CN101477705B - Computer assisted character animation drawing method based on light irradiated ball model - Google Patents
Computer assisted character animation drawing method based on light irradiated ball model Download PDFInfo
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Abstract
The invention discloses a method for rendering character animation in an artistic manner with the assistance of a computer. The method is based on an illumination spherical model. The invention is characterized in that the illumination spherical model which extracts and creates an artistic style from a work of art is applied to rendering of a character model, so that coloring of an artistic style is realized conveniently and rapidly, and character animation can be manufactured as if by non-photorealistic rendering. By drawing on a method for rendering information about illumination on a sphere, the invention ensures that when a complex object which is uniform in illumination material is rendered, the illumination is consistent in an all-round manner. Because of extraction and application of the illumination spherical model, character rendering of the artistic style can be realized conveniently and rapidly only through simple interactive operation, so that rendering efficiency is improved. The invention solves the problems that the prior computer assisted animation has low rendering efficiency, and the traditional image technology cannot give expression to works of an artist flexibly.
Description
Technical field
The present invention relates to area of computer aided character animation method for drafting, relate in particular to a kind of art up method for drafting of area of computer aided character animation based on the lighting sphere model.
Background technology
Aspect non-photorealistic rendering, scholars have explored a lot of technology and have been used for simulating artistical style, and a kind of form wherein of greatest concern is exactly that cel draws or the toon drafting.It is " art " that object is drawn as cartoon that cel draws, and this method for drafting can be given strong implicit sense and children's interesting.This method is very simple simultaneously, promptly uses the depicted as solid lines object, and object is divided into the zone with different colours.In field of Computer Graphics, just bring into use toon to draw style about the nineties in 20th century greatly and realize the combination between three-dimensional model and the two-dimentional cel animation.Compare with other NPR styles, this drafting style is fairly simple, can utilize computing machine to generate automatically at an easy rate.Now, but in business softwares such as Renderman, Softimage, Maya, Autodesk 3ds Max application card air grating method for drafting [Pascal Barla2006] all.And it also is widely used in a lot of video-games, TV play and the film.
Lake etc. [Lake 2000] have openly described the toon colorize method at first.He has proposed the method based on texture and traditional diffuse reflection illumination model, and this painted firmly (hard shading) technology can find the color conversion border, and is then that the both sides, border are painted with constant color respectively.Use three kinds of colors to set up the one dimension texture when realizing the shadow and highlight style.At an end of illumination, 1 or 2 section is set to high light color, and all the other are illumination material color.High light color can obtain through material color and high light factor are multiplied each other automatically.This high light is the irrelevant diffuse reflection Gao Guang of viewpoint.If the drafting DE Specular Lighting need utilize many textures to increase another texture.
In traditional cartoon, illumination and shade are the role of expression artization and the symbol of scene.High light has also been described role's and object in the scene various aspects.Thereby the high light in the cartoon should be the part in semantic symbol rather than the physical model.For this reason, Anjoy and Hiramitsu [Anjoy 2003] have proposed the high optical colour device of 3 dimensional objects, through being the Gao Guang of the simple operations establishment stylization of high light vector field definition.Their painted its uses traditional Blinn specular reflectance model to create initial Gao Guang.Alternatively change initial high light shape through geometric transformation, stylization and boolean's conversion then, up to the shape that obtains to want.The effect that the high light of this method is drawn depends on how to make up one group of good high light vector field, need carry out dull parameter adjustment.
Sloan etc. [Sloan 2001] have proposed a kind of painting methods that utilizes the feeling of unreality illumination model, have realized the painted of illumination model ball is mapped in the actual drafting, and can from original artistic work, set up the illumination model ball through user interactions.System is through illumination model ball and the corresponding relation of drawing the object model surface normal, with painted being applied in the drafting on the illumination model ball then.This method only provides a kind of semiautomatic extraction method of inter-stitched.
