JP2018018302A - Polygon type ground surface feature data generation method and polygon type ground surface feature data generation program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily generate data of a ground surface capable of improving outflow prediction accuracy compared with when grid type GIS data is used.SOLUTION: A polygon type ground surface feature data generation program (AP1) causes a computer (11) to function as: map data storage means (M1) for storing map data including shore line data for identifying a shore line and road data for identifying a road including a bridge; channel extraction means (M5) for extracting a block including the shore line (23) as a channel (26); bridge extraction means (M6) for extracting the bridge (24) adjacent to the channel (26) as the bridge (24) built across the channel (26); and continuous channel generation means (M7) for generating a continuous channel (29) formed by connecting the channel (26) divided by the bridge (27) based on the channel (26) extracted by the channel extraction means (M5) and the bridge (27) extracted by the bridge extraction means (M6).SELECTED DRAWING: Figure 6

Description

  The present invention relates to a polygon-type ground surface feature data creation method and polygon-type ground surface data for creating polygon-type ground surface feature data based on map data that can be obtained, such as GIS (Geographic Information System). Polygon-type surface feature data creation method and polygon-type surface feature for creating polygon-type surface feature data that can be suitably used for analysis of flooding in rivers and heavy rain It relates to a data creation program.

In recent years, particularly in urban basins in large metropolitan areas, inundation damage due to heavy rains such as guerrilla heavy rains and flooding from small and medium rivers has frequently occurred, and countermeasures against these floods are urgently needed. From this situation, the government and the citizens are eager to accurately predict flood runoff and inundation due to torrential rain. For stormwater runoff and flood forecasting, it is common to use data modeling the stormwater runoff process.
As techniques for performing such rainwater outflow and flood prediction, the techniques described in the following Patent Documents 1 to 3 are conventionally known.

  Japanese Patent Application Laid-Open No. 2011-75386 as Patent Document 1 describes the surface of a designated area from the inclination direction and the inclination angle based on the terrain data for each section obtained by dividing the ground surface into a four-sided grid (mesh shape). Determine the runoff coefficient and underground runoff coefficient, accumulate soil rainfall index data per unit time, and calculate the degree of risk per unit time per unit time from the soil rainfall index and each runoff coefficient for each section. The technology to display is described.

  In Japanese Patent Application Laid-Open No. 2016-29533 as Patent Document 2 and Japanese Patent Application Laid-Open No. 2015-129589 as Patent Document 3, the observation area is divided into a plurality of sections in a mesh shape (lattice shape), and rainfall for each section A system that predicts sediment-related disasters based on volume is described. In the techniques described in Patent Documents 2 and 3, when a river passes through each section, it is treated as a river section. It is said that all water flows through the river. Further, in the techniques described in Patent Documents 2 and 3, the direction in which the rain falls is set from the elevation value for each section, and the runoff is set in consideration of the characteristics of the land such as mountains, forests, arable land, and rivers. Depending on the factor, the flow rate is calculated.

Japanese Patent Laying-Open No. 2011-75386 ("0012" to "0016", FIG. 3, FIG. 5 to FIG. 8) JP 2016-29533 A ("0024" to "0040", FIGS. 6 to 10) Japanese Patent Laying-Open No. 2015-129689 (“0014” to “0037”, FIGS. 4 to 8)

(Problems of conventional technology)
As described in Patent Documents 1 to 3, in the conventional model, the available GIS (Geographic Information System) data is limited to the grid shape of the raster shape in which the basin is divided into a grid shape. Most of them were grid type. In particular, in grid-type GIS data, when a river passes through a part of a section of a river, the entire section is regarded as a river. Therefore, even if the river occupies the majority (for example, 90% or more) of the section, even if only a small part (for example, less than 5%) occupies the river, it is treated as the same river section. In addition, in the case of the grid type model, the ratio of water penetration into the soil (penetration rate) and the ratio of non-penetration (impermeability rate) are estimated values such as X% even if buildings and fields are mixed in one section. Be treated. Therefore, the water runoff analysis model adopting the grid type as in the prior art has a problem that there is a limit in improving the runoff prediction accuracy.
In particular, with grid-type GIS data, it is extremely difficult to accurately represent the relationship between features such as complex land cover and buildings in urban basins, rainwater discharge routes, and rivers, and accuracy is likely to deteriorate. There is.

  In addition, grid-type GIS data was created mainly for the purpose of use in city planning, and GIS data classified into city planning such as residential land and industrial zone is being gradually developed. is there. However, no information is given on the penetration and imperviousness of land cover, which plays an important role in the analysis of stormwater runoff, that is, whether rainwater penetrates the ground surface or does not penetrate the ground surface. For this reason, when building a water runoff analysis model, it is necessary to create individual features from aerial photographs, etc., based on the available GIS data such as the Geographical Survey Institute's numerical maps. There are also problems that require a lot of time and effort. With regard to these technologies, the number of research cases is small compared to research related to model development, and the technical accumulation is insufficient.

  This application makes it a technical subject to create easily the ground surface data which can improve the outflow prediction precision compared with the case where grid type GIS data is used.

