A method for functionally modeling a relief feature present in a three-dimensional surface, and an electronic device implementing said method.

Abstract

Method (10) for functional modeling of a relief feature (3) present in a surface, comprising the following steps:- acquisition (11) of a three-dimensional image of said surface, this image being in the form of a point cloud describing this surface;- selection (12) of a plurality of points from the point cloud marking a target relief feature joining said selected points, this target relief feature extending between a first selected point and a second selected point;- extraction (13) from the point cloud of a sub-point cloud around the target relief feature, this sub-point cloud describing a subsurface;- modeling (14) of the subsurface by means of a freeform surface;- determination (15), from a model of the subsurface, of a first topographic line of the subsurface;- determination (16) of a second topographic line and a third topographic line on either side of the first line. Figure to be published with the abbreviation: Fig 2;

Description

Title of the invention: Method for functionally modeling a relief element present in a three-dimensional surface, electronic device implementing said method

[0001] The present invention relates to methods of functional modeling of a relief element included in a three-dimensional surface, as well as to computer program products for adapting electronic devices so that the latter implement such methods.

[0002] The term "relief feature" means a linear groove or projection on a three-dimensional surface. A groove refers to any linear depression, indentation, fold, or channel on the surface of an object, such as a skin crease, nasolabial fold, crease, wrinkle, fine line, or notch in skin, a crack or fissure in a material, or a trench or fault in soil. The term "linear projection" refers to any elevation, protrusion, or, more generally, any local deformation where a portion of the surface extends above the surrounding level along a line, such as a suture line, varicose vein or scar in skin, a weld line or ribs on the surface of a manufactured part, or a wave on the surface of water.A relief feature can be natural, intentionally created for various functional or aesthetic reasons, or resulting from stress, wear, or other factors.

[0003] Methods for detecting and modeling relief features present on the surface of a real object are known from the prior art. However, these methods are limited to a digital representation of the appearance in space, that is, to three-dimensional (3D) geometric characteristics of the relief features. Such a static representation does not allow for a proper study of the dynamic behavior of a relief feature.

[0004] An object of the present invention is to propose one or more functional models of a relief element, in other words models which go beyond a simple static 3D geometric representation in order to simulate the behavior, operation and / or interactions of this relief element in a virtual environment.

[0005] Another object of the present invention is to produce a functional three-dimensional model, namely a geometric model whose use is not limited to visualization but also allows measurement, mechanical simulation and dynamic evaluation of a relief element.

[0006] Firstly, a functional modeling method for a relief element present in a surface is proposed, this method comprising the following steps: - acquisition of a three-dimensional image of said surface, this image being in the form of a point cloud describing this surface; - selection of a plurality of points from the point cloud marking a target relief feature joining said selected points, this target relief feature extending between a first selected point and a second selected point of said plurality of selected points; - extraction of the point cloud from a sub-point cloud around the target relief element, this sub-point cloud describing a sub-surface of said surface; - modeling of the subsurface using a freeform surface parameterized with control points; - determination, from a model of the subsurface, of a first topographic line of the subsurface joining the first selected point and the second selected point; - determination, from the subsurface model, of a second topographic line and a third topographic line on either side of the first topographic line.

[0007] Various additional features may be provided, alone or in combination: - the relief element is a groove; - the first topographic line is a bottom line of the furrow; - the relief element is a linear projection; - the first topographic line is a ridge line of the linear projection; - the deformable surface is a uniform cubic B-Spline surface; - the initial shape of the freeform surface is chosen according to business data; - the surface is initialized by a lattice of control points contained in a plane integrating the first selected point and the second selected point; - the step of determining the second topographic line includes a search for a change of slope, with respect to an axis perpendicular to the longitudinal direction of the target relief element, between a first substantially straight segment and a second substantially straight segment successive of the subsurface starting from the first topographic line.

[0008] Secondly, a computer program product is proposed, implemented on a storage medium and capable of being implemented within a unit of processing of an electronic device and including instructions for implementing the process described above.

[0009] The invention further relates to a computer-readable storage medium containing the instructions for such a computer program product.

[0010] The invention relates to an electronic device comprising: - a processing unit; - a data memory; - a program memory containing the program instructions for such a computer program product.

