Grid surface identification air traffic control method based on airspace grid digitization

Abstract

The invention discloses a grid surface identification air traffic control method based on airspace grid digitization, and belongs to the technical field of aviation, and the method comprises the following steps: carrying out the modeling based on the to-fly airspace of an aircraft, dividing a grid, and drawing up a grid position code and a surface code: constructing a surface passing identification code, and designing a passing permission rule; generating a structural body and inputting the structural body into an airspace management and control system; and planning an airspace channel and recording the course of the aircraft. The invention provides a fixed grid position and fixed plane informatization management and control mode based on a digital grid airspace, and the method comprises the steps: carrying out the precise boundary definition and attribute representation of each region through setting a grid position code, a plane code, a plane passing identification code, a passing permission rule, a parameter Td and a difference value alpha, according to the method, directional display and management of an airspace grid channel corridor are achieved, the route direction management problem in a digital airspace is solved, open use of part of grid space is achieved under the requirement for lower grid precision, and the increasingly increasing capacity requirement in the future is met through more efficient planning and management.

Description

Technical Field

[0001] The present invention relates to the field of aviation technology, and particularly to an air traffic control method based on grid surface identification through airspace grid digitization. Background Art

[0002] With the continuous growth of the demand in the civil aviation transportation industry, airspace planning is no longer limited to flight safety, but requires more refined and efficient coordination of flight routes to avoid air traffic congestion and improve the utilization rate of airspace resources. To meet the increasing demand for airspace use and refined management, airspace grid division technology can be introduced to discretely control the airspace. By constructing grid systems with different precisions, the flight trajectories of aircraft can be accurately analyzed, and dynamic tracking and quantitative analysis of flight paths can be realized.

[0003] However, in practical applications, the grid division technology has problems of insufficient refinement and lack of directionality in the description and recording of flight routes. Due to the relatively general identification of airspace, it is difficult to accurately distinguish the usage attributes and restriction conditions of different regions. For example, in some airspaces where only one-way traffic is allowed, when using the grid division technology to identify flight routes, the one-way traffic characteristics of this region cannot be accurately reflected, and it may even be misidentified as two-way prohibited traffic, which not only causes waste of airspace resources but also may affect the normal flight plans of aircraft. Summary of the Invention

[0004] The present invention aims to overcome the problems of lack of directionality and insufficient refinement in flight route identification in the prior art, and provides an air traffic control method based on grid surface identification through airspace grid digitization.

[0005] To achieve the above object, the technical solution of the present invention is: providing an air traffic control method based on grid surface identification through airspace grid digitization, including the following steps:

[0006] Modeling based on the to-be-flown airspace of the aircraft, dividing the grid and formulating grid position coding and surface coding;

[0007] Constructing a passing identification code for the surface and designing passing permission rules;

[0008] Generation of the structure: generating a structure based on the grid position coding and the surface coding, inputting the passing identification code for the surface and surface information into the structure, and inputting the constructed structure into the airspace control system;

[0009] Airspace channel planning and route record of the aircraft: According to the grid position encoding, the surface encoding, the surface passage identification encoding on the structure body and in combination with the passage permission rule, conduct airspace channel planning of the aircraft and route record of the aircraft; in the airspace control system, compare the route record with the surface passage identification encoding to determine whether the aircraft is flying illegally.

[0010] In one embodiment, in the step of modeling the to-be-flown airspace based on the aircraft, dividing the grid and formulating the grid position encoding and surface encoding, the sum of the surface encodings of the opposite surfaces in the grid unit is a fixed value.

[0011] In one embodiment, in the step of constructing the surface passage identification encoding and designing the passage permission rule, the surface passage identification encoding includes 1 and 0. 1 is the permission-to-pass identification, and any surface with the surface passage identification encoding of 1 allows the aircraft to fly in and out; 0 is the prohibition-to-pass identification, and any surface with the surface passage identification encoding of "0" prohibits the aircraft from flying in, but allows the aircraft to fly out.