In order to solve the technical problem, the polygon type ground surface feature data creation program according to the invention of claim 1 is provided.
Computer
Map data storage means for storing map data including at least water line data for specifying a water line which is a boundary between a land part and a water part on a map and road data for specifying a road including a bridge on the map. ,
A river channel extracting means for extracting, as a river channel, an area that includes a lifetime line and is divided by a bridge, based on the road data and the lifetime data;
Bridge extraction means for extracting a bridge over the river channel extracted by the river channel extraction means based on the road data;
Based on the river channel extracted by the river channel extraction unit and the bridge extracted by the bridge extraction unit, the continuous river channel generating unit that connects the river channels cut by the bridge and generates a continuous river channel,
It is made to function as.

The invention according to claim 2 is the polygon-type ground surface feature data creation program according to claim 1,
Computer
Based on the road data, road element generating means for separating the intersection and the single road part of the road and dividing the single road part into road elements according to a preset length,
It is made to function as.

The invention according to claim 3 is the polygon type ground surface feature data creation program according to claim 1 or 2,
Computer
Map data storage means for storing the map data, including building perimeter data specifying a building boundary on the map and map symbol data specifying the land status on the map;
In a block surrounded by a road, a site generation means for generating a site that is a controlled area of the building based on the building perimeter data,
Based on the map symbol data, attribute assigning means for assigning attribute information specifying the status of the land to the site generated by the site generating means,
It is made to function as.

In order to solve the technical problem, the polygon type ground surface feature data creating method of the invention according to claim 4 is:
Map data storage means for storing map data including at least water line data for specifying a water line which is a boundary between a land part and a water part on a map and road data for specifying a road including a bridge on the map. ,
A river channel extracting step for extracting, as a river channel, an area that includes a water line and is divided by a bridge, based on the road data and the water line data that identifies a water line that is a boundary between a land part and a water part on a map. When,
Based on the road data, a bridge extraction step of extracting a bridge over the river channel extracted by the river channel extraction means;
Based on the river channel extracted by the river channel extracting means and the bridge extracted by the bridge extracting unit, connecting the river channels cut by the bridge, generating a continuous river channel,
It is characterized by performing.

According to the first and fourth aspects of the present invention, it is possible to easily create ground surface data capable of improving the outflow prediction accuracy as compared with the case of using grid type GIS data.
According to the second aspect of the present invention, it is possible to accurately analyze the state of water flowing on the road as compared with the case where no road element is generated.
According to invention of Claim 3, compared with the case where a block is subdivided into a site and attribute information is not provided, the analysis according to the water permeation characteristic can be performed with high accuracy.

FIG. 1 is an explanatory diagram of an outflow analysis system according to Embodiment 1 of the present invention. FIG. 2 is a functional block diagram of the computer main body 12 according to the first embodiment. FIG. 3 is an explanatory diagram of an example of map data according to the first embodiment. FIG. 4 is an explanatory diagram in which only roads in the example of the map data shown in FIG. 3 are extracted. FIG. 5 is an explanatory diagram of a process of extracting a river channel, FIG. 5A is an explanatory diagram in which a portion of a river channel in the example of the map data shown in FIG. 3 is extracted, and FIG. 5B is an explanatory diagram of an example of a pond or a lake that is not extracted as a river channel FIG. 5C is an explanatory diagram of an example of a coastline that is not extracted as a river channel, and FIG. 5D is an explanatory diagram of a method for creating a bridge polygon. FIG. 6 is an explanatory diagram of a continuous river channel generated from the river channel data shown in FIG. FIG. 7 is an explanatory diagram of the block polygon extracted based on the map data shown in FIG. FIG. 8 is an explanatory diagram for explaining an example of division into road elements, FIG. 8A is an explanatory diagram of a road before division, FIG. 8B is an explanatory diagram of a state where an intersection and a single road are separated, and FIG. It is explanatory drawing of the state which divided | segmented the road part into the preset road element. 9 is an explanatory diagram of an example of a block polygon, FIG. 9A is an explanatory diagram when a plurality of buildings exist in the block, FIG. 9B is an explanatory diagram when a buffer is generated in FIG. 9A, and FIG. 9C is a plane Voronoi FIG. 9D is an explanatory diagram in the case where the block is divided by the division method, and FIG. 9D is an explanatory diagram in a state where the boundary of the site that is the control region of each building is generated. FIG. 10 is an explanatory diagram of an example of assigning an attribute based on a map symbol, FIG. 10A is an explanatory diagram of an example of a site to which a map symbol is assigned, and FIG. 10B is a diagram of dividing the site shown in FIG. 10A by the point Voronoi division method FIG. 10C is an explanatory diagram of a result of division by the point Voronoi division method of FIG. 10B. FIG. 11 is an explanatory diagram of a flowchart of polygon-type ground surface feature data creation processing according to the first embodiment. FIG. 12 is an explanatory diagram of a modified example of the embodiment, FIG. 12A is an explanatory diagram of a block polygon as an example before the division, FIG. 12B is an explanatory diagram of a state where the surface Voronoi division is performed, and FIG. FIG. 12D is an explanatory diagram of a state where a site is generated. FIG. 13 is an explanatory diagram of a modified example, FIG. 13A is an explanatory diagram of a state in which surface Voronoi division is performed in an example different from FIG. 12A, and FIG. 13B is an explanatory diagram in the case of generating a buffer in the example of FIG. FIG. 13C is an explanatory diagram of a state in which a site is generated from the results of FIGS. 13A and 13B.