The painted 1 dimension texture that utilizes of traditional T oon is described the change of tone with surface direction and given light source.Barla etc. [Barla 2006] have proposed to support two expansion algorithms of viewpoint relevant effect.The one, to describing the change of tone, use 2 dimension textures to replace 1 dimension texture with surface direction and given light source, wherein the 2nd dimension is relevant with " the tone details " that need, and it can be along with the degree of depth and surface direction change.It two is to have expanded the Toon tinter, utilizes an improved normal field, can realize from original normal, to one that from " abstract shapes ", obtains simpler normal set.
We can say that the research thinking of this respect is mainly based on two aspects: on the one hand, obtain more lively cartoon style.The purpose that cartoon style is drawn is the art up style of simulation cartoon, therefore just needs more true to nature and vivo simulates artistical painting skill.Designing better 1 dimension texture is one of method, and better effect then need be taked more complicated method, for example introduces high light vector field conversion [Anjoy 2003] or 2 dimension textures [Barla 2006] etc. and has all proved feasible method.On the other hand, realize real-time rendering.In order to reduce the burden of CPU, nearest certain methods [Barla 2006] [Anjyo 2006] has all been used vertex shader and pixel coloring device method, realizes the cartoon style rendering algorithm through the GPU programming.And the outer following research also will be along this direction, and exploration has convenient user interactions flexibly, and can realize the real-time animation generation method of complicated cartoon style and various viewpoint relevant effect.
Summary of the invention
The objective of the invention is deficiency, a kind of art up method for drafting of area of computer aided character animation based on the lighting sphere model is provided to prior art.
The objective of the invention is to realize through following technical scheme: a kind of art up method for drafting of area of computer aided character animation based on the lighting sphere model may further comprise the steps:
(1) read in art up sample, choose the available color lump in the image: marquee is a triangle, and rectangle or ellipse provide different method for distilling to the difformity object respectively;
(2) color lump of choosing is mapped on the lighting sphere sphere, obtains spherical dough sheet: each pixel in the traversal plane picture marquee, convert the planimetric coordinates of this pixel into spherical co-ordinate, be mapped on the lighting sphere model, thereby form spherical dough sheet;
(3) fill in the blank slit in the spherical dough sheet that mapping is obtained: each pixel in the traversal lighting sphere model image, do not carry out linear interpolation to the gap that has plane color lump corresponding point mapping in the lighting sphere model upper panel mapping area;
(4) position of the spherical dough sheet of adjustment, be spliced into the lighting sphere model: these spherical dough sheets are carried out translation and rotary manipulation, and the position of adjusting them is until being spliced into a complete spherical diagram picture;
(5) the dough sheet splicing boundary in the lighting sphere model is repaiied retouch processing, make its smooth excessiveness;
(6) using the lighting sphere model paints to the three dimensional character model;
(7) set figure action and camera angle, use the lighting sphere model, output has the character animation sequence of art up style.
The invention has the beneficial effects as follows: the present invention extracts the lighting sphere model of setting up artistic style from artistic work, be applied to playing up of person model, realizes the painted of art up style quickly and easily, produces the character animation of non-photorealistic rendering.Traditional graph image technical support is the drawing three-dimensional space object in real time, but these methods can not embody the expressive force in the artist's work neatly.Present modeling and animation tool often require the self-defined texture of founder, and the nonlinear optical in the inartistic family simulation artistic work is shone.The present invention uses for reference the method for drafting of spheroid illumination information, has guaranteed that its illumination has global coherency when the drafting same light is shone the complex object of material.And extraction and application through the lighting sphere model only need simple interactive operation, just can realize quickly and easily that the personage of art up style draws, and have improved drafting efficient.The drafting efficient that the invention solves the auxiliary cartoon making of active computer is not high, and the traditional images technology can not embody the problem of artist's work expressive force flexibly.
