CN103473811B - Based on the convenient generation method of three-dimensional entity model that two dimension hand-drawing line is drawn - Google Patents

Abstract

Based on the convenient generation method of three-dimensional entity model that two dimension hand-drawing line is drawn, including three below step: 1) designer is according to predefined free hand line input rule, and on layout board, the parallel projection line drawing figure of the physical model needing reconstruction is drawn in artificial hand；Then designer utilizes two dimension hand-drawing line to draw and specifies all surface informations which summit to be made up of a face, and specifies the initial vertax as cube corner.2) from initial cube corner, draw based on two-dimensional line be threedimensional model parallel projection this it is assumed that theoretical according to cube corner, progressively recover the three-dimensional coordinate information on all summits.3) the input information according to designer, identifies all planes on 3D solid and curved surface, respectively the polygon facet on model, banding curved surface, hollow inner cylinder or hollow polygon facet is carried out mesh triangles, and exports three-dimensional entity model.What the invention provides a kind of simple, convenient quick, 3 D complex entity that moulding is abundant accurately generates method.

Description

Based on the convenient generation method of three-dimensional entity model that two dimension hand-drawing line is drawn

Technical field

The two-dimentional hand-drawing line that Patent design of the present invention inputs for designer is drawn, it is provided that a kind of method that can generate three-dimensional entity model conveniently and efficiently.

Background technology

In field of computer aided design, the research generating three-dimensional entity model correlation technique according to the two-dimentional hand-drawing line picture of designer's input obtains general attention.Before building a three-dimensional entity model, the two-dimensional projection line drawing figure of physical model is drawn in designer's often upper according to design and functionally requirement artificial hand on two-dimensional design plate, and computer can be drawn according to two-dimensional line and be reconstructed target three-dimensional entity model directly and accurately.The research of such technology enables to designer's mentality of designing various physical model of convenient generation according to oneself, thus breaking away from the complicated processes of the softwares such as the very professional 3 d modeling software such as AutoCAD of operation, this respect research will be significant.

Existing three-dimensional entity model reconstruction technique can be divided into method two class of draw based on non-precision the two-dimensional line optimization method rebuild and reconstruction of drawing based on accurate two-dimensional line.Two-dimensional line for user's input is drawn, based on the method optimized mainly by building an object function and object function is carried out optimization solving target three-dimensional, this object function can comprise the regularity requirement of some weightings, and these regularities require to build often by the geometrical constraint explored in two dimension manual draw.Relatively time-consuming based on the three-dimension entity design method often ratio optimized, and the searching of geometrical constraint and definition to be comparison professional and the problem of complexity, the result of reconstruction is easily subject to the geometrical constraint regularity that uses and weighter factor is chosen impact and cause inaccurate.

It is that two-dimensional line is drawn as the projection on XOY plane of the target 3D solid based on the accurate two-dimensional line method rebuild of drawing.In other words, it is possible to the summit x coordinate on two-dimensional line picture and y-coordinate are actually corresponded to x coordinate and the y-coordinate on summit on 3D solid.If the subject matter of three-dimension entity design is exactly the z coordinate recovering each summit.The existing method reconstruction mainly for simple polyhedron object carrying out three-dimension entity design based on accurate two-dimensional line picture, the three-dimensional entity model type of reconstruction is single, it is difficult to meet various actual demand.Present invention is generally directed to the reconstruction of complex three-dimensional physical model, designer's input two-dimensional line containing Freehandhand-drawing straight line and Freehandhand-drawing curve is drawn, method can generate 3 D complex physical model conveniently and efficiently, and these models can comprise polygon facet, banding curved surface, hollow inner cylinder or hollow polygon facet etc..

Summary of the invention

For the complicated operation in overcoming existing three-dimensional entity model to generate, reconstructed results is not accurate enough, rebuild the deficiency of the aspects such as the 3D solid profile simple types generated is single, the two-dimentional hand-drawing line designed according to designer is drawn, and what the invention provides a kind of simple, convenient quick, 3 D complex entity that moulding is abundant accurately generates method.

