Method for generating a secure digital model of an object and associated device

Abstract

Method for generating a secure digital model of an object and associated device The method for generating a secure digital model (30) comprises calculating secure vertex coordinates by applying transformation matrices equal to the sum of translation, rotation and distortion matrices to original vertex coordinates. The step of calculating the secure vertex coordinates comprises: - calculating the coordinates of main secure vertices associated with a main part by applying transformation matrices to the coordinates of corresponding main original vertices; and - calculating the coordinates of auxiliary secure vertices associated with an auxiliary part mounted on the main part, by applying a simplified transformation matrix equal to the sum of a translation matrix, a rotation matrix and a zero distortion matrix to the coordinates of corresponding auxiliary original vertices.Figure for abstract: Figure 1.

Description

Title of the invention: Method for generating a secure digital model of an object and associated device

[0001] The present invention relates to a method for generating a secure digital model of an object from an original digital model of said object, the method being implemented by computer,

[0002] the method comprising a step of calculating secure mesh vertex coordinates of the secure digital model by applying transformation matrices to original mesh vertex coordinates of the original digital model, the transformation matrices each being equal to the sum of a translation matrix, a rotation matrix and a distortion matrix.

[0003] For example, the object is a portion of an aircraft.

[0004] Such a method makes it possible to modify geometric parameters of the digital model in order to be able to distribute it or use it in an illustrative, documentary or visual context while keeping the original values ​​of said geometric parameters secret.

[0005] Certain shapes of the object, in particular when the object is an aircraft, have particularities which may affect, for example, the arrangement and / or the aerodynamics. It may therefore be necessary, before transmission to a third party or public dissemination, to slightly modify the shapes by deforming them.

[0006] In the context of an aircraft portion which generally comprises a large number of parts mounted on top of each other, it is necessary to apply the transformation matrices to the digital representations of each of the parts of the aircraft portion in order to avoid an overlap of these digital representations and to maintain consistency of the entire digital model.

[0007] However, applying the transformation matrices to each of the parts of the aircraft portion results in carrying out a considerable number of complex calculations.

[0008] The generation of the secure digital model then requires significant computing power and considerable computing time.

[0009] The aim of the invention is then to propose a method for generating a secure digital model of an object which requires little computing resources and which is rapid in its implementation while allowing the obtaining of a secure digital model which is coherent.

[0010] To this end, the invention relates to a generation method as described above and in which the step of calculating the secure mesh vertex coordinates comprises:

[0011] - a sub-step of calculating the secure mesh vertex coordinates principals associated with at least one principal part of the object by applying transformation matrices to the original principal mesh vertex coordinates associated with the at least one principal part of the object; and

[0012] - a sub-step of calculating the secure mesh vertex coordinates auxiliaries associated with at least one auxiliary part of the object mounted on the at least one main part, by applying a simplified transformation matrix to the original mesh vertex coordinates auxiliaries associated with the at least one auxiliary part of the object, the simplified transformation matrix being equal to the sum of a translation matrix, a rotation matrix and a zero distortion matrix.

[0013] The calculation of secure mesh vertex coordinates is thus simplified by applying simplified transformation matrices (not involving distortion) to the original mesh vertex coordinates associated with certain parts of the aircraft portion.

[0014] According to other advantageous aspects of the invention, the method comprises one or more of the following characteristics, taken in isolation or in all technically possible combinations:

[0015] - at least one transformation matrix applied during the calculation sub-step principal secure mesh vertex coordinates associated with the at least one principal part of the object is equal to the sum of a translation matrix, a rotation matrix and a non-zero distortion matrix;

[0016] - during the sub-step of calculating the secure mesh vertex coordinates auxiliary, auxiliary secure mesh vertex coordinates associated with a plurality of auxiliary parts, in particular with a plurality of identical auxiliary parts, mounted on the same main part, are calculated by applying the same simplified transformation matrix to the original auxiliary mesh vertex coordinates associated with each of these said auxiliary parts;

[0017] - the object comprises a plurality of parts, the method comprising a step of classifying classification of each part as a main part or an auxiliary part,

[0018] each part being classified as being:

[0019] - a main part if the value of the diagonal of a bounding box associated with said part is greater than or equal to a threshold value;

[0020] - an auxiliary part if the value of the diagonal of a bounding box associated with said part is below the threshold value;

[0021] - the threshold value is such that a number of occurrences of the parts of the object including one size of the diagonal of the corresponding bounding box is less than the threshold value is greater than a target number of occurrences;

[0022] - the sub-step of calculating the auxiliary secure mesh vertex coordinates associated with an auxiliary part includes:

[0023] - the calculation of the coordinates of an original center of gravity and the components of original inertia axis vectors of said auxiliary part;

