A method for exploring a viewing point in a rural and urban landscape environment

Abstract

The application discloses a kind of climbing sightseeing point excavation methods in urban and rural landscape environment, comprising the following steps: extracting settlement boundary and water system boundary in settlement remote sensing image, calculating settlement geometric center in settlement boundary;The settlement geometric center is mapped to DEM data, the walking time matrix of each grid of DEM is calculated with settlement center as starting point, and the reachable domain is obtained according to the set walking time threshold t0;The visual field of each grid point is calculated within the scope of reachable domain, and finally the climbing sightseeing point is obtained by sorting and superimposition processing of each grid visual field.The method intelligently excavates the landscape sightseeing point in urban and rural landscape environment by means of remote sensing image, DEM data, and topographic analysis means, and has good universality for different types of settlement landscape site selection with simple parameter setting and convenient use.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of digital terrain analysis and urban and rural environment intelligent planning, and relates to a method for exploring a viewing point in an urban and rural landscape environment. BACKGROUND

[0002] On the vast land of China with changing natural environment styles, the spatial order and pattern of mountains and rivers in different regions create their unique and irreplaceable regional identity. Based on geographic information, the digital and intelligent landscape view calculation is realized by means of terrain and view analysis technology, and the high-quality view pattern and important topographic point in the landscape environment are explored, which has a very important significance for settlement site selection, landscape construction, tourism planning and the like.

[0003] At present, the view analysis and important topographic point screening research of urban and rural planning professionals in the landscape environment are mostly manually preselected a number of observation points, and the analysis is carried out by means of third-party general software such as ArcGIS Engine and Global Mapper with view calculation function. Before the analysis, the parameters need to be manually set according to the experience, and the view range of a certain observation point is simulated to generate, so as to illustrate the view of the point relative to other points. This method only provides simple view calculation function, and lacks intelligent exploration and comparison means of view pattern. In order to more quantitatively analyze the landscape view pattern of urban and rural planning under the view of the landscape environment, Wang Shusheng et al. published an article entitled “Not afraid to climb: a thorough observation and spirit of seeking victory of natural landscape” in the Urban Planning magazine in 2018. The article describes the influence of the spirit of “not afraid to climb” on the observation and spirit of seeking victory of Chinese ancient city planning, and refines the exploration and integration of the ancient people on the landscape resources and potential order. It is clarified that the viewing point is a good point within the walking range of a person in the natural landscape environment, and the viewing point is an important site selection position for the viewing building. According to the above idea, the intelligent exploration and quantitative analysis method and system of the accessible domain and the viewing point in the natural landscape environment are established, which is helpful to form the potential site selection rule of the landscape building with wide view and good visibility, and has important guiding significance for urban and rural construction planning.

[0004] Third-party software such as ArcGIS Engine, Global Mapper does not have the analysis function of the accessible domain and the point of view, and the user needs to sort the view size, re-screen and re-process on the calculation result when using them to calculate the view, and at the same time, the complex parameter setting requires the user to have strong professional knowledge; in addition, the calculation and analysis of these software will calculate the view on the complete terrain data, which is time-consuming and not suitable for practical application. Therefore, based on geographic information, with the help of terrain analysis and view calculation technology, a method for analyzing landscape pattern and exploring the point of view in the mountain and water environment is established, which can realize the digital and intelligent exploration of the point of view in the mountain and water environment without complex parameter setting and with low user cooperation. SUMMARY

[0005] The purpose of the present application is to overcome the shortcomings of the prior art, and to provide a method for exploring the point of view in the urban and rural mountain and water environment, which can explore the point of view in the urban and rural mountain and water environment.

[0006] In order to achieve the above purpose, the method for exploring the point of view in the urban and rural mountain and water environment comprises the following steps:

[0007] 1) Obtain the remote sensing image Y and the digital elevation model G within N kilometers around the target settlement and aligned with the coordinate system;

[0008] 2) Extract the settlement boundary and the water system boundary from the remote sensing image Y to obtain the mask image F of the settlement and the mask image H of the water system;

[0009] 3) Calculate the mean value of the relative coordinates of each mask pixel in the mask image F of the settlement and take it as the geometric center of the settlement

[0010] 4) Calculate the slope factor of the digital elevation model G of the target settlement to obtain the slope matrix S;

[0011] 5) Map the geometric center of the settlement to the digital elevation model G of the target settlement as the starting point of the regional investigation of the settlement, and calculate the path length between the geometric center of the settlement and each grid point in the digital elevation model G of the target settlement to construct the distance matrix D;

