CN104143211B - Method for generating three-dimensional free body based on one image - Google Patents

Abstract

The invention discloses a method for generating a three-dimensional free body based on one image. The method for generating the three-dimensional free body based on one image comprises the steps that drawing lines represented by an object in the two-dimensional image are copied and drawn on the plane of the image in an interactive hand drawing mode by a user according to the input two-dimensional image, wherein the outlines, in the vertical direction, of all parts of the object can be reflected by the lines basically accurately; the structure curves of all subparts of the object are determined firstly, the three-dimensional coordinate information of the subparts of the object are calculated, and the generated three-dimensional symmetrical curves are re-matched with the corresponding subparts of the object according to the connection relation between the curves, so that it is guaranteed that an ordinary curve in each part can be obtained through calculation according to the symmetrical curve of the part. According to the method for generating the three-dimensional free body based on one image, in order to generate the three-dimensional free body with high sense of reality, the texture information of the visible parts of the object in the input image are utilized, corresponding texture information is determined by means of texture coordinates so that the corresponding part of a grid model of the free body can be represented by a system, and the three-dimensional real model with complete textures is obtained by means of the symmetry information of the object.

Description

3 D auto form-creation method based on single image

Technical field

Patent design of the present invention is directed to the single image of input, by means of the interaction imitation of user, there is provided one kind can The method conveniently and efficiently generating the 3 D auto body of realistic effect.

Background technology

In computer graphicss and field of computer aided design, rebuild from single width two-dimensional input image and generate three-dimensional body During, become a difficult point because the depth information of three-dimensional body is difficult to recover, but tended to by means of user mutual Enough reduce its difficulty, such that it is able to efficiently solve this problem.Based on image threedimensional model create and generate in it would be desirable to A kind of relatively simple practical man-machine interaction is enough provided to describe mode for users to use, easily and efficiently to generate three-dimensional body. For cartoon, there is a kind of special method for drafting at present, mainly all of object is decomposed into some more simple Geometry, each decomposes the object subdivision obtaining and is generated by several curve constructions, and the method is by many cartoon artisies Accepted and applied in some 3 d modeling systems.

In succession proposed by many researcheres based on the 3 d modeling system of interaction Freehandhand-drawing, be based partially on Freehandhand-drawing modeling Shape modeling operation often completes in three dimensions.System creates a rough model first, then passes through some special Operation, for example shearing, rotation, merge, deformation etc. little by little add more details for model.However, these special operationals are past Past is not very directly perceived, and requires user must possess corresponding Professional knowledge.On the contrary, three are directly constructed from single width input picture Dimension module then provides a kind of method that simple to operate, efficient quick being applied to general user generates 3 D auto body.Root According to single width input picture, provide throwing on two dimensional surface for the three-dimensional object profile using the distinctive perception of the mankind for system Shadow, and automatically calculated the depth information of the contour of object for generation model by system and extract body surface in input picture Texture and be mapped on threedimensional model, thus generate that there is the 3 D auto body model of object sense of reality in input picture. Simultaneously as real-life three-dimensional body has all shown a certain degree of symmetry, such as animal, building, family in a large number Tool and other organic structure etc..Under orthogonal or perspective projection, as long as can determine the matching relationship between symmetry elements The three dimensional structure of symmetric shape just can be reconstructed completely, our 3 D auto form-creation takes full advantage of this symmetry Feature.

Content of the invention

In order in overcoming 3 D auto Shape design and generating, complex operation, interworking amount be big, sense of reality is poor not Foot, the invention provides a kind of utilization single image simple to operate, efficient quick, strong sense of reality generates 3 D auto body Method.

The technical solution adopted for the present invention to solve the technical problems is:

Based on the 3 D auto form-creation method of single image, described method includes three below step:

1) user, according to the single width two dimensional image of input, depicts image to interact Freehandhand-drawing mode and copy on the image plane The line drawing figure that middle object represents, these lines can accurately reflect object each several part profile in vertical direction substantially.System is certainly The dynamic point catching on free hand line, and interpolation goes out corresponding Quadratic B-spline Curves, with uniform sampling from smooth conic section The polygon broken line that formed of summit carry out the free hand line to user input and carry out discretization, and preserve each sub-portion of object successively The curve construction pair dividing.