[0024] - the calculation of the coordinates of a secure center of gravity by applying a local translation matrix at the coordinates of the original center of gravity;

[0025] - the calculation of the components of the vectors of axes of inertia secured by application from a local rotation matrix to the components of the vectors of the original inertia axes;

[0026] - the calculation of a simplified transformation matrix from the matrix of local translation and local rotation matrix;

[0027] said simplified transformation matrix being applied to the coordinates of the auxiliary original mesh vertices associated with said auxiliary part to calculate the coordinates of auxiliary secure mesh vertices associated with said auxiliary part;

[0028] - the portions of secure digital model corresponding to the coordinates of main secure mesh vertices and the secure digital model portions corresponding to the auxiliary secure mesh vertex coordinates have substantially zero overlap;

[0029] - the method further comprises a step of calculating the coordinates of the vertices of original mesh of the original digital model including a mesh of the object to obtain a raw original digital model of the object;

[0030] - the step of calculating the coordinates of the original mesh vertices comprises a sub-step of optimization of the original raw digital model;

[0031] - the optimization sub-step includes a decimation of the digital model raw original in order to obtain a decimated original digital model of the object, said decimated original digital model being used for the step of calculating the secure mesh vertex coordinates of the secure digital model;

[0032] - the optimization sub-step comprises an enrichment of at least a part of the raw original digital model to be enriched in order to obtain a part of the enriched original digital model, said part of the enriched original digital model being used for the step of calculating the secure mesh vertex coordinates of the secure digital model,

[0033] the enrichment comprising the increase in the number of meshes relating to said part of the original raw digital model to be enriched; and

[0034] the method further comprises:

[0035] - a step of recording in a database the vertex coordinates of main secure meshes associated with each main part of the object for each transformation matrix;

[0036] - a step of recording in the database the vertex coordinates of secure auxiliary meshes associated with each auxiliary part of the object for each simplified transformation matrix.

[0037] The invention further relates to a device for generating a secure digital model of an object from an original digital model of said object, suitable for implementing the method as described above, the device comprising a unit for calculating the coordinates of the secure mesh vertices of the secure digital model by applying transformation matrices to the coordinates of the original mesh vertices of the original digital model, the transformation matrices each being equal to the sum of a translation matrix, a rotation matrix and a distortion matrix,

[0038] the calculation unit comprising:

[0039] - a module for calculating the coordinates of main secure mesh vertices configured to calculate the coordinates of the main secure mesh vertices associated with the at least one main part of the object by applying the transformation matrices to the coordinates of the main original mesh vertices associated with the at least one main part of the object;

[0040] - a module for calculating auxiliary secure mesh vertex coordinates configured to calculate the coordinates of the auxiliary secure mesh vertices associated with the at least one auxiliary part of the object mounted on the at least one main part, by applying a simplified transformation matrix to the coordinates of the auxiliary original mesh vertices associated with the at least one auxiliary part of the object, the simplified transformation matrix being equal to the sum of a translation matrix, a rotation matrix and a zero distortion matrix.

[0041] The invention will appear more clearly on reading the description which follows, given solely by way of non-limiting example, and made with reference to the drawings in which:

[0042] [Fig-1] [Fig.l] is a schematic representation of a digital model original and a secure digital model of an object, in particular an aircraft, superimposed on each other;

[0043] [Fig.2] [Fig.2] is a schematic representation of a digital model original and a secure digital model of a portion of an aircraft wing, said wing portion comprising a main part and an auxiliary part;

[0044] [Fig.3] [Fig.3] is a schematic representation of the sub-step of calculating the main secure mesh vertex coordinates associated with a main part having a simplified cube shape;

[0045] [Fig.4] [Fig.4] is a schematic representation of the sub-step of calculating the auxiliary secure mesh vertex coordinates associated with an auxiliary part having a simplified cube shape;

[0046] [Fig.5] [Fig.5] is a schematic representation of a device for generating the secure digital model of the object;

[0047] [Fig.6] [Fig.6] is a simplified representation of a graph illustrating a dis distribution of the number of distinct parts of an object, in particular an aircraft, as a function of the size of the diagonal of a bounding box of these parts and a graph illustrating a distribution of the number of occurrences of the parts of an object, in particular an aircraft, as a function of the size of the diagonal of a bounding box of these parts; and

[0048] [Fig.7] [Fig.7] is a schematic representation of the method of generating a secure digital model of a portion of aircraft according to the invention.

[0049] With reference to figures 1 to 4, a digital model of an object 10 is described.

[0050] In a specific example of the description, the object 10 is a portion of an aircraft. It It is of course understood that the invention is not limited to the generation of a digital model of a portion of an aircraft.