Next, specific examples of embodiments of the present invention (hereinafter referred to as examples) will be described with reference to the drawings, but the present invention is not limited to the following examples.
In the following description using the drawings, illustrations other than members necessary for the description are omitted as appropriate for easy understanding.

FIG. 1 is an explanatory diagram of an outflow analysis system according to Embodiment 1 of the present invention.
In FIG. 1, the outflow analysis system S according to the first embodiment includes a personal computer 11 as an example of an information processing apparatus that can be used by an operator who performs analysis. The personal computer 11 includes a computer main body 12, a display 13 as an example of a display, and a keyboard 14 and a mouse 15 as examples of an input device.
The personal computer 11 according to the first embodiment is connected to an internetwork 21 as an example of a public line. The personal computer 11 can transmit / receive information to / from a plurality of servers 22 as an example of an information processing apparatus via the internetwork 21.
In the first embodiment, the computer main body 12 is wired to the internetwork 21 via a cable. However, the present invention is not limited to this, and a wireless LAN, Bluetooth (registered trademark), an example of wireless communication, Wireless connection is also possible using any communication technology such as a cellular phone line.

(Description of Control Unit of Computer of Example 1)
FIG. 2 is a functional block diagram of the computer main body 12 according to the first embodiment.
2, the computer main body 12 according to the first embodiment includes an I / O (input / output interface) that performs input / output of signals to / from the outside, adjustment of input / output signal levels, and the like, and a program and data for performing necessary startup processing. ROM (read-only memory) that stores data, RAM (random access memory) for temporarily storing necessary data and programs, and CPU (central processing unit) that performs processing according to the startup program stored in the ROM And a computer device having a clock oscillator and the like, and various functions can be realized by executing programs stored in the ROM and RAM.
The computer main body 12 includes basic software for controlling basic operations, a so-called operating system OS (not shown), a polygonal surface feature data creation program AP1 as an example of an application program, and an outflow analysis program AP2 as an example of an application program. Other software (not shown) is stored.

(Elements connected to the computer main body 12 of the first embodiment)
Output signals from signal output elements such as a keyboard 14 and a mouse 15 are input to the computer main body 12.
The computer main body 12 according to the first embodiment outputs a control signal to a controlled element such as the display 13.

(Function of the computer main body 12)
The polygon type ground surface feature data creation program AP1 according to the first embodiment includes the following functional means (program modules) M1 to M14.

FIG. 3 is an explanatory diagram of an example of map data according to the first embodiment.
The map data storage means M1 stores map data of a region to be analyzed for the outflow of water due to a typhoon or torrential rain. In the first embodiment, GIS data is stored as an example of map data. The GIS data includes, for example, map data including land use information such as map information such as buildings and contour lines and map symbols, in addition to topographic map data such as “Tokyo Metropolitan Scale 1/2500 Topographic Map Standard Data File”. Conventionally known map data can be used. Further, the map data of the first embodiment includes the lifeline data that specifies the waterline that is the boundary between the land and the water on the map, the road data that specifies the road including the bridge on the map, The building perimeter data specifying the boundary of the building and the map symbol data specifying the land condition on the map are included.

FIG. 4 is an explanatory diagram in which only roads in the example of the map data shown in FIG. 3 are extracted.
The road edge extracting means M2 extracts the road edge based on the road data included in the map data. 3 and 4, the road edge extraction means M2 extracts the edge 21 a of the road 21.
Based on the area surrounded by the road edge 21a, the block / river generation means M3 generates a block / river area 22 which is a block or river area. In the first embodiment, the block / river channel region 22 is generated as a polygonal (polygonal) figure surrounded by a road. 3 and 4, the block / river channel region 22 is illustrated as a quadrilateral for ease of understanding, but a triangular shape, a pentagonal shape, or a semicircular shape and a polygonal shape are joined. In some cases, the shape may be irregular. In the present specification and claims, polygonal shapes and indefinite shapes are collectively referred to as “polygon type” and “polygon shape”.
The block / river extraction means M4 cuts out the generated block / river polygon from the map data shown in FIG. 3, and creates only the road data shown in FIG. That is, only road polygon data is extracted from the map data, and the remaining portion becomes a block / river channel polygon (block / river region) 22.

FIG. 5 is an explanatory diagram of a process of extracting a river channel, FIG. 5A is an explanatory diagram in which a portion of a river channel in the example of the map data shown in FIG. 3 is extracted, and FIG. 5B is an explanatory diagram of an example of a pond or a lake that is not extracted as a river channel FIG. 5C is an explanatory diagram of an example of a coastline that is not extracted as a river channel, and FIG. 5D is an explanatory diagram of a method for creating a bridge polygon.
The river channel extraction means M5 extracts the city block / river channel polygon 22 including the water line 23 as the river channel 26 with respect to the city block / river channel polygon 22 surrounded by the road. In FIG. 5A, the river channel extracting means M5 of the first embodiment includes a pair of parallel lifeline 23 in the block / river polygon 22, and both ends of each lifetime line 23 are connected to the block / river polygon 22. If there is, the block / river channel polygon 22 is identified (extracted) as a river channel (river channel polygon) 26. On the map, the water line 23 is given along the area where the water actually flows, and there is usually a portion corresponding to the high waterbed 23a, so the outer circumference of the block / river polygon 22 (= the road 21) There is a gap on the map between the edge 21a) and the water line 23. Therefore, in the first embodiment, when the water line 23 exists inside the block / river channel polygon 22, the entire block / channel polygon 22 including not only the river channel itself but also the portion of the high waterbed 23 a is extracted as the river channel polygon 26. To do.