[0011] Other features and advantages of the invention will become clearer and more concrete upon reading the following description of embodiments, which is made with reference to the accompanying drawings in which:

[0012] [Fig-1] schematically illustrates a surface comprising a relief element according to various modes of implementation;

[0013] [Fig.2] schematically illustrates the steps of a functional modeling process of a relief element present in a surface according to various embodiments;

[0014] [Fig.3] schematically illustrates a subcloud of points extracted from a point cloud describing said surface;

[0015] [Fig.4] schematically illustrates a freeform surface according to various embodiments;

[0016] [Fig.5] schematically illustrates topographic lines characterizing a relief element according to various modes of embodiment;

[0017] [Fig.6] illustrates an electronic device adapted to implement a process according to the invention.

[0018] Figure 1 illustrates an example of a three-dimensional or 3D image 1. Such an image is that of a body area, in this case a human face, comprising one or more cutaneous relief features 3 such as a wrinkle. Alternatively, such an image could depict a fine line, a scar, a varicose vein, or a suture line on any other part of a human body. Such an image 1 could be that of a shell comprising a crack, a weld line, or a bond line in connection with a physical object.

[0019] In connection with [Fig. 1], [Fig. 2] presents a method 10 for functionally modeling a relief element present in a 3D surface according to the invention, said method 10 being intended to be implemented by a processing unit of an electronic device such as a smartphone, a laptop or desktop computer. Such a method 10 comprises a first step 11 of acquiring a three-dimensional image of said surface using means of capture of said electronic device or cooperating with it. This step 11 ultimately consists of producing an image in the form of a point cloud 2 describing this captured surface. Figure 1 illustrates such a point cloud 2 assembled into a point volume that represents the topology of the surface to be studied. Each point in this point cloud 2 is represented by coordinates or by a distance value and a solid angle in a predefined (absolute or relative) three-dimensional coordinate system. This coordinate system is most often associated with the 3D image acquisition device 1, such as a 3D camera, a depth camera, a photogrammetry device, or a 3D scanner (laser scanner, LiDAR, stereoscopic scanner, modulated light scanner, or silhouette scanner, for example).Of course, attributes or data associated with each point in the point cloud 2 can also include other information directly from the captured image, such as information about brightness, color, or grayscale levels. The invention further provides that said step 11 comprises a process consisting of analyzing such a captured image to deduce semantic information or "business knowledge" and thus enrich the attributes or data associated with the points in the point cloud 2.Such an analysis makes it possible to identify the physical body or an area of ​​said body on which the image capture is focused (whether said body is a human, animal, plant or mineral body, or even a material object), in order to determine physical properties (for example, physical properties specific to a tissue, an organ, a bone or a muscle for a biological material or body), and / or biomechanical properties (for example, rigidity, elasticity, toughness, viscoelasticity or resistance to compression, etc.) and thus produce complementary attributes associated with the points of the point cloud.Such processing can rely on pattern recognition or object identification techniques that advantageously, but not exclusively, implement machine learning techniques or, more broadly, any machine learning techniques based on mathematical and statistical approaches to give a computer the ability to "learn" from data, without being explicitly programmed for that purpose. Such processing can also rely on one or more models of captureable surfaces (or skins), models that translate such physical and biomechanical properties according to the nature of said surfaces, to produce the aforementioned complementary attributes, or even on inputs or inputs from the user of the electronic device implementing the process.

[0020] The latter comprises a selection step 12, according to which a plurality of points 21-22 from the point cloud 2 is selected to mark a target relief element 30 joining said selected points 21-22. This target relief element 30 extends between a first selected point 21 and a second selected point 22 of said plurality of points 21-22 selected. These points 21-22 are, for example, selected in a 3D view using a selection tool such as a computer mouse or equivalent. This is an initial marking of the relief element 3 to be modeled to indicate its approximate position on the surface described by the point cloud 2.

[0021] In one embodiment, the target relief element 30 is marked only by a first and a second selected point 21-22 representing the two ends of this target relief element 30, which has the shape of a segment. Alternatively, a plurality of intermediate selected points 21-22 (in particular, two or three) can be considered to mark a curved target relief element 30.

[0022] The selection of points 21-22 by an operator (for example, a medical practitioner or a technician) advantageously allows for the retrieval of technical knowledge. In this case, the selected points 21-22, marking the two ends of the target relief element 30, are considered to be precisely acquired. In one embodiment, the "technical knowledge" includes characteristics of the anatomical structure being studied.