[0012] In one embodiment, in the step of constructing the surface passage identification encoding and designing the passage permission rule, the passage permission rule is: when the surface passage identification encodings of adjacent grid surfaces are both 0, the two surfaces are in a state of prohibiting mutual passage; when the surface passage identification encodings of adjacent grid surfaces are 0 and 1 respectively, only one-way passage is allowed from the surface with the surface passage identification encoding of 0 to the surface with the surface passage identification encoding of 1; when the surface passage identification encodings of adjacent grid surfaces are both 1, the two surfaces are in a state of mutual passage.

[0013] In one embodiment, in the step of constructing the surface passage identification encoding and designing the passage permission rule, use the parameter Td to describe whether the surface passage identification encoding is within the validity period and whether the passage information within the expected time is accurate. The expression of the parameter Td is as follows:

[0014] Td = expected usage time - surface passage identification encoding update time - surface passage identification encoding validity time

[0015] When the value of Td is greater than 0, the surface passage identification encoding is within the validity period and the passage information is accurate and valid; otherwise, the surface passage identification encoding is not within the validity period and the passage information has expired.

[0016] In one embodiment, in the step of airspace channel planning and route record of the aircraft, use the difference α to record the flight direction of the aircraft between adjacent grid units. The expression of the difference α is as follows:

[0017] α = surface encoding of the flying-in surface - surface encoding of the flying-out surface

[0018] Compare the difference α with the surfaces of the aircraft's take-off surface and landing surface in the grid cell through identification codes to determine whether the aircraft has violated the flight rules;

[0019] Each difference α can represent a vector pointing from the center of the take-off grid to the center of the landing grid.

[0020] In one embodiment, in the step of constructing the surface through identification codes and designing the passing permission rules, the surface through identification codes of each surface of any grid cell are independent of each other, and the surface through identification codes of two adjacent surfaces between adjacent grid cells are independent of each other.

[0021] In one embodiment, in the step of generating the above structure, the surface information includes the identification update time, the surface through identification code update time, and the surface through identification code validity time.

[0022] In one embodiment, in the step of modeling the waiting flight airspace of the aircraft, dividing the grid and formulating the grid position code and surface code, the grid position code includes the longitude and latitude division code and the altitude division code, and the longitude and latitude division code and the altitude division code are used to locate the grid cell.

[0023] In one embodiment, in the step of airspace channel planning and the flight route record of the aircraft, when judging the feasibility of moving from any grid cell to an adjacent grid cell, only view the surface through identification code of the surface adjacent to the grid cell in the adjacent grid cell.

[0024] In summary, the present invention provides a grid surface identification air traffic control method based on airspace grid digitization. By setting the grid position code, the surface code, the surface through identification code, the passing permission rule, parameter Td, and difference α, precise boundary definition and attribute characterization are carried out for each region, providing a dynamically manageable and directional solution for the planning of air corridor channels and the description of aircraft flight routes. At the same time, it also provides intuitive and accurate data support for airspace management, effectively improving the safety and efficiency of airspace operation.

[0025] To make the above features and advantages of the invention more obvious and understandable, specific embodiments are hereinafter given and described in detail in conjunction with the accompanying drawings as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a flowchart of a grid surface identification air traffic control method based on airspace grid digitization in the present invention.

[0027] Figure 2Schematic diagram of the surface encoding of the grid unit in the present invention.

[0028] Figure 3 Schematic diagram of the surface passing the identification code and the passing permission rule in the present invention.

[0029] Figure 4 Schematic diagram of the surface passing the identification and the route planning based on the latitude and longitude layer and the height layer in the present invention.

[0030] Figure 5 Schematic diagram of the motion direction recorded by the difference α in the present invention. Detailed implementation manners

[0031] To make the objectives and technical solutions of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0032] Aiming at the problems that the current airspace digital grid subdivision technology lacks directionality in the description and recording of routes and the identification of regions is still too general, a grid surface identification air traffic control method based on airspace grid digitization is proposed. Figure 1 Flowchart of the present invention. As Figure 1 shown, the present invention includes the following steps:

[0033] Step S1: Model based on the to-be-flown airspace of the aircraft, subdivide the grid and formulate the grid position code and surface code;

[0034] Step S2: Construct the surface passing identification code and design the passing permission rule;

[0035] Step S3: Generate a structure based on the grid position code and the surface code, input the surface passing identification code and surface information into the structure, and input the constructed structure into the airspace control system;

[0036] Step S4: Perform airspace channel planning for the aircraft and record the route of the aircraft according to the grid position code, the surface code, the surface passing identification code on the structure and in combination with the passing permission rule; in the airspace control system, compare the route record with the surface passing identification code to determine whether the aircraft is flying illegally.