As shown in FIG. 5B, when a pond or lake exists in the block / river polygon 22, the water line becomes a closed circle, polygon, or irregular shape, and a pair (two) of life lines 23 are formed. It will not be parallel, or both ends will not be connected to the block / river channel polygon 22 (ie, will not close). Moreover, as shown to FIG. 5C, when a shoreline exists, there is only one water line 23 and there is no parallel water line 23 in parallel. Therefore, in the river channel extraction means M5 of the first embodiment, the pond, the lake, the coastline, and the river channel 26 are also distinguished, and only the river channel 26 is extracted with high accuracy.
In addition, as shown in FIG. 5, one river is represented on the map as a plurality of regions (river channels 26) divided by the bridge 24, and the river channel extracting means M5 of the first embodiment is Each region (river channel 26) cut at 24 is extracted.

  The bridge extracting unit M6 extracts the bridge 24 adjacent to the river channel 26 extracted by the river channel extracting unit M5 as a bridge over the river channel 26 based on the road polygon data. The bridge extracting means M6 of the first embodiment extracts the bridge 24 adjacent to the river channel 26 as the river channel polygon 27 in the extracted river channel 26. At this time, as shown in FIG. 5D, for a pair of line segments 24a constituting the edge of the bridge 24, a line segment 24b that connects one end and the other end of the line segment in the counterclockwise direction as an example is derived. A region (polygon) surrounded by the line segments 24 a and 24 b is extracted as a river bridge polygon 27. In the first embodiment, the method of extracting the river bridge polygon 27 from the line segments 24a and 24b is exemplified, but the present invention is not limited to this. For example, if the map data is provided with information identifying that it is a bridge over the river (river bridge), the river bridge polygon 27 can be extracted based on the given information. .

FIG. 6 is an explanatory diagram of a continuous river channel generated from the river channel data shown in FIG.
The continuous river channel generation means M7 connects the river channels 26 cut by the bridge 24 on the basis of the river channel 26 extracted by the river channel extraction unit M5 and the bridge 24 extracted by the bridge extraction unit M6. (Continuous river polygon) 29 is generated. Specifically, the continuous river channel generation means M7 of the first embodiment generates the continuous river channel polygon 29 by connecting the river channel polygon 26 and the river channel polygon 27.

FIG. 7 is an explanatory diagram of the block polygon extracted based on the map data shown in FIG.
The city block extracting unit M8 extracts (generates) city block polygons based on the city block / river channel polygon 22 extracted by the city block / river channel extracting unit M4 and the continuous river channel 29 generated by the continuous river channel generating unit M7. In the block extracting means M8 of the first embodiment, the continuous river channel 29 is cut out (removed) from the block / river channel polygon 22, and the remaining portion is extracted (generated) as a block polygon 30 as shown in FIG. The

FIG. 8 is an explanatory diagram for explaining an example of division into road elements, FIG. 8A is an explanatory diagram of a road before division, FIG. 8B is an explanatory diagram of a state where an intersection and a single road are separated, and FIG. It is explanatory drawing of the state which divided | segmented the road part into the preset road element.
The road element generation means M9 separates the intersection of the road and the single road portion based on the road polygon data, and divides the single road portion into road elements according to a preset length. In FIG. 8, with respect to the intersecting road 31 shown in FIG. 8A, the road element generation means M9 divides the road 31 into a single road portion 32 that is a portion without intersection (or branching) and a plurality of single road portions 32. Is divided into intersecting portions 33 that intersect (or branch or merge). And each single road part 32 is divided | segmented into the road element 32a according to the preset length L1 along the direction where the single road part 32 is extended.

  The road element generation means M9 according to the first embodiment is configured so that the road element 32a is located at the center in the width direction when the width is equal to or larger than the preset width L2 with respect to the width direction of each single road portion 32. Divide further into Therefore, in each road element 32a, it is possible to analyze the water flowing from the adjacent road element 32a or the block 30. Further, the road element generation means M9 of the first embodiment also divides the continuous river channel polygon 29 into river channel elements according to a preset length L1. For each river channel element, it is possible to calculate and analyze not only the rainwater flowing from the road element 32a but also the amount of river water flowing from the upstream river channel element.

  The block dividing means M10 divides the area inside the block polygon 30 based on the map data. When the block dividing means M10 of the first embodiment includes boundary line data such as a vegetation world, an arable land world, a zone boundary, a fence, and a fence inside the block polygon 30, each block is based on the boundary line data. The interior of the polygon 30 is divided according to the use situation such as vegetation and arable land. If the block polygon 30 does not include boundary data, the block polygon 30 is not divided.

9 is an explanatory diagram of an example of a block polygon, FIG. 9A is an explanatory diagram when a plurality of buildings exist in the block, FIG. 9B is an explanatory diagram when a buffer is generated in FIG. 9A, and FIG. 9C is a plane Voronoi FIG. 9D is an explanatory diagram in the case where the block is divided by the division method, and FIG.
The building polygon generation means M11 generates the building polygon 36 based on the building perimeter data included in the map data. In FIG. 9, the building polygon generation means M11 is a building polygon 36 which is a polygon surrounded by building outer periphery data specifying the outer periphery of the building in the area inside each block polygon 30 processed by the block dividing means M10. Is generated.

