observation is in visual results when described height of observation observes three-dimensional terrain model corresponding to described DEM model data for analog subscriber；The display parameters such as certain described height of observation, resolution and display area can carry out personalized customization before described first three-dimensional terrain model shows, and displays with corresponding display parameters.
Step S102: utilize described DEM model data to calculate and obtain landform relative altitude.
According to the step S101 DEM model data obtained, calculate in described DEM model data the difference of height value corresponding to the most High aititude height value corresponding with minimum height above sea level, it is thus achieved that described landform relative altitude.Described landform relative altitude can pass through to travel through all height value in described DEM model data, and the mode therefrom obtaining minimum and peak obtains.
Step S103: obtain the height of observation that the current ken is corresponding.
When user needs to check greater area of three-dimensional terrain model, to understand the overall picture of whole three-dimensional terrain model, then need to adjust the ken and include the display area of bigger three-dimensional terrain model, the height of observation that now ken is corresponding bigger；When user needs to check the three-dimensional terrain model of less area, to understand the details of partial 3 d relief model, then need to adjust and observe the display area including less three-dimensional terrain model, the height of observation that now ken is corresponding less.In the specific implementation, user generally uses the mode of mouse or keyboard operation, carries out real-time ken adjustment, facilitates user to consult three-dimensional terrain model.When the ken is adjusted to the ken of appropriate observation by user, can according to the variable quantity of mouse or keyboard operation, carry out the conversion of height of observation, to obtain the height of observation of the current ken, the concrete calculating process that described height of observation is determined according to the variable quantity of mouse or keyboard operation is those skilled in the art's common technology, does not repeat them here.
Step S104: according to described height of observation and described landform relative altitude, computed altitude ratio.
Obtain described landform relative altitude by step S102, and step S103 obtain described height of observation, calculate according to below equation and determine described aspect ratio:
X0=h/Hmax, wherein, X0 is aspect ratio, and h is height of observation, and Hmax is landform relative altitude.
Step S105: according to described aspect ratio, adjust the sampling span of space polygon corresponding to the current ken.
In embodiments of the present invention, described sampling span can be understood as sampling every line number, be generally positive integer and minima be 1.When described sampling span is 1, by generating described three-dimensional terrain model with complete DEM model data, thus generates described three-dimensional terrain model and include all of DEM model data information, there is the highest level of detail；When described sampling span is not 1, with described sampling span, the space polygon that DEM model data is corresponding will be sampled, the DEM model data having segment space polygon corresponding will not be sampled, and generate described three-dimensional terrain model according to the space polygon after sampling, the described three-dimensional terrain model thus generated has a degree of loss of detail, but amount of calculation can be reduced rapidly, thus improve calculating speed.
Referring to Fig. 2, for the schematic flow sheet of a kind of span method of adjustment of sampling that the embodiment of the present invention provides, the method comprises the following steps:
Step S1051: preset base altitude ratio.
Described base altitude is determined than the visual custom according to user, generally observes the visual effect being obtained in that optimum with the viewing distance of landform relative altitude 0.65 times, it is thus determined that described base altitude ratio is 0.65；Certainly, in the specific implementation, user can set described base altitude ratio for any number according to self custom, and adjusts needs according to reality, it is possible to arranges any number of base altitude ratio.
Step S1052: judge that whether described aspect ratio is more than described base altitude ratio.
According to the step S104 aspect ratio obtained, it is judged that whether the aspect ratio that currently ken is corresponding is more than described base altitude ratio；When user changes the ken, for instance improve described height of observation, then the aspect ratio of the calculated current ken increases；When user reduces described height of observation, then the aspect ratio of the calculated current ken reduces, and the aspect ratio that the acquiescence display ken of described first three-dimensional terrain model certainly obtained in step S101 is corresponding can be base altitude ratio.
Step S1053: if the aspect ratio that currently ken is corresponding is more than described base altitude ratio, increase sampling span.
If user improves height of observation to facilitate the overall picture obtaining three-dimensional terrain model, carrying out ken adjustment by adjusting described height of observation, when adjusting the suitable ken, aspect ratio corresponding to the current ken more than described base altitude ratio, then increases described sampling span.