[0037] It should be noted that the above step sequence is not fixed and can be adjusted according to actual needs.

[0038] In step S1, during the process of digitizing and modeling the airspace, preferably, the cylindrical projection method can be adopted to convert the airspace into a digital model of a two-dimensional plane, and further combined with height elements to establish a three-dimensional airspace model.

[0039] After the modeling is completed, the airspace model will be discretely meshed according to longitude-latitude-height, and the meshing standard and precision can be set according to the situation. For example, the mesh dissection is performed with a minimum longitude of 5°, a minimum latitude of 5°, and a minimum height of 100 meters.

[0040] Each of the meshed grid cells will be position-coded, and the face code of each grid face will be defined to obtain the grid position code and the face code.

[0041] The grid position code includes a longitude-latitude division code and a height division code. The establishment of the longitude-latitude division code and the height division code helps to quickly locate the grid cell. During the setting process of the grid position code, binary coding methods including but not limited to can be selected. For example, the number of binary coding digits can be limited according to the number of levels divided by the dissection precision, so that the binary coding positions occupied by each precision are the same, that is, the number of binary coding digits of each grid cell under the same precision level is the same.

[0042] Based on the grid position code, each face of each grid cell will be coded. As Figure 2 shown, during the coding process, a spatial rectangular coordinate system is established, and the three axes of the spatial rectangular coordinate system are defined as south, east, and up. Taking any grid cell as an example, the grid cell is placed in the spatial rectangular coordinate system, and the center of the grid cell is located at the origin. For the convenience of representation, the vertices of the grid cell are defined as letters a-h, where the vertex (west, north, down) is a, the vertex (west, south, down) is b, the vertex (west, south, up) is c, the vertex (west, north, up) is d, the vertex (east, north, down) is e, the vertex (east, south, down) is f, the vertex (east, south, up) is g, and the vertex (east, north, up) is h. Preferably, the faces of the grid cell are coded using integer-type numbers for more intuitive reading. At the same time, in order to quickly match the adjacent faces between any two adjacent grid cells during the application process, the sum of the face codes of the opposite faces in all grid cells will be set to a fixed value. For example, the faces of the unit grid are coded with the numbers 0-5. By Figure 2It can be known that the face code of the face formed by vertices a - b - c - d is 0, the face code of the face formed by vertices a - e - h - d is 1, the face code of the face formed by vertices a - b - f - e is 2, the face code of the face formed by vertices c - d - h - g is 3, the face code of the face formed by vertices b - c - g - f is 4, and the face code of the face formed by vertices e - f - g - h is 5. Among them, the face formed by vertices a - b - c - d and the face formed by vertices e - f - g - h (see Figure 2 (A)), the face formed by vertices a - e - h - d and the face formed by vertices b - c - g - f (see Figure 2 (B)), the face formed by vertices a - b - f - e and the face formed by vertices c - d - h - g (see Figure 2 (C)) are all opposite faces, and the sum of the face codes between opposite faces is a fixed value of 5. In the subsequent airspace channel planning process, if it is necessary to move from the current grid cell to an adjacent grid cell, it is necessary to pass through the face with the face code of n (n ∈ Z, n ∈ [0, 5]) in the current grid cell and the adjacent grid face of the face with the face code of 5 - n in the adjacent grid cell. Then, only the face passing identification code of the face with the face code of 5 - n needs to be viewed.

[0043] Furthermore, in order to more efficiently implement the air traffic route planning management in airspace digitization, a face passing identification code will be added to each face of each grid cell. In step S2, the face passing identification code includes "1" and "0". It is stipulated that the identification "1" is the permission - to - pass identification, that is, in any grid cell, the face with the face passing identification code of "1" is the face allowed to pass within the grid cell; and it is stipulated that the identification "0" is the prohibition - to - pass identification, that is, in any grid cell, the face with the face passing identification code of "0" is the face that is prohibited from flying into but can fly out within the grid cell (see Table 1).