  The controlled area extracting means M12 generates a site that is the controlled area of the building polygon 36. 9A and 9B, the dominating region extraction means M12 of the first embodiment generates a buffer 37a of approximately 5 m from each building polygon 36 and generates a polygonal region surrounded by the buffer 37a as the buffer polygon 37. . Therefore, the buffer polygon 37 is slightly larger than the building polygon 36. Therefore, when the shape of the building polygon 36 is intricate or there is a structure such as a small storeroom in the vicinity of the building, a region that includes and envelopes them is generated as the buffer polygon 37. The

The site generation means M13 generates a site that is the dominant area of the building based on the building perimeter data in the block 30 extracted by the block extraction means M8. As shown in FIGS. 9B to 9D, the site generation means M13 uses the surface polygonal division method using the buffer polygon 37 generated by the dominant area extraction means M12 using the building polygon 36 based on the building perimeter data. Is used to generate a site 38 which is a controlled area. Here, the Voronoi division method is a well-known region division method also called the Thiessen method, and the Voronoi division method (point Voronoi division method) is a perpendicular bisector of line segments that connect points to a plurality of points. Is the division method with the boundary of the dominating area (site) at that point. In the surface Voronoi division method, as shown in FIG. 9C, the site 38 is generated with the vertical bisector of the line segment 41 that is the shortest distance between the surfaces (polygons) 37 instead of the points as the boundary 38a of the site 38. To do.
In the first embodiment, when the surface Voronoi division method is performed, if the building polygon 36 is too small, the accuracy of the surface Voronoi division may deteriorate, and the dominant region extraction unit M12 generates the buffer 37a. The surface (polygon) that is the target of surface Voronoi division must have a certain size. Therefore, when the region is divided by a method different from the plane Voronoi division, it is not essential to generate the buffer 37a, and it can be performed as necessary.

  The attribute assigning means M14 has a map symbol discriminating means M14a and a site dividing means M14b. Based on the map symbol data, the attribute giving means M14 specifies attribute information for identifying the status of the land in the site 38 generated by the site generating means M13. Is granted.

FIG. 10 is an explanatory diagram of an example of assigning an attribute based on a map symbol, FIG. 10A is an explanatory diagram of an example of a site to which a map symbol is assigned, and FIG. 10B is a diagram of dividing the site shown in FIG. 10A by the point Voronoi division method FIG. 10C is an explanatory diagram of a result of division by the point Voronoi division method of FIG. 10B.
The map symbol discrimination means M14a discriminates the position to which the map symbol is assigned and the type of the map symbol based on the map symbol data. In the example shown in FIG. 10A, the map symbol discriminating means M14a includes, in the site 38, the positions and contents of map symbols 51, 52, and 54 that specify broadleaf forests (green spaces) and map symbols 53 that specify the ground. Distinguish green and ground). Note that the map symbols are not limited to those illustrated, but can be discriminated for any used symbols. For example, map symbols relating to green spaces include “broad-leaved forest”, “coniferous forest”, “bamboo forest”, “yes pine forest”, “Shinochi”, “palmaceous forest”, and the like.

When a plurality of different map symbols are included in the area, the site 38 is subdivided by the point Voronoi division method.
10B, in the site dividing means M14b of the first embodiment, when the point Voronoi division is performed with the positions of the map symbols 51 to 54 as the points 51 to 54, line segments 56, 57, 58 is generated. In the site division means M14b of the first embodiment, a polyline (line segments 56 to 58, line segments 56 to 58, so as to construct an irregular triangle network having the map symbols 51 to 54 as vertices for the region of the site 38 including a plurality of map symbols. TIN line). When only two map symbols (points) are included, a polyline connecting the two points is generated. Here, the line segment is generated only when the attribute of the map symbol is different, for example, between the point 51 and the point 53, and the same kind as the point 51-point 52. It is also possible to adopt a method in which no line segment is generated between the map symbols.

  In the site division means M14b according to the first embodiment, when the line segments 56 to 58 pass through the building polygon 36, the intersection 59 between the line segments 56 and 57 and the building polygon 36 is set to the points 59a and 59b for point Voronoi division. , 59c, 59d. At this time, the intersection point 59 is set to a point 59 having the same attribute as the end (points 51, 52, 54) close to the line segments 56, 57. Specifically, in FIG. 10B, the intersection 59 a is set as “green space” having the same attribute as the point 51, and the intersection 59 b is set as “ground” having the same attribute as the point 53. Similarly, the intersection point 59 c is set to “green ground” that has the same attribute as the point 52, and the intersection point 59 d is set to “ground” that has the same attribute as the point 53. In this way, intersections 59a to 59d are generated and attributes are assigned to perform point Voronoi division so that the building becomes a clear boundary for land use and the influence of map symbols does not extend across the building. Is possible.

