CN109948493B - Automatic radial water system identification method based on morphological characteristics - Google Patents
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Abstract
The invention discloses a radial water system automatic identification method based on morphological characteristics, which comprises the following steps: (1) extracting a watershed intersection point based on the watershed data; (2) Aiming at the river basin intersection points, extracting the shortest distance between any intersection point and the adjacent intersection point thereof, and taking half of the distance as the radius of a circular buffer area of the intersection point; (3) Clipping vector water system data based on the circular buffer area; (4) Removing non-radiation river reach based on water system data in the circular buffer area; (5) Counting the characteristics of the flow direction and the accumulated length of the river to judge whether the water system has the characteristics of diverging from the center to the periphery; (6) Counting the characteristics of the river source points and the outlet points, and judging whether the total number of the river source points of the water system is greater than the total number of the outlet points and whether the average distance between each source point and the central point of the circular buffer area is less than the average distance between each outlet point and the central point; (7) river characteristic-based water system type identification; (8) determining a specific range of the radial water system. The method identifies the radial water system based on the morphological characteristics, and has the advantages of low algorithm complexity, high automation degree and good identification accuracy.
Description
Technical Field
The invention belongs to the field of geographic information technology application, and particularly relates to a radial water system automatic identification method based on morphological characteristics.
Background
The water system type division can quickly judge the diversity of the landform and the complexity of the geological structure of a certain region, and provides scientific basis and application value for the research of the region landform and the geology. Different water system types have different morphological characteristics, and common water system types include a dendritic water system, a parallel water system, a lattice water system, a radial water system (also called radial water system), a centripetal water system (also called radial water system), a ring water system, and the like.
In recent years, some progress has been made in semi-automated or automated identification processes for water system types. Zhang (Zhang, guilbert. Automatic river design page recognition in river networks [ J ]. International Journal of geographic Information Science,2013,27 (12)) employs a method for automatically recognizing the type of water system, and the classification mainly depends on different geometric indexes (such as the connection angle between rivers and the shape of a river basin) and fuzzy set theory. Jung (Jung K, marpu P R, ouarda T B M J. Improved classification of secondary network using junction angles and secondary tributary lengths [ J ]. Geomorphology,2015,239 (Complete): 41-47.) first directly classifies the water systems in the river area by using the connecting angles between the secondary tributaries, and then estimates the power law index according to the flow direction distribution of the secondary river, thereby further distinguishing the water system types. Jung (Jung K, ouarda T B M J. Classification of drainage network types in the area and semi-area regions of Arizona and California [ J ]. Journal of Arid Environments,2017, 144.) mainly distinguishes between the types of water systems in arid and semi-arid areas and judges the presence or absence of feather-like water systems in these areas by a method of scale invariance. These studies lay a foundation for the identification of water system types within a single watershed, but there is little research on the identification of cross-watershed water system types (e.g., radial water systems). In view of this situation, a method for identifying radial and centripetal water systems (decongestant, wangliang, lemmons circle, lisanbo, chinese patent, CN108805146A, 2018-11-13) has been proposed by decongestant and the like, but this method is based only on existing local water systems and a small number of rules, and cannot identify an ideal water system type when the water system range is expanded.
Disclosure of Invention
The purpose of the invention is as follows: in order to solve the problems, the invention provides the radial water system automatic identification method based on the morphological characteristics, which is based on the vector water system and the watershed data, and has the advantages of low algorithm complexity, high automation degree and good identification accuracy.