2) calculating of each subdivision curve construction depth coordinate of three-dimensional body and the discrete generation of threedimensional model.In order to count For the sake of calculation curve construction depth coordinate is convenient, system is used drafting plane as xoy plane, comprises the input line drawing of symmetric information The figure then parallel projection as three-dimensional body curve construction, projecting direction is perpendicular to drafting plane.System determines that object is each first The curve construction of subdivision simultaneously calculates their three-dimensional coordinate information, and the curve construction collection of each subdivision of object generally comprises two Bar symmetrical curve and two general curves.Method travels through all of symmetrical curve first, and the three-dimensional coordinate information of symmetrical curve can It is calculated according to the known plane of symmetry, the three dimensional symmetry curve of generation will match it again according to the annexation between curve Corresponding object subdivision can be calculated by with the symmetrical curve of a part with the general curve in ensureing each partly.Thing Body each several part can be categorized into two distinct types of subdivision: with regard to the plane of symmetry from symmetrical single part with regard to the plane of symmetry Two symmetrical parts.This two classes subdivision is different in the method calculating ordinary construction curve.From symmetric part General curve in situation directly can be calculated by its symmetrical curve；And it is only necessary to utilize in mutually symmetrical with part situation Symmetrical curve calculates the general curve of one of subdivision, and the general curve of another part can be by mutually antimeric general Curve is obtained using symmetry.

Specifically, the summit x coordinate on hand-drawing line picture in two-dimentional Freehandhand-drawing plane and y-coordinate are actually corresponded to three-dimensional The physically x coordinate on summit and y-coordinate, need recovery is only the z coordinate on each summit.For two in each subdivision Bar symmetrical curve, it is possible to use following formula calculating each of which sampled point z coordinate:

$\begin{array}{c}{z}_{\mathrm{si}}=-\frac{1}{2}(\frac{(x_{\mathrm{si}}+x_{\mathrm{si}}^{\′})\·x^s}{z^s}+\frac{(y_{\mathrm{si}}+y_{\mathrm{si}}^{\′})\·y^s}{z^s}+\frac{(x_{\mathrm{si}}-x_{\mathrm{si}}^{\′})\·x^g}{z^g}+\frac{(y_{\mathrm{si}}-y_{\mathrm{si}}^{\′})\·y^g}{z^g})\\ z_{\mathrm{si}}^{\′}=-\frac{1}{2}(\frac{(x_{\mathrm{si}}+x_{\mathrm{si}}^{\′})\·x^s}{z^s}+\frac{(y_{\mathrm{si}}+y_{\mathrm{si}}^{\′})\·y^s}{z^s}-\frac{(x_{\mathrm{si}}-x_{\mathrm{si}}^{\′})\·x^g}{z^g}-\frac{(y_{\mathrm{si}}-y_{\mathrm{si}}^{\′})\·y^g}{z^g})\end{array}---\left(1\right)$

Wherein, z_siWith z '_siFor point of symmetry z coordinate to be asked, x_si, x '_siAnd y_si, y '_siIt is respectively the x of point of symmetry, y sits Mark, n_s(x^s,y^s,z^s) it is plane of symmetry normal vector, n_g(x^g,y^g,z^g) it is a vector in the plane of symmetry.Simultaneously for each Subdivision can using following formula calculate respective pair of general curve up-sampling point z coordinate point:

$\begin{array}{c}{z}_{\mathrm{gi}}=-\frac{1}{2}(\frac{({2x}_{\mathrm{gi}}-x_{\mathrm{si}}-x_{\mathrm{si}}^{\′})\·x^s}{z^s}+\frac{({2y}_{\mathrm{gi}}-y_{\mathrm{si}}-y_{\mathrm{si}}^{\′})\·y^s}{z^s}+\frac{(x_{\mathrm{si}}+x_{\mathrm{si}}^{\′})\·x^s}{z^s}+\frac{(y_{\mathrm{si}}+y_{\mathrm{si}}^{\′})\·y^s}{z^s})\\ z_{\mathrm{gi}}^{\′}=-\frac{1}{2}(\frac{({2x}_{\mathrm{gi}}^{\′}-x_{\mathrm{si}}-x_{\mathrm{si}}^{\′})\·x^s}{z^s}+\frac{({2y}_{\mathrm{gi}}^{\′}-y_{\mathrm{si}}-y_{\mathrm{si}}^{\′})\·y^s}{z^s}+\frac{(x_{\mathrm{si}}+x_{\mathrm{si}}^{\′})\·x^s}{z^s}+\frac{(y_{\mathrm{si}}+y_{\mathrm{si}}^{\′})\·y^s}{z^s})\end{array}---\left(2\right)$