  Further, the site division means M14b of the first embodiment performs division in consideration of the influence range of green space. Here, the map symbols having the land use information are mixed with those representing the land use of the block such as the ground and those indicating vegetation such as the broadleaf forest. The map symbol indicating vegetation expresses the land use of the area by the distribution of multiple map symbols.For example, when there is a planting zone around the ground, the map symbol corresponding to the green space is distributed in a line shape doing. For this reason, if a point symbol of a tree planting and other map symbols are treated as equivalent and a point Voronoi division is performed, an excessively large green area is extracted. In order to solve this problem, division is performed in consideration of the influence range of the green space. Specifically, since the influence range of the green map symbol is determined to be about 5 m from visual observation of an aerial photograph or the like, 10 m, which is twice the influence range from the green map symbol 54 on the TIN line 58. A point 61 having the attribute of the side that is not green (the ground 53 that is the end opposite to the green area 54 of the TIN line 58) is generated. Here, the reason that the influence range is doubled is that when a point Voronoi division is performed, a dividing line (boundary line) is drawn at the middle of the two points, that is, the position of the influence range. .

  Based on the points 51 to 54, 59a to 59d and 61 generated in this way, as shown in FIG. 10B, the point Voronoi division, that is, the perpendicular bisector of the line connecting the points is used as a boundary. A line segment 62 is generated. And the attribute according to the attribute of each point 51-54, 59a-59d, 61 contained in the area | region 63a-63k is provided with respect to the area | region 63a-63k divided | segmented by the line segment 62 or the building polygon 36. . And when the attribute of an adjacent area | region is the same, an area | region is connected and it becomes one area | region. Therefore, in FIG. 10B, all of the regions 63a to 63d are “green space”, and thus are integrated into the region 63a ′ as shown in FIG. 10C. Similarly, in FIG. 10B, the regions 63f to 63h, 63j are adjacent and all become “ground”, and thus are integrated into the region 63f ′ as shown in FIG. 10C. Note that the regions 63e and 63i do not have a map symbol in the range surrounded by the building polygon 36 and the line segment 62, and therefore, the “interspace” attribute is specified to specify that the region has no map symbol. The

The runoff analysis program AP2 performs analysis on water runoff such as water flow during rainfall and river overflow based on the polygon type ground surface feature data created by the polygon type ground surface feature data creation program AP1. . The runoff analysis program AP2 is similar to the conventional runoff analysis programs described in Patent Documents 1 to 3 using grid type map data except that polygon type ground surface feature data is used. It is possible to use a runoff analysis program.
In the runoff analysis program AP2, when determining the water flow, in the polygonal surface feature data, the water permeation characteristic data is associated with each attribute (road, building, green space, ground, etc.). Therefore, it is necessary to assign the degree of water penetration. In addition, it is necessary to assign altitude data to each block 30, road element 32a, and intersection 33 to determine and set the direction of water flow (from the high altitude side to the low side). As for the altitude, since there is a 5m square mesh altitude data map, it can be assigned by applying it so that it overlaps (superimposes layers) on the polygonal surface feature data. Is possible. At this time, as the elevation, for example, the elevation corresponding to the centroid (center of gravity) of the road element 32a, the river channel polygon 26, the building polygon 36, and the respective areas 63a ′, 63e, 63i, 63f ′, 63k of the site is adopted. Is possible.

(Explanation of flowchart of Example 1)
Next, a control flow in the computer main body 12 according to the first embodiment will be described with reference to a flowchart, a so-called flowchart.

(Explanation of flowchart of polygon-type ground surface feature data creation processing sensor arrangement setting processing in computer main body 12)
FIG. 11 is an explanatory diagram of a flowchart of polygon-type ground surface feature data creation processing according to the first embodiment.
The process of each step ST in the flowchart of FIG. 11 is performed according to a program stored in the computer main body 12. This process is executed in parallel with other various processes of the computer main body 12.
The flowchart shown in FIG. 11 is started when the polygon type ground surface feature data creation program AP1 is started.

In ST1 of FIG. 11, the GIS data of the area for which the polygon type ground surface feature data is to be created is acquired. Then, the process proceeds to ST2.
In ST2, the road edge 21a is extracted from the GIS data. Then, the process proceeds to ST3.
In ST3, the block / river channel polygon 22 is generated from the area surrounded by the road edge 21a. Then, the process proceeds to ST4.
In ST4, the block / river polygon 22 is cut out from the GIS data to create the road polygon 21. Then, the process proceeds to ST5.
In ST5, the area surrounded by the bridge and the water line is extracted as a river polygon 26 from each block / river polygon 22. Then, the process proceeds to ST6.

In ST 6, the area sandwiched by the river polygon 26 from the road polygon 21 is extracted as the river bridge polygon 27. Then, the process proceeds to ST7.
In ST7, the river channel polygon 26 and the river channel polygon 27 are connected to create a continuous channel polygon 29. Then, the process proceeds to ST8.
In ST8, a block polygon 30 in which the continuous channel polygon 29 is excluded from the block / river polygon 22 is created. Then, the process proceeds to ST9.
In ST9, the following processes (1) and (2) are executed, and the process proceeds to ST10.
(1) The road 31 is divided into a single road portion 32 and an intersection portion 33.
(2) The divided single road portion 32 is divided into road elements 32a according to a preset length L1.