The technical scheme is as follows: the invention provides a radial water system automatic identification method based on morphological characteristics, which comprises the following steps:
(1) Constructing D-TIN according to the adjacency relation between the flow domains, extracting the intersection point of any three adjacent flow domains through a TIN surface as the intersection point of the flow domains, and storing the intersection point in List < IPoint > InterPoints;
(2) Storing the distance between the adjacent basin intersection points to an array Ldis [ n ] [ n ] based on the InterPoints, acquiring the shortest distance from any basin intersection point to the adjacent intersection point, taking half of the shortest distance as the radius of the circular buffer area of the current basin intersection point, generating a corresponding circular buffer area and adding the circular buffer area to the buffer List;
(3) Taking a round buffer zone set BufferList as a cutting unit, taking a water system of the whole research zone as a cutting element, generating River elements in the buffer zone and storing the River elements in the set List < River > River List;
(4) Traversing the water system set river List in each circular buffer area, calculating the distance dis1 from the head point of each river to the intersection point of the river basin and the distance dis2 from the tail point of each river to the intersection point of the river basin, extracting a river reach with the grade of 1-2 and with dis1< dis2, and marking the river reach as a radiation river reach, namely dflag =1; otherwise, marking the river reach as a non-radiation river reach, namely dflag =0;
(5) In each circular buffer area, counting the flow direction frequency and the accumulated length of the radiant river flow in each direction interval by using a rose diagram; only when the flow direction frequency number and the accumulation length counted in each azimuth interval are both larger than zero, the river of the area meets the characteristic of divergence to the periphery, and flag1=1 of the area is marked; otherwise, flag1=0 for marking the region;
(6) Calculating the total source point number Scount and the total outlet point number Ecount of the river in each circular buffer area, and respectively recording the average distance from each source point and each outlet point to the central point of the circular buffer area, namely the river basin intersection point as D1 and D2; when Scount is more than or equal to Ecount and D1 is less than D2, marking flag2=1 in the region; otherwise, flag2=0 for marking the region;
(7) Counting the values of flag1 and flag2 in each area, and judging that a radial water system exists in the area only when the values of flag1 and flag2 are 1 simultaneously; on the contrary, no radial water system exists in the area;
(8) If a radial water system exists in the circular buffer area, extracting characteristic points according to the elevation change characteristics of points in the buffer area and the distance characteristics between the points and the central point, wherein the connecting line of the characteristic points is the range of the radial water system.
Further, the specific steps of extracting the watershed intersections in the step (1) are as follows:
(1.1) traversing the data of the stream domains, constructing a region adjacency graph by using adjacency relations between the stream domains, and storing the adjacency relations between any two stream domains in an adjacency matrix rag [ m ] [ m ], wherein m is the number of the stream domains; if the two flow fields are adjacent, marking the adjacency relation between the two flow fields as 1; otherwise, the label is 0;
(1.2) traversing the adjacency matrix rag, taking a river basin with any two adjacency relations of each row as 1, if two selected river basins also have adjacent relations, forming a closed triangle, and adding the closed triangle into List < DTIN > DTINList until all the river basins with the adjacency relations are traversed; wherein the data structure of the D-TIN is as follows:
Struct DTIN
{
int dtinid; // any D-TIN face id
List < Int > lyid; // three contiguous basins id constituting an arbitrary triangular face
List < IPoint > zpoint; // three vertex coordinates which are coordinates of the centroid points of three adjoining basins constituting an arbitrary triangular surface
}
(1.3) traversing the DTINList, finding out three adjacent watersheds corresponding to any one triangular surface, and respectively extracting circumscribed rectangles R1, R2 and R3 of the three adjacent watersheds;
(1.4) obtaining an intersecting rectangle InterRec of the circumscribed rectangles R1, R2 and R3, and adding the intersecting rectangle InterRec into List < InterRec > InterRecList; the data structure corresponding to the intersected rectangle is as follows:
(1.5) converting all the basin boundaries into point-like data, finding the corresponding basin boundary points in the intersected rectangles through the adjacent basin id corresponding to the intersected rectangles InterRec, and adding the points into List < IPoint > lypts;
(1.6) marking the same coordinates to appear three times by using a watershed boundary point lypts in the circularly intersected rectangle InterRec, taking points with different watershed ids of the three coordinates as watershed intersection points, and adding the watershed intersection points into a set List < IPoint > InterPoints;
and (1.7) until all D-TIN surfaces are traversed.
Further, the specific steps of generating the circular buffer in step (2) are as follows:
(2.1) constructing a TIN surface through a stream domain intersection set InterPoints and storing the TIN surface to a set List < LTIN > LTinList; the data structure for LTIN is as follows:
(2.2) defining a two-dimensional array Ldis [ n ] [ n ], wherein n is the number of river basin intersections, and the value of each line in the array is the distance value from the river basin intersection corresponding to the current line number to the other intersections; then traversing any TIN surface in the LTinList, calculating the distance between any two points on the TIN surface, and storing the distance into the corresponding Ldis [ n ] [ n ]; when the id of the two points is the same, the distance is 0; when no TIN edge exists between the two points, the distance is infinite;
(2.3) traversing the Ldis arrays, acquiring the minimum value which is not 0 in each line, taking half of the minimum value as the radius of the circular buffer area of the intersection point of the watershed corresponding to the line, and storing the radius to the array Mdis [ n ];
(2.4) calculating the average distance ad of all Mdis [ j ], wherein min is less than or equal to Mdis [ j ] and less than or equal to max, and min and max are selected according to the characteristics of the drainage basin, and j belongs to {0,1,2, \8230;, n }; if min is less than or equal to Mdis [ j ] and less than or equal to max, taking Mdis [ j ] as the buffer radius of the intersection point and generating a circular buffer area; if Mdis [ j ] > max or Mdis [ j ] < min, using ad as the buffer radius of the center point, generating a circular buffer area, and storing the circular buffer area to a circular buffer area set BufferList.