Description of drawings
Fig. 1 is based on the process flow diagram of the art up method for drafting of area of computer aided character animation of lighting sphere model;
Fig. 2 is original artistic work image;
Among Fig. 3, being that the present invention uses triangle to select frame to extract irregular position color lump (a), (b) is that the present invention uses rectangle to select frame to extract cylindricality position color lump, is that the present invention uses ellipse to select frame to extract spherical position color lump (c);
Among Fig. 4, being that available color lump in the original artistic work image is mapped to the image on the lighting sphere model (a), (b) is that the result images after interpolation is filled is carried out in the blank slit that mapping obtains in the color lump;
Among Fig. 5, (a) being the lighting sphere model image that splicing is accomplished, (b) is splicing boundary to be carried out image repair the lighting sphere model image of retouching after the processing;
Fig. 6 be lighting sphere modelling of the present invention to modelling to corresponding relation;
Fig. 7 is the person model image after the present invention utilizes the Rendering of lighting sphere model;
Fig. 8 is the character animation sequence that the present invention uses the lighting sphere modeling rendering.
Embodiment
The present invention is based on the art up method for drafting of area of computer aided character animation of lighting sphere model, comprise following principle:
(1) mapping relations of apex coordinate from the plane to the sphere:
Wherein, dx=x-X, dy=y-Y, X, Y are sphere centre coordinate, R is the lighting sphere spherical radius.
(2) mapping relations of apex coordinate from the sphere to the plane:
Wherein, dx=abs (x-X), dy=abs (y-Y), c=R*sin (atan (dx, dy)), X, Y are sphere centre coordinate, R is a spherical radius.
(3) model formation of TV inpainting:
Wherein, E repaiies the circle zone of retouching extension, and D retouches the zone for repairing, and constant a is a threshold value.
The present invention is based on the art up method for drafting of area of computer aided character animation of lighting sphere model, may further comprise the steps:
1. read in art up sample, choose the available color lump in the image, marquee is a triangle, and rectangle or ellipse provide different method for distilling to the difformity object respectively.
Extraction such as this irregularly shaped position of figure skin art up painted uses triangle to select frame; Extraction is art up painted such as this cylindricality of personage's straight hair position, uses rectangle to select frame; Extraction is art up painted such as this spherical position of personage's eyeball, uses ellipse to select frame.
2. the color lump of choosing in the step 1 is mapped on the lighting sphere sphere, obtains spherical dough sheet.Each pixel in the traversal plane picture marquee converts the planimetric coordinates of this pixel into spherical co-ordinate, is mapped on the lighting sphere model, thereby forms spherical dough sheet;
Converting plane picture into the spherical diagram picture, is through each pixel in the mapping relations mapping choice box of pixel coordinate from the plane to the sphere.The mapping relations of the plane of above-mentioned principle (1) point to sphere are used in employed pixel position coordinates conversion.
3. fill in the blank slit in the spherical dough sheet that mapping obtains to step 2.Each pixel in the traversal lighting sphere model image carries out linear interpolation to the gap that does not have plane color lump corresponding point mapping in the lighting sphere model upper panel mapping area;
Judge earlier that before interpolation blank spot on the sphere is whether in the dough sheet zone.Determination methods is: at first use the mapping relations of the sphere of above-mentioned principle (2) point to the plane, a certain blank spot that calculates on the sphere is mapped to the position on the plane, judges the whether color lump inside on the plane, this position then.Carry out interpolation operation afterwards, input is the rgb value of the adjacent non-blank-white pixel of pixel color, and output is the color of these RGB mean values.
4. the position of the spherical dough sheet that obtains of set-up procedure 3 is spliced into the lighting sphere model.These spherical dough sheets are carried out translation and rotary manipulation, and the position of adjusting them is until being spliced into a complete spherical diagram picture;
In splicing, can translation have dough sheet, also can from artistic work, extract the new dough sheet of interpolation to the lighting sphere model to step 3 by repeating step 1 with rotation.
5. the dough sheet splicing boundary in the lighting sphere model of step 4 generation is repaiied and retouch processing, make its smooth excessiveness;
To the smooth treatment of dough sheet splicing boundary, be the method for using the Tv Inpainting of above-mentioned principle (3) point, image color lump splicing boundary is repaiied retouch.