[0012] 6) Calculate the walking speed on each grid in the digital elevation model G of the target settlement according to the slope matrix S to obtain the marching speed matrix V;

[0013] 7) Divide the distance matrix D obtained in step 5) by the marching speed matrix V obtained in step 6) to obtain the distance matrix D of the settlement geometric center A matrix T of walking time length of each grid in the target settlement digital elevation model G, wherein a travel time length threshold t0 is set, and when an element value T(i,j) in the matrix T of walking time length is less than or equal to t0, it is indicated that the grid belongs to the reachable domain of t0 hours of walking from the settlement center A reachable domain label matrix A is constructed;

[0014] 8) A visible domain label matrix W of each point A(i,j) in the reachable domain label matrix A is calculated ij , to obtain a set of visible domain matrices W{W 11 ,W 12 ,…,W mn}, wherein when an element value of the visible domain W ij is 1, it is indicated that the grid is visible to the point A(i,j), and when the element value of the visible domain W ij is 0, it is indicated that the grid is invisible to the point A(i,j);

[0015] 9) The number of elements with a value of 1 in each W ij matrix in step 8) is counted and taken as the visible domain range value of the point A(i,j), and the visible domain range values of all A(i,j)=1 elements in the reachable domain label matrix A are sorted from large to small, the top β elements are screened, and a set of climbing and sightseeing points B in the reachable domain label matrix A is constructed.

[0016] The remote sensing image Y and the digital elevation model G in step 1) are respectively:

[0017]

[0018]

[0019] wherein the number of pixels of Y is l×k, and the number of grids of G is m×n.

[0020] The settlement mask image F in step 2) is:

[0021]

[0022] The mask image H of the water system is:

[0023]

[0024] The settlement geometric center in step 3) is:

[0025] The slope matrix S in step 4) is:

[0026]

[0027]

[0028] Wherein, G(i,j) is the grid of relative coordinate i,j in digital elevation model G, and e is the grid accuracy of digital elevation model G.

[0029] The distance matrix D in step 5) is:

[0030]

[0031] Wherein, D(i,j)=d1+d2+…+d u (8)

[0032]

[0033] Wherein, e is the grid accuracy of digital elevation model G, h is the elevation difference between G(i1,j1) and G(i2,j2), u is the number of grids to be traversed from c0 to G(i,j) in P, d1 is the path length from c0 to G(1,0), and d2 is the path length from G(1,0) to G(1,1).

[0034] The travel speed matrix V in step 6) is:

[0035]

[0036] Wherein, V(i,j) is the average travel speed from to G(i,j) grid point.

[0037] The walking time matrix T and the reachable domain marking matrix A in step 7) are respectively:

[0038]

[0039]

[0040] The present application has the following beneficial effects:

[0041] The method for exploring the climbing and sightseeing point in the urban and rural landscape environment has the following advantages: the settlement boundary and the water system boundary are extracted from the settlement remote sensing image, the settlement geometric center is calculated in the settlement boundary, the settlement geometric center is mapped to the digital elevation model, the walking time matrix from the settlement center to each grid in the digital elevation model is calculated, and the reachable domain is obtained according to the set walking time threshold t0; the visual field of each grid point in the reachable domain is calculated, and the climbing and sightseeing point is finally obtained through the sorting and superposition processing of the visual field of each grid. The present application intelligently explores the landscape sightseeing point in the urban and rural landscape environment by means of remote sensing image, DEM data and terrain analysis, and has the advantages of simple parameter setting, convenient use and good universality for different types of settlement landscape site selection. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 A schematic diagram of the street travel path point set P from the settlement center c0 to the grid point G(i,j);

[0043] Figure 2 A flow chart of the analysis and calculation of the present application;

[0044] Figure 3 A flow chart of the calculation of the distance matrix;

[0045] Figure 4 A flow chart of the calculation of the speed matrix in the calculation of the reachable domain;

[0046] Figure 5 A remote sensing image of the case settlement in Example 1;

[0047] Figure 6 DEM data of the case settlement in Example 1;

[0048] Figure 7 A boundary mask image of the case settlement in Example 1;

[0049] Figure 8 A water system mask image of the case settlement in Example 1;

[0050] Figure 9 A 0.5-hour reachable domain schematic diagram of the case settlement in Example 1;

[0051] Figure 10 A schematic diagram of the sightseeing points explored on the 0.5-hour reachable domain of the case settlement in Example 1. DETAILED DESCRIPTION

[0052] In order to make the personnel in the art better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments, and are not intended to limit the scope of the present application. In addition, in the following description, the description of the known structures and technologies is omitted to avoid unnecessary confusion of the concepts disclosed in the present application. Based on the embodiments in the present application, all other embodiments obtained by the person of ordinary skill in the art without making creative efforts should belong to the scope of protection of the present application.