Further, the step (3) specifically comprises:
(3-1) the River elements in the buffer area are generated by using the round buffer area set BufferList as a cutting unit and the water system of the whole research area as a cutting element and are stored in the set List < River > River List. The data structure of River is as follows:
further, the step (4) of removing the non-radiation river reach based on the water system data in the circular buffer area comprises the following specific steps:
(4.1) traversing all river element sets riverList, and screening rivers with the grades of 1 and 2;
(4.2) traversing all rivers with river grades 1 and 2, and calculating the distances d from the tail point and the head point of any river to the intersection point of the river basin 2 And d 1 If d is satisfied 2 -d 1 >k 1 *len；k 1 ∈[0,1]And len is the river length, then the river is marked as a radiation river (dflag = 1); conversely, the river is a non-radiative river (dflag = 0).
Further, the specific steps of counting the characteristics of the flow direction and the cumulative length of the river in the step (5) and determining whether the water system has the characteristics of diverging from the center to the periphery are as follows:
(5.1) equally dividing 360 ° into N intervals with a threshold T2, where N =360 °/T2, N being a positive integer, distributing the river course flow direction values over the intervals [0 °, N °), [ N °,2N °), [ (N-1) × T1,360 °);
(5.2) traverse the RiverList, calculate the respective river flow direction by List < IPoint > linetops. Counting the frequency of the river flow in each circular buffer area in each interval and the accumulated length of the river in each interval, and respectively storing the frequency and the accumulated length of the river in each interval to arrays a [ N ] and len [ N ], wherein when any a [ s ] is larger than 0, s belongs to [0, N ], and any len [ s ] is larger than r 100, and when r is a positive integer, marking the buffer area as flag1=1; otherwise, the buffer is marked flag1=0.
Further, the specific steps of counting the characteristics of the river source points and the outlet points in the step (6) and judging whether the total number of the river source points of the water system is greater than the total number of the outlet points and whether the average distance between each source point and the central point of the circular buffer area is smaller than the average distance between each outlet point and the central point are as follows:
(6.1) traversing the radiant river section with dflag =1 in any RiverList, wherein when the FROM _ NODE = NULL of a river, the river is an originating river, and the total number of source points of a water system in the area is increased by 1 (marked as Scount = Scount + 1) and added into the source point set which is marked as List < IPoint > YPointList; when the TO _ NODE = NULL of a river, the river is a total afflux river, the number of outlet points of a water system in the area is increased by 1 and is recorded as Ecount = Ecount +1, and the added points are added TO an outlet point set and are recorded as List < IPoint > CPointList;
(6.2) traversing the source point set YPointList and the exit point set CPointList in each circular buffer area, respectively calculating the distance from each river source point and each river exit point to the central point of the circular buffer area, namely the distance from the corresponding river basin intersection point, and then respectively calculating the average values D1 and D2 of the distances;
(6.3) if Scount is more than or equal to Ecount and D1 is less than D2, marking flag2=1 in the area; otherwise, flag2=0.
Further, the specific step of determining the specific range of the radial water system in the step (8) is as follows:
(8.1) sequentially traversing each circular buffer area with a radial water system, taking a river basin intersection point as a center, taking a threshold T3 as N auxiliary radiuses, wherein N =360 °/T3, N is any positive integer, and discretizing the auxiliary radiuses into point-shaped data;
(8.2) superposing the point data and the DEM to obtain the elevation values of each point on the auxiliary Radius, and storing the elevation values to a point elevation set List < Radius > Radius List of any buffer area; the data structure of Radius is as follows:
(8.3) traversing each auxiliary Radius in any Radius List, acquiring the point on each auxiliary Radius, which is closest to the central point and has the largest height difference, as a characteristic point, and connecting all the characteristic points according to the Radius arrangement sequence to form the range of the radial water system.
