CN104143211A - 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, for the single image of input, by means of user's mutual imitation, provides a kind of method that can generate quickly and easily the 3 D auto body of realistic effect.

Background technology

In computer graphics and field of computer aided design, from single width two dimension input picture, rebuild generating three-dimensional object process, because the depth information of three-dimensional body is difficult to recover to become a difficult point, yet by means of user interactions, often can reduce its difficulty, thereby can effectively address this problem.In three-dimensional model based on image creates and generates, hope can provide a kind of comparatively simple and practical man-machine interaction to describe mode for user, with generating three-dimensional body easily and efficiently.For cartoon, there is at present a kind of special method for drafting, mainly that all objects are decomposed into some more simple geometric configuratioies, the object subdivision that each decomposition obtains is generated by several curve constructions, and the method is accepted by many cartoon artists and obtained application in some 3 d modeling systems.

3 d modeling system based on mutual Freehandhand-drawing is proposed in succession by many researchers, and the shape modeling operation of part based on Freehandhand-drawing modeling completes often in three dimensions.First system creates a rough model, and then, by some special operations, such as shearing, rotation, merging, distortion etc. little by little added more details for model.Yet these special operationals are not often very directly perceived, and require user must possess corresponding professional knowledge.On the contrary, from single width input picture, directly structure three-dimensional model provides the method for a kind of general user's of being applicable to simple to operate, the free body of efficient quick generating three-dimensional.According to single width input picture, utilize the distinctive perception of the mankind to provide the projection of three-dimensional object profile on two dimensional surface for system, and automatically calculate for the depth information of the contour of object of generation model and extract the texture of input picture body surface and be mapped to three-dimensional model by system, thereby generate the 3 D auto body model with the object sense of reality in input picture.Meanwhile, because a large amount of real-life three-dimensional bodies have all shown symmetry to a certain degree, such as animal, building, furniture and other organic structure etc.Under quadrature or perspective projection, as long as can determine that the matching relationship between symmetry element just can reconstruct the three-dimensional structure of symmetric shape completely, takes full advantage of this symmetry feature in our 3 D auto form-creation.

Summary of the invention

For overcome 3 D auto Shape design and generate in complicated operation, interworking amount is large, the sense of reality is poor deficiency, the invention provides a kind of method of utilizing the free body of single image generating three-dimensional of simple to operate, efficient quick, strong sense of reality.

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

3 D auto form-creation method based on single image, described method comprises following three steps:

1) user, according to the single width two dimensional image of input, copies and depicts the line drawing figure that objects in images represents in mutual Freehandhand-drawing mode on the plane of delineation, and these lines can accurately reflect object each several part profile in vertical direction substantially.Point on system automatic capturing Freehandhand-drawing lines, and interpolation goes out corresponding quadratic b-spline curve, use the polygon broken line of the summit formation of uniform sampling from smooth quafric curve to carry out discretize to the Freehandhand-drawing lines of user's input, and preserve successively the curve construction pair of each subdivision of object.

2) calculating of each subdivision curve construction depth coordinate of three-dimensional body and the discrete generation of three-dimensional model.For calculate curve construction depth coordinate convenient for the purpose of, system is used and is drawn plane as XOY plane, the input line that comprises symmetric information is drawn as the parallel projection of three-dimensional body curve construction, projecting direction is perpendicular to drawing plane.The curve construction of first definite each subdivision of object of system also calculates their three-dimensional coordinate information, and the curve construction collection of each subdivision of object comprises two symmetrical curves and two general curves conventionally.First method travels through all symmetrical curves, the three-dimensional coordinate information of symmetrical curve can calculate according to the known plane of symmetry, and the three-dimensional symmetrical curve of generation can be calculated by the symmetrical curve with a part of to guarantee the general curve in each part again match its corresponding object subdivision according to the annexation between curve.Object each several part can be categorized into two kinds of dissimilar subdivisions: about the certainly symmetrical single part of the plane of symmetry with about two symmetrical parts of the plane of symmetry.This two classes subdivision is different in the method for calculating ordinary construction curve.General curve in symmetric part situation can directly be calculated by its symmetrical curve; And in mutual symmetric part situation, only need to utilize symmetrical curve to calculate the general curve of one of them subdivision, the general curve of another part can utilize symmetry to obtain by mutual antimeric general curve.