6. the lighting sphere model of applying step 5 generations is painted to the three dimensional character model;
Each different parts of personage extracted respectively generate independently lighting sphere model, be applied to then on the corresponding site of person model.The lighting sphere model is the standard image format storage of 256*256 with the pixel size.For given lighting sphere model image, when drawing, system, establishes N through the normal direction access images texture on object model surface
GBe the normal direction of summit global coordinate system, M is the model view matrix, N
LBe the normal direction of summit local coordinate system, N is then arranged
G=M * N
L, the vertex texture coordinate is ((N
GX+1)/2, (N
GY+1)/2).
7. set figure action and camera angle, use the lighting sphere model, output has the character animation sequence of art up style.
The core of the inventive method is to set up the lighting sphere model that art up style is drawn in a series of extraction artist's works, utilizes these lighting sphere models that art up style is applied in the drafting of character animation then.
Describe the present invention in detail according to accompanying drawing and embodiment below, it is more obvious that the object of the invention and effect will become.
Embodiment
Below utilize our example of realizing, promptly extract during the art up painted character animation that is applied to us in the cartoon " flowers and trees are blue " draws, describe the embodiment of idiographic flow, the following (see figure 1) of step:
1) reads in art up sample, choose the available color lump (see figure 2) in the image.Marquee is a triangle, and rectangle or ellipse provide different method for distilling to the difformity object respectively; Triangle selects frame to be used in and extracts the art up painted of irregularly shaped position, like figure skin (seeing Fig. 3 (a)); Rectangle selects frame to be used in and extracts the art up painted of cylindricality position, like personage's straight hair (seeing Fig. 3 (b)); Ellipse selects frame to be used in and extracts the art up painted of spherical position, like personage's eyeball (seeing Fig. 3 (c)).
2) color lump of choosing in the step 1) is mapped on the lighting sphere sphere, obtains spherical dough sheet (seeing Fig. 4 (a)).Each pixel in the traversal plane picture marquee converts the planimetric coordinates of this pixel into spherical co-ordinate, is mapped on the lighting sphere model, thereby forms spherical dough sheet.
3) to step 2) blank slit in the spherical dough sheet that obtains of mapping fills (seeing Fig. 4 (b)).Each pixel in the traversal lighting sphere model image carries out linear interpolation to the gap that does not have plane corresponding point mapping in the dough sheet mapping area on the lighting sphere model.Need before interpolation to judge that blank spot on the sphere is whether in the dough sheet zone.Determination methods is: a certain blank spot that at first calculates on the sphere is mapped to the position on the plane, judge then this position whether on the plane color lump inner.
4) set-up procedure 3) position of the spherical dough sheet that obtains, be spliced into lighting sphere model (seeing Fig. 5 (a)).These spherical dough sheets are carried out translation and rotary manipulation, and the position of adjusting them is until being spliced into a complete spherical diagram picture;
5) the dough sheet splicing boundary in the lighting sphere model that step 4) is generated is repaiied and is retouched processing, makes its smooth excessiveness (seeing Fig. 5 (b)).The method of Tv Inpainting in the operational applications image processing techniques is repaiied image color lump splicing boundary and is retouched.
6) applying step 5) the lighting sphere model that generates is to three dimensional character model colouring (see figure 7).Each different parts of personage extracted respectively generate independently lighting sphere model, be applied to then on the corresponding site of person model.The lighting sphere model is the standard image format storage of 256*256 with the pixel size.For given lighting sphere model image, through the normal direction access images texture on object model surface, mapping relations were as shown in Figure 6 when system drew.If N
GBe the normal direction of summit global coordinate system, M is the model view matrix, N
LBe the normal direction of summit local coordinate system, N is then arranged
G=M * N
L, the vertex texture coordinate is ((N
GX+1)/2, (N
GY+1)/2).