By adopting the technical scheme, the invention has the following beneficial effects:
the method effectively identifies the radial water system by extracting a plurality of links such as river basin intersection points, calculating the radius of a circular buffer area, extracting the characteristics of a radiation river reach, the characteristics of the flow direction and the accumulated length of a river, the characteristics of a river source point and an outlet point and the like. The radial water system is identified based on the vector water system and the watershed data, the algorithm complexity is low, the automation degree is high, and the identification accuracy is good.
Drawings
FIG. 1 is a flow chart of the present invention;
FIG. 2 is a schematic illustration of vector flow field data and water system data for a cottage mountain in an embodiment;
FIG. 3 is a rose diagram of the river discharge frequency and the cumulative length of the regional river discharge in which the characteristics of the river discharge direction and the cumulative length of the river are satisfied in the specific embodiment (wherein, (a) is a rose diagram of the river discharge frequency of region No. 3, (b) is a rose diagram of the river cumulative length of region No. 3, (c) is a rose diagram of the river discharge frequency of region No. 7, and (d) is a rose diagram of the river cumulative length of region No. 7);
FIG. 4 is a radial water system identification result graph for the entire flow field of a cottage mountain in an embodiment;
FIG. 5 is a partial enlarged result view within the rectangular box of FIG. 4;
FIG. 6 is a result diagram of feature points for region No. 3 in an exemplary embodiment;
FIG. 7 is a graph showing the result of defining the water system range of zone No. 3 in the example;
FIG. 8 is a result chart of feature points for region No. 7 in the exemplary embodiment;
FIG. 9 is a diagram showing the result of defining the water system range of the No. 7 area in the example.
Detailed Description
The present invention is further illustrated by the following examples, which are intended to be purely exemplary and are not intended to limit the scope of the invention, as various equivalent modifications of the invention will occur to those skilled in the art upon reading the present disclosure and fall within the scope of the appended claims.
As shown in fig. 1, the present embodiment provides a radial water system identification method based on morphological characteristics, using cottage mountain as a research area and vector watershed data and water system data of fig. 2 as experimental data, and includes the following steps:
(1) And D-TIN is constructed according to the adjacency relation among the streaming domains, the intersection points of any three adjacent streaming domains are extracted through a TIN surface to serve as the streaming domain intersection points, and the intersection points are stored in List < IPoint > InterPoints. The method specifically comprises the following steps:
(1.1) traversing the data of the stream domains, constructing a region adjacency graph by using adjacency relations between the stream domains, and storing the adjacency relations between any two stream domains in an adjacency matrix rag [ m ] [ m ] (m is the number of the stream domains). If the two flow fields are adjacent, marking the adjacency relation between the two flow fields as 1; otherwise, the flag is 0. In this embodiment, m =19;
(1.2) traversing the adjacency matrix rag, taking the basin with any two adjacency relations of each row as 1, if the two selected basins also have adjacent relations, forming a closed triangle, and adding the closed triangle into List < DTIN > DTINList until all basins with the adjacency relations are traversed. In this example, 16D-TIN surfaces are formed;
(1.3) traversing the DTINList, finding out three adjacent watersheds corresponding to any one triangular surface, and respectively extracting circumscribed rectangles R1, R2 and R3 of the three adjacent watersheds;
(1.4) obtaining an intersecting rectangle InterRec of the circumscribed rectangles R1, R2 and R3, and adding the intersecting rectangle InterRec into List < InterRec > InterRecList. In this embodiment, 16 intersecting rectangles are generated in total;
(1.5) converting all the basin boundaries into point-like data, finding out corresponding basin boundary points in an intersected rectangle through an adjacent basin id corresponding to the intersected rectangle InterRec, and adding the border points into List < IPoint > lypts;
(1.6) marking the same coordinates to appear three times by circulating the watershed boundary points lypts in the intersected rectangle InterRec, taking the points with the same watershed ids of the three coordinates as watershed intersection points, and adding the points into the set List < IPoint > InterPoints. The specific coordinates are shown in table 1:
TABLE 1 watershed intersection coordinates
And (1.7) until all D-TIN surfaces are traversed.
