Railway right-of-way modeling method, computer program and associated device

Abstract

The invention relates to a method for modeling railway right-of-way, comprising the steps: assigning each point of a point cloud to a corresponding cell of a horizontal (xOy) plane mesh; for each cell, calculating a corresponding height; determining the membership of each cell, based on the corresponding height, to a respective class; distributing the cells belonging to a "structure" class into sets of cells, each belonging to the same structure (48); for each set of cells, detecting at least one end portion (50) of the corresponding structure (48); for each end portion (50), assigning to the structure the unassigned cells located opposite the end portion (50); and for each structure, associating said structure (48) with the points belonging to the cells corresponding to said structure (48). Figure 8

Description

Title of the invention: Method for modeling railway right-of-way, computer program and associated device. Technical field

[0001] The present invention relates to a method for modelling railway right-of-way.

[0002] The invention also relates to a computer program and a device implementing such a method.

[0003] The invention applies to the field of monitoring engineering structures, hydraulic structures, or any other underground structure located on a railway network. Prior art

[0004] Tunnels are complex linear engineering structures whose characteristics depend on the nature of the terrain (rocks, friable soils, presence of aquifers), their method of drilling / excavation and construction (tunnel boring machine, cutter, etc.), as well as the geographical context (urban tunnel, number of lanes, electrified line, etc.).

[0005] Operations carried out in tunnels require the implementation of measures adapted to the confined environment. Therefore, knowledge of the tunnel's configuration is essential for optimally preparing maintenance interventions in advance and thus ensuring the safety of personnel. Knowledge of the three-dimensional details of the tunnels is essential to guarantee the safety, durability, and efficiency of operations related to tunnel maintenance and operation.

[0006] Databases listing such works generally include diagrams detailing the access points, niches and other elements of said works.

[0007] However, location errors have been observed in such databases. It has also been observed that the distances between these elements, their respective geographical positions, and the tunnel height are not always mentioned therein.

[0008] However, knowing the height of a tunnel is important because it allows one to determine the amount of soil present above the tunnel and thus prevent risks related to the geological environment of the structure. This knowledge also allows compliance with the DT / DICT regulations ("Declaration of Works", "Declaration of Intent to Commence Works") to ensure the safety of work near tunnels.

[0009] To determine the height of a tunnel and the exact position of the niches, it has been proposed to carry out manual surveys using agents moving on foot along the railway network (particularly in the tunnels) and equipped with GPS (Global Positioning System), total stations and rangefinders.

[0010] However, such a method does not give complete satisfaction.

[0011] Indeed, the accuracy of geographical positioning can be greatly altered in tunnel areas, particularly in mountainous areas (absence of GPS signal).

[0012] In addition, to calculate the three-dimensional position at each point of the tunnel with good accuracy, specific topographic measurements must be implemented by surveyors from reference measurement points, the accessibility of which may be compromised.

[0013] Besides the difficulty of determining a reliable geographical position, surveying the elements of a tunnel by a walking tour is very time-consuming and is made difficult by the lack of light in the tunnel.

[0014] Moreover, the narrow configuration of the tunnels constitutes a significant danger when agents are moving around in the event of rail traffic.

[0015] One object of the present invention is to remedy at least one of the drawbacks of the prior art.

[0016] Another object of the invention is to propose a method for modelling a railway track which is automatic and reliable. Description of the invention

[0017] To this end, the invention relates to a method of the aforementioned type, the method being implemented by computer and comprising the following steps: • from a cloud of points representing solid surfaces seen radially by a moving object traveling along a railway, each point being associated with a set of respective coordinates in a predetermined three-dimensional frame, a vertical axis of the three-dimensional frame being oriented parallel to the direction of the gravitational field, and being orthogonal to a horizontal plane comprising the other two axes of the three-dimensional frame, assignment of each point to a corresponding mesh of a predetermined mesh of the horizontal plane, according to the coordinates of said point in the horizontal plane; • for each mesh, calculation of a corresponding height, equal to a difference between the maximum and minimum coordinates, along the vertical axis, of the points assigned to said mesh; • determination of the membership of each mesh, according to the corresponding calculated height, to a class of unaffected meshes, to a class of excluded meshes, to a structure, or to a low zone of the railway, in which the rails are not locally arranged in a structure; • distribution of stitches belonging to a work into sets of stitches each belonging to the same work; • for each set of meshes belonging to the same structure, detection of at least one end portion of said structure; • for each detected end portion, the first assignment to the corresponding work of unassigned meshes belonging to a sector of the horizontal plane that extends along a longitudinal axis of the end portion, and which presents, transversely, a predetermined extent around said longitudinal axis; and • for each work, association of said work with the points belonging to the meshes corresponding to said work.