[0023] In conjunction with [Fig. 3], as illustrated therein, a subcloud 20 of points around the target relief feature 30 is extracted from the point cloud 2 during an extraction step 13, this subcloud 20 of points describing a subsurface of the initial surface. The subcloud 20 of points incorporates, for example, the points of the point cloud 2 located within a predefined distance of the target relief feature 30. The subcloud 20 of points is thus associated with a local subsurface of the groove or linear protrusion.

[0024] As shown in [Fig. 3], a three-dimensional Cartesian coordinate system R(0x, Oy, Oz) is associated with the extracted subcloud 20 such that the two endpoints 21, 22 of the target relief element 30 lie on the Oy axis equidistant from the center O of the coordinate system. In other words, the two ends of the target relief element 30 are centered on the origin of the Cartesian coordinate system on the Oy axis (i.e., located on the Oy axis symmetrically on either side of the origin O of the coordinate system R). The origin O of the coordinate system is placed at the midpoint of the segment joining the two ends of the target relief element 30, as illustrated in [Fig. 4]. These two endpoints have coordinates (0, -yO, 0) and (0, yO, 0), where -yO and yO are respectively the ordinates of the first and second points 21 and 22 selected to delimit the target relief element 30. Furthermore, the xOy plane is chosen so that the projection of the subcloud 20 of points onto this plane is maximized.Indeed, a rotation around the Oy axis is applied to the 20-point subcloud, or equivalently to the R(0x, Oy, Oz) coordinate system, until the projection onto the xOy plane of the subsurface described by the 20-point subcloud is maximal. This subsurface is therefore as close as possible to the xOy plane, and its shape is mainly described by elevations and / or depressions along the Oz axis.

[0025] Such an arrangement of the coordinate system R(0x, Oy, Oz) advantageously flattens the sub-cloud 20 of points of interest onto the xOy plane, with the Oz axis providing the height / depth of the target relief element 30. This step aims, in particular, to focus the subsequent steps on the subsurface of interest around the target relief element 30 to be modeled. Since isometries are applied to the sub-cloud 20 of points, it is possible to return to the initial coordinate system associated with the point cloud 2 using inverse transformations, as the measurement calculations are identical in both coordinate systems.

[0026] In connection with Figures 2 and 4, during a modeling step 14 of a process 10 according to the invention, the subsurface described by the subcloud 20 of points is modeled by means of a freeform (continuous and differentiable) surface 23 of the B-Spline type, a NURBS (Non-Uniform Rational Basis Splines) surface, a Bézier surface, or a T-Spline surface. As shown in [Fig. 4], the freeform surface 23 is parameterized using control points 24. The modeling step 14 iteratively adjusts the freeform surface 23 until it represents the subcloud 20 of points by passing through it sufficiently closely to eliminate artifacts while highlighting its shape characteristics. The adjustment of the freeform surface 23 is carried out by moving its control points 24.

[0027] Indeed, referring to [Fig. 4], an iterative algorithm refines the alignment of the control points 24 of the freeform surface 23 with the subsurface described by the subcloud 20 of points, minimizing the distance between them. This algorithm implements an iterative registration process to align the freeform surface 23 with the subsurface described by the subcloud 20 of points, by moving one or more control points 24 of the freeform surface 23.

[0028] In one embodiment, the freeform surface 23 is a uniform cubic B-spline surface. Advantageously, a uniform cubic B-spline surface allows for the reproduction of local variations in shape while maintaining a level of continuity and differentiability consistent with the surface to be modeled. In one embodiment, a uniform cubic B-spline surface is associated with a local lattice of sixteen control points 24 (4x4), this local lattice being part of a global lattice of NxM control points 24 that covers the subsurface described by the subcloud 20 of points to be modeled. The displacement of a control point 24 produces a deformation of the freeform surface 23 on the four first-order neighboring tiles and the twelve second-order neighboring tiles (the deformations on the twelve second-order neighbors being quite small compared to those applied on the four first-order neighboring tiles).

[0029] In one embodiment, a freeform surface 23 is first initialized by a lattice of NxM control points 24 arranged regularly in the xOy plane (i.e., their z-coordinate is 0) and comprising the segment joining the two endpoints on the Oy axis of the target relief element 30. More generally, the freeform surface 23 is initialized by a lattice of control points 24 contained in a plane incorporating the first selected point 21 and the second selected point 22.