(2) And storing the distance between the adjacent basin intersections to an array Ldis [ n ] [ n ] based on InterPoints, acquiring the shortest distance from any basin intersection to the adjacent intersection, taking half of the shortest distance as the radius of the circular buffer area of the current basin intersection, generating a corresponding circular buffer area and adding the circular buffer area to the buffer list. The method specifically comprises the following steps:
(2.1) constructing a TIN surface through the stream domain intersection set InterPoints and saving the TIN surface to a set List < LTIN > LTinList. In this embodiment, 24 TIN surfaces are formed;
and (2.2) traversing any TIN surface in the LTinList, calculating the distance between any two points on the TIN surface, and storing the distance into the corresponding Ldis [ n ] [ n ]. When the id of the two points is the same, the distance is 0; when there is no TIN edge between two points, the distance is ∞. In this embodiment, n =16;
(2.3) traversing the Ldis arrays, obtaining the minimum value which is not 0 in each line, taking half of the minimum value as the radius of the circular buffer area of the intersection point of the drainage basin corresponding to the line, and storing the radius to the array Mdis [ n ], which is specifically shown in a table 4.2;
(2.4) calculating the average distance ad of all Mdis [ j ] (min is more than or equal to Mdis [ j ] < max, and min and max are selected according to the characteristics of the drainage basin, wherein j belongs to {0,1,2, \ 8230;, n }). If min is less than or equal to Mdis [ j ] and less than or equal to max, taking Mdis [ j ] as the buffer radius of the intersection point and generating a circular buffer area; if Mdis [ j ] > max or Mdis [ j ] < min, then ad is used as the buffer radius of the center point, a circular buffer area is generated, and the circular buffer area is added into the BufferList. In this example, min =200, max =1000, ad =498.41m.
TABLE 2 buffer radius information Table
(3) And cutting the vector water system of the research area based on BufferList, and storing the cut water system to a set List < River > River List.
(4) Traversing the water system set river List in each circular buffer area, calculating the distance dis1 from the head point of each river to the intersection point of the river basin and the distance dis2 from the tail point of each river to the intersection point of the river basin, extracting a river reach with the grade of 1 and 2, wherein dis1 is less than dis2, and marking the river reach as a radiation river reach, namely dflag =1; otherwise, marking the river reach as a non-radiation river reach, namely dflag =0; . The method specifically comprises the following steps:
and (4.1) traversing all river element sets riverList, and screening the rivers with the levels of 1 and 2. In this example, the total number of rivers and the number of rivers of 1 and 2 levels are specifically shown in table 3;
(4.2) traversing all rivers with river grades 1 and 2, and calculating the distances d from the tail point and the head point of any river to the intersection point of the river basin 2 And d 1 If d is satisfied 2 -d 1 >k 1 *len(k 1 ∈[0,1]Len is the river length), then the river is marked as a radiating river (dflag = 1); conversely, the river is a non-radiative river (dflag = 0). In this example, k1=0.5, and the number of radiation rivers in each circular buffer is specifically shown in table 3;
TABLE 3 characteristic river number
(5) And in each circular buffer area, counting the flow direction frequency and the accumulated length of the radiant river flow in each direction interval by using a rose diagram. Only when the flow direction frequency number counted in each azimuth interval and the accumulated length are both larger than zero, the river in the area meets the characteristic of divergence to the periphery, and flag1=1 of the area is marked; otherwise, flag1=0 for marking the region. The method specifically comprises the following steps:
(5.1) equally dividing 360 ° into N intervals (N =360 °/T2, N being a positive integer) with a threshold T2, distributing the river flow direction values over the intervals [0 °, N °), [ N °,2N °), [ (N-1) × T1,360 °). In this embodiment, T2=30 °, N =12;
(5.2) traverse the RiverList, calculate the respective river flow direction by List < IPoint > linetops. Counting the frequency of the river flow in each circular buffer area in each interval and the accumulated length of the river in each interval, respectively storing the frequency and the accumulated length of the river in each interval to arrays a [ N ] and len [ N ], and marking the buffer area as flag1=1 when any a [ s ] >0 (s belongs to [0, N ]) and any len [ s ] > r 100 (r is a positive integer); otherwise, the buffer is marked flag1=0. In this embodiment, r =1, and only the rivers in the two circular buffers with id 3 and 7 satisfy the feature of diverging to the periphery. The direction rose diagram statistical result of the river frequency and the accumulated length in each azimuth interval is shown in figure 3;