[0051] In the example of [Fig. 1], the aircraft portion corresponds to the entire aircraft.

[0052] In the example of [Fig.2], the aircraft portion corresponds to a wing of the aircraft.

[0053] The aircraft portion comprises a plurality of parts.

[0054] In the context of the invention, the parts of the aircraft portion illustrated on the digital model are each a main part or an auxiliary part mounted on a main part. The classification of the parts of the aircraft portion as a main part or an auxiliary part will be detailed below.

[0055] In the example of [Fig.2], the aircraft portion comprises wing skin elements 12 fixed to ribs, stringers and wing spar soles by means of rivets 14. In this example, the skin elements 12 are main parts and the rivets 14 are auxiliary parts mounted on the skin elements 12.

[0056] In Figures 1 and 2, an original digital model 20 of the corresponding aircraft portion and a secure digital model 30 of said aircraft portion are illustrated.

[0057] The original digital model 20 corresponds to a digital representation of the aircraft portion which has geometric dimensions corresponding to the real geometric dimensions of said aircraft portion.

[0058] The secure digital model 30 corresponds to a digital representation of the aircraft portion which has secure geometric dimensions different from the real geometric dimensions of said aircraft portion, while remaining close to these real geometric dimensions.

[0059] The secure digital model 30 can thus be revealed to a third party while allowing the real geometric sizes of the parts of the aircraft portion to be kept secret and while maintaining an overall shape of the aircraft portion which is realistic and coherent.

[0060] For example, the geometric quantities to be secured with regard to an aircraft engine nacelle are:

[0061] - the overall volume of the engine nacelle with for example a variation between the actual total volume and the total secured volume substantially equal to +5%;

[0062] - the length of the engine nacelle, with for example a variation between the length actual and the secured length substantially equal to -3%;

[0063] - the minimum distance between the engine nacelle and the fuselage with for example a variation between the actual minimum distance and the safe minimum distance substantially equal to +3%;

[0064] - the orientation of the engine axis of the engine nacelle with for example a variation between the real motor axis and the safe motor axis substantially equal to -1°.

[0065] In the example of [Fig.l], the original digital model 20 of the aircraft is superimposed on the secure digital model 30 of the same aircraft.

[0066] In the example of [Fig.2], the secure digital model 30 of the wing is offset in space relative to the original digital model 20 due to the deformations applied to the original digital model 20 to obtain the secure digital model 30.

[0067] In the example of [Fig. 3], an original digital model 20 of a simplified main part of an aircraft portion and a secure digital model 30 of said simplified main part obtained by a method according to the invention, which will be described later, are described.

[0068] The simplified main part is cubic in shape. According to the example of [Fig.3], the original digital model 20 of the simplified main part undergoes translation, rotation and distortion to obtain the secure digital model 30 of the simplified main part.

[0069] The original digital model 20 of the simplified main part comprises a plurality of main original mesh vertices 22. Each main original mesh vertex 22 has spatial coordinates x, y, z relative to an absolute reference frame. The secure digital model 30 of the simplified main part comprises a plurality of main secure mesh vertices 32. Each main secure mesh vertex 32 has spatial coordinates x', y', z' relative to the absolute reference frame.

[0070] As will be detailed below, the main secure mesh vertex coordinates 32 are calculated by applying transformation matrices to the co ordinates of main original mesh vertices 22, the transformation matrices each being equal to the sum of a translation matrix, a rotation matrix and a distortion matrix. In other words, the spatial coordinates x', y', z' of the main secure mesh vertices 32 are of the form x' = f(x, y, z), y' = g(x, y, z) and z' = h(x, y, z) where f, g and h are transformation functions composing the corresponding transformation matrix.

[0071] In the example of [Fig.4], an original digital model 20 of a simplified auxiliary part of an aircraft portion and a secure digital model 30 of said simplified auxiliary part obtained by the method according to the invention are described. For example, the simplified auxiliary part is mounted on a main part as described above.

[0072] The simplified auxiliary part is cubic in shape. According to the example of [Fig.4] and in accordance with the method according to the invention, the original digital model 20 of the simplified main part undergoes a translation and a rotation without distortion to obtain the secure digital model of the simplified auxiliary part.

[0073] The original digital model 20 of the simplified auxiliary part comprises a plurality of auxiliary original mesh vertices 24. Each auxiliary original mesh vertex 24 has spatial coordinates x, y, z relative to the absolute reference frame. The secure digital model 30 of the simplified auxiliary part comprises a plurality of auxiliary secure mesh vertices 34. Each auxiliary secure mesh vertex 34 has spatial coordinates x', y', z' relative to the absolute reference frame.