Specifically, the summit x coordinate on hand-drawing line in two-dimentional Freehandhand-drawing plane is drawn and y coordinate reality are corresponding to x coordinate and the y coordinate on summit on three-dimensional body, and what need recovery is only the z coordinate on each summit.For two symmetrical curves in each subdivision, can utilize following formula to calculate their each sampled point z coordinates:

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

Wherein, z _siand z ' _sifor symmetric points z coordinate to be asked, x _si, x ' _siand y _si, y ' _sibe respectively the x of symmetric points, y coordinate, N _s(x ^s, y ^s, z ^s) be plane of symmetry normal vector, N _g(x ^g, y ^g, z ^g) for being positioned at a vector of the plane of symmetry.Meanwhile, for each subdivision, can utilize following formula to calculate the z coordinate points of a pair of general curve up-sampling point separately:

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

Wherein, z _giand z ' _gifor asymmetric generic point z coordinate to be asked, x _gi, x ' _giand y _gi, y ' _gibe respectively the x of asymmetric generic point, y coordinate.In addition, for a subdivision and another subdivision in object, about the symmetrical situation of the plane of symmetry, it is as follows that method can be utilized by the asymmetric general curve of one of them subdivision symmetry automatically to calculate the asymmetric general curve of another subdivision:

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

Wherein, x ^s, y ^sand z ^sbe respectively plane of symmetry normal vector coordinate, x _gi, y _giand z _gibe respectively the x of asymmetric point on general curve, y and z coordinate.

Thereby, about the object subdivision situation of the plane of symmetry self symmetry, according to the plane of symmetry of user's appointment, first utilize (1) formula to calculate the three-dimensional coordinate of two symmetrical curve up-sampling points, obtain corresponding three-dimensional structure curve; Recycling (2) formula calculates the three-dimensional coordinate of two asymmetric general curve up-sampling points, obtains corresponding three-dimensional structure curve.For a subdivision and another subdivision in object about the symmetrical situation of the plane of symmetry, to belonging to respectively two pairs of symmetrical curves of two subdivisions, first utilize (1) formula to calculate respectively the three-dimensional coordinate of every pair of symmetrical curve up-sampling point, obtain corresponding three-dimensional structure curve; Then utilize (2) formula to calculate the three-dimensional coordinate of two asymmetric general curve up-sampling points of one of them subdivision, obtain corresponding three-dimensional structure curve; Finally utilize (3) formula by two asymmetric general curves of last subdivision, to be calculated the three-dimensional coordinate of two asymmetric general curve up-sampling points of another subdivision, obtain corresponding three-dimensional structure curve.

After each part has been determined curve construction separately, utilize rotation mixed method just can generate corresponding parametric surface, and parametric surface discretize is obtained representing the three-dimensional grid model of free body.

3) in order to generate the 3 D auto body with the height sense of reality, utilize the texture information of object visible part in input picture, need to be in input picture be given on the three-dimensional grid model surface generating the color and vein information of object; Yet, according to single width input picture, rebuild the color and vein that the three-dimensional model generating can only obtain objects in images visible part, consider the symmetry characteristic of the 3 D auto body that we generate, can the monosymmetric part of the hypothesized model plane of symmetry there is identical texture, thereby only need give texture information to the model part of the object plane of symmetry one side, the texture information of model opposite side can utilize symmetry conveniently to obtain; The final 3 D auto body with the height sense of reality that generates.

Technical conceive of the present invention is: the two dimensional image based on user's input, and user depicts two-dimentional hand-drawn outline lines in interactive mode on the plane of delineation, and these lines are that three-dimensional body curve construction is in the rectangular projection of drawing in plane.The three-dimensional model generating is comprised of some subdivisions conventionally, and the three-dimensional structure curve depth information of each subdivision can be calculated by the symmetry of object, by these curve constructions, can generate parametric surface and discretize obtains three-dimensional grid model.Utilize input picture to increase texture to the three-dimensional model surface visible part generating, and utilize symmetry to carry out texture repair to shield portions, thereby generate the 3 D auto body with the height sense of reality.

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

Accompanying drawing explanation

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

Fig. 2 is usingd the three-dimensional model Preliminary Results that user's delineation lines bar generates as input in Fig. 1.

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

Fig. 4 is method exemplary plot of three-dimensional model surface being carried out to texture mapping of the present invention.

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

Embodiment

Below in conjunction with accompanying drawing, the various 3 D auto body effects of technical method of the present invention and generation are further described and are described in detail.