Preferably, according to the described aspect ratio of the current ken and described base altitude ratio, calculating and determine the described sampling span that the current ken is corresponding, namely the difference degree according to the described aspect ratio of the current ken with described base altitude ratio, adjusts described sampling span.
In the specific implementation, described sampling span is carried out phase step type adjustment, if the aspect ratio of the current ken is more than described base altitude ratio, then directly described sampling span is adjusted to a fixed numbers, for instance described fixed numbers is 3 or other numerical value etc..Certainly, user can arrange adjustable strategies flexibly in the specific implementation, first base altitude ratio and the second base altitude ratio such as can be set, described first base altitude ratio is less than described second base altitude ratio, if the aspect ratio of the current ken is more than described first base altitude ratio and less than described second base altitude ratio, the sampling span value that can arrange the current ken is the first fixed numbers, for instance described first fixed numbers is 2；If the aspect ratio of the current ken is more than described second base altitude ratio, it is possible to the sampling span value arranging the current ken is the second fixed numbers, described second fixed numbers is 3 etc..
It addition, according to the described aspect ratio of the current ken and described base altitude ratio, described sampling span is carried out progressive adjustments.Such as calculate according to equation below:
Current ken sampling span=current ken aspect ratio/base altitude is than+sampling span coefficient, wherein, owing to the value of span of sampling is generally positive integer, front ken aspect ratio can being rounded divided by after base altitude ratio, described sampling span coefficient could be arranged to the constant values such as sampling span corresponding to the 0,1 or first three-dimensional terrain model.
Step S1054: if the aspect ratio that currently ken is corresponding is less than described base altitude ratio, reduce sampling span.
If user reduces height of observation to facilitate the details obtaining three-dimensional terrain model, carrying out ken adjustment by adjusting described height of observation, when adjusting the suitable ken, aspect ratio corresponding to the current ken less than described base altitude ratio, then reduces described sampling span.
Equally, according to the described aspect ratio of the current ken and described base altitude ratio, calculating and determine the described sampling span that the current ken is corresponding, namely the difference degree according to the described aspect ratio of the current ken with described base altitude ratio, adjusts described sampling span.
And, the adjustment process of described sampling span can for the phase step type adjustment as described in step S1053 or progressive adjustments.Described phase step type is adjusted, if the aspect ratio of the current ken is less than described base altitude ratio, then directly the sampling span of the current ken being adjusted to a fixed numbers, described fixed numbers can be 2 or 1, described sampling span is minimum is adjusted to 1, namely comprises all of dimensional topography details；By arranging the mode of multiple base altitude ratio, adjust sampling span adjustable strategies flexibly, specifically, first base altitude ratio and the second base altitude ratio is set, described second base altitude ratio is less than described first base altitude ratio, if the aspect ratio of the current ken is less than the first base altitude ratio, more than described second base altitude ratio, the sampling span of the current ken is adjusted to the first fixed numbers, for instance described first fixed numbers is 2；If the aspect ratio of the current ken is less than described second base altitude ratio, the sampling span of the current ken is adjusted to the second fixed numbers, for instance described second fixed numbers is 1 etc..For described progressive adjustments, according to the described aspect ratio of the current ken and described base altitude ratio, calculate the sampling span determining the current ken.Such as in the specific implementation, described sampling span can be calculated by following formula:
Current ken sampling span=sampling span coefficient-base altitude is than/current ken aspect ratio, wherein, described sampling span coefficient could be arranged to arbitrary constant, for instance could be arranged to any number such as 4, and equally possible base altitude is rounded than the numerical value obtained divided by current ken aspect ratio.
It should be noted that the computing formula that currently the sampling span of the ken is gradual can be other arbitrary forms, those skilled in the art can determine sampling span and base altitude ratio and the mathematical calculating relations of current ken aspect ratio as required.
Step S106: according to the space polygon in the described sampling span current ken of sampling, and show the second three-dimensional terrain model according to sampling rear space polygon.