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

Based on the convenient generation method of three-dimensional entity model that two dimension hand-drawing line is drawn, comprise the following steps:

Step 1, designer is according to predefined free hand line input rule, and the two-dimensional parallel projection line drawing figure of the physical model needing reconstruction is drawn in upper according to design and functionally requirement artificial hand on layout board；Then utilize two dimension hand-drawing line to draw and specify all surface informations which summit to be made up of a face, and specify the initial vertax as cube corner；

Step 2, from initial cube corner, draw based on two-dimensional line be threedimensional model parallel projection this it is assumed that theoretical according to cube corner, progressively recover the three-dimensional coordinate information on all summits；

Draw based on two-dimensional line is three-dimensional entity model parallel projection it is assumed that the summit x coordinate on two-dimensional line picture and y-coordinate can actually correspond to x coordinate and the y-coordinate on summit on 3D solid, it is necessary to the z coordinate on only each summit of recovery.Assuming that initial cube corner summit z coordinate is 0, utilize cube corner theory can calculate the z coordinate on each summit as follows: the O that sets up an office is cube corner, assume that a, b and c are with an O three angles between space vector OA, OB and OC perpendicular to each other being starting point respectively, then summit A, B and C z coordinate can obtain with below equation (1):

$z_A=z_O\±\sqrt{-\frac{\left(\cos b\right)\left(\cos c\right)}{\left(\cos a\right)}}\·\left|\mathrm{OA}\right|$

$z_B=z_O\±\sqrt{-\frac{\left(\cos a\right)\left(\cos c\right)}{\left(\cos b\right)}}\·\left|\mathrm{OB}\right|$

$z_C=z_O\±\sqrt{-\frac{\left(\cos a\right)\left(\cos b\right)}{\left(\cos c\right)}}\·\left|\mathrm{OC}\right|---\left(1\right)$

Wherein cosa, cosb, cosc ≠ 0；The length of | OA |, | OB |, | OC | respectively vector OA, OB, OC；z_O,z_A,z_B,z_CThe respectively z coordinate of some O and some A, B and C；

For the plane in three dimensions, it is known that can uniquely determining a plane at 3, its equation can be expressed as: Ax+By+Cz+D=0；If it is known that any x coordinate and y-coordinate in this plane, it is possible to try to achieve third dimension z coordinate as follows: z=-(D+Ax+By)/C, C ≠ 0.Utilize the method can recover the summit z coordinate of known x coordinate and y-coordinate in all known planes；

For the curved surface situation that Freehandhand-drawing curved lines is formed, method utilizes second order B-spline curves to be similar to Freehandhand-drawing curve, difference intensive sampling series of discrete sampling summit on second order B-spline curves, and curved surface is carried out discrete trigonometric, such that it is able to utilize said method to recover the third dimension z coordinate on discrete summit；

Step 3, input information according to designer, identify all planes on 3D solid and curved surface, respectively the polygon facet on model, banding curved surface, hollow inner cylinder or hollow polygon facet are carried out mesh triangles by being sequentially connected with neighbouring sample summit, and export three-dimensional entity model.

Further, the free hand line input rule described in step 1 is:

Rule one: straight line represents the limit of plane；

Rule two: curve represents the curved boundaries of curved surface；

Rule three: straight dashed line represents the polygonal limit of hollow being positioned within a face, imaginary curve represents the hole being positioned within a face；

Rule four: generate connecting line, connecting line can inform which face system bore is positioned at, or informs that two circular cavities forms cylinder；

Input information according to designer in step 3, identify all planes on 3D solid and curved surface, as the polygon facet on model, banding curved surface, hollow inner cylinder or hollow polygon facet carry out mesh triangles by being sequentially connected with neighbouring sample summit, concrete identification and method for reconstructing be:

A the identification of () banding curved surface and reconstruction: a given face, if this face meets: a1) be made up of four summits, two straight flanges and two curl；A2) four summits are not shared by two curl；So this face is actually a banding face, will complete the reconstruction in this face after its trigonometric ratio；