With reference to accompanying drawing 1---accompanying drawing 5, a kind of 3 D auto form-creation method based on single image, described method comprises following three steps:

1) based on single image, in imitation mode alternately, depicting two-dimentional hand-drawing line draws.As shown in Figure 1, user describes two-dimentional Freehandhand-drawing lines in interactive mode on the plane of delineation, and these lines can accurately reflect object each several part profile in vertical direction substantially.Point on system automatic capturing Freehandhand-drawing lines, and interpolation goes out corresponding quadratic b-spline curve, use the polygon broken line of the summit formation of uniform sampling from smooth quafric curve to carry out discretize to the Freehandhand-drawing lines of user's input, and preserve successively the curve construction pair of each subdivision of object.

2) calculating of each subdivision curve construction depth coordinate of three-dimensional body and the discrete generation of three-dimensional model.For calculate curve construction depth coordinate convenient for the purpose of, system is used and is drawn plane as XOY plane, the input line that comprises symmetric information is drawn as the parallel projection of three-dimensional body curve construction, projecting direction is perpendicular to drawing plane.The curve construction of first definite each subdivision of object of system also calculates their three-dimensional coordinate information, and the curve construction collection of each subdivision of object comprises two symmetrical curves and two general curves conventionally.First method travels through all symmetrical curves, the three-dimensional coordinate information of symmetrical curve can calculate according to the known plane of symmetry, and the three-dimensional symmetrical curve of generation can be calculated by the symmetrical curve with a part of to guarantee the general curve in each part again match its corresponding object subdivision according to the annexation between curve.Object each several part can be categorized into two kinds of dissimilar subdivisions: about the certainly symmetrical single part of the plane of symmetry with about two symmetrical parts of the plane of symmetry.This two classes subdivision is different in the method for calculating ordinary construction curve.General curve in symmetric part situation can directly be calculated by its symmetrical curve; And in mutual symmetric part situation, only need to utilize symmetrical curve to calculate the general curve of one of them subdivision, the general curve of another part can utilize symmetry to obtain by mutual antimeric general curve.

Specifically, the summit x coordinate on hand-drawing line in two-dimentional Freehandhand-drawing plane is drawn and y coordinate reality are corresponding to x coordinate and the y coordinate on summit on three-dimensional body, and what need recovery is only the z coordinate on each summit.For two symmetrical curves in each subdivision, can utilize following formula to calculate their each sampled point z coordinates:

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

Wherein, z _siand z ' _sifor symmetric points z coordinate to be asked, x _si, x ' _siand y _si, y ' _sibe respectively the x of symmetric points, y coordinate, N _s(x ^s, y ^s, z ^s) be plane of symmetry normal vector, N _g(x ^g, y ^g, z ^g) for being positioned at a vector of the plane of symmetry.Meanwhile, for each subdivision, can utilize following formula to calculate the z coordinate points of a pair of general curve up-sampling point separately:

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

Wherein, z _giand z ' _gifor asymmetric generic point z coordinate to be asked, x _gi, x ' _giand y _gi, y ' _gibe respectively the x of asymmetric generic point, y coordinate.In addition, for a subdivision and another subdivision in object, about the symmetrical situation of the plane of symmetry, it is as follows that method can be utilized by the asymmetric general curve of one of them subdivision symmetry automatically to calculate the asymmetric general curve of another subdivision:

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

Wherein, x ^s, y ^sand z ^sbe respectively plane of symmetry normal vector coordinate, x _gi, y _giand z _gibe respectively the x of asymmetric point on general curve, y and z coordinate.

Thereby, about the object subdivision situation of the plane of symmetry self symmetry, according to the plane of symmetry of user's appointment, first utilize (1) formula to calculate the three-dimensional coordinate of two symmetrical curve up-sampling points, obtain corresponding three-dimensional structure curve; Recycling (2) formula calculates the three-dimensional coordinate of two asymmetric general curve up-sampling points, obtains corresponding three-dimensional structure curve.For a subdivision and another subdivision in object about the symmetrical situation of the plane of symmetry, to belonging to respectively two pairs of symmetrical curves of two subdivisions, first utilize (1) formula to calculate respectively the three-dimensional coordinate of every pair of symmetrical curve up-sampling point, obtain corresponding three-dimensional structure curve; Then utilize (2) formula to calculate the three-dimensional coordinate of two asymmetric general curve up-sampling points of one of them subdivision, obtain corresponding three-dimensional structure curve; Finally utilize (3) formula by two asymmetric general curves of last subdivision, to be calculated the three-dimensional coordinate of two asymmetric general curve up-sampling points of another subdivision, obtain corresponding three-dimensional structure curve.