7) set figure action and camera angle, use the lighting sphere model, output has the character animation sequence (see figure 8) of art up style.
Claims (1)
1. the art up method for drafting of area of computer aided character animation based on the lighting sphere model is characterized in that, may further comprise the steps:
(1) read in art up sample, choose the available color lump in the image: marquee is a triangle, and rectangle or ellipse provide different method for distilling to the difformity object respectively;
(2) color lump of choosing is mapped on the lighting sphere sphere, obtains spherical dough sheet: each pixel in the traversal plane picture marquee, convert the planimetric coordinates of this pixel into spherical co-ordinate, be mapped on the lighting sphere model, thereby form spherical dough sheet;
(3) fill in the blank slit in the spherical dough sheet that mapping is obtained: each pixel in the traversal lighting sphere model image, do not carry out linear interpolation to the gap that has plane color lump corresponding point mapping in the lighting sphere model upper panel mapping area;
(4) position of the spherical dough sheet of adjustment, be spliced into the lighting sphere model: these spherical dough sheets are carried out translation and rotary manipulation, and the position of adjusting them is until being spliced into a complete spherical diagram picture;
(5) the dough sheet splicing boundary in the lighting sphere model is repaiied retouch processing, make its smooth excessiveness;
(6) using the lighting sphere model paints to the three dimensional character model;
(7) set figure action and camera angle, use the lighting sphere model, output has the character animation sequence of art up style;
Wherein, in the said step (1), said triangle marquee is used in and extracts the art up painted of irregularly shaped position, and the rectangle marquee is used in and extracts the art up painted of cylindricality position, and oval marquee is used in and extracts the art up painted of spherical position;
Said step (2) converts plane picture into the spherical diagram picture, through each pixel in the mapping relations mapping choice box of pixel coordinate from the plane to the sphere; Employed plane to the mapping relations of sphere is:
wherein; Dx=x-X; Dy=y-Y; X; Y is a sphere centre coordinate, and R is the lighting sphere spherical radius;
In the said step (3), before interpolation, judge earlier blank spot on the sphere whether in the dough sheet zone, determination methods is: at first the spherical co-ordinate reverse is changed to planimetric coordinates, judges that then this planimetric coordinates is whether in the available color lump choice box of primary sample image; Employed sphere to the mapping relations on plane is:
wherein; Dx=abs (x-X); Dy=abs (y-Y); C=R*sin (atan (dx; Dy)); X, Y are sphere centre coordinate, and R is a spherical radius;
Said step (5) is specially: use the method for retouching of repairing of Tv Inpainting model in the image processing techniques image color lump splicing boundary is repaiied to retouch;
Said step 6) is specially: for given lighting sphere image, through the corresponding relation of spheroid normal and color, it is directly applied in cartoon figure's the modeling and drafting; During drafting, through object model normal to a surface access images texture, implementation model stylized painted.
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| CN101826214B (en) * | 2010-03-29 | 2012-06-27 | 中山大学 | Photon mapping-based global illumination method |
| CN101794454B (en) * | 2010-04-08 | 2012-01-04 | 西安交通大学 | Oil painting stylizing method based on image |
| CN102663766B (en) * | 2012-05-04 | 2014-10-22 | 云南大学 | Non-photorealistic based art illustration effect drawing method |
| CN104063888B (en) * | 2014-06-19 | 2016-11-02 | 云南大学 | A kind of wave spectrum artistic style method for drafting based on feeling of unreality |
| CN105809726B (en) * | 2016-03-04 | 2018-07-03 | 大连米乐宏业科技有限公司 | A kind of method that static map changes into Dynamic Graph |
| US9881413B2 (en) * | 2016-06-09 | 2018-01-30 | Adobe Systems Incorporated | Illumination-guided example-based stylization of 3D renderings |
| CN112268506B (en) * | 2020-08-31 | 2022-06-07 | 中国航发南方工业有限公司 | Data splicing method based on non-contact optical scanning detection |
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