[0018] Indeed, thanks to such a process, a reliable and precise 3D mapping of each structure is carried out, so that characteristics of the structure (contour, entrances, niches) are likely to be precisely located.

[0019] In particular, a difference between the altitude obtained from a conventional digital terrain model and the maximum elevation of the tunnel is easily obtained. This information is important because it indicates the amount of soil present above the structure and allows for the calculation of risks related to the geological environment of the structure. This knowledge also enables compliance with the DT / DICT decrees to ensure the safety of work near tunnels.

[0020] The work around and within each structure is therefore likely to be coordinated on the basis of reliable information.

[0021] In the case where the points are detected by means of a capture system implementing LiDAR technology, a high-quality geographic accuracy measurement is obtained by exploiting a GPS / inertial center / odometer hybridization offered by said capture system.

[0022] Advantageously, the process according to the invention has one or more of the following characteristics, taken individually or in any technically feasible combination:

[0023] for each work, the coordinates of a respective entry are a function of the coordinates of the points assigned to the meshes belonging to said work and connected to a low zone;

[0024] During the determination step, any given mesh is considered to belong to a structure if: • the corresponding height is greater than a predetermined minimum height; and / or • said cell belongs to a group of connected cells having the same height, up to a predetermined height difference, an area of ​​a surface defined by said group being greater than a predetermined minimum area; and / or • said mesh belongs to a group of connected meshes having the same height, up to a predetermined height difference, the surface defined by said group having one of a set of predetermined characteristic shapes;

[0025] each calculated height is assigned to a height interval, each height interval being associated with a respective color, the detection and first assignment steps being implemented on the basis of a two-dimensional image in which each mesh is represented by a respective set of pixels, the pixels associated with the same mesh having the color of the height interval to which the height of said mesh belongs;

[0026] The first assignment step includes, for each detected end portion, an iterative extension of the end portion by a dilation with a horizontal mask along the longitudinal axis of said end portion;

[0027] The process further comprises, for each work, the following steps: • second assignment, to said work, of each group of connected unassigned meshes that is adjacent to the part of said work strictly contained between the corresponding end portions; and • association of the points belonging to the corresponding meshes of the said work;

[0028] The process comprises, for each work, the implementation of an iterative loop comprising the following phases: • from a current point of interest and a current normal vector, selection of a current plane of interest as being a plane located at a predetermined distance from the current point of interest and whose normal vector is the current normal vector; • definition of a current interest volume from the current interest plan; • identification of points associated with said work and belonging to the current volume of interest; • updating the position of the current point of interest from a position of the identified points; • updating the normal vector to be a direction vector of a line passing through the current interest point and the previous interest point; • projection of the identified points, along the current normal vector, onto a projection plane passing through the current point of interest and whose normal vector is the current normal vector.

[0029] According to another aspect of the invention, a computer program is proposed comprising executable instructions which, when executed by computer, implement the steps of the process as defined above.

[0030] The computer program can be in any computer language, such as for example in machine language, in C, C++, JAVA, Python, etc.

[0031] According to another aspect of the invention, a computer device for modeling railway right-of-way is proposed, configured to: • from a cloud of points representing solid surfaces seen radially by a moving object traveling along a railway, each point being associated with a set of respective coordinates in a predetermined three-dimensional frame, a vertical axis of the three-dimensional frame being oriented parallel to the direction of the gravitational field, and being orthogonal to a horizontal plane comprising the other two axes of the three-dimensional frame, assign each point to a corresponding mesh of a predetermined mesh of the horizontal plane, according to the coordinates of said point in the horizontal plane; • for each mesh, calculate a corresponding height, equal to a difference between the maximum and minimum coordinates, along the vertical axis, of the points assigned to said mesh; • determine the membership of each mesh, based on the corresponding calculated height, to a class of unaffected meshes, to a class of excluded meshes, to a structure, or to a low zone of the railway, in which the rails are not locally arranged in a structure; • distribute the stitches belonging to a project into sets of stitches, each belonging to the same project; • for each set of stitches belonging to the same work, detect at least one end portion of said work; • for each detected end portion, perform an initial assignment to the corresponding structure of unassigned meshes belonging to a sector of the horizontal plane that extends along a longitudinal axis of the end portion, and which presents, transversely, a predetermined extent around said longitudinal axis; and • For each piece, associate said piece with points belonging to the meshes corresponding to said piece.