[0030] Next, for each control point 24, a displacement D along the Oz direction is determined that maximizes a predefined proximity criterion between the four neighboring tiles and the points of the subcloud 20 of points they cover. The proximity criterion is, for example, the sum of the squares of the distances (along the Oz direction) from the points of the subcloud 20 to the freeform surface 23. The control point 24 with the largest displacement D (i.e., the most distant from the subsurface described by the subcloud of points) is displaced by the distance D. These last two steps can be repeated as long as the predefined proximity criterion is greater than a predefined threshold value. Advantageously, this results in a surface model, for example of the B-Spline type, fitted to the subsurface described by the subcloud 20 of points.This model is defined by one or more parametric functions of the free surface, depending on the final position of the 24 control points.

[0031] The 24 control points form elementary surface tiles (or "patches") allowing to highlight and eliminate noise and artifacts (outliers in the subcloud 20 of points), to locally represent the subcloud 20 of points by a smooth surface and with controlled precision, and to recalibrate data and / or integrate new data.

[0032] In another embodiment, the initial shape of the freeform surface 23 is chosen based on business data, in particular the geometric or anatomical structure of the point subcloud 20 (for example, the relationships between the phalanges of a hand or those between the elements of a face, the physiological constraints on these components, the mechanical properties of all the muscles and tendons, as well as the skin, the existence of visible wrinkles or veins), making it possible to accelerate the convergence of the above steps for modeling the point subcloud 20 and improve its accuracy. A freeform surface 23 whose initial geometry is similar to that of the target point subcloud 20 advantageously reduces the number of iterations of the aforementioned modeling steps.Advantageously, business data indicating representative points of the subsurface to be modeled also makes it possible to reduce any noise contained in the position data of the points in the subcloud of 20 points.

[0033] In conjunction with [Fig. 2] and as illustrated by [Fig. 5], from the model obtained of the subsurface, the process 10 comprises a step 15 of determining a The first topographic line 31 of said subsurface joins the first selected point 21 and the second selected point 22. This first topographic line 31 corresponds, in effect, to a bottom line (in the case of a furrow) or a crest line (in the case of a linear protrusion) of the target relief element 30. The first topographic line is constrained at the two selected endpoints. The first selected point 21 and the second selected point 21 constitute two predefined passage points of the first topographic line 31.

[0034] The first topographic line 31 joining the selected points 21, 22 can be visualized as a broken line (degree one spline) or as a "flexible" line (degree three spline). This first topographic line 31 constitutes a first snap line for a model describing / reproducing the bottomline or ridgeline of the target relief element 30. Starting from an initial broken line joining the previously selected points 21, 22, said step 15 consists of sampling this broken line uniformly along the Oy axis when the number of selected points 21-22 is less than a predefined value (for example, 10). In other words, by having a broken line defined by the selected points 21-22 approximating the first topographic line 31, a new broken line with more points, or more generally, a predefined number of points depending on the application, is determined.This sampling method advantageously allows for a sufficient number of intermediate points between the two ends of the target relief element 30.

[0035] In one embodiment, the first topographic line 31 is determined using a constrained elastic model; that is, a broken line joining two fixed points (the two ends of the relief element 30) and able to deform until it follows the bottom line of a furrow or the crest line of a linear projection within the measure of a maximum elastic stress.

[0036] For each intermediate point (whether selected or added by sampling, with the exception of the endpoints), a local extremum on the subsurface around this intermediate point is sought, namely the lowest point (in the case of a furrow) or the highest point (in the case of a linear protrusion) in the immediate vicinity of said intermediate point (for example, within a predefined distance of said intermediate point). This local extremum replaces the corresponding intermediate point. This search for local extrema is iterated as long as the length of the first topographic line 31 is less than a predefined proportion of the initial length of the first topographic line or as long as the difference between two successive lengths of the first topographic line 31 is less than a predefined threshold (for example, 2% or 5%).The line thus determined is used as support for a cubic spline curve which characterizes the first topographic line 31 of the subsurface described by the subcloud 20 of points.

[0037] A second topographic line 32 and a third topographic line 33 on either side of the first topographic line 31 are also determined, in a step 16 of the process 10, from the model of the subsurface described by the subcloud 20 of points. The second topographic line 32 and the third topographic line 33 correspond to the edges of the target relief element 30 on either side of the first topographic line 31.

[0038] In one embodiment, the two boundary lines are determined by moving a plane parallel to the xOy plane in the direction of the Oz axis. To this end, step 16 consists of moving a horizontal plane vertically (i.e., one for which z is constant) and maintaining the line of intersection of this plane with the nearest subsurface, or more generally, the subsurface located within a predefined distance of the first topographic line 31. Domain knowledge can advantageously be used to define said predefined distance according to the intended application (for example, the detection of wrinkles / creases, cracks / splits, or the detection of varicose veins / reticular veins).