[0044] Table 1 Face Passing Identification and Its Functions

[0045]

[0046] In addition, the face passing identification codes of each face of any grid cell are independent of each other, and the face passing identification codes of two adjacent faces between adjacent grid cells are independent of each other. The face passing identification code can more intuitively reflect the available parts (i.e., the faces allowed to pass) in each grid cell, reducing the accuracy requirements for grid route planning to a certain extent; and the face passing identification code provides a solution to the problem of difficult implementation of passage permission management in a specified direction in digital airspace (such as the take - off / landing ports of airports).

[0047] According to the surface, corresponding passage permission rules can be formulated through identification coding to reflect the passage conditions between adjacent grids. Combined with Figure 3 It can be known that when the surface passage identification codes of a group of adjacent grid surfaces are all "0", the passage requests between the two surfaces are not allowed, and they are in a state of prohibiting mutual passage; when the surface passage identification codes of a group of adjacent grid surfaces are "0" and "1" respectively, only one-way passage is allowed from the surface with the surface passage identification code of "0" to the surface with the surface passage identification code of "1"; when the surface passage identification codes of a group of adjacent grid surfaces are all "1", the mutual passage permission between the two surfaces is opened. Preferably, if an aircraft wants to move from the current grid cell to an adjacent grid cell, it only needs to check the surface passage identification code of the surface adjacent to the grid cell in the adjacent grid cell. If the surface passage identification code of the adjacent surface is 1, the aircraft can pass smoothly; if the surface passage identification code of the adjacent surface is 0, the aircraft cannot pass.

[0048] In addition, in order to ensure passage efficiency and traffic safety, the timeliness of the surface passage coding will be limited. By comparing the estimated passage time of the target grid cell, the update time of the surface passage identification code stored in the structure body, and the valid time of the surface passage identification code, it is confirmed whether the surface passage identification code is within the valid period and whether the passage information within the estimated time is accurate. The timeliness of the surface passage coding and the accuracy of the passage information can both be intuitively described by the parameter Td:

[0049] Td = Estimated usage time - Surface passage identification code update time - Surface passage identification code valid time

[0050] Among them, both the estimated usage time and the identification update time are time points; the valid time of the identification code is the length of the time period, that is, the duration. When the Td value is greater than 0, the surface passage identification code is within the valid period and the passage information is accurate and valid; otherwise, the surface passage identification code is not within the valid period and the passage information has expired, and the passage information needs to be manually confirmed.

[0051] In step S3, a structure array is used to record the grid position coding, the surface coding, the surface passage coding, and the surface information. The surface information includes but is not limited to the update time of the surface passage identification code, the valid time of the surface passage identification code, the parameter Td, and the meteorological information within the grid. If you need to query / change / call relevant information, just operate according to the viewing / modifying method of the structure array.

[0052] In step S4, the airspace channel planning includes but is not limited to one-way channel planning, two-way channel planning, and variable channel planning.

[0053] In the one-way channel planning, such asFigure 4 As shown in (A), the surfaces of adjacent grid faces of each grid cell along the same longitude or latitude direction can be set to "0|1" or "1|0" through identification coding, and the aircraft will pass unidirectionally from the surface with identification coding "0" to the surface with identification coding "1"; or the longitude and latitude elements can be fixed, and only the change of altitude element is considered. For example, Figure 4 As shown in (B), the surfaces of each adjacent upper and lower grid face are coded as or When, the aircraft can move up or down within a certain altitude.

[0054] In the two-way channel planning, as Figure 4 As shown in (C), each adjacent grid face of each grid cell along a certain longitude or latitude direction can be set to "0|1", and each adjacent grid face of each grid cell along another longitude or latitude direction can be set to "1|0", and the adjacent grid faces between the two opposite channels are all set to Different aircraft can move relatively in the two completely separated opposite channels. Or only the altitude and longitude elements can be used as variables, and the latitude element between a certain group of the grid cells is fixed. For example, Figure 4 As shown in (D), the surfaces of each adjacent upper and lower grid face of the grid cell are coded as The latitude element between another group of the grid cells is also fixed, and the surfaces of each adjacent upper and lower grid face of it are coded as The adjacent grid faces between the two opposite channels are "0|0", so as to realize the opposite flight of ascending or descending in the two adjacent channels. Similarly, other methods of the two-way channel planning can also be carried out according to the surface identification coding and the passing permission rules.