[0053] The structural schematic diagram according to the disclosed embodiment is shown in the accompanying drawings. The drawings are not drawn to scale, in which some details are exaggerated for the purpose of clarity and some details can be omitted. The shapes of various regions, layers and the relative size and positional relationship therebetween shown in the drawings are only exemplary, and in actuality, there can be deviations due to manufacturing tolerances or technical limitations, and a person skilled in the art can additionally design regions / layers with different shapes, sizes and relative positions according to actual needs.

[0054] Reference Figure 1 The method for exploring a viewing and sightseeing point in a rural and urban landscape environment according to the present application comprises the following steps:

[0055] 1) Obtain a remote sensing image Y and a digital elevation model G (DEM data) in a coordinate system within a range of 50 kilometers around a target settlement, that is,

[0056]

[0057]

[0058] wherein the number of pixels of Y is l x k, and the number of grids of G is m x n.

[0059] 2) Extract a settlement boundary and a water system boundary from the remote sensing image Y containing the target settlement to obtain a mask image F of the settlement and a mask image H of the water system;

[0060] The specific operation of step 2) is as follows:

[0061] Extract the settlement boundary from the remote sensing image Y containing the target settlement to obtain a mask marking image F of the settlement, as shown in equation (3), wherein each pixel within the settlement boundary is marked as 1, i.e., a settlement mask pixel, and the pixel outside the boundary is marked as 0, and p and q are the coordinates of the pixel.

[0062]

[0063] At the same time, considering the influence of rivers and lakes in the landscape environment on the exploration of the viewing and sightseeing point, the water system is extracted from Y to obtain a mask marking image H of the water system, as shown in equation (4), wherein each pixel value within the water system boundary is marked as 2, i.e., a water system mask pixel, and the pixel value outside the boundary is marked as 0, and p and q are the coordinates of the pixel.

[0064]

[0065] 3) Calculate the mean value of the relative coordinates of each pixel in the settlement mask marking image F and take this as the geometric center of the settlement that is,

[0066] 4) Extract the slope factor from the DEM data G of the target settlement to obtain the slope matrix S.

[0067] The specific operation of step 4) is as follows:

[0068] The slope factor is calculated from the DEM data G of the target settlement to obtain the slope matrix S, as shown in Equation (5).

[0069]

[0070]

[0071] Where G(i,j) is a certain DEM grid, i and j are its relative coordinates, and e is the grid accuracy of the DEM.

[0072] 5) Mapped into the digital elevation model G, serving as the starting point for the regional survey of the settlement, calculations are performed. The path length between each grid point in the digital elevation model is calculated, and then a distance matrix D is constructed based on the calculation results.

[0073]

[0074] The specific operation of step 5) is as follows:

[0075] Will Mapped into the digital elevation model, it serves as the starting point for the area under investigation, with... Figure 1 If G(i,j) is the target point, then according to the street-level movement method, we can obtain the following from... The path point set P{c0,G(1,0),G(1,1),…,G(i,j)} from the starting point to the G(i,j) grid in the digital elevation model is then calculated according to equation (8). The path length D(i,j) to G(i,j).

[0076] D(i,j)=d1+d2+…+d u (8)

[0077] Where u is the number of grid cells in P that need to be traversed from c0 to G(i,j), and d1 is... Figure 1 Let c0 be the path length from G(1,0), d2 be the path length from G(1,0) to G(1,1), and d3, ..., d... u This continues until point G(i,j) is reached.

[0078] Let d α Let G(i1,j1) and G(i2,j2) be the path length between any two adjacent points G(i1,j1) and G(i2,j2) in P. Then we have

[0079]

[0080] where e is the grid precision of the DEM, and h is the elevation difference between G(i1, j1) and G(i2, j2).

[0081] The path length D(i, j) from c0to the rest of the grid points in the DEM is calculated in sequence, and the distance matrix D from c0to each grid point in the DEM is obtained, i.e., formula (7).