[0032] The device according to the invention can be any type of device such as a server, a computer, a tablet, a calculator, a processor, a computer chip, programmed to implement the method according to the invention, for example by executing the computer program according to the invention. Brief description of the figures

[0033] The invention will be better understood upon reading the following description, given solely by way of non-limiting example and made with reference to the accompanying drawings in which:

[0034] [Fig.1] is a flowchart of a process according to the invention;

[0035] [Fig. 2] is a schematic representation of a device implementing the process of [Fig.1];

[0036] [Fig.3] is a schematic representation of an orthogonal three-dimensional frame used during the implementation of the process of [Fig.1];

[0037] [Fig.4] is a schematic representation of a mesh of a horizontal plane in the three-dimensional frame of [Fig.3];

[0038] [Fig.5] is a schematic representation of a set of points assigned to the same mesh, and projected into a plane comprising a vertical axis and a horizontal axis of the three-dimensional frame of [Fig.3];

[0039] [Fig.6] is a representation of the mesh of [Fig.4], each mesh being coded by a color representing a respective height;

[0040] [Fig.7] is similar to [Fig.6], each mesh being coded by a color representative of a corresponding class;

[0041] [Fig.8] is analogous to [Fig.7], the tunnel being partially detected;

[0042] [Fig.9] is analogous to [Fig.8], the tunnel being fully detected, except of corresponding niches;

[0043] [Fig. 10] is analogous to [Fig. 9], the tunnel being fully detected, including the corresponding niches; and

[0044] [Fig.1 1] is a detail of a schematic cross-sectional representation, along a horizontal plane, of a tunnel.

[0045] It is understood that the embodiments described below are by no means limiting. In particular, variants of the invention may be conceived comprising only a selection of the features described below, isolated from the other features described, if this selection of features is sufficient to confer a technical advantage or to differentiate the invention from the prior art. This selection includes at least one preferably functional feature without structural details, or with only a portion of the structural details if this portion alone is sufficient to confer a technical advantage or to differentiate the invention from the prior art.

[0046] In particular, all the variants and embodiments described are combinable with each other if there is no technical obstacle to this combination.

[0047] In the figures and in the rest of the description, elements common to several figures retain the same reference. Detailed description

[0048] A method 2 for modelling a railway right-of-way, said railway right-of-way comprising a railway track, is illustrated by [Fig.1].

[0049] The modeling process 2 is capable of being implemented by any computer device 4 ([Fig.2]) comprising a memory 6 and a processor 8 connected together.

[0050] More specifically, the memory 6 is configured to store a modeling program 10 according to the invention. Furthermore, the processor 8 is configured to execute instructions from the modeling program 10 in order to implement the modeling method 2.

[0051] Memory 6 is further configured to store, in a corresponding memory location 12, a point cloud.

[0052] By "point cloud", it is understood, in the context of the present invention, as a set of points 14 ([Fig.3]), each associated with a respective set of coordinates in a predetermined three-dimensional frame 16.

[0053] In particular, the points 14 of the point cloud stored in memory location 12 are representative of the solid surfaces seen radially by a mobile moving along the railway track.

[0054] In this case, a vertical axis (Oz) of the three-dimensional frame is oriented parallel to the direction of the gravitational field. Furthermore, the vertical axis (Oz) is orthogonal to a horizontal plane (xOy) comprising the other two axes (Ox) and (Oy) of the three-dimensional frame.

[0055] For example, the point cloud was acquired using a telemetry device, such as a LiDAR (Light Detection and Ranging) device mounted on a railway vehicle traveling along the track. The point cloud may also have been acquired by other types of static or dynamic systems.

[0056] In addition, each point 14 of the point cloud is associated with a unique identifier.

[0057] As previously stated, the computer device 4 is configured to implement the modeling process 2.

[0058] More specifically, as illustrated by [Fig.1], the modeling process 2 comprises an assignment step 22, a calculation step 24, a categorization step 28, a distribution step 30, a detection step 32, a first assignment step 34 and an association step 36.

[0059] Optionally, the modeling process 2 further includes a second assignment step 38, followed by an auxiliary association step 40.