[0074] As will be detailed below, the auxiliary secure mesh vertex coordinates 34 associated with an auxiliary part are calculated by applying a simplified transformation matrix to the auxiliary original mesh vertex coordinates 24 associated with said auxiliary part, in particular to the coordinates of each of the auxiliary original mesh vertices 24 associated with said auxiliary part. In other words, the spatial coordinates x', y', z' of the auxiliary secure mesh vertices 34 are of the form x' = a(x, y, z), y' = b(x, y, z) and z' = c(x, y, z) where a, b and c are transformation functions composing the corresponding simplified transformation matrix.

[0075] The simplified transformation matrix is ​​equal to the sum of a translation matrix, a rotation matrix and a zero distortion matrix. The simplified transformation matrix thus corresponds to a translation and / or a rotation without distortion.

[0076] Each mesh of the original digital model 20 or of the secure digital model 30 is delimited by at least three mesh vertices.

[0077] In the example of [Fig.4], an original center of gravity 26 and axes of inertia originals 27 of the simplified auxiliary part are illustrated.

[0078] A secure center of gravity 36 and secure axes of inertia 37 of the simplified auxiliary part are also illustrated.

[0079] Also, in the example of [Fig. 4], a bounding box 28 (or "bounding box" in English) encompassing the simplified auxiliary part is also illustrated. By "bounding box" is meant the smallest volume (parallel piped) encompassing the geometry of the auxiliary part. The bounding box 28 is in particular oriented along the original axes of inertia 27 of the auxiliary part. In other words, the faces of the bounding box are each orthogonal to an original axis of inertia 27 of the auxiliary part. In the example of [Fig. 4], the simplified auxiliary part having a simple cube shape, the original digital model 20 of said simplified auxiliary part has a shape substantially identical to the real shape of said simplified auxiliary part, so that the bounding box 28 is delimited by all of the faces of the original digital model 20.In other words, in this simple case, the corners of the bounding box 28 correspond to the main original mesh vertices 22 of the original digital model.

[0080] Further, a diagonal 29 of the bounding box 28 is also illustrated in [Fig.4],

[0081] Advantageously, the functions a, b and c are continuous functions (at least C°) in the domain of the bounding box 28.

[0082] Still advantageously, the portions of secure digital model 30 corresponding to the coordinates of main secure mesh vertices 32 and the portions of secure digital model 30 corresponding to the coordinates of auxiliary secure mesh vertices 34 have zero overlap. In other words, the volumes delimited by the main secure mesh vertices 32 and the volumes delimited by the auxiliary secure mesh vertices 34 do not collide.

[0083] With reference to [Fig.5], a device 40 is described for generating a secure digital model 30 of a portion of aircraft from an original digital model 20 of said portion of aircraft.

[0084] The device 40 comprises a unit 70 for calculating secure mesh vertex coordinates 32, 34 of the secure digital model 30.

[0085] Advantageously, the device 40 further comprises:

[0086] - a unit 42 for calculating original mesh vertex coordinates 22, 24 of the original digital model 20;

[0087] - a unit 60 for classifying each part of the aircraft portion; and

[0088] - a unit 90 for recording vertex coordinates in a database secure mesh 32, 34.

[0089] The unit 42 comprises a module 44 for meshing the aircraft portion.

[0090] Advantageously, the unit 42 further comprises an optimization module 46.

[0091] The meshing module 44 is configured to generate the original raw digital model 20 of the aircraft portion.

[0092] The optimization module 46 is configured to optimize the raw original digital model 20 in order to obtain an optimized original digital model 20.

[0093] The optimization module notably comprises a decimation sub-module 48 and an enrichment sub-module 50.

[0094] The decimation sub-module 48 is configured to decimate the raw original digital model 20 in order to obtain a decimated original digital model 20 of the aircraft portion.

[0095] The enrichment sub-module 50 is configured to enrich at least a portion of the raw original digital model, to be enriched, in order to obtain an enriched portion of enriched original digital model 20. The enrichment comprises increasing the number of meshes relating to said portion to be enriched.

[0096] The classification unit 60 is configured to classify each part of the aircraft portion as a main part or an auxiliary part.

[0097] [Fig.6] presents a first graph (at the top of [Fig.6]) illustrating an example of a distribution of the number of distinct parts NP of an object, in particular of an aircraft, as a function of the size D of the diagonal of a bounding box of these parts, and a second graph (at the bottom of [Fig.6]) illustrating an example of a distribution of the number of occurrences NO of each part of an object, in particular of said aircraft of the first graph, as a function of the size D of the diagonal of a bounding box of these parts.