[0039] In another embodiment, the two boundary lines of the relief element are detected by searching for a "break point" on the subsurface in a direction perpendicular to the longitudinal direction of the relief element. This break point marks a change in slope with respect to the Oz axis (or any other axis perpendicular to the longitudinal direction of the target relief element 30) between a first substantially straight segment and a second substantially straight segment (the first and second segments being joined at this break point) of the subsurface starting from the first topographic line 31.

[0040] The break point is detectable approximately on the "rounded" edge of the transition from the inside to the outside of the relief element. Taking a first point A on the bottom / ridge of the relief element and a second point B outside the relief element in the direction of the Ox axis, the break point C is the point joining two substantially straight sections AC and CB.

[0041] For example, when the first topographic line 31 is composed of a plurality of points (for example 10 points) intermediate between the first selected point 21 and the second selected point 22, step 16 then consists of implementing the following process for each of said intermediate points: - sampling of the intersection of the subsurface with the xOy plane passing through said intermediate point; - search for the first change of direction (for example, using a cross product of successive sampling points) greater than a predefined threshold in the two sections on either side of said intermediate point to detect, respectively, a first break point included in the first edge line and a second break point included in the second edge line.

[0042] Advantageously, any one of the embodiments described above for edge line detection can be adopted depending on the morphology of the relief element and the intended use of the functional modeling of this relief element (for example, the envisaged medical application of the functional modeling of a wrinkle).

[0043] The method 10 thus provides a freeform model constrained at the two selected ends of the target relief element 30 and by three lines (the bottom or ridge line and the two edge lines). A further optimization step of the resulting model can be considered by repeating the previous optimization step, but taking into account the determined topographic lines 31-33 as constraints to be respected. Such a step improves the reliability and robustness of the three-dimensional model.

[0044] This advantageously results in a model allowing all simulations and measurements on an area of ​​interest of the surface under study. It is, for example, possible to retrieve various descriptors of the relief element such as its length, its curvature, the variation of its width, its depth or its height over its length, its volume, its possible deformations taking into account the mechanical (or biomechanical) properties of the surface, its possible reactions to predefined actions (product injection, tensions, pressures for example).

[0045] When it comes to a skin surface (for example, the surface of a face), the embodiments described above advantageously allow for an exhaustive characterization of the human skin relief (for example, a characterization of wrinkles or a scar according to many geometric criteria such as, for example, length, width, depth, volume, or curvature) so as to be able to more easily search for an appropriate treatment, to follow over time or to evaluate the success of an intervention or the effectiveness of a treatment (a skincare product for example).

[0046] This functional three-dimensional model includes information on how the relief element behaves or interacts with its environment or in response to a predefined action. To this end, the resulting functional three-dimensional model advantageously incorporates mechanical parameters related to the biomechanical study of the anatomical structure under investigation.

[0047] Advantageously, the embodiments presented above, including in particular those of modeling the subsurface by means of a free-form surface, make it possible to integrate data of different modalities, of different resolutions, and not geometrically registered in space, to eliminate noise and artifacts and to control the accuracy with which the results are produced.

[0048] As shown in [Fig. 6], an electronic device 100 arranged to implement a method according to the invention (as described in connection with [Fig. 2]) comprises a central processing unit 111 (in the form of one or more microprocessors or microcontrollers) which controls, by means of signals carried by a communication bus symbolized in [Fig. 6] by double arrows in single lines, electronic elements including a memory. The latter comprises a data memory 112 and a program memory 113, said memories 112 and 113 possibly forming a single physical unit. The term "memory" refers to any computer memory, whether volatile or non-volatile. Non-volatile memory is computer memory whose technology retains its data in the absence of an electrical power supply. It may contain data resulting from input, calculations, measurements, and / or program instructions.The main non-volatile memories currently available are electrically writable, such as EPROM (Erasable Programmable Read-Only Memory), or electrically writable and erasable, such as EEPROM (Electrically Erasable Programmable Read-Ordy Memory), flash, SSD (Solid-State Drive), etc. Non-volatile memories are distinguished from so-called "volatile" memories, whose data is lost when power is removed.The main volatile memory technologies currently available utilize RAM (Random Access Memory, also known as "random access memory"), DRAM (dynamic random access memory, requiring regular updates), SRAM (static random access memory, requiring such updates during power failure), DPRAM or VRAM (particularly suited to video), etc. An electronic device 100 may also include one or more matrix image sensors 114 in the form of a depth camera (or a 3D camera). Such an electronic device 100 may include means of communication 115 with the outside world in the form of an input unit and an output unit. To operate, such an electronic device 100 generally includes an electrical power source 116, external or internal, such as one or more batteries.The processing unit 111 may also include means 117 for controlling an input and / or output human-machine interface. An "output human-machine interface" is defined as any means, used alone or in combination, for outputting or delivering a graphical, haptic, auditory, or, more generally, human-perceptible representation. Such an output human-machine interface may consist, but is not limited to, of one or more screens, loudspeakers, or other suitable alternative means. An "interface" is defined as... "Input human-machine interface" refers to a computer keyboard, a pointing device, a touchscreen, a microphone, or, more generally, any interface designed to translate gestures or instructions issued by a human into control or parameter data. Advantageously, input and output human-machine interfaces can be a single physical entity.