[0060] Alternatively, or in a complementary manner, the modeling process 2 preferably includes a cutting step 42.

[0061] Assignment step 22

[0062] The computer device 4 is configured to, during the assignment step 22, assign each point 14 of the point cloud to a corresponding mesh 44 ([Fig.4]), according to the coordinates of said point in the horizontal plane.

[0063] Each cell 44 belongs to a predetermined mesh 46 of the horizontal plane (xOy). Such a mesh 46 is, for example, generated on the fly, during the execution of the modeling process 2, based on a predetermined mesh size and the extreme positions, in the horizontal plane (xOy), of the points 14 of the point cloud. Furthermore, each cell 44 is uniquely identified.

[0064] Such an assignment step 22 can be likened to a projection of the points 14 onto the mesh 46 along the vertical axis (Oz), each point 14 being assigned to the mesh 44 to which the respective projection belongs.

[0065] Calculation step 24

[0066] In addition, for each mesh 44, the computer device 4 is configured to calculate, during the calculation step 24, a corresponding height H ([Fig.5]).

[0067] For each mesh 44, the corresponding height H is equal to a difference between the maximum coordinate and the minimum coordinate, along the vertical axis (Oz), of the points 14 assigned to said mesh 44.

[0068] Advantageously, in the absence of a point assigned to a given mesh 44, the corresponding height is considered to be zero. Such a feature is advantageous, insofar as it facilitates subsequent categorization of the meshes 44 on the basis of their height H.

[0069] The result of such a height calculation is illustrated by [Fig. 6]. More precisely, [Fig. 6] is a representation of a mesh 46, each cell 44 being coded by a color representing the respective calculated height H. In this figure: • the 44 meshes having a height less than a first predetermined height Hi (for example zero) are associated with a plain white filling pattern; • the 44 meshes having a height between the first height Hi and a second predetermined height H2, strictly greater than the first height Hb are associated with a white filling pattern with sparse black dots; • the 44 meshes having a height between the second height H2 and a predetermined third height H3, strictly greater than the second height H2, are associated with a white filling pattern with dense black dots; • The 44 meshes having a height greater than a predetermined fourth height H4, strictly greater than the third height H3, are associated with a white filling pattern with oblique black stripes.

[0070] Categorization step 28

[0071] For each mesh 44, the computer device 4 is configured so as to determine, during the categorization step 28, the membership of said mesh in a corresponding class, according to the respective calculated height.

[0072] More specifically, the computer device 4 is configured to determine the membership of each mesh 44 in one of: a class of unaffected meshes, a class of excluded meshes, a "tunnel" class, or a "low zone" class.

[0073] For the purposes of this invention, "low zone" means an area of ​​the railway track in which the rails are not locally arranged in a structure. In other words, a low zone is an area of ​​the railway track in which the rails are not vertically screened by a railway structure.

[0074] Preferably, during such a categorization step 28, any given mesh 44 is considered to belong to a tunnel (i.e., it is associated with the class "tunnel") if the corresponding height is greater than a predetermined minimum height.

[0075] Such a minimum height corresponds, in particular, to an average railway tunnel height, determined by observing several tunnels. For example, the minimum height is between 7 m (meters) and 9 m, for example equal to 8 m.

[0076] Alternatively, or complementaryly, if the mesh 44 belongs to a group of connected meshes having the same height (up to a predetermined height difference), then it is considered that said mesh 44 belongs to a tunnel if an area of ​​a surface defined by said group is greater than a predetermined minimum area.

[0077] For example, for a mesh 46 where each mesh 44 is a square of 6 centimeters on each side, knowing that a tunnel is at least 10 m by 8 m, which corresponds to 22200 meshes, the minimum area can be taken to be equal to 50% of such a value, i.e. 11100 meshes.

[0078] Alternatively, or complementaryly, if the mesh 44 belongs to a group of connected meshes having the same height (up to a predetermined height difference), then it is considered that said mesh 44 belongs to a tunnel if the surface defined by said group has one of a set of predetermined characteristic shapes.

[0079] For example, the meshes of a group of meshes defining a given surface are considered to belong to a tunnel if said surface has a rectangular shape.

[0080] Preferably, during the categorization step 28, a mesh 44 is considered to belong to the class of excluded meshes if no point is assigned to said mesh, and / or if the corresponding height H is zero.