[0098] As seen in [Fig.6], the distribution of the number of distinct parts NP as a function of the size D of the bounding box diagonal is similar to a Gaussian function. The first graph of [Fig.6] therefore illustrates that the object (here the aircraft) has a relatively low number NP of distinct parts with a relatively low bounding box diagonal size D (left end of the curve). Furthermore, the second graph of [Fig.6] illustrates that the object (the same aircraft) has relatively high occurrence numbers for each distinct part with a relatively low bounding box diagonal size D (left end of the curve).In other words, the object has few distinct parts with a relatively small bounding box diagonal size D but these distinct parts are present a relatively high number of times in the aircraft (relatively high number of occurrences compared to parts with a larger bounding box diagonal size D).

[0099] With reference to [Fig.6], each part is advantageously classified as being:

[0100] - a main part if the value of the diagonal 29 of the bounding box 28 associated with said part is greater than or equal to a threshold value DT;

[0101] - an auxiliary part if the value of the diagonal 29 of the bounding box 28 associated with said part is lower than the threshold value DT.

[0102] Advantageously, the threshold value DT is such that the number of occurrences NO of the parts whose size D of the diagonal of the corresponding bounding box is less than the threshold value DT is greater than a target number of occurrences NOC. For example, the target number of occurrences NOC is equal to 2.

[0103] The number of target NOC occurrences depends on the dimensions of the original digital model 20, a level of detail present on the original digital model 20 and / or a desired target level of precision for the secure digital model 30.

[0104] The target number of occurrences NOC is notably defined so that parts having a relatively high number of occurrences NO are classified as auxiliary parts.

[0105] Advantageously, the threshold value DT is proportional to a desired maximum deformation.

[0106] The desired maximum deformation is, for example, the largest desired distance among desired distances between each of the original mesh vertices 22, 24 of the original digital model 20 and the corresponding secure mesh vertex 32, 34 of the secure digital model 30.

[0107] The unit 70 is configured to calculate the secure mesh vertex coordinates 32, 34 of the secure digital model 30.

[0108] The unit 70 comprises a module 72 for calculating the coordinates of main secure mesh vertices 32 and a module 74 for calculating the coordinates of auxiliary secure mesh vertices 34.

[0109] The module 72 is configured to calculate the coordinates of the main secure mesh vertices 32 associated with each main part by applying the transformation matrices to the coordinates of the main original mesh vertices 22 associated with each corresponding main part.

[0110] The module 74 is configured to calculate the coordinates of auxiliary secure mesh vertices 34 associated with each auxiliary part by applying a simplified transformation matrix to the coordinates of the original auxiliary mesh vertices 24 associated with each corresponding auxiliary part.

[0111] In particular, the module 74 is configured to calculate the auxiliary secure mesh vertex coordinates 34 associated with several auxiliary parts, in particular with a plurality of identical auxiliary parts, mounted on the same main part by applying the same simplified transformation matrix to the coordinates of the auxiliary original mesh vertices 24 associated with each of these said auxiliary parts.

[0112] Module 74 includes in particular:

[0113] - a sub-module 76 for calculating the coordinates of the original center of gravity 26 and of components of original inertia axis vectors 27;

[0114] - a sub-module 78 for calculating the coordinates of secure centers of gravity 36;

[0115] - a sub-module 80 for calculating components of inertia axis vectors secured 37; and

[0116] - a sub-module 82 for calculating simplified transformation matrices.

[0117] The sub-module 76 is configured to calculate the coordinates of the original center of gravity 26 and the components of the original inertia axis vectors 27 of each auxiliary part.

[0118] The sub-module 78 is configured to calculate the coordinates of the secure center of gravity 36 of each auxiliary part by applying a local translation matrix to the coordinates of the corresponding original center of gravity 26. By “local” translation matrix is ​​meant the translation matrix corresponding to the translation undergone locally at the original center of gravity 26 by the auxiliary part.

[0119] The sub-module 80 is configured to calculate the components of the secured inertia axis vectors 37 of each auxiliary part by applying a local rotation matrix to the components of the corresponding original inertia axis vectors 27. By “local” rotation matrix, we mean the rotation matrix corresponding to the rotation undergone locally by the original inertia axes 27 of the auxiliary part.

[0120] The sub-module 82 is configured to calculate a simplified transformation matrix from the local translation matrix and the local rotation matrix. In particular, the simplified transformation matrix is ​​equal to the sum of the local translation matrix and the local rotation matrix. In other words, for the simplified transformation matrix, the distortion matrix is ​​zero.

[0121] Unit 90 is configured to record secure mesh vertex coordinates 32, 24.

[0122] The unit 90 comprises a database 92, a module 94 for recording the coordinates of main secure mesh vertices 32 and a module 96 for recording the coordinates of auxiliary secure mesh vertices 34.