After each part has been determined curve construction separately, utilize rotation mixed method just can generate corresponding parametric surface, and parametric surface discretize is obtained to sealing grid surface as shown in Figure 3, the 3 D auto body complete model of generation is as shown in Figure 2.

3) three-dimensional model superficial makings is synthetic to generate the 3 D auto body with the stronger sense of reality.In general, the object in input picture has often comprised many details and superficial makings, in order to generate the 3 D auto body with the height sense of reality, the three-dimensional grid model surface that need to generate in first two steps give input picture in object color texture information.Yet, because user is only for system provides single two dimensional image, rebuild the color and vein that the three-dimensional model generating can only obtain objects in images visible part.Consider the symmetry characteristic of rebuilding the 3 D auto body generating, can the monosymmetric part of the hypothesized model plane of symmetry there is identical texture, thereby only need give texture information to the model part of the object plane of symmetry one side, the texture information of model opposite side can utilize symmetry conveniently to obtain.As shown in Figure 4, suppose that T1 and T2 are the visible part of model, T2 and T3 are respectively the model plane of symmetry near the part of screen one side, the texture of T1 and T2 part can directly obtain in input picture, and for the T3 part of blocking, because its region comprising is often less, can simply vertical screen direction in T2 part be blocked to the texture copy of T3 part in the past.Like this, remaining T4 part texture just can corresponding symmetric part texture replication obtain in T2.Yet the texture of T1 part might not be identical with corresponding symmetric part texture in T2 in actual picture, this may cause the joining place of T1 and T4 to have rough transition.For this reason, method is only directly carried out texture mapping to T2 part, and the texture of T1 part is obtained by its symmetric part texture replication equally.In addition,, for the mutual symmetric part of model, the texture mapping that we only carry out above-mentioned steps to a part is wherein processed, and the texture of another part is obtained by its symmetrical partial replication.When carrying out texture mapping, can directly the geometric coordinate of object be projected to drafting plane, and the texture coordinate using the coordinate of subpoint as model is realized texture.Accompanying drawing 5 has provided the partial 3-D free form body Model design sketch being generated by this method design.

Accompanying drawing 1 is the input picture example that comprises the lines of outline that user interactions describes; Accompanying drawing 2 is to using user's delineation lines in accompanying drawing 1 to draw as the 3 D auto body complete model exemplary plot of input generation; Accompanying drawing 3 is the single part grid surface of object effect exemplary plot; Accompanying drawing 4 is three-dimensional model surface to be carried out to the method exemplary plot of texture mapping; Accompanying drawing 5 is partial 3-D free form body Model exemplary plot that this method design generates, accompanying drawing 5 (a) is the input two dimensional image that comprises generation animal to be reconstructed and has provided the lines of outline that user interactions is described, accompanying drawing 5 (b) is the three-dimensional structure curve that has recovered the three-dimensional body each several part after three-dimensional coordinate information, accompanying drawing 5 (c) is to rebuild the three-dimensional model Preliminary Results generating, accompanying drawing 5 (d, e) is the 3 D auto body after texture is synthetic and under two different visual angles, observes respectively the three-dimensional model of realistic effect.

Claims (1)

1. the 3 D auto form-creation method based on single image, comprises following three steps:

1) user, according to the single width two dimensional image of input, copies and depicts the line drawing figure that objects in images represents in mutual Freehandhand-drawing mode on the plane of delineation, and these lines can accurately reflect object each several part profile in vertical direction substantially; Point on system automatic capturing Freehandhand-drawing lines, and interpolation goes out corresponding quadratic b-spline curve, use the polygon broken line of the summit formation of uniform sampling from smooth quafric curve to carry out discretize to the Freehandhand-drawing lines of user's input, and preserve successively the curve construction pair of each subdivision of object;

2) calculating of each subdivision curve construction depth coordinate of three-dimensional body and the discrete generation of three-dimensional model; For calculate curve construction depth coordinate convenient for the purpose of, system is used and is drawn plane as XOY plane, the input line that comprises symmetric information is drawn as the parallel projection of three-dimensional body curve construction, projecting direction is perpendicular to drawing plane;

First determine the curve construction of each subdivision of object and calculate their three-dimensional coordinate information, the curve construction collection of each subdivision of object comprises two symmetrical curves and two general curves conventionally; First travel through all symmetrical curves, the three-dimensional coordinate information of symmetrical curve can calculate according to the known plane of symmetry, and the three-dimensional symmetrical curve of generation can be calculated by the symmetrical curve with a part of to guarantee the general curve in each part again match its corresponding object subdivision according to the annexation between curve;