[0055] Furthermore, when the air traffic flow increases, the variable lane planning can be carried out to realize the stratification and diversion of the air traffic flow in altitude. When carrying out the variable channel planning, if only the longitude and latitude levels are considered, as Figure 4 As shown in (E), on the basis of the one-way channel planning, the surfaces of each adjacent face between two groups of adjacent grid cells can be set with identification coding as Then the aircraft can carry out two-way lane change between the adjacent grid cells in the same direction; as Figure 4 As shown in (G), the surfaces of each adjacent face between two groups of adjacent grid cells can also be set with identification coding as or Then the aircraft can carry out one-way lane change between the adjacent grid cells in the same direction. If only the lane change at the altitude level is considered, as Figure 4As shown in (F), based on the one-way channel planning, the surfaces of the adjacent upper and lower faces between two adjacent grid units can be set with identification codes as indicating that the bottom end of the upper grid unit and the top end of the lower grid unit are open to each other, which means that the aircraft can freely change lanes within a certain altitude; for example Figure 4 As shown in (H), the surfaces of the adjacent upper and lower faces can also be set with identification codes as or to provide conditions for the aircraft to change lanes unidirectionally up and down. Similarly, other methods of variable lane planning can also be carried out according to the surface identification code and the passing permission rule.

[0056] In addition, the flight route is recorded by the difference between the surface codes of the flying-in surface and the flying-out surface. The specific method is as follows: when the aircraft crosses different grid units, record the digital number of the flying-out surface and the digital number of the flying-in surface, and the difference obtained by subtraction is α. The difference α is used to confirm the flight direction of the aircraft between adjacent grid units. The expression of the difference α is as follows:

[0057] α = surface code of the flying-in surface - surface code of the flying-out surface

[0058] Combined with Table 2 and Figure 5 it can be seen that due to the characteristic that the sum of the surface codes of adjacent grid surfaces is fixed, the number of the differences α is limited. Taking the sum of the surface codes of adjacent grid surfaces as 5 as an example, the differences α are ±1, ±3, and ±5 respectively. The specific numerical sources and flight direction descriptions are shown in Table 2.

[0059] Table 2 Relationship between the difference α, the surface code of the flying-in surface, the surface code of the flying-out surface, and the flight direction

[0060]

[0061] Each difference α can represent a vector pointing from the center of the flying-out grid to the center of the flying-in grid. By checking multiple recorded differences α, the traveled route of the aircraft's directionality can be obtained, realizing the discretization and directional expression of the flight route under airspace digitization. By comparing the difference α, the surface identification code, and the passing permission rule, it can be further judged whether the aircraft is flying illegally. For example, when the aircraft flies from one grid unit into an adjacent grid unit, the difference α is recorded as -5, which indicates that the aircraft has passed through the surface with the surface code of "5" (flying-out surface) of a certain grid unit and the surface with the surface code of "0" (flying-in surface) of another grid unit, and the permission for these two surfaces is "0 (flying-out surface)|0 (flying-in surface)", so it can be judged that the aircraft has flown illegally.

[0062] In summary, the present invention provides an air traffic control method for grid surface identification based on spatial domain grid digitization. By setting the grid position code, the surface code, the surface passing identification code, the passing permission rule, parameter Td, and difference α, precise boundary definition and attribute characterization are carried out for each region, providing a dynamically manageable and directional solution for the planning of air corridor channels and the description of aircraft routes. At the same time, it also provides intuitive and accurate data support for airspace management, effectively improving the safety and efficiency of airspace operation.

[0063] Although the present invention has been disclosed above by way of examples, it is not intended to limit the present invention. Any person with ordinary knowledge in the relevant technical field may make some modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to that defined by the appended patent application scope.

Claims

1. An air traffic control method for grid surface identification based on airspace grid digitization, characterized in that It includes the following steps: Model based on the waiting flight airspace of the aircraft, divide the grid and formulate the grid position coding and surface coding; Construct the surface passing identification coding and design the passing permission rules; Generation of the structure: Generate a structure based on the grid position coding and the surface coding, input the surface passing identification coding and surface information into the structure, and input the constructed structure into the airspace control system; Airspace channel planning and flight route recording of the aircraft: According to the grid position coding, the surface coding, the surface passing identification coding on the structure and in combination with the passing permission rules, conduct airspace channel planning for the aircraft and record the flight route of the aircraft; In the airspace control system, compare the flight route record with the surface passing identification coding to determine whether the aircraft is flying illegally.