[0123] The database 92 is configured to store data corresponding to the secure mesh vertex coordinates 32, 34.

[0124] The module 94 is configured to record in the database 92 the coordinates of main secure mesh vertices 32 associated with each main part of the aircraft portion for each transformation matrix.

[0125] The module 96 is configured to record in the database 94 the auxiliary secure mesh vertex coordinates 34 associated with each auxiliary part of the aircraft portion for each simplified transformation matrix.

[0126] In the example of [Fig.5], the device 40 comprises an information processing system formed for example of a memory and a processor associated with the memory.

[0127] In the example of [Fig.5], the units 42, 60, 70 and 90, the modules 44, 46, 72, 74, 92, 94, 96 and the sub-modules 48, 50, 76, 78, 80 and 82 are each produced in the form of software, or a software brick, executable by the processor and stored in the memory.

[0128] In a variant not shown, the units 42, 60, 70 and 90, the modules 44, 46, 72, 74, 92, 94, 96 and the sub-modules 48, 50, 76, 78, 80 and 82 are each produced in the form of a programmable logic component, such as an FPGA (Field Programmable Gate Array) or an integrated circuit, such as an ASIC (Application Specific Integrated Circuit).

[0129] When the device 40 is produced in the form of one or more software programs, that is to say in the form of a computer program, also called a computer program product, it is furthermore capable of being recorded on a medium, not shown, readable by a computer. The computer-readable medium is for example a medium capable of storing electronic instructions and of being coupled to a bus of a computer system. By way of example, the readable medium is an optical disk, a magneto-optical disk, a ROM memory, a RAM memory, any type of non-volatile memory (for example FLASH or NVRAM) or a magnetic card. A computer program comprising software instructions is then stored on the readable medium.

[0130] With reference to [Fig.7], a method 100 is described for generating the secure digital model 30 of a portion of aircraft according to the invention, from the original digital model 20 of said portion of aircraft.

[0131] The method 100 is implemented by computer, in particular by the device 40 described above.

[0132] Advantageously, the method 100 comprises a step 110 of calculating the original mesh vertex coordinates 22, 24 of the original digital model 20.

[0133] In particular, step 110 comprises a meshing (or digitization or even spatial discretization or even tessellation) of the aircraft portion to obtain an original raw digital model 20 of the aircraft portion.

[0134] In particular, step 110, in particular the meshing, comprises a sub-step 112 of optimization of the original raw digital model.

[0135] For example, sub-step 112 comprises a decimation 112A of the raw original digital model 20 in order to obtain a decimated original digital model 20 of the aircraft portion. Advantageously, the decimated original digital model 20 is used for a step 130 of calculating the secure mesh vertex coordinates 32, 34 of the secure digital model 30, described below.

[0136] According to another example, the sub-step 112 comprises an enrichment 112B of at least a portion of the raw original digital model 20 to be enriched in order to obtain a portion of the enriched original digital model 20. The enrichment comprises increasing the number of meshes relating to said portion of the raw original digital model to be enriched. Advantageously, said portion of the enriched original digital model 20 is used for the step 130 of calculating the secure mesh vertex coordinates 32, 34 of the secure digital model 30, described below.

[0137] Still advantageously, the method 100 comprises a step 120 of classifying each part as a main part or an auxiliary part. The classification step 120 makes it possible to sort the parts of the aircraft portion in order to distinguish the parts for which it is possible to neglect the distortion component (and therefore to simplify the calculation of the secure mesh vertex coordinates), in particular the parts of relatively small volume, without harming the consistency of the secure digital model 30.

[0138] The method 100 comprises a step 130 of calculating the secure mesh vertex coordinates 32, 34 of the secure digital model 30 by applying transformation matrices to the original mesh vertex coordinates 22, 24 of the original digital model 20.

[0139] Step 130 comprises:

[0140] - a sub-step 132 of calculating the secure mesh vertex coordinates principals 32 associated with at least one principal part of the aircraft portion by applying the transformation matrices to the original mesh vertex coordinates principals 22 associated with the at least one principal part of the aircraft portion 10;

[0141] - a sub-step 134 of calculating the secure mesh vertex coordinates auxiliaries 34 associated with at least one auxiliary part of the aircraft portion mounted on the at least one main part, by applying a simplified transformation matrix to the original mesh vertex coordinates auxiliaries 24 associated with the at least one auxiliary part of the aircraft portion.

[0142] Advantageously, at least one transformation matrix applied during sub-step 132 is equal to the sum of a translation matrix, a rotation matrix and a distortion matrix, in which the distortion matrix is ​​non-zero. According to a particular example, each of the set of transformation matrices applied during substep 132 is equal to the sum of a translation matrix, a rotation matrix and a distortion matrix, in which the distortion matrix is ​​non-zero.