[0081] Preferably, during the categorization step 28, any given mesh 44 is considered to belong to the lower zone if the corresponding height is non-zero and is less than or equal to a predetermined height limit.

[0082] Such a height limit is, preferably, representative of the maximum height, theoretical or observed, of the surface of a rail relative to the ground on which it rests, for one or more given railway track(s).

[0083] Preferably, during the categorization step 28, a grid cell 44 is considered unassigned if it cannot be associated with one of the other three classes. For example, this applies to grid cells for which there is doubt (for example, due to the value of the height H, or variations in the height H in the vicinity of said grid cells) as to the nature of the objects to which the points associated with said grid cells correspond. This is particularly the case near the entrance of a tunnel, in the presence of vegetation 47.

[0084] The result of implementing such a categorization on the cells of [Fig. 6] is illustrated by [Fig. 7]. More precisely, in [Fig. 7], each cell 44 is coded by a color representing the class to which it belongs. In this figure: • the 44 unaffected stitches are associated with a grid pattern; • the 44 excluded stitches are associated with a white filling pattern; • The 44 stitches associated with the "tunnel" class are associated with a black fill pattern; and • The 44 stitches associated with the "low zone" class are associated with a white fill pattern with black dots.

[0085] Distribution step 30

[0086] In addition, the computer device 4 is configured so as to distribute, during the distribution step 30, the meshes 44 belonging to the "tunnel" class into sets of meshes.

[0087] At the end of the distribution step, each set of meshes is formed of meshes belonging to the same tunnel 48.

[0088] Preferably, to achieve such a distribution, the computer device 4 is configured to associate, to the same tunnel 48, a set of connected meshes all belonging to the class “tunnel”.

[0089] It follows that the meshes of the same tunnel 48 form a (at least partial) representation of said tunnel.

[0090] Detection step 3 2

[0091] In addition, for each set of meshes belonging to the same tunnel 48, the computer device 4 is configured so as to detect, during the detection step 32, at least one end portion 50 of said tunnel 48 (that is to say an end portion of the representation of said tunnel 48).

[0092] Preferably, to perform such detection, the computer device 4 is configured to implement an image processing algorithm.

[0093] In this case, each calculated height H has been previously assigned to a height interval, each height interval being associated with a respective color.

[0094] Furthermore, in this case, detection is implemented on the basis of a two-dimensional image in which each mesh 44 is represented by a respective pixel or a respective set of adjacent pixels. More precisely, the pixels associated with the same mesh exhibit the color of the height interval to which the height of said mesh belongs.

[0095] In this case, the image processing algorithm preferably includes an implementation of a segmentation mask, an expected shape of a tunnel end portion being, in particular, a rectangular shape.

[0096] Preferably, for each detected end portion 50, the computer device 4 is further configured to determine a longitudinal axis AA of said end portion 50, along which said end portion 50 extends.

[0097] Such a longitudinal axis A- A belongs to the horizontal plane (xOy).

[0098] First assignment step 3 4

[0099] In addition, for each detected end portion 50, the computer device 4 is configured so as to, during the first assignment step 34, assign (where possible) unassigned meshes 44 (i.e. belonging to the class "unassigned meshes") to the tunnel 48 corresponding to said end portion 50.

[0100] More precisely, for a given end portion 50, the computer device 4 is configured to assign, to the respective tunnel 48, the unassigned meshes 44 located in a sector of the horizontal plane (xOy): • which extends, from said end portion 50, along the longitudinal axis AA of end portion 50; and • which presents, transversely, a predetermined extent L around said longitudinal axis.

[0101] Such a feature exploits the property that, in its end portions, a tunnel 48 is straight in the horizontal plane. Such a feature also exploits the property that, in its end portions, a tunnel 48 has a substantially constant width.

[0102] The result of implementing such a first assignment on the unassigned meshes of [Fig.7] is illustrated by [Fig.8]. More specifically, in [Fig.8], the meshes 44 initially unassigned and now assigned to tunnel 48 by the implementation of the first assignment step 34 form a segment 52 associated with a black and white checkerboard filling pattern.

[0103] At the end of the first assignment step 34, the initially unassigned meshes which are now assigned to the tunnel 48 (i.e. the meshes 44 forming the segment 52) ​​are considered as belonging to the class “tunnel”.