Wherein, z_giWith z '_giFor asymmetric general z coordinate to be asked, x_gi, x '_giAnd y_gi, y '_giIt is respectively asymmetric one As point x, y-coordinate.In addition, for subdivision in object with another subdivision with regard to the symmetrical situation of the plane of symmetry, Method can be calculated automatically from the non-of another subdivision by the asymmetric general curve of one of subdivision using symmetry Symmetrical general curve is as follows:

$\begin{array}{cc}{x}_{\mathrm{gi}}^{\′}=\frac{({\left(y^s\right)}^2+{\left(z^s\right)}^2-{\left(x^s\right)}^2)\·x_{\mathrm{gi}}-{2x}^s\·(y_{\mathrm{gi}}\·y^s+z_{\mathrm{gi}}\·z^s)}{{\left(x^s\right)}^2+{\left(y^s\right)}^2+{\left(z^s\right)}^2}& y_{\mathrm{gi}}^{\′}=\frac{({\left(x^s\right)}^2+{\left(z^s\right)}^2-{\left(y^s\right)}^2)\·y_{\mathrm{gi}}-{2y}^s\·(x_{\mathrm{gi}}\·x^s+z_{\mathrm{gi}}\·z^s)}{{\left(x^s\right)}^2+{\left(y^s\right)}^2+{\left(z^s\right)}^2}\\ z_{\mathrm{gi}}^{\′}=\frac{({\left(x^s\right)}^2+{\left(y^s\right)}^2-{\left(z^s\right)}^2)\·z_{\mathrm{gi}}-{2z}^s\·(x_{\mathrm{gi}}\·x^s+y_{\mathrm{gi}}\·y^s)}{{\left(x^s\right)}^2+{\left(y^s\right)}^2+{\left(z^s\right)}^2}& \left(3\right)\end{array}$

Wherein, x^s, y^sAnd z^sIt is respectively plane of symmetry normal vector coordinate, x_gi, y_giAnd z_giIt is respectively asymmetric on general curve X, y and the z coordinate of point.

Thus, with regard to the symmetrical object subdivision situation of the plane of symmetry itself, the plane of symmetry specified according to user, first with (1) formula calculates the three-dimensional coordinate of two symmetrical curve up-sampling points, obtains three-dimensional curve construction accordingly；(2) formula of recycling Calculate the three-dimensional coordinate of two asymmetric general curve up-sampling points, obtain three-dimensional curve construction accordingly.For in object One subdivision with another subdivision with regard to the symmetrical situation of the plane of symmetry, symmetrical to two couple being belonging respectively to two subdivisions Curve, calculates the three-dimensional coordinate of each pair symmetrical curve up-sampling point respectively first with (1) formula, obtains three-dimensional construction accordingly Curve；Then the three-dimensional coordinate of two asymmetric general curve up-sampling points of one of subdivision is calculated using (2) formula, Obtain three-dimensional curve construction accordingly；Finally calculated separately by two asymmetric general curves of previous subdivision using (3) formula The three-dimensional coordinate of two asymmetric general curve up-sampling points of one subdivision, obtains three-dimensional curve construction accordingly.

After each part determines respective curve construction, just can be generated accordingly using rotation mixed method Parametric surface, and parametric surface discretization is obtained with the three-dimensional grid model representing free body.

3) in order to generate the 3 D auto body with high presence, using the stricture of vagina of object visible part in input picture Reason information, needs to give the color and vein information of object in input picture on the three-dimensional grid model surface generating；However, according to Single width input picture rebuild generate threedimensional model can only obtain objects in images visible part color and vein it is contemplated that we The symmetric properties of the 3 D auto body generating are it can be assumed that the monosymmetric part of the model plane of symmetry has identical stricture of vagina Reason, thus only texture information need to be given to the model part of object plane of symmetry side, and the texture information of model opposite side then may be used Conveniently to be obtained using symmetry；Ultimately generate the 3 D auto body with high presence.