According to the sampling span that above-mentioned steps is determined, the space polygon in the current ken is sampled.nullWhen user improves height of observation，Space polygon in the ken increases，By increasing the mode of described sampling span，Sample the space polygon in the current ken，And show the second three-dimensional terrain model according to the space polygon after sampling，Described second three-dimensional terrain model is different from described first three-dimensional terrain model，It it is the three-dimensional terrain model produced after resampling，The space polygon participating in calculating correspondingly is reduced by said process，Thus having neutralized the ken to expand the space polygon increased，Thus EQUILIBRIUM CALCULATION FOR PROCESS load is referring to figure，Simulation dimensional topography scene graph when the height of observation that provides for the embodiment of the present invention referring to Fig. 3 is higher，The aspect ratio of the current ken is 1.4396，Base altitude ratio is 0.65，The numerical value that the aspect ratio of the current ken compares after rounding divided by described base altitude is 2，Thus set the sampling span of the current ken as 2；When user reduces height of observation, space polygon in the ken reduces, by reducing the mode of sampling span, when not increasing calculated load, increase the detailed information of three-dimensional terrain model in the ken, and generate described second three-dimensional terrain model according to the space polygon after sampling, thus improving the visual effect of three-dimensional terrain model, simulation dimensional topography scene graph when the height of observation that provides for the embodiment of the present invention referring to Fig. 4 is less, height of observation now is much smaller than base altitude ratio 0.65, the most described sampling span is adjusted to 1, described three-dimensional terrain model is shown with the highest level of detail.
In order to save calculating resource further, on the basis of the display control method of three-dimensional terrain model shown in Fig. 1, according to described aspect ratio, before adjusting the sampling span of space polygon corresponding to the current ken, further comprise the steps of: according to space polygon number in the current ken, it may be judged whether carry out sampling span adjustment.
In the specific implementation, first pre-set space polygon quantity threshold, described space polygon quantity threshold can be determined according to the hardware of the computer such as data such as CPU or internal memory, to ensure in described space polygon quantity threshold, computer calculates resource can support that the data of respective numbers space polygon process；After completing ken adjustment, such as can improve described height of observation or reduce described height of observation, the number of the space polygon that statistics comprises in the current ken after adjusting, judge that whether current ken space polygon number is more than described space polygon quantity threshold, if greater than, then carry out the adjustment of sampling span according to the process of step S1051 to step S1054, with EQUILIBRIUM CALCULATION FOR PROCESS resource；If it is less, judge the adjustment without carrying out sampling span, thus omitting corresponding sampling span computing and carrying out resampling according to sampling span and show that the second three-dimensional terrain model etc. processes step.
Referring to Fig. 5, the schematic flow sheet of display control method for the another kind of three-dimensional terrain model that the embodiment of the present invention provides, on the basis of the display control method of three-dimensional terrain model shown in Fig. 1, in order to increase the motility of described sampling span adjustment and save calculating resource further, the method is further comprising the steps of:
Step S201: be distributed according to the space polygon in the current ken, the current ken is divided into multiple ken block.
In with a varied topography or gradient big rise and fall shaped area, generally use more space polygon and remove approaching to reality landforms, the shaped area of or gentle gradient simple in landform, then use less space polygon just can complete landform sign.Therefore, the density degree according to space polygon distribution, the current ken is divided into multiple ken block, less for space polygon region is subdivided in a ken block, region more for space polygon is subdivided in another ken block.Certainly, in the specific implementation, user can the current ken of decile, make ken block be of the same size；And, user can manually operate in input coordinate or mouse slip etc., select to be divided into the current ken different ken blocks.
Step S202: judge whether described ken block carries out sampling span adjustment.
By above-mentioned steps utilizing the mode of space polygon number judge whether to sampling span, in embodiments of the present invention, ken block space polygon threshold value can be set, thus judging that whether space polygon number that each ken block comprises is more than described ken block space polygon threshold value, if greater than, then need to carry out sampling span adjustment, if it is less, judge without carrying out sampling span adjustment.
Step S203: carry out sampling span adjustment respectively to needing the one or more ken blocks adjusted.