In ST10, in each block polygon 30, the block polygon is divided based on the boundary line data. Then, the process proceeds to ST11.
In ST11, a building polygon 36 is generated from the building perimeter line. Then, the process proceeds to ST12.
In ST12, a buffer area 37 is generated in the building polygon 36. Then, the process proceeds to ST13.
In ST13, the area divided based on the boundary line data from the block 30 is divided by the surface Voronoi method based on the building polygon 36 to generate the site 38. Then, the process proceeds to ST14.
In ST14, the positions and contents of the map symbols 51 to 54 are extracted from the map data. Then, the process proceeds to ST15.

In ST15, the area is divided for each site 38 by the point Voronoi method based on the map symbols 51 to 54. Then, the process proceeds to ST16.
In ST16, attributes are assigned to the divided area 63 of the site 38 based on the map symbols 51 to 54 (in this case, adjacent areas having the same attribute are integrated). Then, the polygon type ground surface feature data creation process is terminated.

(Operation of Example 1)
In the runoff analysis system S of the first embodiment having the above-described configuration, when the polygon-type surface feature data creation program AP1 is started, GIS data is acquired based on the GIS data, and the road polygon 21, the block / river channel are acquired. A polygon 22 is generated. Then, the river channel polygon 26 and the river channel bridge polygon 27 are automatically extracted, and a continuous river channel polygon 29 is generated. Further, after the road 21 is separated into the single road portion 32 and the intersection portion 33, the single road portion 32 is divided into road elements 32a. In the block polygon 30, first, after dividing the polygon based on the boundary line data, a site 38 is generated according to the building polygon 36. Further, the site 38 is divided based on the map symbols 51 to 54 and given attributes. In this way, polygon-type ground surface feature data having continuous river channel polygons 29, with regions subdivided according to building polygons 36 and map symbols 51-54, and attributes are automatically created. The Then, runoff analysis is performed using the created polygonal surface feature data.

  Therefore, as described in Patent Documents 1 to 3, in the outflow analysis system S of the first embodiment that automatically generates the continuous river polygon 29 compared to the case of performing the outflow analysis using a grid-type map, Only the portion of the river channel is accurately expressed as the continuous river channel polygon 29. Therefore, compared with the conventional case using a grid type map, in Example 1, it is possible to perform a water outflow analysis with high accuracy. In particular, in the first embodiment, the continuous river channel polygon 29 is automatically generated, and labor and time can be greatly reduced as compared with the conventional technique in which the river channel is manually determined.

Moreover, in Example 1, the road 21 is divided | segmented into the road element 32a, and an outflow analysis is performed linked | related with elevation data. Therefore, it is possible to analyze a state in which water flows from the block 30 to the continuous river channel polygon 29 through the road 21 at the time of rainfall or river flooding. In particular, when a conventional grid-type map is used, each grid may include not only roads with low water permeability but also green spaces, fields, forests, and the like with relatively high permeability. Therefore, the conventional grid-type map can be analyzed only in an approximate form such as the average amount of water flowing through the entire grid, and it is difficult to analyze the exact flow of water. On the other hand, in Example 1, the flow of water can be analyzed and simulated with high accuracy.
Note that it is difficult to determine from which side of the road the water flows with one road polygon 21 without being divided into road elements 32a. By dividing, the water flowing through the road 21 can be analyzed easily and accurately.

  Further, in the first embodiment, a site 38 of the building polygon 36 is generated in the city block 30 to subdivide the city block 30 and the inside of each site 38 is further subdivided based on the map symbols 51 to 54. And attributes are given. Therefore, compared to the case where water can be analyzed only in an approximate form as in a conventional grid-type map, in Example 1, the actual land use status (roads, green spaces, ground, fields, forests, etc.) Accordingly, it is possible to perform analysis with high accuracy.

(Example of change)
As mentioned above, although the Example of this invention was explained in full detail, this invention is not limited to the said Example, A various change is performed within the range of the summary of this invention described in the claim. It is possible. Modification examples (H01) to (H06) of the present invention are exemplified below.
(H01) In the above embodiment, the polygon type ground surface feature data creation program AP1 and the runoff analysis program AP2 have been incorporated into one personal computer 11, but the present invention is not limited to this. That is, the configuration is not limited to the configuration in which the central processing is performed by one information terminal, and it is also possible to adopt a configuration in which each means M1 to M14 is arranged in a plurality of information terminals connected by an internetwork and performs distributed processing. . For example, the map data storage means M1 can be arbitrarily changed, for example, using the one stored in the server of the public office, or incorporating the outflow analysis program AP2 into a local government terminal.

(H02) In the above embodiment, the type, location, number, etc. of the specific map data and map symbols exemplified are the area of the map data to be applied (urban area, local area, etc.), scale, and required analysis. It can be appropriately changed according to the accuracy and the like.
(H03) In the above-described embodiment, it is desirable to perform the process of generating the road element 32a, or to perform the process of subdividing the area based on the map symbol and adding the attribute, but the present invention is not limited to this. For example, if the accuracy is satisfied only by generating the continuous river polygon 29 according to the required accuracy of the runoff analysis, only the continuous river polygon 29 is generated and no other processing is performed. Can be polygon-type ground surface feature data having a grid-type region as in the prior art.