The technology design of the present invention is: the two dimensional image based on user input, and user is on the image plane with interactive mode side Formula depicts two-dimentional hand-drawn outline lines, and these lines are rectangular projection on drawing plane for the three-dimensional body curve construction.Raw The threedimensional model becoming generally is grouped into by some sub-portions, and the three-dimensional curve construction depth information of each subdivision can be by object Symmetry is calculated, can be with generation parameter curved surface and discretization obtains three-dimensional grid model by these curve constructions.Using defeated Enter image to the threedimensional model surface visible part increase texture generating, and carried out texture using symmetry to shield portions to repair Mend, thus generating the 3 D auto body with high presence.

Beneficial effects of the present invention are mainly manifested in: simple to operate, efficient quick, strong sense of reality.

Brief description

Fig. 1 is the input picture example that the present invention comprises that user describes lines.

Fig. 2 is to describe, using user in Fig. 1, the threedimensional model Preliminary Results that lines generate as input.

Fig. 3 is the object single subdivision grid surface effect exemplary plot of the present invention.

Fig. 4 is the method exemplary plot that threedimensional model surface is carried out with texture mapping of the present invention.

Fig. 5 is the partial 3-D free form body Model exemplary plot of the design generation of the present invention.

Specific embodiment

Technical method to the present invention and the various 3 D auto body effects generating are retouched further below in conjunction with the accompanying drawings State and describe in detail.

Referring to the drawings 1--- accompanying drawing 5, a kind of 3 D auto form-creation method based on single image, described method bag Include three below step:

1) it is based on single image and depict two-dimentional hand-drawing line picture to interact imitation mode.As shown in Figure 1, user is in figure In image plane, two-dimentional free hand line is described in interactive mode, these lines can accurately reflect object each several part substantially in Vertical Square Profile upwards.System catches the point on free hand line automatically, and interpolation goes out corresponding Quadratic B-spline Curves, with from smooth The polygon broken line that in conic section, the summit of uniform sampling is formed carrys out the free hand line to user input and carries out discretization, and according to The secondary curve construction pair preserving each subdivision of object.

2) calculating of each subdivision curve construction depth coordinate of three-dimensional body and the discrete generation of threedimensional model.In order to count For the sake of calculation curve construction depth coordinate is convenient, system is used drafting plane as xoy plane, comprises the input line drawing of symmetric information The figure then parallel projection as three-dimensional body curve construction, projecting direction is perpendicular to drafting plane.System determines that object is each first The curve construction of subdivision simultaneously calculates their three-dimensional coordinate information, and the curve construction collection of each subdivision of object generally comprises two Bar symmetrical curve and two general curves.Method travels through all of symmetrical curve first, and the three-dimensional coordinate information of symmetrical curve can It is calculated according to the known plane of symmetry, the three dimensional symmetry curve of generation will match it again according to the annexation between curve Corresponding object subdivision can be calculated by with the symmetrical curve of a part with the general curve in ensureing each partly.Thing Body each several part can be categorized into two distinct types of subdivision: with regard to the plane of symmetry from symmetrical single part with regard to the plane of symmetry Two symmetrical parts.This two classes subdivision is different in the method calculating ordinary construction curve.From symmetric part General curve in situation directly can be calculated by its symmetrical curve；And it is only necessary to utilize in mutually symmetrical with part situation Symmetrical curve calculates the general curve of one of subdivision, and the general curve of another part can be by mutually antimeric general Curve is obtained using symmetry.