[0082] 6) According to the slope matrix S obtained in step 4), the walking speed on each grid in the digital elevation model is calculated, and the travel speed matrix V is constructed according to the calculation result, wherein the walking speed of a person is v0km / h.

[0083] The specific operation of step 6) is:

[0084] According to the slope matrix S obtained in step 4), the relative speed matrix V of travel in the digital elevation model is calculated according to formula (10) r ;

[0085]

[0086] For the grid marked 2 in the water system mask image H obtained in step 2), the relative travel speed V r (i, j) is corrected by multiplying the adjustment coefficient p of travel in the water system by formula (11) on the calculation result of formula (10).

[0087] V rα (i, j) = V r (i, j) x p, p e (0, 1) (11)

[0088] According to Figure 1 , the grid point set P passed through from c0to G(i, j) is calculated, and the relative speed V of all grids in the grid point set P is accumulated to obtain V sum , at this time, according to formula (12), the ratio F of the relative travel speed V sum of each grid to V α (i, j) is taken as the travel difficulty coefficient on the grid, that is,

[0089]

[0090] where u is the number of grids traversed from c0to G(i, j) in P.

[0091] According to formula (13), the grid point set P passed through from c0to G(i, j) is calculated ​​​The average travel speed V(i, j) from the grid point G(i, j) is obtained, and a speed matrix V of travel on each grid in the DEM is obtained.

[0092]

[0093] 7) The distance matrix D obtained in step 5) is divided by the travel speed matrix V obtained in step 6), and a travel time matrix T of each DEM grid point is obtained. A travel time threshold t0 is set, and when the element value T(i, j) in the T matrix is <= t0, it is indicated that the grid belongs to the reachable domain from the settlement center The reachable domain of departure and t0 hours of walking is recorded as a reachable domain marker matrix A.

[0094] The specific operation of step 7) is as follows:

[0095] The distance matrix D obtained in step 5) is divided by the travel speed matrix V obtained in step 6), and a travel time matrix T of each DEM grid point is obtained. A travel time threshold t0 is set, and the relationship between the element value T(i, j) in the T matrix and t0 is checked, to obtain a walking reachable domain A(i, j) as shown in equation (15). When T(i, j) <= t0, A(i, j) is assigned a marker value 1, indicating that the grid belongs to the reachable domain from the settlement center , otherwise A(i, j) is assigned a marker value 0, indicating that the grid is not reachable within t0 hours of walking.

[0096]

[0097]

[0098] 8) The visible domain marker matrix W of each A(i, j) = 1 point in the reachable domain A is calculated ij , to obtain a visible domain matrix set W {W 11 ,W 12 ,…,W mn}, wherein the visible domain W ij is a marker matrix of the same size as the DEM data G, and the element value is 1 when the grid is visible to A(i, j), and the element value is 0 when the grid point is not visible to A(i, j).

[0099] The specific operation of step 8) is as follows:

[0100] 8a) Install the third-party function library of python-gdal (the development version is 3.3.1), call the gdal.ViewshedGenerate function in the third-party function library of python-gdal, input the latitude and longitude coordinates of a certain A(i,j) = 1 point in the reachable domain as the observation point of the person, set the basic parameters such as the observer height and the maximum observation distance, and calculate and generate the visibility domain label matrix W of the A(i,j) point by using the function ij ;

[0101] 8b) Set the observation point selection interval in the DEM data, loop through the observation points A(i,j) = 1 in the reachable domain, calculate the visibility domain label matrix of all observation points, and obtain the visibility domain set W{W 11 ,W 12 ,…,W mn}.

[0102] 9) Count the number of elements with a value of 1 in each W ij matrix in step 8), as the visibility range value of the point A(i,j), sort the visibility range values of all A(i,j) = 1 points in A from large to small, and select the top β elements to obtain the set of climbing and sightseeing points B in the reachable domain A.

[0103] Example Two

[0104] Reference Figure 2 To verify the rationality and effectiveness of the climbing and sightseeing points discovered by the present application in the urban and rural landscape environment, the Qingmuguan Town in Ningqiang County, Hanzhong City, Shaanxi Province is selected as a case settlement, and the test data includes remote sensing images and DEM data of the Qingmuguan area, as shown in Figure 5 and Figure 6 , the data is obtained from the 91 satellite map assistant, and the basic information is shown in Table 1, the precision is the real size corresponding to a unit grid or a pixel, and the unit is meter.

[0105] Table 1

[0106]

[0107] Figure 10 The travel time threshold t0 is 0.5 hours, and the case settlement climbing and sightseeing point position map automatically discovered by the present application is used. For the convenience of observation, the number of climbing and sightseeing points is set to 3. Among them, the diamond marked point is the climbing and sightseeing point, and the circular marked point is the geometric center of the settlement. In order to present the rationality of the climbing and sightseeing point discovery method more finely, the view grid number γ of the sightseeing point and the view domain proportion are taken as the quality evaluation basis, and the evaluation results of the first three sightseeing points are shown in Table 2.

[0108] Table 2

[0109]

Claims

1. A method for discovering scenic spots in urban and rural landscape environments, characterized in that, Includes the following steps: 1) Acquire remote sensing images of the target settlement and its surrounding area within a radius of N kilometers, aligned to the coordinate system. Y and digital elevation model G ; 2) For remote sensing images The boundaries of the settlement and the water system are extracted to obtain a mask image of the settlement. and masked images of water systems ; 3) Calculate the mask image of the settlement. Mean of relative coordinates of each mask pixel within the mask And take this as the geometric center of the settlement. ; 4) Digital elevation model of the target settlement G Slope factor calculation is performed to obtain the slope matrix. ; 5) Construct the distance matrix ; 6) Based on the slope matrix Calculate the digital elevation model of the target settlement G The walking speed matrix is ​​obtained by measuring the walking speed on each grid. ; 7) Construct the reachable domain label matrix ; 8) Calculate the reachable domain label matrix various points in the middle visible field label matrix The set of visible field matrices is obtained. Among them, when the visible field of view When an element has a value of 1, it means that the grid is... Visible, when the visible area When the element value is 0, it represents that the grid point is a pair. Invisible; 9) Statistical analysis of each item in step 8) The number of elements with a value of 1 in the matrix, and use this as the point. The visible field range value, for the reachable field label matrix All Sort elements by their visible area values ​​from largest to smallest, and filter the top-ranked elements. The elements are used to construct the reachable field label matrix. Collection of scenic spots for climbing ; The specific operation of step 5) is as follows: The geometric center of the settlement Digital elevation model mapped to the target settlement G In the middle, as the starting point for regional investigation of settlements, the geometric center of the settlement is calculated. Digital elevation model of the target settlement G The path lengths between points in each grid cell are used to construct a distance matrix. ; The specific operation of step 7) is as follows: The distance matrix obtained in step 5) Divide by the travel speed matrix obtained in step 6) To obtain the geometric center of the settlement Digital elevation model for reaching the target settlement G Walking time matrix of medium grid Among them, setting a travel time threshold When the walking time matrix element values ​​in ≤ When this occurs, it indicates that the grid belongs to the area originating from the settlement center. Departure, on foot Hourly reachable domains, construct reachable domain label matrix .

2. The method for discovering scenic spots in urban and rural landscape environments according to claim 1, characterized in that, Remote sensing image in step 1) Y and digital elevation model G They are respectively: (1) (2) in, Y The number of pixels is l , G The number of grids is .

3. The method for discovering scenic spots in urban and rural landscape environments according to claim 2, characterized in that, Masked marker image of settlement for: (3) Masked image of water system for: (4)。 4. The method for discovering scenic spots in urban and rural landscape environments according to claim 3, characterized in that, The center of the settlement , .

5. The method for discovering scenic spots in urban and rural landscape environments according to claim 1, characterized in that, Slope matrix for: (5) (6) in, For digital elevation model G The relative coordinates are , The grid, For digital elevation model G The grid accuracy.

6. The method for discovering scenic spots in urban and rural landscape environments according to claim 1, characterized in that, Distance matrix for: (7) in, (8) (9) In the formula, For digital elevation model G Grid accuracy, for and The elevation difference between them for Zhong Cong Departure to The number of grid cells to be traversed. for Walk to Path length, for Walk to The path length.

7. The method for discovering scenic spots in urban and rural landscape environments according to claim 1, characterized in that, Travel speed matrix for: (10) in, From Departure to The average travel speed of the grid points From Departure point The number of grid cells to be traversed. For point Is it a marker value for a settlement area? For point The relative speed of travel.

8. The method for discovering scenic spots in urban and rural landscape environments according to claim 1, characterized in that, Walking time matrix and reachable domain label matrix They are respectively: (11) (12)。

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