[0104] [Fig.9] is similar to [Fig.8], the 44 meshes of the "tunnel" class belonging to the same tunnel 48 being all associated with a black filling pattern. As shown in this figure, the representation of tunnel 48 has been extended by the segment bearing the numerical reference 52 on [Fig.8].

[0105] In the case where the mesh 46 is represented in image form, as described with reference to the detection step 32, then preferably during the first assignment step 34, for each detected end portion 50, the computer device 4 is configured to iteratively extend said end portion 50 by means of a horizontal mask, along the longitudinal axis AA of said end portion 50.

[0106] Association step 3 6

[0107] In addition, for each tunnel 48, the computer device 4 is configured to, during the association step 36, associate said tunnel 48 with the points of the point cloud which are assigned to the meshes 44 corresponding to said tunnel 48.

[0108] Preferably, for each tunnel 48, the computer device 4 is further configured to calculate coordinates of a respective input 54.

[0109] In particular, the computer device 4 is configured to calculate said coordinates of the inlet 54 as a function of the coordinates of the points of the meshes 44 which belong to said tunnel 48 and which are connected to a low zone (i.e. meshes 44 at which the tunnel 48 opens onto a low zone).

[0110] Second assignment step 38

[0111] Preferably, for each tunnel 48, the computer device 4 is configured so as to assign said tunnel 48, during the second assignment step, at least one group 56 of related unassigned meshes, said group of meshes 56 being adjacent to the part of said tunnel which is strictly contained between the corresponding end portions 50.

[0112] In this way, the niches 56 of the tunnel, whose meshes are likely to have been classified as unaffected meshes, are joined to said tunnel 48.

[0113] Such a second assignment step 38 is advantageous. Indeed, niche detection is important for the safety of construction and maintenance work, as it allows for the identification of areas where special measures must be taken to reinforce the structure or to prevent potential risks of collapse. Furthermore, updating the location of niches can also be used to plan the installation of equipment or systems in the tunnel, taking into account the available space and geometric constraints.

[0114] Furthermore, by considering only the part of the tunnel 48 which is strictly contained between the corresponding end portions 50, the vegetation 47 likely to be present at the entrances 54 of the tunnel, and potential source of false positives (vegetation assimilated to a niche), is not taken into account, which is advantageous.

[0115] The result of implementing such a second assignment on the unassigned cells of [Fig. 9] is illustrated by [Fig. 10]. More specifically, [Fig. 10] only shows the cells of the "tunnel" class obtained at the end of the second assignment step 38 and belonging to the same tunnel 48 (solid black filling pattern).

[0116] Auxiliary association step 40

[0117] In this case, for each tunnel, the computer device 4 is configured so as to associate said tunnel, during the auxiliary association step 40, the points belonging to the meshes newly assigned to said tunnel.

[0118] Cutting step 42

[0119] Preferably, the cutting step 42 is carried out after the auxiliary association step 40. However, the cutting step 42 is also likely to be carried out after the association step 36.

[0120] More specifically, for each tunnel 48 (white fill pattern with black dots), the computing device 4 is configured to choose, from a current interest point In and a current normal vector one, a current interest plane P.

[0121] More specifically, the current plane of interest P is chosen as a plane of the three-dimensional frame 16 which is located at a predetermined distance D from the current point of interest In, and whose normal vector is the current normal vector u n.

[0122] In addition, the computer device 4 is configured to define a current interest volume V from the selected current interest plane P.

[0123] For example, the current volume of interest V is delimited by two planes located on either side of the current plane of interest P, having a predetermined distance E from the current plane of interest P, for example 25 cm.

[0124] In addition, the computer device 4 is configured to identify the points 14 which are associated with said tunnel 48 and which belong to the current volume of interest V.

[0125] In addition, the computer device 4 is configured to update the position of the current point of interest In +i from a position of the identified points.

[0126] Preferably, the current point of interest updated In +[ is, among the identified points, the one with the highest altitude (i.e. the coordinate along the vertical axis).

[0127] Preferably, the computer device 4 is also configured to determine the highest altitude Zmax and / or the lowest altitude Zmin among the points of the current volume of interest V. In this case, the computer device 4 is further configured to associate, with the current plane of interest P, the altitude Zmax and / or the altitude Zmin and, preferably, the coordinates of the corresponding points 14.

[0128] In addition, the computer device 4 is configured to update the current normal vector u n+i as a direction vector of a straight line passing through the current interest point I and the previous interest point.