By the judgement of step S202, to needing the one or more ken blocks adjusted to carry out sampling span adjustment respectively, concrete sampling span adjusts process and may refer to step S1051 to step S1054, does not repeat them here.
In embodiments of the present invention, by the current ken being divided into multiple ken block, judge whether each ken block respectively to need to adjust sampling span, thus rejecting the ken block that need not adjust, then only to needing the part ken block adjusted to be adjusted without carrying out global adaptation, advantageously reduce operand, improve computational efficiency.
As seen from the above-described embodiment, the display control method of the three-dimensional terrain model that the embodiment of the present invention provides, by obtaining DEM model data, and generate the first three-dimensional terrain model according to DEM model data；Utilize described DEM model data to calculate and obtain landform relative altitude；Obtain the height of observation that the current ken is corresponding；According to described height of observation and described landform relative altitude, computed altitude ratio；According to described aspect ratio, adjust the sampling span of space polygon corresponding to the current ken；Last according to the space polygon in the described sampling span current ken of sampling, and show the second three-dimensional terrain model according to sampling rear space polygon.In practical work process, when the space polygon increased number in the ken, increase described sampling span, neutralize increasing of space polygon number, thus balancing algorithms load；When the ken reduces, by reducing described sampling span, when not increasing operand, show the details of more dimensional topography, strengthen visual effect；By above-mentioned adjustment, the active balance conflict of computer speed and visual effect, strengthen Consumer's Experience.
Description by above embodiment of the method, those skilled in the art is it can be understood that can add the mode of required general hardware platform by software to the present invention and realize, hardware can certainly be passed through, but in a lot of situation, the former is embodiment more preferably.Based on such understanding, the part that prior art is contributed by technical scheme substantially in other words can embody with the form of software product, this computer software product is stored in a storage medium, including some instructions with so that a computer equipment (can be personal computer, server, or the network equipment etc.) perform all or part of step of method described in each embodiment of the present invention.And aforesaid storage medium includes: the various media that can store program code such as read only memory (ROM), random access memory (RAM), magnetic disc or CDs.
Corresponding with the display control method embodiment of a kind of three-dimensional terrain model provided by the invention, present invention also offers the display control unit of a kind of three-dimensional terrain model.
Referring to Fig. 6, the structural representation of the display control unit of a kind of three-dimensional terrain model provided for the embodiment of the present invention, this device includes:
First three-dimensional terrain model generation module 11, is used for obtaining DEM model data, and generates the first three-dimensional terrain model according to described DEM model data；
Landform relative altitude computing module 12, is used for utilizing described DEM model data to calculate and obtains landform relative altitude；
Height of observation acquisition module 13, for obtaining the height of observation that the current ken is corresponding；When the ken is adjusted to when needing the ken observed by user, obtain the height of observation that the current ken is corresponding；
Aspect ratio computing module 14, for according to described height of observation and described landform relative altitude, computed altitude ratio；
Sampling span adjusting module 15, for according to described aspect ratio, adjusting the sampling span of space polygon corresponding to the current ken；
Sampling display module 16, is used for according to the space polygon in the described sampling span current ken of sampling, and according to sampling rear space polygon display three-dimensional terrain model.
Preferably, described aspect ratio computing module 14 compares according to below equation computed altitude:
X0=h/Hmax, wherein, X0 is aspect ratio, and h is height of observation, and Hmax is landform relative altitude.
Referring to Fig. 7, for the structural representation of a kind of span adjusting module of sampling that the embodiment of the present invention provides, described sampling span adjusting module 15 includes:
Base altitude, than presetting module 151, is used for presetting base altitude ratio；
Aspect ratio judge module 152, is used for judging that whether described aspect ratio is more than described base altitude ratio；
Sampling span management module 153, for the result according to described aspect ratio judge module 152, if described aspect ratio is more than described base altitude ratio, increases described sampling span；If described aspect ratio is less than or equal to described base altitude ratio, reduce sampling span, and minimum sampling span is 1.
Preferably, described sampling span management module 153, according to described aspect ratio and described base altitude ratio, calculate the described sampling span determining the current ken.