[0143] The application of simplified transformation matrices for parts qualified as auxiliary, mounted on a main part, makes it possible to simplify the generation of the secure model while ensuring the obtaining of a coherent secure model, that is to say a secure model in which the overlap between the portions of secure digital model corresponding to the coordinates of main secure mesh vertices and the portions of secure digital model corresponding to the coordinates of auxiliary secure mesh vertices have a substantially zero overlap. In other words, when viewing the secure model, the collisions between the auxiliary parts and the main parts are substantially invisible to the observer.

[0144] Advantageously, during sub-step 134, the auxiliary secure mesh vertex coordinates 34 associated with a plurality of auxiliary parts, in particular with a plurality of identical auxiliary parts, mounted on the same main part are calculated by applying the same simplified transformation matrix to the auxiliary original mesh vertex coordinates 24 associated with each of these said auxiliary parts.

[0145] Thanks to sub-step 134 and in particular thanks to classification step 120, the production of the secure digital model is simplified since the relatively small parts (those classified as auxiliary parts) are translated and / or rotated without distortion, in a similar manner.

[0146] Advantageously, sub-step 134 comprises:

[0147] - the calculation 134A of the original center of gravity coordinates 26 and the components of original inertia axis vectors 27 of the at least one auxiliary part (left part of [Fig.4]);

[0148] - the calculation 134B of the coordinates of a secure center of gravity 36 by application of a local translation matrix at the coordinates of the original center of gravity 26 (central part of [Fig.4]);

[0149] - the calculation 134C of the components of the secured inertia axis vectors 37 by ap plication of a local rotation matrix to the components of the vectors of the original inertia axes 27 (central part of [Fig.4]);

[0150] - the calculation 134D of a simplified transformation matrix from the matrix of local translation and local rotation matrix.

[0151] The calculated simplified transformation matrix is ​​applied to the coordinates of the auxiliary original mesh vertices 24 associated with the at least one auxiliary part, in particular to all of the auxiliary original mesh vertices 24 associated with the at least one auxiliary part. at least one auxiliary part, to calculate the auxiliary secure mesh vertex coordinates 34 associated with said at least one auxiliary part (right part of [Fig.4]).

[0152] Advantageously, the method 100 comprises a recording 140 of the secure mesh vertex coordinates 32, 34.

[0153] In particular, the method 100 comprises:

[0154] - a step 142 of recording in the database 92 the coordinates of 32 main secure mesh vertices associated with each main part of the aircraft portion for each transformation matrix;

[0155] - a step 144 of recording in the database 92 the coordinates of 34 auxiliary secure mesh vertices associated with each auxiliary part of the aircraft portion for each simplified transformation matrix.

[0156] Thanks to the invention, the secure digital model 30 of the aircraft portion is obtained by requiring less computing power and / or computing time compared to the methods of the prior art.

Claims

Claims

1. A method (100) for generating a secure digital model (30) of an object (10) from an original digital model (20) of said object (10), the method (100) being implemented by computer, the method (100) comprising a step (130) of calculating secure mesh vertex coordinates (32, 34) of the secure digital model (30) by applying transformation matrices to original mesh vertex coordinates (22, 24) of the original digital model (20), the transformation matrices each being equal to the sum of a translation matrix, a rotation matrix and a distortion matrix, characterized in that the step (130) of calculating the secure mesh vertex coordinates (32,34) comprises: - a sub-step (132) of calculating the coordinates of main secure mesh vertices (32) associated with at least one main part of the object (10) by applying transformation matrices to the coordinates of main original mesh vertices (22) associated with the at least one main part of the object (10); and - a sub-step (134) of calculating the coordinates of auxiliary secure mesh vertices (34) associated with at least one auxiliary part of the object (10) mounted on the at least one main part, by applying a simplified transformation matrix to the coordinates of auxiliary original mesh vertices (24) associated with the at least one auxiliary part of the object (10), the simplified transformation matrix being equal to the sum of a translation matrix, a rotation matrix and a zero distortion matrix.,

2. Method (100) according to claim 1, wherein at least one transformation matrix applied during the sub-step (132) of calculating the coordinates of main secure mesh vertices (32) associated with the at least one main part of the object (10) is equal to the sum of a translation matrix, a rotation matrix and a non-zero distortion matrix.

3. Method (100) according to claim 1 or 2, wherein during the sub-step (134) of calculating the auxiliary secure mesh vertex coordinates, auxiliary secure mesh vertex coordinates (34) associated with a plurality of auxiliary parts, in particular with a plurality of identical auxiliary parts, mounted on the same part main, are calculated by applying the same simplified transformation matrix to the original auxiliary mesh vertex coordinates (24) associated with each of these said auxiliary parts.

4. A method (100) according to any preceding claim, wherein the object (10) comprises a plurality of parts, the method (100) comprising a step (120) of classifying each part as a main part or an auxiliary part, each part being classified as being: - a main part if the value of the diagonal (29) of a bounding box (28) associated with said part is greater than or equal to a threshold value (Dt); - an auxiliary part if the value of the diagonal (29) of a bounding box (28) associated with said part is less than the threshold value (DT).

5. Method (100) according to claim 4, wherein the threshold value (DT) is such that a number of occurrences (NO) of the parts of the object (10) of which a size (D) of the diagonal (29) of the corresponding bounding box (28) is less than the threshold value (DT), is greater than a target number of occurrences (NOC).

6. A method (100) according to any preceding claim, wherein the sub-step (134) of calculating auxiliary secure mesh vertex coordinates (34) associated with an auxiliary part comprises: - calculating (134A) coordinates of an original center of gravity (26) and components of original inertia axis vectors (27) of said auxiliary part; - calculating (134B) coordinates of a secure center of gravity (36) by applying a local translation matrix to the coordinates of the original center of gravity (26); - calculating (134C) components of secure inertia axis vectors (37) by applying a local rotation matrix to components of original inertia axis vectors (27); - calculating (134D) a simplified transformation matrix from the local translation matrix and the local rotation matrix;said simplified transformation matrix being applied to the coordinates of the auxiliary original mesh vertices (24) associated with said auxiliary part to calculate the coordinates of auxiliary secure mesh vertices (34) associated with said auxiliary part.;

7. A method (100) according to any preceding claim, wherein the secure digital model portions (30) corresponding to the main secure mesh vertex coordinates (32) and the secure digital model portions (30) corresponding to the auxiliary secure mesh vertex coordinates (34) have substantially zero overlap.

8. Method (100) according to any one of the preceding claims, comprising a step (110) of calculating the coordinates of the original mesh vertices (22, 24) of the original digital model (20) comprising a mesh of the object (10) to obtain a raw original digital model (20) of the object (10).

9. Method (100) according to claim 8, wherein the step (110) of calculating the coordinates of the original mesh vertices (22, 24) comprises a sub-step (112) of optimizing the original raw digital model (20).

10. Method (100) according to claim 9, wherein the optimization sub-step (112) comprises a decimation (112A) of the raw original digital model (20) in order to obtain a decimated original digital model (20) of the object (10), said decimated original digital model (20) being used for the step (130) of calculating the secure mesh vertex coordinates (32, 34) of the secure digital model (30).

11. Method (100) according to claim 9 or 10, wherein the optimization sub-step (112) comprises an enrichment (112B) of at least a part of the raw original digital model (20) to be enriched in order to obtain a part of the enriched original digital model (20), said part of the enriched original digital model (20) being used for the step (130) of calculating the secure mesh vertex coordinates (32, 34) of the secure digital model (30), the enrichment (112B) comprising the increase in the number of meshes relating to said part of the raw original digital model (20) to be enriched.

12. Method (100) according to any one of the preceding claims, further comprising: - a step (142) of recording in a database (92) the coordinates of main secure mesh vertices (32) associated with each main part of the object (10) for each transformation matrix; - a step (142) of recording in the database (92) the auxiliary secure mesh vertex coordinates (34) associated with each auxiliary part of the object (10) for each simplified transformation matrix.

13. Device (40) for generating a secure digital model (30) of an object (10) from an original digital model (20) of said object (10), suitable for implementing the method (100) according to any one of the preceding claims, the device (40) comprising a unit (70) for calculating the coordinates of the secure mesh vertices (32, 34) of the secure digital model (30) by applying transformation matrices to the coordinates of original mesh vertices (22, 24) of the original digital model (20), the transformation matrices each being equal to the sum of a translation matrix, a rotation matrix and a distortion matrix, the calculation unit (70) comprising: - a module (72) for calculating the coordinates of the main secure mesh vertices (32) configured to calculate the coordinates of the main secure mesh vertices (32) associated with the at least one main part of the object (10) by applying the transformation matrices to the coordinates of the main original mesh vertices (22) associated with the at least one main part of the object (10); - a module (74) for calculating the coordinates of auxiliary secure mesh vertices (34) configured to calculate the coordinates of the auxiliary secure mesh vertices (34) associated with the at least one auxiliary part of the object (10) mounted on the at least one main part, by applying a simplified transformation matrix to the coordinates of the auxiliary original mesh vertices (24) associated with the at least one auxiliary part of the object (10), the simplified transformation matrix being equal to the sum of a translation matrix, a rotation matrix and a zero distortion matrix.

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