[0129] Furthermore, the computer device 4 is configured to project the identified points, along the updated current normal vector un+i, onto a projection plane passing through the updated current point of interest In and whose normal vector is the updated current normal vector un+i. Preferably, the computer device 4 is also configured to associate, with said cutting plane, the determined altitude Zmax and / or altitude Zmin and, preferably, the coordinates of the corresponding points 14.

[0130] This results in a cut of tunnel 48 at the updated current point of interest In+1.

[0131] Such a loop is repeated iteratively during the cutting step 42.

[0132] Preferably, the normal vector of interest is initialized as the vector normal at the tunnel entrance. In addition, the point of interest is preferably initialized as the maximum altitude point of tunnel 48 at its entrance.

[0133] Obviously, the invention is not limited to the case of modeling a tunnel, and can be extended to any railway structure, in particular to any linear railway structure, such as a hydraulic structure.

[0134] In this case, the class "tunnel" is likely to be renamed "structure", for the sake of generality.

[0135] Hydraulic structures are characterized by their circular cross-section. However, in this case, the implementation of modeling method 2 remains similar to that described previously. In particular, in such a structure, there is a difference in elevation (the height H defined previously) among the points associated with the different cells of the mesh. Each height (or range of heights) can therefore be coded by a corresponding color, as described previously.

[0136] A modification may be made in the case of the assignment step, to take into consideration the fact that the sides of the structure will be of a slightly different color from the center (in other words, on the edges of the structure, the height is lower compared to the center than in a conventional tunnel).

[0137] Operation

[0138] The operation of the computer device 4 will now be described.

[0139] During a preliminary configuration step, a point cloud is stored in memory location 12 of memory 6.

[0140] Then, during the assignment step 22, the computer device 4 assigns each point 14 of the point cloud to a corresponding mesh 44 of the predetermined mesh 46, according to the coordinates of said point in the horizontal plane (xOy).

[0141] Then, during the calculation step 24, the computer device 4 calculates, for each mesh 44, a corresponding height H.

[0142] Then, during the categorization step 28, the computer device 4 determines, for each mesh 44, the membership of said mesh in a corresponding class, based on the respective calculated height. In particular, the computer device 4 determines the membership of each mesh 44 in one of the following: the class of unaffected meshes, the class of excluded meshes, the "work" class, or the "low zone" class.

[0143] Then, during the distribution step 30, the computer device 4 distributes the meshes 44 belonging to the "work" class into sets of meshes. In this case, the meshes in the same set of meshes belong to the same work.

[0144] Then, during the detection step 32, the computer device 4 detects, for each set of meshes belonging to the same work, at least one end portion of said work.

[0145] Then, during the first assignment step 34, for each detected end portion 50, the computer device 4 assigns, to the corresponding work, the unassigned meshes 44 present between said end portion 50 and the opposite lower zone.

[0146] Then, during the association step 36, the computer device 4 associates, to each work, the points of the point cloud which are assigned to the meshes 44 corresponding to said work.

[0147] Preferably, for each work, the computer device 4 also calculates coordinates of at least one respective entry 54.

[0148] Preferably, during the optional second assignment step 38, the computer device 4 assigns, to each work, at least one group 56 of related unassigned meshes, each group corresponding to a niche.

[0149] Then, during the auxiliary association step 40, the computer device 4 associates, to each work, the points belonging to the meshes newly assigned to said work.

[0150] Preferably, during the optional cutting step 42, the computer device 4 determines a plurality of (substantially) vertical cutting planes of the work.

[0151] Preferably, the computer device 4 stores, for each cutting plane, the altitude Zmax and / or the altitude Zmin and, preferably, the coordinates of the corresponding points 14.

[0152] Of course, the invention is not limited to the examples just described.