Specifically, the summit x coordinate on hand-drawing line picture in two-dimentional Freehandhand-drawing plane and y-coordinate are actually corresponded to three-dimensional The physically x coordinate on summit and y-coordinate, need recovery is only the z coordinate on each summit.For two in each subdivision Bar symmetrical curve, it is possible to use following formula calculating each of which sampled point z coordinate:

$\begin{array}{c}{z}_{\mathrm{si}}=-\frac{1}{2}(\frac{(x_{\mathrm{si}}+x_{\mathrm{si}}^{\′})\·x^s}{z^s}+\frac{(y_{\mathrm{si}}+y_{\mathrm{si}}^{\′})\·y^s}{z^s}+\frac{(x_{\mathrm{si}}-x_{\mathrm{si}}^{\′})\·x^g}{z^g}+\frac{(y_{\mathrm{si}}-y_{\mathrm{si}}^{\′})\·y^g}{z^g})\\ z_{\mathrm{si}}^{\′}=-\frac{1}{2}(\frac{(x_{\mathrm{si}}+x_{\mathrm{si}}^{\′})\·x^s}{z^s}+\frac{(y_{\mathrm{si}}+y_{\mathrm{si}}^{\′})\·y^s}{z^s}-\frac{(x_{\mathrm{si}}-x_{\mathrm{si}}^{\′})\·x^g}{z^g}-\frac{(y_{\mathrm{si}}-y_{\mathrm{si}}^{\′})\·y^g}{z^g})\end{array}---\left(1\right)$

Wherein, z_siWith z '_siFor point of symmetry z coordinate to be asked, x_si, x '_siAnd y_si, y '_siIt is respectively the x of point of symmetry, y sits Mark, n_s(x^s,y^s,z^s) it is plane of symmetry normal vector, n_g(x^g,y^g,z^g) it is a vector in the plane of symmetry.Simultaneously for each Subdivision can using following formula calculate respective pair of general curve up-sampling point z coordinate point:

$\begin{array}{c}{z}_{\mathrm{gi}}=-\frac{1}{2}(\frac{({2x}_{\mathrm{gi}}-x_{\mathrm{si}}-x_{\mathrm{si}}^{\′})\·x^s}{z^s}+\frac{({2y}_{\mathrm{gi}}-y_{\mathrm{si}}-y_{\mathrm{si}}^{\′})\·y^s}{z^s}+\frac{(x_{\mathrm{si}}+x_{\mathrm{si}}^{\′})\·x^s}{z^s}+\frac{(y_{\mathrm{si}}+y_{\mathrm{si}}^{\′})\·y^s}{z^s})\\ z_{\mathrm{gi}}^{\′}=-\frac{1}{2}(\frac{({2x}_{\mathrm{gi}}^{\′}-x_{\mathrm{si}}-x_{\mathrm{si}}^{\′})\·x^s}{z^s}+\frac{({2y}_{\mathrm{gi}}^{\′}-y_{\mathrm{si}}-y_{\mathrm{si}}^{\′})\·y^s}{z^s}+\frac{(x_{\mathrm{si}}+x_{\mathrm{si}}^{\′})\·x^s}{z^s}+\frac{(y_{\mathrm{si}}+y_{\mathrm{si}}^{\′})\·y^s}{z^s})\end{array}---\left(2\right)$

Wherein, z_giWith z '_giFor asymmetric general z coordinate to be asked, x_gi, x '_giAnd y_gi, y '_giIt is respectively asymmetric one As point x, y-coordinate.In addition, for subdivision in object with another subdivision with regard to the symmetrical situation of the plane of symmetry, Method can be calculated automatically from the non-of another subdivision by the asymmetric general curve of one of subdivision using symmetry Symmetrical general curve is as follows:

$\begin{array}{cc}{x}_{\mathrm{gi}}^{\′}=\frac{({\left(y^s\right)}^2+{\left(z^s\right)}^2-{\left(x^s\right)}^2)\·x_{\mathrm{gi}}-{2x}^s\·(y_{\mathrm{gi}}\·y^s+z_{\mathrm{gi}}\·z^s)}{{\left(x^s\right)}^2+{\left(y^s\right)}^2+{\left(z^s\right)}^2}& y_{\mathrm{gi}}^{\′}=\frac{({\left(x^s\right)}^2+{\left(z^s\right)}^2-{\left(y^s\right)}^2)\·y_{\mathrm{gi}}-{2y}^s\·(x_{\mathrm{gi}}\·x^s+z_{\mathrm{gi}}\·z^s)}{{\left(x^s\right)}^2+{\left(y^s\right)}^2+{\left(z^s\right)}^2}\\ z_{\mathrm{gi}}^{\′}=\frac{({\left(x^s\right)}^2+{\left(y^s\right)}^2-{\left(z^s\right)}^2)\·z_{\mathrm{gi}}-{2z}^s\·(x_{\mathrm{gi}}\·x^s+y_{\mathrm{gi}}\·y^s)}{{\left(x^s\right)}^2+{\left(y^s\right)}^2+{\left(z^s\right)}^2}& \left(3\right)\end{array}$

Wherein, x^s, y^sAnd z^sIt is respectively plane of symmetry normal vector coordinate, x_gi, y_giAnd z_giIt is respectively asymmetric on general curve X, y and the z coordinate of point.