The identification of b space plane polygon facet that () is likely to comprise lagoon island and reconstruction: b1) check the vertex sequence constituting this plane, if there is curl between two adjacent vertexs, then the approximate vertex sequence of this curl is inserted into the position between two summits；B2) search for all connecting lines and find the institute's hole being attached thereto, using these holes lagoon island as this plane polygon；A space plane polygon being likely to comprise lagoon island can be obtained through the two step, the reconstruction in this face will be completed after its trigonometric ratio；

C the identification of () hollow inner cylinder and hollow polygon facet and reconstruction: for any one connecting line, if it is connected to two circular cavities, then the two hole is actually formed an interior curved surface of column, will complete the reconstruction in this face after its trigonometric ratio.

The technology of the present invention is contemplated that: in theories of vision, and so-called cube corner refers to the structure that three rays perpendicular to each other launched in three dimensions are formed by a summit.Utilize cube corner theoretical, and the coordinate on known cube corner summit, it is possible to recover the apex coordinate adjacent with cube corner, and then progressively recover all apex coordinates.According to some input rules that predefined two dimension hand-drawing line is drawn, method can quickly recognize the elements such as the plane constituting object module and curved surface, and generates three-dimensional entity model according to its recovered apex coordinate.The patent provides a kind of convenient generation method of three-dimensional entity model drawn based on two dimension hand-drawing line.

Beneficial effects of the present invention is mainly manifested in: simple, convenient quick, moulding is enriched.

Accompanying drawing explanation

Fig. 1 is that user inputs two dimension hand-drawing line picture example；

Fig. 2 is the three-dimension entity design result of the two-dimensional line picture of 1 input with reference to the accompanying drawings；

Fig. 3 is cube corner exemplary plot；

Fig. 4 is patch Triangulation Algorithm exemplary plot；

Fig. 5 a is that the two-dimentional hand-drawing line that user inputs is drawn；

Fig. 5 b, Fig. 5 c are the three-dimensional entity model design sketchs of Fig. 5 a.

Fig. 6 a is that the two-dimentional hand-drawing line that user inputs is drawn；

Fig. 6 b, Fig. 6 c are the three-dimensional entity model design sketchs of Fig. 6 a.

Detailed description of the invention

Various 3D solid effects below in conjunction with the accompanying drawing technical method to the present invention and generation are further described and describe in detail.

With reference to accompanying drawing 1---accompanying drawing 6, based on the convenient generation method of 3D solid that two dimension hand-drawing line is drawn, described method includes three below step:

1) designer is according to predefined free hand line input rule, and the parallel projection line drawing figure of the physical model needing reconstruction is drawn in upper according to design and functionally requirement artificial hand on layout board.The free hand line input rule of definition is as follows:

Rule one: straight line represents the limit of plane.Article one, limit can be shared by two faces, the straight line AB and straight line AD etc. in accompanying drawing 1.

Rule two: curve represents the curved boundaries of curved surface.Curl C in accompanying drawing 1～D.

Rule three: straight dashed line represents the polygonal limit of hollow being positioned within a face, imaginary curve represents the hole being positioned within a face.Polygon F in accompanying drawing 1, it is positioned at inside face ABC～DA, then its area encompassed will form hollow polygon, the F in reconstruction effect in accompanying drawing 2 in face ABC～DA.E～E in accompanying drawing 1, will form the hole of a hollow.

Rule four: generate connecting line.Connecting line can inform which face system bore is positioned at, or informs that two circular cavities forms cylinder.Connecting line EA in accompanying drawing 1, EB and EC represent that hole E is positioned at inside face ABC～DA, and connecting line FA, FC and FD represent that polygon hole F is positioned at inside face ABC～DA；And connecting line EE ' represents that hole E and hole E ' forms an inner cylinder (E in accompanying drawing 2), connect FF ' and represent that inner polygon hole F and inner polygon hole F ' forms polygon cylinder (F in accompanying drawing 2).