In order to save calculating resource, the display control unit of described three-dimensional terrain model also includes sampling span and adjusts judge module, for according to space polygon number in the current ken, it may be judged whether carry out sampling span adjustment；After being used for ken adjustment, the judgement of judge module is adjusted by described sampling span, if without carrying out sampling span adjustment, then can omit the calculating of sampling span, according to sampling span resampling the subsequent step generating the second three-dimensional terrain model, saving calculating resource.
Referring to Fig. 8, the structural representation of the display control unit of the another kind of three-dimensional terrain model provided for the embodiment of the present invention, on the basis of Fig. 6 shown device, this device also includes:
Ken piecemeal module 21, for being distributed according to the space polygon in the current ken, is divided into multiple ken block by the current ken；
Ken block sampling span management module 22, is used for judging whether described ken block carries out sampling span adjustment, carries out sampling span adjustment respectively to needing the one or more ken blocks adjusted.
In embodiments of the present invention, by the current ken being divided into multiple ken block, judge whether each ken block respectively to need to adjust sampling span, thus rejecting the ken block that need not adjust, then only to needing the part ken block adjusted to be adjusted without carrying out global adaptation, advantageously reduce operand, improve computational efficiency.
As seen from the above-described embodiment, the display control unit of the three-dimensional terrain model that the embodiment of the present invention provides, by obtaining DEM model data, and generate the first three-dimensional terrain model according to DEM model data；Utilize described DEM model data to calculate and obtain landform relative altitude；Obtain the height of observation that the current ken is corresponding；According to described height of observation and described landform relative altitude, computed altitude ratio；According to described aspect ratio, adjust the sampling span of space polygon corresponding to the current ken；Last according to the space polygon in the described sampling span current ken of sampling, and show the second three-dimensional terrain model according to sampling rear space polygon.In practical work process, when the space polygon increased number in the ken, increase described sampling span, neutralize increasing of space polygon number, thus balancing algorithms load；When the ken reduces, by reducing described sampling span, when not increasing operand, show the details of more dimensional topography, strengthen visual effect；By above-mentioned adjustment, the active balance conflict of computer speed and visual effect, strengthen Consumer's Experience.
For convenience of description, it is divided into various unit to be respectively described with function when describing apparatus above.Certainly, the function of each unit can be realized in same or multiple softwares and/or hardware when implementing the present invention.
Each embodiment in this specification all adopts the mode gone forward one by one to describe, between each embodiment identical similar part mutually referring to, what each embodiment stressed is the difference with other embodiments.Especially for device or system embodiment, owing to it is substantially similar to embodiment of the method, so describing fairly simple, relevant part illustrates referring to the part of embodiment of the method.Apparatus and system embodiment described above is merely schematic, the wherein said unit illustrated as separating component can be or may not be physically separate, the parts shown as unit can be or may not be physical location, namely may be located at a place, or can also be distributed on multiple NE.Some or all of module therein can be selected according to the actual needs to realize the purpose of the present embodiment scheme.Those of ordinary skill in the art, when not paying creative work, are namely appreciated that and implement.
It should be noted that, in this article, the such as relational terms of " first " and " second " or the like is used merely to separate an entity or operation with another entity or operating space, and not necessarily requires or imply the relation that there is any this reality between these entities or operation or sequentially.And, term " includes ", " comprising " or its any other variant are intended to comprising of nonexcludability, so that include the process of a series of key element, method, article or equipment not only include those key elements, but also include other key elements being not expressly set out, or also include the key element intrinsic for this process, method, article or equipment.When there is no more restriction, statement " including ... " key element limited, it is not excluded that there is also other identical element in including the process of described key element, method, article or equipment.
The above is only the specific embodiment of the present invention, makes to skilled artisans appreciate that or realize the present invention.The multiple amendment of these embodiments be will be apparent to one skilled in the art, and generic principles defined herein can without departing from the spirit or scope of the present invention, realize in other embodiments.Therefore, the present invention is not intended to be limited to the embodiments shown herein, and is to fit to the widest scope consistent with principles disclosed herein and features of novelty.