Thus, with regard to the symmetrical object subdivision situation of the plane of symmetry itself, the plane of symmetry specified according to user, first with (1) formula calculates the three-dimensional coordinate of two symmetrical curve up-sampling points, obtains three-dimensional curve construction accordingly；(2) formula of recycling Calculate the three-dimensional coordinate of two asymmetric general curve up-sampling points, obtain three-dimensional curve construction accordingly.For in object One subdivision with another subdivision with regard to the symmetrical situation of the plane of symmetry, symmetrical to two couple being belonging respectively to two subdivisions Curve, calculates the three-dimensional coordinate of each pair symmetrical curve up-sampling point respectively first with (1) formula, obtains three-dimensional construction accordingly Curve；Then the three-dimensional coordinate of two asymmetric general curve up-sampling points of one of subdivision is calculated using (2) formula, Obtain three-dimensional curve construction accordingly；Finally calculated separately by two asymmetric general curves of previous subdivision using (3) formula The three-dimensional coordinate of two asymmetric general curve up-sampling points of one subdivision, obtains three-dimensional curve construction accordingly.

After each part determines respective curve construction, just can be generated accordingly using rotation mixed method Parametric surface, and parametric surface discretization is obtained with closing grid surface as shown in Figure 3, the 3 D auto body of generation is complete Integral mould is as shown in Figure 2.

3) synthesis of three-dimensional model surface texture is to generate the 3 D auto body with stronger sense of reality.In general, Object in input picture has usually contained many details and superficial makings, in order to generate the 3 D auto with high presence Body, needs to give object color texture information in input picture on the three-dimensional grid model surface that first two steps generate.However, by Only provide single two dimensional image for system in user, rebuild the threedimensional model generating and can only obtain objects in images visible portions The color and vein dividing.In view of rebuilding the symmetry characteristic of the 3 D auto body generating it can be assumed that model plane of symmetry both sides pair The part claiming has identical texture, thus only texture information need to be given to the model part of object plane of symmetry side, and model The texture information of opposite side then conveniently can be obtained using symmetry.As shown in Figure 4 it is assumed that t1 and t2 is the visible portions of model Point, t2 and t3 is respectively the part near screen side for the model plane of symmetry, then the texture of t1 and t2 part can be by input picture Direct access, and for the t3 part blocked, because the region that it comprises is often less, can simply by t2 partly in vertically shield The texture copy of t3 part is blocked in the past in curtain direction.So, remaining t4 texure just can be by antimere corresponding in t2 Point texture replication obtains.However, the texture of t1 part symmetric part texture corresponding with t2 might not in actual picture Identical, this may lead to the joining place of t1 and t4 to have rough transition.For this reason, method is only partly directly carried out to t2 Texture mapping, and the texture of t1 part is equally obtained by its symmetric part texture replication.Additionally, the mutual antimere for model Point, the texture mapping that we only carry out above-mentioned steps to a portion is processed, and symmetrical by it to the texture of another part Part replicates and obtains.When carrying out texture mapping, directly the geometric coordinate of object can be projected to drafting plane, and will project The coordinate of point realizes texture mapping as the texture coordinate of model.Accompanying drawing 5 gives the partial 3-D being generated by this method design Free form body Model design sketch.