[0049] Such an electronic device 100 may consist of a mobile phone (or "smartphone" according to Anglo-Saxon terminology), a tablet computer, or a desktop or laptop computer. The arrangement of the functional modeling method according to the invention, which can be implemented by such a device 100 that we might describe as "consumer-grade," allows the use of non-specific or specialized capture means for implementing the invention. Such a device 100, for example a smartphone, can be adapted by loading into its program memory 113 a computer program P containing instructions to trigger, upon their execution, the implementation of a method according to the invention.This computer program P can use any programming language, and can be in the form of source code, object code, or code intermediate between source and object code, such as in an interpreted form, partially or fully compiled, or in any other desirable form.

Claims

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3.

4. Demands Method (10) for functional modeling of a relief element (3) present in a surface (1), this method (10) being implemented by a processing unit (111) of an electronic device (100) and comprising the following steps: - acquisition (11) of a three-dimensional image (1) of said surface, this image being in the form of a cloud (2) of points describing this surface; - selection (12) of a plurality of points (21-22) of the point cloud marking a target relief element (30) joining said selected points (21-22), this target relief element (30) extending between a first selected point (21) and a second selected point (22) of said plurality of selected points; - extraction (13) from the point cloud (2) of a sub-cloud (20) of points (21-22) around the target relief element (30), this sub-cloud of points describing a subsurface of said surface; - modeling (14) of the subsurface by means of a freeform surface (23) parameterized using control points (24); - determination (15), from a model of the subsurface, of a first topographic line (31) of the subsurface joining the first selected point (21) and the second selected point (22); - determination (16), from the subsurface model, of a second topographic line (32) and a third topographic line (33) on either side of the first topographic line (31). Method (10) according to the preceding claim, characterized in that the relief element (3) is a groove. Method (10) according to the preceding claim, characterized in that the first topographic line (31) is a bottom line of the furrow. Method (10) according to claim 1, characterized in that the relief element (3) is a linear projection.

5. Method (10) according to the preceding claim, characterized in that the first topographic line (31) is a ridge line of the linear projection.

6. Method (10) according to any one of the preceding claims, characterized in that the freeform surface (23) is a uniform cubic B-Spline surface.

7. Method (10) according to any one of the preceding claims, characterized in that an initial shape of the freeform surface (23) is chosen according to business data.

8. Method (10) according to any one of claims 1 to 6, characterized in that the surface (23) is initialized by a lattice of control points (24) included in a plane integrating the first selected point (21) and the second selected point (22).

9. Method (10) according to any one of the preceding claims, characterized in that the step of determining the second topographic line (32) includes a search for a change in slope, with respect to an axis perpendicular to the longitudinal direction of the target relief element (30), between a first substantially straight segment and a second substantially straight segment of the subsurface starting from the first topographic line (31).

10. Electronic device (100) comprising: - a processing unit (111); - a data memory (112); - a program memory (113); said electronic device being characterized in that the processing unit (111) is arranged to implement a method (10) for functional modeling of a relief element (3) present in a surface (1) according to any one of the preceding claims.

11. Product computer program (P) implemented on a memory medium, capable of being implemented within a computer processing unit and comprising instructions for the implementation of a method for functional modeling of a relief element present in a surface according to any one of claims 1 to 9.

12. Computer-readable storage medium containing instructions for a computer program product according to the preceding claim.

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