According to above input rule, designer can draw the two-dimensional parallel projection line drawing figure of physical model according to designing requirement and functional requirement at two dimension painting canvas left-hand seat, then designer needs to specify which point to constitute a face, these information are using as the initial information identifying the comprised special surface of object module, and to specify which summit be initial cube corner.

2) from initial cube corner, theoretical according to cube corner, progressively recover the three-dimensional coordinate information on all summits.Drawing based on two-dimensional line is three-dimensional entity model parallel projection it is assumed that the summit x coordinate on two-dimensional line picture and y-coordinate can actually correspond to x coordinate and the y-coordinate on summit on 3D solid, thus needing the z coordinate on the only each summit recovered.Assuming that initial cube corner summit z coordinate is 0, utilize cube corner theory can calculate the z coordinate on each summit as follows:

If accompanying drawing 3 is a cubical parallel projection figure, its midpoint O is cube corner, cube corner usually by three that share a starting point in space limit perpendicular to each other constitute.Theoretical according to cube corner, it is possible to set up the second vertical parallel projection of cube corner and the relation of its three dimensional structure.In accompanying drawing 3, the x coordinate on each summit and y-coordinate conveniently can obtain from line drawing figure, it is necessary to recovery is its third dimension z coordinate.Assume that a, b and c are vector angles between OA, OB and OC in figure, then summit A, B and C z coordinate can obtain with below equation (1):

$z_A=z_O\±\sqrt{-\frac{\left(\cos b\right)\left(\cos c\right)}{\left(\cos a\right)}}\·\left|\mathrm{OA}\right|,$

$z_B=z_O\±\sqrt{-\frac{\left(\cos a\right)\left(\cos c\right)}{\left(\cos b\right)}}\·\left|\mathrm{OB}\right|,$

$z_C=z_O\±\sqrt{-\frac{\left(\cos a\right)\left(\cos b\right)}{\left(\cos c\right)}}\·\left|\mathrm{OC}\right|---\left(1\right)$

Wherein cosa, cosb, cosc ≠ 0；The length of | OA |, | OB |, | OC | respectively vector OA, OB, OC；z_O,z_A,z_B,z_CThe respectively z coordinate of some O and some A, B and C.

For the plane in three dimensions, it is known that can uniquely determining a plane at 3, its equation can be expressed as: Ax+By+Cz+D=0.If it is known that any x coordinate and y-coordinate in this plane, it is possible to try to achieve third dimension z coordinate as follows: z=-(D+Ax+By)/C, C ≠ 0.Utilize the method can recover the summit z coordinate of known x coordinate and y-coordinate in all known planes.It is illustrated for accompanying drawing 1 below, assuming that user have selected summit A as the z coordinate of cube corner postulated point A is 0, then can calculate and recover the coordinate of summit A ', B and D according to formula (1), and then may determine that the equation of plane ABCD, plane ABB ' A ' and plane ADD ' A ', the equation utilizing plane ABCD can calculate and recover the coordinate of summit C, in like manner summit B ' and summit D ' also can be resumed, and the recovery on these summits so that plane A ' B ' C ' D ' equation is determined, can may finally recover summit C '.So far the coordinate on all summits can be determined.

It is to be noted, for the curved surface situation that Freehandhand-drawing curved lines is formed, method utilizes second order B-spline curves to be similar to Freehandhand-drawing curve, difference intensive sampling series of discrete sampling summit on B-spline curves, and curved surface is carried out discrete trigonometric, thus utilize said method to recover the third dimension z coordinate on discrete summit.Patch Triangulation Algorithm therein adopts the method being sequentially connected with neighbouring sample summit as shown in Figure 4 to form gore.3) the input information according to designer, identify all planes on 3D solid and curved surface, respectively the polygon facet on model, banding curved surface, hollow inner cylinder or hollow polygon facet are carried out mesh triangles by being sequentially connected with neighbouring sample summit, and export three-dimensional entity model.