Accompanying drawing 1 is the input picture example of the lines of outline comprising user mutual description；Accompanying drawing 2 is with user in accompanying drawing 1 Describe the 3 D auto body complete model exemplary plot that line drawing figure generates as input；Accompanying drawing 3 is that object single part grid is bent Face effect exemplary plot；Accompanying drawing 4 is the method exemplary plot that threedimensional model surface is carried out with texture mapping；Accompanying drawing 5 is this method design The partial 3-D free form body Model exemplary plot generating, accompanying drawing 5 (a) is to comprise the input two dimensional image generating animal to be reconstructed simultaneously Give the lines of outline of user mutual description, accompanying drawing 5 (b) is the three-dimensional body each several part after having recovered three-dimensional coordinate information Three-dimensional curve construction, accompanying drawing 5 (c) is to rebuild the threedimensional model Preliminary Results generating, and accompanying drawing 5 (d, e) is after textures synthesis 3 D auto body and observe the threedimensional model of realistic effect respectively under two different visual angles.

Claims (1)

1. the 3 D auto form-creation method based on single image it is characterised in that:

1) the single width two dimensional image according to input, is copied in the way of interacting Freehandhand-drawing on the image plane and depicts objects in images The lines figure representing, free hand line therein includes representing the symmetrical curve of object and asymmetric general curve；And automatically catch Sampled point on free hand line, interpolation goes out corresponding Quadratic B-spline Curves, with the summit of uniform sampling from smooth conic section The polygon broken line being formed carries out discretization to the free hand line of input, preserves the curve construction of each subdivision of object successively Right；

2) calculating of 3 D auto body each subdivision curve construction depth coordinate and the discrete generation of threedimensional model: in order to calculate For the sake of curve construction depth coordinate is convenient, it is used Freehandhand-drawing plane as xoy plane, the input lines figure comprising symmetric information is then made For the parallel projection of three-dimensional body curve construction, projecting direction is perpendicular to Freehandhand-drawing plane；

Determine the curve construction of each subdivision of object first and calculate their three-dimensional coordinate information, the structure of each subdivision of object Make curve set and comprise two symmetrical curves and two general curves；Then all of symmetrical curve, the three-dimensional of symmetrical curve are traveled through Coordinate information is calculated using the known plane of symmetry, and the three dimensional symmetry curve of generation is by according to the annexation between curve again Match its corresponding object subdivision to be calculated by with the symmetrical curve of a part with the general curve in ensureing each partly Arrive；

Object each several part is classified into two distinct types of subdivision, with regard to the plane of symmetry from symmetrical single subdivision and with regard to Two symmetrical subdivisions of the plane of symmetry；The three-dimensional coordinate information of the general curve from symmetric part is straight by its symmetrical curve Connect and be calculated；For mutually symmetrical with part situation, the general curve calculating one of subdivision using symmetrical curve is three-dimensional Coordinate information, in another subdivision, the three-dimensional coordinate information of general curve is by mutually antimeric generalized curvilinear coordinate Information Pull Symmetry is calculated；

Summit x coordinate on free hand line figure in two-dimentional Freehandhand-drawing plane and y-coordinate correspond on three-dimensional body the x coordinate on summit and Y-coordinate, need recovery is only the z coordinate on each summit；For two symmetrical curves in each subdivision, using following formula Calculating each of which sampled point z coordinate:

$\begin{array}{c}{z}_{si}=-\frac{1}{2}\left(\frac{(x_{si}+x_{si}^{\′})\·x^s}{z^s}+\frac{(y_{si}+y_{si}^{\′})\·y^s}{z^s}+\frac{(x_{si}-x_{si}^{\′})\·x^g}{z^g}+\frac{(y_{si}-y_{si}^{\′})\·y^g}{z^g}\right)\\ z_{si}^{\′}=-\frac{1}{2}\left(\frac{(x_{si}+x_{si}^{\′})\·x^s}{z^s}+\frac{(y_{si}+y_{si}^{\′})\·y^s}{z^s}-\frac{(x_{si}-x_{si}^{\′})\·x^g}{z^g}-\frac{(y_{si}-y_{si}^{\′})\·y^g}{z^g}\right)\end{array}---\left(1\right)$

Wherein, z_siWith z '_siFor the z coordinate of point of symmetry to be asked, x_si, x '_siAnd y_si, y '_siIt is respectively the x of point of symmetry, y-coordinate, n_s (x^s,y^s,z^s) it is plane of symmetry normal vector, n_g(x^g,y^g,z^g) it is a vector in the plane of symmetry；For each subdivision, profit With following formula calculate respective pair of general curve up-sampling point z coordinate:

$\begin{array}{c}{z}_{gi}=-\frac{1}{2}\left(\frac{(2x_{gi}-x_{si}-x_{si}^{\′})\·x^s}{z^s}+\frac{(2y_{gi}-y_{si}-y_{si}^{\′})\·y^s}{z^s}+\frac{(x_{si}+x_{si}^{\′})\·x^s}{z^s}+\frac{(y_{si}+y_{si}^{\′})\·y^s}{z^s}\right)\\ z_{gi}^{\′}=-\frac{1}{2}\left(\frac{(2x_{gi}^{\′}-x_{si}-x_{si}^{\′})\·x^s}{z^s}+\frac{(2y_{gi}^{\′}-y_{si}-y_{si}^{\′})\·y^s}{z^s}+\frac{(x_{si}+x_{si}^{\′})\·x^s}{z^s}+\frac{(y_{si}+y_{si}^{\′})\·y^s}{z^s}\right)\end{array}---\left(2\right)$

Wherein, z_giWith z '_giFor the z coordinate of asymmetric general point to be asked, x_gi, x '_giAnd y_gi, y '_giIt is respectively asymmetric general The x of point, y-coordinate；For subdivision in object with another subdivision with regard to the symmetrical situation of the plane of symmetry, using wherein The three-dimensional coordinate information of the asymmetric general curve of one subdivision calculates the asymmetric general of another subdivision according to symmetry The three-dimensional coordinate information of curve, is calculated as follows:

$\begin{array}{c}{x}_{gi}^{\′}=\frac{({\left(y^s\right)}^2+{\left(z^s\right)}^2-{\left(x^s\right)}^2)\·x_{gi}-2x^s\·(y_{gi}\·y^s+z_{gi}\·z^s)}{{\left(x^s\right)}^2+{\left(y^s\right)}^2+{\left(z^s\right)}^2}\\ y_{gi}^{\′}=\frac{({\left(x^s\right)}^2+{\left(z^s\right)}^2-{\left(y^s\right)}^2)\·y_{gi}-2y^s\·(x_{gi}\·x^s+z_{gi}\·z^s)}{{\left(x^s\right)}^2+{\left(y^s\right)}^2+{\left(z^s\right)}^2}\\ z_{gi}^{\′}=\frac{({\left(x^s\right)}^2+{\left(y^s\right)}^2-{\left(z^s\right)}^2)\·z_{gi}-2z^s\·(x_{gi}\·x^s+y_{gi}\·y^s)}{{\left(x^s\right)}^2+{\left(y^s\right)}^2+{\left(z^s\right)}^2}\end{array}---\left(3\right);$

Thus, with regard to the symmetrical object subdivision situation of the plane of symmetry itself, according to the specified plane of symmetry, calculate first with (1) formula Go out the three-dimensional coordinate of two symmetrical curve up-sampling points, obtain three-dimensional curve construction accordingly；(2) formula of recycling calculates two The three-dimensional coordinate of asymmetric general curve up-sampling point, obtains three-dimensional curve construction accordingly；For a subdivision in object With another subdivision with regard to the symmetrical situation of the plane of symmetry, to two pairs of symmetrical curves being belonging respectively to two subdivisions, first Calculate the three-dimensional coordinate of each pair symmetrical curve up-sampling point using (1) formula, obtain three-dimensional curve construction accordingly；Then utilize (2) formula calculates the three-dimensional coordinate of two asymmetric general curve up-sampling points of one of subdivision, obtains corresponding three Dimension curve construction；Finally calculate the two of another subdivision using (3) formula by two asymmetric general curves of previous subdivision The three-dimensional coordinate of bar asymmetric general curve up-sampling point, obtains three-dimensional curve construction accordingly；

After each part determines respective curve construction, generate corresponding parametric surface using rotation mixed method, And parametric surface discretization obtained with the three-dimensional grid model representing free body；

3) in order to generate the 3 D auto body with high presence, using the texture letter of object visible part in input picture Breath, gives the color and vein information of object in input picture to the three-dimensional grid model surface generating；Right using free body Title property, the monosymmetric part of the object plane of symmetry has identical texture, is obtained according to the texture information of object plane of symmetry side The texture information of object opposite side；Ultimately generate the 3 D auto body with high presence.