Claims

1. Demands Method (2) for modelling railway right-of-way, the method being implemented by computer and comprising the steps: • from a cloud of points representing solid surfaces seen radially by a mobile moving along a railway, each point being associated with a set of respective coordinates in a predetermined three-dimensional frame (16), a vertical axis (Oz) of the three-dimensional frame being oriented parallel to the direction of the gravitational field, and being orthogonal to a horizontal plane (xOy) comprising the two other axes (Ox, Oy) of the three-dimensional frame, assignment (22) of each point (14) to a corresponding mesh (44) of a predetermined mesh (46) of the horizontal plane (xOy), according to the coordinates of said point (14) in the horizontal plane; • for each mesh (44), calculation (24) of a corresponding height (H), equal to a difference between the maximum and minimum coordinates, along the vertical axis (Oz), of the points (14) assigned to said mesh; • determination (28) of the membership of each mesh (44), according to the corresponding calculated height, of a class of unaffected meshes, of a class of excluded meshes, of a structure, or of a low zone of the railway, in which the rails are not locally arranged in a structure; • distribution (30) of the stitches belonging to a work into sets of stitches each belonging to the same work; • for each set of meshes belonging to the same work, detection (32) of at least one end portion of said work; • for each detected end portion, first assignment (34) to the corresponding work of the unassigned meshes belonging to a sector of the horizontal plane which extends along a longitudinal axis (AA) of the end portion, and which has, transversely, a predetermined extent around said longitudinal axis (AA); and • for each work, association (36) said work of the points (14) belonging to the meshes corresponding to said work.

2. A method according to claim 1, wherein, for each work, the coordinates of a respective input are a function of the coordinates of the points (14) assigned to the meshes (44) belonging to said work and connected to a low zone.

3. A method according to claim 1 or 2, wherein, during the determination step (28), any given mesh is considered to belong to a structure if: • the corresponding height is greater than a predetermined minimum height; and / or • said mesh belongs to a group of connected meshes having the same height, up to a predetermined height difference, an area of ​​a surface defined by said group being greater than a predetermined minimum area; and / or • said mesh belongs to a group of connected meshes having the same height, up to a predetermined height difference, the surface defined by said group having one of a set of predetermined characteristic shapes.

4. A method according to any one of claims 1 to 3, wherein each calculated height is assigned to a height interval, each height interval being associated with a respective color, the detection (32) and first assignment (34) steps being implemented on the basis of a two-dimensional image in which each mesh is represented by a respective set of pixels, the pixels associated with the same mesh having the color of the height interval to which the height of said mesh belongs.

5. A method according to claim 4, wherein the first assignment step (34) comprises, for each detected end portion, an iterative extension of the end portion by a dilation with a horizontal mask along the longitudinal axis of said end portion.

6. A method according to any one of claims 1 to 5, further comprising, for each work, the steps: • second assignment (38), to said work, of each group of connected unassigned meshes which is adjacent to the part of said work strictly contained between the corresponding end portions; and • association (40) to said work of the points belonging to the meshes corresponding to said work.

7. A method according to any one of claims 1 to 6, comprising, for each structure, the implementation of an iterative loop including the following steps: • starting from a current point of interest and a current normal vector, selection of a current plane of interest as a plane located at a predetermined distance from the current point of interest and whose normal vector is the current normal vector; • definition of a current volume of interest from the current plane of interest; • identification of the points associated with said structure and belonging to the current volume of interest; • updating the position of the current point of interest from a position of the identified points; • updating the normal vector as a direction vector of a line passing through the current point of interest and the previous point of interest;• projection of the identified points, along the current normal vector, onto a projection plane passing through the current point of interest and whose normal vector is the current normal vector.

8. A computer program comprising executable instructions which, when executed by computer, implement the steps of the process according to any one of claims 1 to 7.

9. A computer device (4) for modeling railway right-of-way, configured to: • from a point cloud representing solid surfaces viewed radially by a moving object traveling along a railway track, each point being associated with a set of respective coordinates in a three-dimensional coordinate system predetermined, a vertical axis of the three-dimensional frame being oriented parallel to the direction of the gravitational field, and being orthogonal to a horizontal plane comprising the other two axes of the three-dimensional frame, assign each point to a corresponding mesh of a predetermined mesh of the horizontal plane, according to the coordinates of said point in the horizontal plane; for each mesh, calculate a corresponding height, equal to a difference between the maximum and minimum coordinates, along the vertical axis, of the points assigned to said mesh; determine the membership of each mesh, based on the corresponding calculated height, to a class of unaffected meshes, to a class of excluded meshes, to a structure, or to a low zone of the railway, in which the rails are not locally arranged in a structure; to distribute the stitches belonging to a work into sets of stitches each belonging to the same work; for each set of stitches belonging to the same work, detect at least one end portion of said work; for each detected end portion, perform a first assignment to the corresponding work of the unassigned meshes belonging to a sector of the horizontal plane which extends along a longitudinal axis of the end portion, and which presents, transversely, a predetermined extent around said longitudinal axis; and for each work, associate said work with points belonging to the meshes corresponding to said work.

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