(H04) In the above-described embodiment, the case where the created polygon type ground surface feature data is applied to the flood runoff analysis is exemplified, but the present invention is not limited to this. Since the flood runoff analysis does not consider the water that has penetrated underground, for example, the polygon type surface feature data was applied to the groundwater infiltration recharge analysis, and the water soaked in the underground or fell on the roof It can also be used for analysis when rain flows to underground storage facilities. In addition, it can be applied to evapotranspiration analysis for each feature to analyze the ease of evaporation based on the presence or absence of features and how wet the soil is, and to accurately analyze the effects on temperature and the heat island phenomenon It is also possible to use it.
(H05) In the above embodiment, the partition polygon 30 and the site 38 are divided by using the Voronoi method when dividing the block polygon 30 and the site 38. However, the present invention is not limited to this. For example, the division method can be arbitrarily changed, for example, by dividing the inside of the line segment site 38 parallel to the line segment in the longitudinal direction of the building.

FIG. 12 is an explanatory diagram of a modified example of the embodiment, FIG. 12A is an explanatory diagram of a block polygon as an example before the division, FIG. 12B is an explanatory diagram of a state where the surface Voronoi division is performed, and FIG. FIG. 12D is an explanatory diagram of a state where a site is generated.
FIG. 13 is an explanatory diagram of a modified example, FIG. 13A is an explanatory diagram of a state in which surface Voronoi division is performed in an example different from FIG. 12A, and FIG. 13B is an explanatory diagram in the case of generating a buffer in the example of FIG. FIG. 13C is an explanatory diagram of a state in which a site is generated from the results of FIGS. 13A and 13B.

(H06) In the above-described embodiment, the use of the buffer 37a is illustrated when the site 38 is generated or divided. However, the present invention is not limited to the exemplified configuration. For example, the buffer 37a may not be used (that is, buffer = 0 [m]). Accordingly, it is possible to perform surface Voronoi division based on the outer peripheral line of the building polygon 36. In addition, in a densely populated area where buildings are close to each other, there is a case where the buffers 37a overlap each other or the buffer 37a protrudes outside the block polygon 30 when the buffer 37a is set. Corresponding to such a case, for example, the site 38 can be generated as shown in FIGS. That is, first, as shown in FIGS. 12A and 12B, surface Voronoi division is performed without generating the buffer 37a. Next, as shown in FIG. 12C, the buffer 37a is generated based on a preset distance (maximum influence distance of the building). Then, as shown in FIG. 12D, the overlapping portion of the surface Voronoi division and the buffer 37a, specifically, the edge 30a of the block 30, the line 30b of the surface Voronoi division of FIG. 12B, and the edge of the buffer 37a of FIG. 12C A region surrounded by 37b is generated as a site 38 of each building polygon 36. In such a case, even in a densely populated house as shown in FIG. 13, it is possible to divide the site relatively realistic and close to the actual situation. The area 38 ′ inside the block polygon 30 that has not been determined as the site 38 is assigned a property by similarly applying the attribute assigning means M 14 of the site 38 including the building 36 as a site not including the building 36. It is possible.

11 ... Computer,
21 ... Road,
23 ... Water line,
24, 27 ... the bridge,
26 ... River,
27 ... A bridge over the river,
29 ... continuous river channel,
30 ... Block,
32 ... single path part,
32a ... road elements,
33 ... intersection,
36 ... Building,
38 ... site,
51-54 ... Map symbol,
AP1: Polygon type ground surface feature data creation program,
L1 ... a preset length,
M1 ... Map data storage means,
M5 ... River channel extraction means,
M6: Bridge extraction means,
M7: Continuous river channel generating means,
M9: road element generation means,
M13 ... site generation means,
M14 ... attribute assigning means.

Claims (4)

Computer
Map data storage means for storing map data including at least water line data for specifying a water line which is a boundary between a land part and a water part on a map and road data for specifying a road including a bridge on the map. ,
A river channel extracting means for extracting, as a river channel, an area that includes a lifetime line and is divided by a bridge, based on the road data and the lifetime data;
Bridge extraction means for extracting a bridge over the river channel extracted by the river channel extraction means based on the road data;
Based on the river channel extracted by the river channel extraction unit and the bridge extracted by the bridge extraction unit, the continuous river channel generating unit that connects the river channels cut by the bridge and generates a continuous river channel,
A polygon type ground surface feature data creation program characterized by functioning as Computer
Based on the road data, road element generating means for separating the intersection and the single road part of the road and dividing the single road part into road elements according to a preset length,
The polygon-type ground surface feature data creation program according to claim 1, wherein Computer
Map data storage means for storing the map data, including building perimeter data specifying a building boundary on the map and map symbol data specifying the land status on the map;
In a block surrounded by a road, a site generation means for generating a site that is a controlled area of the building based on the building perimeter data,
Based on the map symbol data, attribute assigning means for assigning attribute information specifying the status of the land to the site generated by the site generating means,
The polygon-type ground surface feature data creation program according to claim 1 or 2, wherein Map data storage means for storing map data including at least water line data for specifying a water line which is a boundary between a land part and a water part on a map and road data for specifying a road including a bridge on the map. ,
A river channel extracting step for extracting, as a river channel, an area that includes a water line and is divided by a bridge, based on the road data and the water line data that identifies a water line that is a boundary between a land part and a water part on a map. When,
Based on the road data, a bridge extraction step of extracting a bridge over the river channel extracted by the river channel extraction means;
Based on the river channel extracted by the river channel extracting means and the bridge extracted by the bridge extracting unit, connecting the river channels cut by the bridge, generating a continuous river channel,
A polygon-type ground surface feature data creation method characterized by executing: