Mother type ship transformation design method and system based on three-dimensional geometric model

Abstract

The invention belongs to the technical field of ship engineering CAD three-dimensional modeling, and particularly relates to a mother type ship transformation design method and system based on a three-dimensional geometric model, and the method comprises the steps: obtaining a three-dimensional profile point coordinate set of a mother type ship, and constructing a ship body profile according to an NURBS curve formed by the profile point coordinate set; modifying the coordinates of the data point; generating a CAD three-dimensional model of the target ship based on the modified data point coordinate transformation; according to the method, various molded line transformation methods are randomly combined and selected, molded line transformation operation, driving point modification and molded line modification are carried out in a program one by one according to the sequence of linear transformation, piecewise linear transformation, a 1-CP method and middle cross section coefficient transformation, and finally a transformed molded line result is displayed. The method has the advantages of reducing the number of times of repeated modeling and simulation verification, supporting collaborative optimization of multiple parameters such as the main scale, the prismatic coefficient and the buoyancy center position, ensuring that the molded line meets the function and performance requirements, being capable of being implemented in domestic CAD software, and reducing dependence on foreign software.

Description

Technical Field

[0001] The present invention belongs to the technical field of ship engineering CAD three-dimensional modeling, and specifically relates to a method and system for transforming the design of a parent ship based on a three-dimensional geometric model. Background Art

[0002] In the basic design stage of a ship, according to the requirements of the ship's functional characteristics, general arrangement, main dimensions, etc., a complete set of ship hull lines needs to be designed. These ship hull lines not only need to meet the ship's functional and layout requirements, but also need to have a certain degree of fairness, and can initially meet the overall performance requirements of the ship. If CAD is used again for the preliminary design of the hull lines, the hull lines need to undergo a large number of hydrodynamic simulation optimizations and model test demonstrations and comparisons before gradually becoming a relatively mature set of hull lines. The general designer usually relies on foreign three-dimensional design software to assist in the original three-dimensional modeling of the hull lines and the design of hull line transformation at this stage to design the preliminary hull lines of the ship. In the general environment of the country's strong support for the independent research and development of domestic shipbuilding industry software, this patent will effectively combine the theoretical method of hull line transformation with the three-dimensional geometric construction function of the ship to achieve rapid transformation design and modeling of the hull lines within domestic CAD software. Summary of the Invention

[0003] To solve the problems raised in the above background art, the present invention provides a method and system for transforming the design of a parent ship based on a three-dimensional geometric model.

[0004] To achieve the above object, the first aspect of the present invention provides a method for transforming the design of a parent ship based on a three-dimensional geometric model, based on existing approximate parent ship form values, including the steps of:

[0005] Step S100, obtaining the three-dimensional form value point coordinate set of the parent ship, and constructing the ship hull line according to the NURBS curve formed by the form value point coordinate set;

[0006] Step S200, modifying the form value point coordinates;

[0007] Step S300, generating a CAD three-dimensional model of the target ship based on the transformed form value point coordinates.

[0008] Preferably, in step S200, the modification of the form value point coordinates includes at least one of the following methods:

[0009] a. Scaling the form value points according to the main dimension ratio of the target ship to the parent ship;

[0010] b. Moving the longitudinal coordinate values of the form value points within a certain range of the ship hull line, and keeping the coordinate values of the form value points outside the range unchanged to generate a new set of three-dimensional form value points, thereby realizing the transformation of the ship form value point coordinates;

[0011] c. The cross-sectional area of each station of the ship is longitudinally shifted by a distance S to achieve the prismatic coefficient C P , the length of the parallel middle body l P , the longitudinal coordinate value x of the center of buoyancy B modification; the user defines the change amount x B of the longitudinal position of the center of buoyancy of the target ship, the prismatic coefficient C P change amount, and the change amounts of the lengths l P of the front and rear parallel middle bodies, and applies relevant functions to calculate the change amounts δC PF and δC PA of the prismatic coefficients of the front and rear bodies; then, the change amount of the cross-sectional position is solved through the change amounts of the prismatic coefficients of the front and rear bodies, so as to realize the change of the coordinate values of the ship's hull line points by setting parameters including but not limited to the displacement volume, block coefficient, and longitudinal coordinate value of the center of buoyancy.

[0012] d. By setting the midship section coefficient of the target ship, comparing the size relationship with the midship section coefficient of the parent ship, and magnifying or reducing the radius of the bilge arc line in a certain step to make it close to the set midship section coefficient value.

[0013] Preferably, in the method a, the proportional scaling formula is as follows:

[0014] x n = (L PPn / L PP0 ) x0; y n = (B n / B0) y0; z n = (d n / d0) z0; where:

[0015] Lpp, B, and d respectively represent the length between perpendiculars, molded breadth, and draft;

[0016] x n , y n , z n respectively represent the coordinate values of the designed hull line;

[0017] x0, y0, and z0 respectively represent the coordinate values of the parent ship hull line.

[0018] Preferably, in the method b, there are four methods including the translation transformation without constraints at the bow and stern ends, the translation transformation with constraints at the bow end, the translation transformation with constraints at the stern end, and the translation transformation with constraints at both ends, where:

[0019] When there are no constraints, the cross-section lines at the corresponding positions are translated along the X direction, and the X values of the cross-section lines at other positions remain unchanged;

[0020] When there are constraints, the X values of the cross-section lines within the range are moved proportionally;

[0021] Preferably, in the method c, the cross-sectional area curve is divided into two parts, the front half and the rear half, for separate modification, and then the area curve and modification parameters of the half-body are made dimensionless. When there is a parallel middle body, only C is modified. P :

[0022] The calculation formula for the movement amount of the front half-body cross-section is:

[0023]

[0024] The calculation formula for the movement amount of the rear half-body cross-section is:

[0025]

[0026] Among them, the change amounts of the prismatic coefficients of the front and rear bodies, δC PF and δC PA .

[0027] Preferably, in the method c, the cross-sectional area curve is divided into two parts, the front half and the rear half, for separate modification, and then the area curve and modification parameters of the half-body are made dimensionless. At the same time, C P and l P The scenario is as follows:

[0028] When there is a parallel middle body:

[0029] The calculation formula for the movement amount of the front half-body cross-section is:

[0030]

[0031] In the formula: A F = C PF (1 - 2x BF ) - l PF (1 - C PF );

[0032] The calculation formula for the movement amount of the rear half-body cross-section is:

[0033]

[0034] In the formula: A A = C PA (1 - 2x BA ) - l PA (1 - C PA );

[0035] When there is no parallel middle body:

[0036] The movement amount of the front half-body cross-section is:

[0037]

[0038] The movement amount of the afterbody cross-section is as follows:

[0039]

[0040] Preferably, in the said method c, the cross-sectional area curve is divided into two parts, the forebody and the afterbody, for separate modification, and then the area curves and modification parameters of the half-bodies are made dimensionless. Among them, C P and l P , x B are modified simultaneously in the following scenarios:

[0041] When there is a parallel middle body,

[0042] The calculation formula for the change amount of the prismatic coefficient of the forebody is:

[0043]

[0044] The calculation formula for the change amount of the prismatic coefficient of the afterbody is:

[0045]

[0046] When there is no parallel middle body,

[0047] The calculation formula for the change amount of the prismatic coefficient of the forebody is:

[0048]

[0049] The calculation formula for the change amount of the prismatic coefficient of the afterbody is:

[0050]

[0051] Preferably, in the said method c, the cross-sectional area curve is divided into two parts, the forebody and the afterbody, for separate modification, and then the area curves and modification parameters of the half-bodies are made dimensionless. Among them, only x B is modified in the following scenarios:

[0052] The calculation formula for the movement amount of each station's cross-section line is:

[0053] δx = cy

[0054] In the formula: y is the vertical coordinate of the cross-sectional area curve at x, and c is the ratio of the modification amount of the center of buoyancy position to the vertical coordinate of the centroid of the area under the curve.

[0055] Preferably, the transformation of the midship cross-sectional coefficient is achieved by iteratively adjusting the bilge radius of curvature to make the error between the midship cross-sectional coefficient C m of the target ship and the set value less than 1%.

[0056] A parent ship transformation design system based on a three-dimensional geometric model proposed in the second aspect of the present invention includes:

[0057] An acquisition unit for acquiring a set of three-dimensional offset point coordinates of a parent ship and constructing a hull line according to the NURBS curve formed by the set of offset point coordinates;

[0058] A modification unit for modifying the offset point coordinates;

[0059] A modeling unit for generating a CAD three-dimensional model of a target ship based on the transformed offset point coordinates after modification.

[0060] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0061] The present invention arbitrarily combines and selects various hull line transformation methods, and performs hull line transformation operations one by one inside the program in the order of linear transformation, piecewise linear transformation, 1-C P method, and midship section coefficient transformation, drives the modification of driving points and hull lines, and finally displays the result of the transformed hull line; reduces the number of repeated modeling and simulation verification times, supports the collaborative optimization of multiple parameters such as main dimensions, prismatic coefficient, and position of the center of buoyancy, ensures that the hull line meets the functional and performance requirements, can be implemented in domestic CAD software, and reduces the dependence on foreign software. Description of the Drawings

[0062] Figure 1 It is a schematic flow chart of the modeling method of the present invention;

[0063] Figure 2 It is an example display diagram in an embodiment of the present invention. Detailed Embodiment

[0064] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0065] The present invention is based on the theoretical method of hull line transformation, drives the offset points forming the hull line to be modified according to the transformation rules of the parent ship. Each offset point is composed of three-dimensional coordinate values, and the hull line is expressed by the NURBS curve formed by fitting these offset points. The modified offset points drive the modification of the hull line, and finally the hull surface is constructed from the transformed hull line to form a three-dimensional CAD model of the hull.

[0066] This transformation design method is a line similarity transformation based on the existing approximate parent ship form values, mainly including three transformation methods. The hull lines after transformation can basically meet the basic functional requirements in the preliminary design stage of the ship, and only need to be further designed on this basis subsequently.

[0067] This transformation method defines the main dimensions data of the parent ship and corresponds to the actual model data. The hull model is divided into the forebody, parallel middle body, and afterbody, and their positions are initially defined. Specifically as follows:

[0068]

[0069] The technical solution of the present invention is further described below:

[0070] A method for transforming and designing a parent ship based on a three-dimensional geometric model provided by the first aspect of the present invention, based on the existing approximate parent ship form values, includes the steps: Step S100, obtaining the three-dimensional form value point coordinate set of the parent ship, and constructing the hull lines according to the NURBS curve formed by the form value point coordinate set; Step S200, modifying the form value point coordinates; including any one or a combination of the following methods:

[0071] Method a. Scaling the form value points according to the main dimension ratio of the target ship and the parent ship; specifically:

[0072] For the linear / affine transformation of the hull lines, determine the scaling ratios in the length direction, width direction, and height direction of the transformed ship through the main dimensions of the target ship and the parent ship (parameters such as the length between perpendiculars, beam, draft, etc.), proportionally transform the coordinate values of the form value points that make up the lines, and thus generate the coordinate values of the form value points to achieve the transformation of the hull form value points, and form the hull lines for constructing the hull surface according to the rules with these form value points. In the affine transformation, the block coefficient Cb, the center of buoyancy, the waterplane and cross-section characteristics remain unchanged. The scaling formula is as follows:

[0073] x n =(L PPn / L PP0 )x0; y n =(B n / B0)y0; z n =(d n / d0)z0; where:

[0074] Lpp, B, d respectively represent the length between perpendiculars, beam, and draft;

[0075] x n 、y n 、z n respectively represent the coordinate values of the designed hull lines;

[0076] x0, y0, and z0 respectively represent the coordinate values of the parent hull form lines.

[0077] Method b. By moving the coordinate values of the form points in the longitudinal direction of the hull form within a certain range, and keeping the coordinate values of the form points outside the range unchanged, a new set of three-dimensional form points is generated to achieve the transformation of the hull form point coordinates; specifically:

[0078] The piecewise linear transformation of the hull form is achieved by moving the coordinate values of the form points in the longitudinal direction of the hull form within a certain range, while keeping the coordinate values of the form points outside the range unchanged. Thus, a new set of three-dimensional form points is generated to realize the transformation of the hull form points, and these form points are combined according to rules to form the hull form lines for constructing the hull surface. This piecewise linear transformation method is divided into four methods: the translational transformation without constraints at the bow and stern ends, the translational transformation with bow-end constraints, the translational transformation with stern-end constraints, and the translational transformation with both ends constrained. When there are no constraints, the transverse sections at corresponding positions are translated along the X direction, and the X values of the transverse sections at other positions remain unchanged. When there are constraints, the X values of the transverse sections within the range are moved proportionally. When there are no constraints, the transverse sections at corresponding positions are translated along the X direction, and the X values of the transverse sections at other positions remain unchanged. When there are constraints, the X values of the transverse sections within the range are moved proportionally.

[0079] Method c. 1-C P Method: The basic principle of this method is to move the transverse sectional area of each station of the ship longitudinally by a certain distance S to achieve the modification of the prismatic coefficient C P , the length of the parallel middle body l P , and the longitudinal coordinate value x of the center of buoyancy B . The transverse sectional area curve is divided into two parts, the front and rear half bodies, for separate modification, and then the area curves and modification parameters of the half bodies are made dimensionless. By setting the linear characteristic parameters of the target ship, different forms of quadratic function polynomials are used to solve the moving values of the transformed hull transverse sectional area curve. The user defines the change amount x B of the longitudinal position of the center of buoyancy of the target ship, the change amount of the prismatic coefficient C P , and the change amount of the length l P of the front and rear parallel middle bodies. By applying relevant functions, the change amounts of the prismatic coefficients δC PF and δC PA of the front and rear bodies are obtained. Then, the change amount of the transverse sectional position is solved through the change amounts of the prismatic coefficients of the front and rear bodies. Finally, by setting parameters such as the displacement volume, block coefficient, and longitudinal coordinate value of the center of buoyancy, the change of the hull form line values is determined. Taking the front half body as an example, according to the amount of modification parameters, the 1-C P method also has different forms. Specifically:

[0080] In one embodiment, the cross-sectional area curve is divided into two parts, the front and rear half bodies, for separate modification, and then the area curves and modification parameters of the half bodies are made dimensionless. When there is a parallel middle body, only C is modified. P :

[0081] The formula for calculating the movement amount of the cross-section of the front half body is:

[0082]

[0083] The formula for calculating the movement amount of the cross-section of the rear half body is:

[0084]

[0085] Where the change amounts of the prismatic coefficients of the front and rear bodies are δC PF and δC PA .

[0086] In one embodiment, the cross-sectional area curve is divided into two parts, the front and rear half bodies, for separate modification, and then the area curves and modification parameters of the half bodies are made dimensionless. When both C P and l P are modified simultaneously, the scenario is as follows:

[0087] When there is a parallel middle body:

[0088] The formula for calculating the movement amount of the cross-section of the front half body is:

[0089]

[0090] In the formula: A F = C PF (1 - 2x BF ) - l PF (1 - C PF );

[0091] The formula for calculating the movement amount of the cross-section of the rear half body is:

[0092]

[0093] In the formula: A A = C PA (1 - 2x BA ) - l PA (1 - C PA );

[0094] When there is no parallel middle body:

[0095] The movement amount of the cross-section of the front half body is:

[0096]

[0097] The movement amount of the cross-section of the rear half body is:

[0098]

[0099] In one embodiment, the cross-sectional area curve is divided into two parts, the front and rear half bodies, for separate modification, and then the area curves and modification parameters of the half bodies are made dimensionless. Among them, C P and l P 、x B are modified in the following scenarios:

[0100] When there is a parallel middle body,

[0101] The calculation formula for the change amount of the prismatic coefficient of the front half body is:

[0102]

[0103] The calculation formula for the change amount of the prismatic coefficient of the rear half body is:

[0104]

[0105] When there is no parallel middle body,

[0106] The calculation formula for the change amount of the prismatic coefficient of the front half body is:

[0107]

[0108] The calculation formula for the change amount of the prismatic coefficient of the rear half body is:

[0109]

[0110] In one embodiment, the cross-sectional area curve is divided into two parts, the front and rear half bodies, for separate modification, and then the area curves and modification parameters of the half bodies are made dimensionless. Among them, only x B is modified in the following scenarios:

[0111] The calculation formula for the movement amount of each station's transverse section line is:

[0112] δx = cy

[0113] where: y is the vertical coordinate of the cross-sectional area curve at x, and c is the ratio of the modification amount of the center of buoyancy position to the vertical coordinate of the centroid of the area under the curve.

[0114] Method d. Midship section coefficient transformation method. This method mainly modifies the bilge radius of the midship section profile of the three major main ship types with a parallel midship body, and thus transforms and designs the hull lines corresponding to the displacement. By setting the midship section coefficient of the target ship, comparing the size relationship with the midship section coefficient of the parent ship, the radius of the bilge arc line is enlarged or reduced in a certain step length to make it as close as possible to the set midship section coefficient value.

[0115] In one embodiment, the midship section coefficient transformation iteratively adjusts the bilge radius to make the error between the target ship's midship section coefficient C m and the set value less than 1%.

[0116] The above four methods of hull line transformation can be arbitrarily combined and selected, and the hull line transformation operations are carried out one by one inside the program in the order of linear transformation, piecewise linear transformation, 1-C P method, and midship section coefficient transformation, driving point and hull line modification, and finally showing the transformed hull line result. Refer to Figure 2 .

[0117] Step S300, generating a CAD three-dimensional model of the target ship based on the modified hull value point coordinate transformation.

[0118] To better understand the present invention, the following further briefly elaborates on the present invention according to specific embodiments:

[0119] Embodiment 1

[0120] Taking a certain cargo ship as the parent ship, the main dimensions of the target ship are enlarged by 10%. The hull value point coordinates are scaled by the above linear transformation, and the stern hull line is adjusted by piecewise linear transformation, and the translation range is X ∈ [0.7Lpp, Lpp] ∈ [0.7Lpp, Lpp]; the 1-C P method is used to correct the position of the center of buoyancy Xb, and the parameter is set as δX B = 0.02Lpp, and the midship section coefficient C m is adjusted to the target value to generate the final three-dimensional model.

[0121] Furthermore, for the oil tanker, the prismatic coefficient C P is modified, for example, from 0.75 to 0.71, and the parallel middle body length L P is synchronously adjusted. P The 1-C

[0122] method is applied to calculate the fore / aft body cross-section movement amount. Then, combined with the midship section coefficient transformation, the bilge line is optimized to generate a fair hull line.

[0123] Although embodiments of the present invention have been shown and described, those of ordinary skill in the art will appreciate that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A transformation design method for a parent ship based on a three-dimensional geometric model, based on the existing approximate parent ship form values, characterized in that, Including the steps: Step S100: Obtain the three-dimensional offset point coordinate set of the parent ship, and construct the hull lines based on the NURBS curves formed by the offset point coordinate set; Step S200: Modify the offset point coordinates; Step S300: Generate the CAD three-dimensional model of the target ship based on the transformed modified offset point coordinates.

2. The transformation design method of the parent ship based on the three-dimensional geometric model according to claim 1, characterized in that, In step S200, the modification of the offset point coordinates includes at least one of the following methods: a. Scale the offset points according to the main dimension ratio between the target ship and the parent ship; b. Move the longitudinal coordinates of the offset points within a certain range of the hull lines, and keep the coordinates of the offset points outside the range unchanged to generate a new three-dimensional offset point set, thereby realizing the transformation of the hull offset point coordinates; c. The prismatic coefficient C is achieved by longitudinally moving the cross-sectional areas of each station of the ship by a distance S P , the length of the parallel middle body l P , the longitudinal coordinate value x of the center of buoyancy B modification; the user defines the change amount x B of the longitudinal position of the center of buoyancy of the target ship, the change amount of the prismatic coefficient C P and the change amount of the length l P of the front and rear parallel middle bodies, and applies relevant functions to obtain the change amounts δC PF and δC PA of the front and rear bodies; then, the change amount of the cross-sectional position is solved through the change amounts of the prismatic coefficients of the front and rear bodies, so as to realize the determination of the change of the coordinate values of the ship hull line type points by setting parameters including but not limited to the displacement volume, block coefficient, and longitudinal coordinate value of the center of buoyancy. d. By setting the midship section coefficient of the target ship, compare the size relationship with the midship section coefficient of the parent ship, and magnify or reduce the radius of the bilge arc line in a certain step to make it close to the set midship section coefficient value.

3. A method for transforming and designing a parent ship based on a three-dimensional geometric model according to claim 2, characterized in that, In the method a, the scaling formula is as follows: x n = (L PPn / L PP0 ) x0; y n = (B n / B0) y0; z n = (d n / d0) z0; Where: Lpp, B, and d respectively represent the length between perpendiculars, the molded breadth, and the draft; x n 、y n 、z n respectively represent the coordinate values of the designed hull lines; x0, y0, and z0 respectively represent the hull line coordinate values of the parent ship.

4. A method for transforming and designing a parent ship based on a three-dimensional geometric model according to claim 2, characterized in that, In the method b, there are four methods including the translation transformation without constraints at the bow and stern, the translation transformation with bow constraint, the translation transformation with stern constraint, and the translation transformation with both ends constrained. Among them: When there is no constraint, the transverse sections at the corresponding positions are translated along the X direction, and the X values of the transverse sections at other positions remain unchanged; When there is a constraint, the X values of the transverse sections within the range are moved proportionally.

5. A method for transforming the design of a parent ship based on a three-dimensional geometric model according to claim 2, characterized in that In the said method c, the cross-sectional area curve is divided into two parts, the front and the rear half-hulls, for separate modification. Then, the area curves and modification parameters of the half-hulls are made dimensionless. Among them, when there is a parallel middle body, only C is modified P : The calculation formula for the movement amount of the transverse sections in the forebody is: The calculation formula for the movement amount of the transverse sections in the afterbody is: Among them, the variation amounts of the prismatic coefficients of the forebody and the afterbody are δC PF and δC PA .

6. The method for transforming and designing a parent ship based on a three-dimensional geometric model according to claim 2, wherein In the said method c, the cross-sectional area curve is divided into two parts, the front and the rear half-bodies, for separate modification, and then the area curves and modification parameters of the half-bodies are made dimensionless, where C P and l P The scenario is as follows: When there is a parallel middle body: The calculation formula for the movement amount of the transverse sections in the forebody is: Where: A F = C PF (1 - 2x BF ) - l PF (1 - C PF ) The calculation formula for the movement amount of the transverse sections in the afterbody is: Where: A A = C PA (1 - 2x BA ) - l PA (1 - C PA ) When there is no parallel middle body: The movement amount of the transverse sections in the forebody is: The movement amount of the transverse sections in the afterbody is:

7. A method for transforming and designing a parent ship based on a three-dimensional geometric model according to claim 2, characterized in that In the said method c, the cross-sectional area curve is divided into two parts, namely the front and rear half-bodies, for separate modification, and then the area curves and modification parameters of the half-bodies are made dimensionless. Among them, C P and l P 、x B The scenarios for are as follows: When there is a parallel middle body, The calculation formula for the change amount of the prismatic coefficient in the forebody is: The calculation formula for the change amount of the prismatic coefficient in the afterbody is: When there is no parallel middle body, The calculation formula for the change amount of the prismatic coefficient in the forebody is: The calculation formula for the change amount of the prismatic coefficient in the afterbody is:

8. A method for transforming the design of a parent ship based on a three-dimensional geometric model according to claim 2, characterized in that In the said method c, the cross-sectional area curve is divided into two parts, the front half and the rear half, for separate modification. Then, the area curve and modification parameters of the half-body are made dimensionless. Among them, only x B has the following scenario: The calculation formula for the movement amount of each station's transverse section is: δx = cy In the formula: y is the vertical coordinate of the transverse section area curve at x, and c is the ratio of the modification amount of the center of buoyancy position to the vertical coordinate of the centroid of the area under the curve.

9. A method for transforming and designing a parent ship based on a three-dimensional geometric model according to claim 2, characterized in that, The transformation of the midship section coefficient is achieved by iteratively adjusting the bilge radius so that the error between the midship section coefficient C of the target ship and the set value is less than 1%. m ​ 10. A parent ship transformation design system based on a three-dimensional geometric model, characterized in that Including: An acquisition unit for obtaining the three-dimensional offset point coordinate set of the parent ship and constructing the hull lines based on the NURBS curves formed by the offset point coordinate set; A modification unit for modifying the offset point coordinates; A modeling unit for generating the CAD three-dimensional model of the target ship based on the transformed modified offset point coordinates.

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