After utilizing cube corner theory to recover the coordinate on all summits of 3D solid, method also needs to input information according to designer and rebuilds each face of three-dimensional entity model further, and it identifies and method for reconstructing is as follows:

A the identification of () banding curved surface and reconstruction: a given face, if this face meets: a1) be made up of four summits, two straight flanges and two curl；A2) four summits are not shared by two curl.So this face is actually a banding face, and by its trigonometric ratio.Such as accompanying drawing 1, below initial situation, DCC ' D ' is perceived as a plane, but it meets above-mentioned two condition, it is made up of four summits, article two, straight flange CC ' and DD ', article two, curl C～D and C '～D ' is connected on these four summits and does not share summit, then face DCC ' D ' is considered as a banding face D～CC '～D ' D, and it is rebuild effect and sees accompanying drawing 2.

The identification of b space plane polygon facet that () is likely to comprise lagoon island and reconstruction: b1) check the vertex sequence constituting this plane, if there is curl between two adjacent vertexs, then the approximate vertex sequence of this curl is inserted into the position between two summits；B2) search for all connecting lines and find the institute's hole being attached thereto, using these holes lagoon island as this plane polygon.A space plane polygon being likely to comprise lagoon island can be obtained through this two step, the reconstruction in this face will be completed after its trigonometric ratio.Such as accompanying drawing 1, plane ABB ' A ', not curl between summit, also it is absent from lagoon island, then it is taken as common space plane polygon., there is curl in plane ABCD, then be inserted between C and D by the approximate vertex sequence of this curl, become plane ABC～D between C and D of summit；Further, the known hole E of connecting line EA, EB and EC it is positioned at this internal plane, the known polygon F of connecting line FA, FC and FD is positioned at this internal plane, then hole E and F is using the lagoon island as plane ABC～D.

C the identification of () hollow inner cylinder and hollow polygon facet and reconstruction: for any one connecting line, if it is connected to two circular cavities, then the two hole is actually formed an interior curved surface of column, and method is carried out trigonometric ratio.In accompanying drawing 1, connecting line EE ' is connected to hole E and E ', then they actually constitute an interior curved surface of column, and it is rebuild shown in the hollow inner cylinder E in effect such as accompanying drawing 2.If connecting line is connected to two internal polygons, then they are actually formed a polygon inner cylinder.In accompanying drawing 1, connecting line FF ' is connected to polygon F and polygon F ', and the two polygon lays respectively at plane ABC～D and A ' B ' C '～D ' inside, then the two polygon has actually constituted a hollow polygon facet, it is rebuild shown in the F in effect such as accompanying drawing 2.

Utilizing the result of above-mentioned identification and reconstruction, the method rebuilds 3D solid object module in accordance with the following steps: 1) travel through each face, judges by method (a) and rebuilds this face；If be unsatisfactory for (a), process by method (b).2) retrieving each connecting line, undertaken judging whether hollow inner cylinder and hollow polygon facet by method (c), if existed, by its trigonometric ratio, being finally completed reconstruction and the generation of target three-dimensional entity model.

Accompanying drawing 5 is the complex parts effect rebuild according to two-dimensional line picture, accompanying drawing 5 (a) is that the two-dimentional hand-drawing line that user inputs is drawn, and accompanying drawing 5 (b) and accompanying drawing 5 (c) are observe the three-dimensional entity model result utilizing two-dimensional line picture to rebuild under different observation visual angles respectively；Accompanying drawing 6 is the complicated entity effect rebuild according to two-dimensional line picture, accompanying drawing 6 (a) is that the two-dimentional hand-drawing line that user inputs is drawn, and accompanying drawing 6 (b) and accompanying drawing 6 (c) are observe the three-dimensional entity model result utilizing two-dimensional line picture to rebuild under different observation visual angles respectively.