Claims (12)
1. the display control method of a three-dimensional terrain model, it is characterised in that comprise the following steps:
Obtain DEM model data, and generate the first three-dimensional terrain model according to described DEM model data；
Utilize described DEM model data to calculate and obtain landform relative altitude；
Obtain the height of observation that the current ken is corresponding；
According to described height of observation and described landform relative altitude, computed altitude ratio；
According to described aspect ratio, adjust the sampling span of space polygon corresponding to the current ken；
According to the space polygon in the described sampling span current ken of sampling, and show the second three-dimensional terrain model according to sampling rear space polygon.
2. the display control method of three-dimensional terrain model according to claim 1, it is characterised in that described according to described height of observation with described landform relative altitude, computed altitude ratio includes formula calculated below:
X0=h/Hmax, wherein, X0 is aspect 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, it is characterised in that described adjust the sampling span of space polygon corresponding to the current ken according to described aspect ratio, including:
Preset base altitude ratio；
Judge that whether described aspect ratio is more than described base altitude ratio；
If it is, increase described sampling span；Or,
If it does not, reduce described sampling span, and minimum sampling span is 1.
4. the display control method of three-dimensional terrain model according to claim 3, it is characterised in that according to the described aspect ratio of the current ken and described base altitude ratio, calculates and determines the described sampling span that the current ken is corresponding.
5. the display control method of three-dimensional terrain model according to claim 1, it is characterised in that described according to described aspect ratio, before adjusting the sampling span of space polygon corresponding to the current ken, also includes:
According to space polygon number in the current ken, it may be judged whether carry out sampling span adjustment.
6. the display control method of three-dimensional terrain model according to claim 5, it is characterised in that also include:
It is distributed according to the space polygon in the current ken, the current ken is divided into multiple ken block；
Judge whether described ken block carries out sampling span adjustment, carry out sampling span adjustment respectively to needing the one or more ken blocks adjusted.
7. the display control unit of a three-dimensional terrain model, it is characterised in that including:
First three-dimensional terrain model generation module, is used for obtaining DEM model data, and generates the first three-dimensional terrain model according to described DEM model data；
Landform relative altitude computing module, is used for utilizing described DEM model data to calculate and obtains landform relative altitude；
Height of observation acquisition module, for obtaining the height of observation that the current ken is corresponding；
Aspect ratio computing module, for according to described height of observation and described landform relative altitude, computed altitude ratio；
Sampling span adjusting module, for according to described aspect ratio, adjusting the sampling span of space polygon corresponding to the current ken；
Sampling display module, is used for according to the space polygon in the described sampling span current ken of sampling, and according to sampling rear space polygon display three-dimensional terrain model.
8. the display control unit of three-dimensional terrain model according to claim 7, it is characterised in that described aspect ratio computing module compares according to below equation computed altitude:
X0=h/Hmax, wherein, X0 is aspect ratio, and h is height of observation, and Hmax is landform relative altitude.
9. the display control unit of three-dimensional terrain model according to claim 7, it is characterised in that described sampling span adjusting module also includes:
Base altitude, than presetting module, is used for presetting base altitude ratio；
Aspect ratio judge module, is used for judging that whether described aspect ratio is more than described base altitude ratio；
Sampling span management module, for the result according to described aspect ratio judge module, if described aspect ratio is more than described base altitude ratio, increases described sampling span；If described aspect ratio is less than or equal to described base altitude ratio, reduce sampling span, and minimum sampling span is 1.
10. the display control unit of three-dimensional terrain model according to claim 9, it is characterised in that described sampling span management module, according to described aspect ratio and described base altitude ratio, calculates the described sampling span determining the current ken.
11. the display control unit of three-dimensional terrain model according to claim 1, it is characterised in that also include:
Sampling span adjusts judge module, for according to space polygon number in the current ken, it may be judged whether carry out sampling span adjustment.
12. the display control unit of three-dimensional terrain model according to claim 11, it is characterised in that also include:
Ken piecemeal module, for being distributed according to the space polygon in the current ken, is divided into multiple ken block by the current ken；
Ken block sampling span management module, is used for judging whether described ken block carries out sampling span adjustment, carries out sampling span adjustment respectively to needing the one or more ken blocks adjusted.
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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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