2. The air traffic control method for grid surface identification based on airspace grid digitization according to claim 1, wherein In the step of modeling based on the waiting flight airspace of the aircraft, dividing the grid and formulating the grid position coding and surface coding, the sum of the surface codings of the opposite surfaces in the grid unit is a fixed value.

3. The air traffic control method for grid surface identification based on airspace grid digitization according to claim 2, wherein In the step of constructing the surface passing identification coding and designing the passing permission rules, the surface passing identification coding includes 1 and 0. 1 is the permission to pass identification. Any surface with the surface passing identification coding of 1 allows the aircraft to fly in and out; 0 is the prohibition to pass identification. Any surface with the surface passing identification coding of "0" prohibits the aircraft from flying in, but allows the aircraft to fly out.

4. The air traffic control method for grid surface identification based on spatial domain grid digitization according to claim 3, wherein In the step of constructing the surface passing identification coding and designing the passing permission rules, the passing permission rules are as follows: When the surface passing identification codings of adjacent grid surfaces are both 0, the two surfaces are in a state of prohibiting mutual passage; When the surface passing identification codings of adjacent grid surfaces are 0 and 1 respectively, only one-way passage is allowed from the surface with the surface passing identification coding of 0 to the surface with the surface passing identification coding of 1; When the surface passing identification codings of adjacent grid surfaces are both 1, the two surfaces are in a state of mutual passage.

5. The method for air traffic control with grid surface identification based on airspace grid digitization according to claim 1, wherein In the step of constructing the surface passing identification coding and designing the passing permission rules, use the parameter Td to describe whether the surface passing identification coding is within the validity period and whether the passing information within the expected time is accurate. The expression of the parameter Td is as follows: Td = expected usage time - surface passing identification coding update time - surface passing identification coding validity time When the value of Td is greater than 0, the surface passing identification coding is within the validity period and the passing information is accurate and valid; otherwise, the surface passing identification coding is not within the validity period and the passing information has expired.

6. The air traffic control method for grid surface identification based on spatial domain grid digitization according to claim 1, wherein In the step of airspace channel planning and flight route recording of the aircraft, use the difference α to record the flight direction of the aircraft between adjacent grid units. The expression of the difference α is as follows: α = surface coding of the flying-in surface - surface coding of the flying-out surface Compare the difference α with the surface passing identification codings of the flying-out surface and the flying-in surface of the aircraft in the grid unit to determine whether the aircraft has flown illegally; Each difference α can represent a vector pointing from the center of the flying-out grid to the center of the flying-in grid.

7. The method for air traffic control of grid surface identification based on spatial domain grid digitization according to claim 3, wherein, In the step of encoding the construction surface through identification and designing through the approval rule, the surface through identification encoding of each surface of any one of the grid cells is independent of each other, and the surface through identification encoding of two adjacent surfaces between adjacent grid cells is independent of each other.

8. A grid surface identification air traffic control method based on airspace grid digitization according to claim 1, characterized in that, In the step of generating the above-mentioned structure, the surface information includes the time for updating through identification, the time for updating the surface through identification encoding, and the valid time of the surface through identification encoding.

9. The air traffic control method for grid surface identification based on airspace grid digitization according to claim 1, wherein, In the step of modeling the to-be-flown airspace based on the aircraft, dividing the grid and formulating the grid position encoding and surface encoding, the grid position encoding includes the longitude and latitude division code and the altitude division code, and the longitude and latitude division code and the altitude division code are used to locate the grid cell.

10. A method for air traffic control of grid surface identification based on spatial domain grid digitization according to any one of claims 2-4, characterized in that, In the step of planning the airspace channel and recording the flight route of the aircraft, when judging the feasibility of moving from any one grid cell to an adjacent grid cell, only the surface through identification encoding of the surface adjacent to the grid cell in the adjacent grid cell is viewed.

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