(6) And calculating the total source point number Scount and the total outlet point number Ecount of the river in each circular buffer area, and the average distance (respectively marked as D1 and D2) from each source point and each outlet point to the central point (namely the river basin intersection point) of the circular buffer area. When Scount is larger than or equal to Ecount and D1 is smaller than D2, marking flag2=1 of the area; otherwise, flag2=0 for marking the region. The method specifically comprises the following steps:
(6.1) traversing the radiant river section with dflag =1 in any RiverList, wherein when the FROM _ NODE = NULL of a river, the river is an originating river, and the total number of source points of a water system in the area is increased by 1 (marked as Scount = Scount + 1) and added into the source point set which is marked as List < IPoint > YPointList; when a river is a total river which converges TO TO _ NODE = NULL, the number of exit points of the water system in the area is increased by 1 (noted as Ecount = Ecount + 1) and added TO the set of exit points noted as List < IPoint > CPointList. In this embodiment, the number of source points and exit points in each circular buffer area is specifically shown in table 4;
(6.2) traversing the source point set YPointList and the exit point set CPointList in each circular buffer area, respectively calculating the distance from each river source point and each river exit point to the central point (namely the corresponding river basin intersection point) of the circular buffer area, and then respectively calculating the average values D1 and D2 of the distances. In this embodiment, D1 and D2 in each circular buffer are specifically shown in table 4;
(6.3) if Scount is more than or equal to Ecount and D1 is less than D2, marking flag2=1 in the area; otherwise, flag2=0. In this embodiment, as can be seen from table 4, all the rivers in the circular buffer area satisfy this condition.
TABLE 4 river Source and Outlet Point characteristics
(7) Counting the values of flag1 and flag2 in each area, and judging that a radial water system exists in the area only when the values of flag1 and flag2 are 1 simultaneously; on the other hand, it is judged that no radial water system exists in this region. In the present embodiment, only radial water systems exist in the circular buffers of yid =3 and yid =7, the identification result is shown in fig. 4, and fig. 5 is a partial enlarged result diagram in the rectangular frame in fig. 4.
(8) If a radial water system exists in the circular buffer area, extracting characteristic points according to the elevation change characteristics of points in the buffer area and the distance characteristics between the points and the central point, wherein the connecting line of the characteristic points is the range of the radial water system. The method specifically comprises the following steps:
(8.1) sequentially traversing each circular buffer area having a radial water system, centering on the intersection of the drainage areas, making N auxiliary radii (N =360 °/T3, N being any positive integer) with the threshold T3, and discretizing the auxiliary radii into point-like data. In this example, since only two areas have radial water systems, N is 33 and 28;
(8.2) superposing the point data and the DEM to obtain the elevation values of each point on the auxiliary Radius, and storing the elevation values to a point elevation set List < Radius > Radius List of any buffer area;
(8.3) traversing each auxiliary Radius in any Radius List, acquiring the point on each auxiliary Radius, which is closest to the central point and has the largest height difference, as a characteristic point, and connecting all the characteristic points according to the Radius arrangement sequence to form the range of the radial water system. In this example, the characteristic point heights in the buffer areas where the radial water system exists are shown in table 5, and the characteristic point result graphs are shown in fig. 6 and 8. The results of defining the water system range are shown in fig. 7 and 9.
TABLE 5 elevation of characteristic points in areas where radial water systems are present
The water system in the 16 identification cells (i.e., the circular buffer) was superimposed on the topographic information, and then was manually interpreted, and it was found that only the water systems in the regions of yid =3 and yid =7 matched the characteristics of the radial water system, indicating that the human identification result matched the experimental result of the present invention. Therefore, the accuracy rate of automatic identification of the radial water system in the Lushan area is 100%, the false alarm probability is 0, and the miss probability is 0.
While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
Claims (7)
1. A radial water system automatic identification method based on morphological characteristics is characterized by comprising the following steps:
(1) Constructing D-TIN according to the adjacency relation between the flow domains, extracting the intersection point of any three adjacent flow domains through a D-TIN surface as the intersection point of the flow domains, and storing the intersection point in List < IPoint > InterPoints;
(2) Based on InterPoints, storing the distance between adjacent basin intersections to an array Ldis [ n ] [ n ], acquiring the shortest distance from any one basin intersection to an adjacent intersection, taking half of the shortest distance as the radius of the circular buffer area of the current basin intersection, generating a corresponding circular buffer area and adding the circular buffer area to buffer List;
(3) Taking a round buffer zone set BufferList as a cutting unit, taking a water system of the whole research zone as a cutting element, generating River elements in the buffer zone and storing the River elements in the set List < River > River List;
(4) Traversing a water system set river List in each circular buffer area, calculating the distance dis1 from the head point of each river to the intersection point of the river basin and the distance dis2 from the tail point of each river to the intersection point of the river basin, extracting river sections with the grades of 1 and 2, wherein dis1 is less than dis2, and marking the river sections as radiation river sections, namely dflag =1; otherwise, marking the river reach as a non-radiation river reach, namely dflag =0;
(5) In each circular buffer area, counting the flow direction frequency and the accumulated length of the radiant river flow in each direction interval by using a rose diagram; only when the flow direction frequency number counted in each azimuth region and the accumulated length are both larger than zero, the river in the circular buffer region meets the characteristic of divergence to the periphery, and flag1=1 of the region is marked; otherwise, flag1=0 for marking the region;
(6) Calculating the total source point number Scount and the total outlet point number Ecount of the river in each circular buffer area, and respectively recording the average distance from each source point and each outlet point to the central point of the circular buffer area, namely the river basin intersection point as D1 and D2; when Scount is larger than or equal to Ecount and D1 is smaller than D2, marking flag2=1 in the area; otherwise, flag2=0 for marking the region;
(7) Counting the values of flag1 and flag2 in each area, and only when the values of flag1 and flag2 are both 1, judging that a radial water system exists in the area; on the contrary, no radial water system exists in the area;
(8) If a radial water system exists in the circular buffer area, extracting characteristic points according to the elevation change characteristics of points in the buffer area and the distance characteristics between the points and the central point, wherein the connecting line of the characteristic points is the range of the radial water system.
2. The method for automatically identifying the radial water system based on the morphological characteristics as claimed in claim 1, wherein the concrete step of extracting the river basin intersection in the step (1) is as follows:
(1.1) traversing the data of the stream domains, constructing a region adjacency graph by using adjacency relations between the stream domains, and storing the adjacency relations between any two stream domains in an adjacency matrix rag [ m ] [ m ], wherein m is the number of the stream domains; if the two flow fields are adjacent, marking the adjacency relation between the two flow fields as 1; otherwise, the label is 0;
(1.2) traversing the adjacency matrix rag, taking a basin with any two adjacency relations of each row as 1, if two selected basins also have an adjacent relation, forming a closed triangle, and adding the closed triangle into List < DTIN > DTINList until all basins with the adjacency relation are traversed;
(1.3) traversing the DTINList, finding out three adjacent watersheds corresponding to any one triangular surface, and respectively extracting circumscribed rectangles R1, R2 and R3 of the three adjacent watersheds;
(1.4) obtaining an intersecting rectangle InterRec of the circumscribed rectangles R1, R2 and R3, and adding the intersecting rectangle InterRec into List < InterRec > InterRecList;
(1.5) converting all the basin boundaries into point-like data, finding out the corresponding basin boundary points in the intersected rectangles through the adjacent basin id corresponding to the intersected rectangles InterRec, and adding the corresponding basin boundary points into List < IPoint > lypts;
(1.6) marking the same coordinates to appear three times by using a watershed boundary point lypts in the circularly intersected rectangle InterRec, taking points with different watershed ids of the three coordinates as watershed intersection points, and adding the watershed intersection points into a set List < IPoint > InterPoints;
and (1.7) until all D-TIN surfaces are traversed.
3. The method for automatically identifying the radial water system based on the morphological characteristics as claimed in claim 1, wherein the specific steps of generating the circular buffer area in the step (2) are as follows:
(2.1) constructing a TIN surface through a stream domain intersection set InterPoints and storing the TIN surface to a set List < LTIN > LTinList;
(2.2) defining a two-dimensional array Ldis [ n ] [ n ], wherein n is the number of river basin intersections, and the value of each line in the array is the distance value from the river basin intersection corresponding to the current line number to the other intersections; then traversing any TIN surface in the LTinList, calculating the distance between any two points on the TIN surface, and storing the distance into the corresponding Ldis [ n ] [ n ]; when the id of the two points is the same, the distance is 0; when no TIN edge exists between the two points, the distance is infinite;
(2.3) traversing the Ldis arrays, acquiring the minimum value which is not 0 in each line, taking half of the minimum value as the radius of the circular buffer area of the intersection point of the watershed corresponding to the line, and storing the radius to the array Mdis [ n ];
(2.4) calculating the average distance ad of all Mdis [ j ], wherein min is less than or equal to Mdis [ j ] and less than or equal to max, and min and max are selected according to the characteristics of the drainage basin, and j belongs to {0,1,2, \8230;, n }; if min is less than or equal to Mdis [ j ] and less than or equal to max, taking Mdis [ j ] as the buffer radius of the intersection point and generating a circular buffer area; if Mdis [ j ] > max or Mdis [ j ] < min, taking ad as the buffer radius of the center point, generating a circular buffer area, and storing the circular buffer area to a circular buffer area set BufferList.