Object each several part can be categorized into two kinds of dissimilar subdivisions: about the certainly symmetrical single part of the plane of symmetry with about two symmetrical parts of the plane of symmetry; This two classes subdivision is different in the method for calculating ordinary construction curve; General curve in symmetric part situation can directly be calculated by its symmetrical curve; And in mutual symmetric part situation, only need to utilize symmetrical curve to calculate the general curve of one of them subdivision, the general curve of another part can utilize symmetry to obtain by mutual antimeric general curve;

Summit x coordinate on hand-drawing line in two-dimentional Freehandhand-drawing plane is drawn and y coordinate reality are corresponding to x coordinate and the y coordinate on summit on three-dimensional body, and what need recovery is only the z coordinate on each summit; For two symmetrical curves in each subdivision, can utilize following formula to calculate their each sampled point z coordinates:

$z_{\mathrm{si}}=-\frac{1}{2}(\frac{(x_{\mathrm{si}}+x_{\mathrm{si}}^{\′})\·x^s}{z^s}+\frac{(y_{\mathrm{si}}+y_{\mathrm{si}}^{\′})\·y^s}{z^s}+\frac{(x_{\mathrm{si}}-x_{\mathrm{si}}^{\′})\·x^g}{z^g}+\frac{(y_{\mathrm{si}}-y_{\mathrm{si}}^{\′})\·y^g}{z^g})$

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

Wherein, z _siand z ' _sifor symmetric points z coordinate to be asked, x _si, x ' _siand y _si, y ' _sibe respectively the x of symmetric points, y coordinate, N _s(x ^s, y ^s, z ^s) be plane of symmetry normal vector, N _g(x ^g, y ^g, z ^g) for being positioned at a vector of the plane of symmetry; Meanwhile, for each subdivision, can utilize following formula to calculate the z coordinate points of a pair of general curve up-sampling point separately:

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

Wherein, z _giand z ' _gifor asymmetric generic point z coordinate to be asked, x _gi, x ' _giand y _gi, y ' _gibe respectively the x of asymmetric generic point, y coordinate; In addition, for a subdivision and another subdivision in object, about the symmetrical situation of the plane of symmetry, it is as follows that method can be utilized by the asymmetric general curve of one of them subdivision symmetry automatically to calculate the asymmetric general curve of another subdivision:

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

Wherein, x ^s, y ^sand z ^sbe respectively plane of symmetry normal vector coordinate, x _gi, y _giand z _gibe respectively the x of asymmetric point on general curve, y and z coordinate;

Thereby, about the object subdivision situation of the plane of symmetry self symmetry, according to the plane of symmetry of user's appointment, first utilize (1) formula to calculate the three-dimensional coordinate of two symmetrical curve up-sampling points, obtain corresponding three-dimensional structure curve; Recycling (2) formula calculates the three-dimensional coordinate of two asymmetric general curve up-sampling points, obtains corresponding three-dimensional structure curve; For a subdivision and another subdivision in object about the symmetrical situation of the plane of symmetry, to belonging to respectively two pairs of symmetrical curves of two subdivisions, first utilize (1) formula to calculate respectively the three-dimensional coordinate of every pair of symmetrical curve up-sampling point, obtain corresponding three-dimensional structure curve; Then utilize (2) formula to calculate the three-dimensional coordinate of two asymmetric general curve up-sampling points of one of them subdivision, obtain corresponding three-dimensional structure curve; Finally utilize (3) formula by two asymmetric general curves of last subdivision, to be calculated the three-dimensional coordinate of two asymmetric general curve up-sampling points of another subdivision, obtain corresponding three-dimensional structure curve;

After each part has been determined curve construction separately, utilize rotation mixed method just can generate corresponding parametric surface, and parametric surface discretize is obtained representing the three-dimensional grid model of free body;

3) in order to generate the 3 D auto body with the height sense of reality, utilize the texture information of object visible part in input picture, need to be in input picture be given on the three-dimensional grid model surface generating the color and vein information of object; Yet, according to single width input picture, rebuild the color and vein that the three-dimensional model generating can only obtain objects in images visible part, consider the symmetry characteristic of the 3 D auto body that we generate, can the monosymmetric part of the hypothesized model plane of symmetry there is identical texture, thereby only need give texture information to the model part of the object plane of symmetry one side, the texture information of model opposite side can utilize symmetry conveniently to obtain; The final 3 D auto body with the height sense of reality that generates.