4. The method for automatically identifying the radial water system based on the morphological characteristics as claimed in claim 1, wherein the step (4) of eliminating the non-radiation river reach based on the water system data in the circular buffer area comprises the following specific steps:
(4.1) traversing all river element sets riverList, and screening rivers with the grades of 1 and 2;
(4.2) traversing all rivers with river grades 1 and 2, and calculating the distances d from the tail point and the head point of any river to the intersection point of the river basin 2 And d 1 If d is satisfied 2 -d 1 ＞k 1 *len；k 1 ∈[0，1]If len is the river length, marking the river as a radiation river, namely dflag =1; conversely, the river is a non-radiative river, i.e., dflag =0.
5. The method for automatically identifying a radial water system based on morphological characteristics as claimed in claim 1, wherein the step (5) of counting the characteristics of the flow direction and the cumulative length of the river and determining whether the water system has characteristics diverging from the center to the periphery comprises the following specific steps:
(5.1) equally dividing 360 ° into N intervals with a threshold T2, where N =360 °/T2, N being a positive integer, distributing the river flow direction values over the intervals [0 °, N °), [ N °,2N °), [ (N-1) × T1,360 °);
(5.2) traversing the riverList, calculating each river flow direction through List < IPoint > linetops, counting the frequency of the river flow direction in each interval in each circular buffer area and the accumulated length of the river in each interval, and respectively storing the frequency and the accumulated length of the river in each interval into arrays a [ N ] and len [ N ], when any a [ s ] is more than 0, wherein s belongs to [0, N ], and any len [ s ] is more than r 100, and when r is a positive integer, marking the buffer area as flag1=1; otherwise, the buffer is marked flag1=0.
6. The method for automatically identifying a radial water system based on morphological characteristics as claimed in claim 1, wherein the step (6) of counting the characteristics of the river source points and the outlet points judges whether the total number of the river source points of the water system is larger than the total number of the outlet points and whether the average distance between each source point and the central point of the circular buffer area is smaller than the average distance between each outlet point and the central point, and comprises the following specific steps:
(6.1) traversing the radiant river sections with dflag =1 in any RiverList, wherein when the FROM _ NODE = NULL of a river, the river is an originating river, the total source point number of the water system in the area is increased by 1 and is marked as Scount = Scount +1, and the source point number is added to the source point set and is marked as List < IPoint > YPointList; when the TO _ NODE = NULL of a river, the river is a total river which is converged into the river, the number of the outlet points of the water system in the area is increased by 1, the number is recorded as Ecount = Ecount +1, and the outlet points are added into a set of outlet points, and the set is recorded as List < IPoint > CPointList;
(6.2) traversing the source point set YPointList and the exit point set CPointList in each circular buffer area, respectively calculating the distance from each river source point and each river exit point to the central point of the circular buffer area, namely the distance from the corresponding river basin intersection point, and then respectively calculating the average values D1 and D2 of the distances;
(6.3) if Scount is more than or equal to Ecount and D1 is less than D2, marking flag2=1 in the area; otherwise, flag2=0.
7. The method for automatically identifying a radial water system based on morphological characteristics as claimed in claim 1, wherein the specific step of determining the specific range of the radial water system in the step (8) is as follows:
(8.1) sequentially traversing each circular buffer area with a radial water system, taking a river basin intersection point as a center, taking a threshold T3 as N auxiliary radiuses, wherein N =360 °/T3, N is any positive integer, and discretizing the auxiliary radiuses into point-shaped data;
(8.2) superposing the point data and the DEM to obtain the elevation values of each point on the auxiliary Radius, and storing the elevation values to a point elevation set List < Radius > Radius List of any buffer area;
(8.3) traversing each auxiliary Radius in any Radius List, acquiring the point on each auxiliary Radius, which is closest to the central point and has the largest height difference, as a characteristic point, and connecting all the characteristic points according to the Radius arrangement sequence to form the range of the radial water system.
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