Claims (1)

1. the convenient generation method of three-dimensional entity model drawn based on two dimension hand-drawing line, comprises the following steps:

Step 1, designer is according to predefined free hand line input rule, and the two-dimensional parallel projection line drawing figure of the physical model needing reconstruction is drawn in upper according to design and functionally requirement artificial hand on layout board；Then utilize two dimension hand-drawing line to draw and specify all surface informations which summit to be made up of a face, and specify the initial vertax as cube corner；Free hand line input rule described in step 1 is:

Rule one: straight line represents the limit of plane；

Rule two: curve represents the curved boundaries of curved surface；

Rule three: straight dashed line represents the polygonal limit of hollow being positioned within a face, imaginary curve represents the hole being positioned within a face；

Rule four: generate connecting line, connecting line can inform which face system bore is positioned at, or informs which two circular cavities forms cylinder；

Step 2, from initial cube corner, draw based on two-dimensional line be threedimensional model parallel projection this it is assumed that theoretical according to cube corner, progressively recover the three-dimensional coordinate information on all summits；

Draw based on two-dimensional line is three-dimensional entity model parallel projection it is assumed that the summit x coordinate on two-dimensional line picture and y-coordinate can actually correspond to x coordinate and the y-coordinate on summit on 3D solid, it is necessary to the z coordinate on only each summit of recovery；Assuming that initial cube corner summit z coordinate is 0, utilize cube corner theory can calculate the z coordinate on each summit as follows: the O that sets up an office is cube corner, assume that a, b and c are with an O three angles between space vector OA, OB and OC perpendicular to each other being starting point respectively, then summit A, B and C z coordinate can obtain with below equation (1):

$z_A=z_O\±\sqrt{-\frac{\left(\cos b\right)\left(\cos c\right)}{\left(\cos a\right)}}\·\left|OA\right|$

$z_B=z_O\±\sqrt{-\frac{\left(\cos a\right)\left(\cos c\right)}{\left(\cos b\right)}}\·\left|OB\right|$

$z_C=z_O\±\sqrt{-\frac{\left(\cos a\right)\left(\cos b\right)}{\left(\cos c\right)}}\·\left|OC\right|---\left(1\right)$

Wherein cosa, cosb, cosc ≠ 0；The length of | OA |, | OB |, | OC | respectively vector OA, OB, OC；z_O,z_A,z_B,z_CThe respectively z coordinate of some O and some A, B and C；

For the plane in three dimensions, it is known that can uniquely determining a plane at 3, its equation can be expressed as: Ax+By+Cz+D=0；If it is known that any x coordinate and y-coordinate in this plane, it is possible to try to achieve third dimension z coordinate as follows: z=-(D+Ax+By)/C, C ≠ 0；Utilize the method can recover the summit z coordinate of known x coordinate and y-coordinate in all known planes；

For the curved surface situation that Freehandhand-drawing curved lines is formed, method utilizes second order B-spline curves to be similar to Freehandhand-drawing curve, difference intensive sampling series of discrete sampling summit on second order B-spline curves, and curved surface is carried out discrete trigonometric, such that it is able to utilize said method to recover the third dimension z coordinate on discrete summit；

Step 3, input information according to designer, identify all planes on 3D solid and curved surface, respectively the polygon facet on model, banding curved surface, hollow inner cylinder or hollow polygon facet are carried out mesh triangles by being sequentially connected with neighbouring sample summit, and export three-dimensional entity model；

Input information according to designer in step 3, identify all planes on 3D solid and curved surface, as the polygon facet on model, banding curved surface, hollow inner cylinder or hollow polygon facet carry out mesh triangles by being sequentially connected with neighbouring sample summit, concrete identification and method for reconstructing are；

A the identification of () banding curved surface and reconstruction: a given face, if this face meets: a1) be made up of four summits, two straight flanges and two curl；A2) four summits are not shared by two curl；So this face is actually a banding face, will complete the reconstruction in this face after its trigonometric ratio；

The identification of b space plane polygon facet that () is likely to comprise lagoon island and reconstruction: b1) check the vertex sequence constituting this plane, if there is curl between two adjacent vertexs, then the approximate vertex sequence of this curl is inserted into the position between two summits；B2) search for all connecting lines and find the institute's hole being attached thereto, using these holes lagoon island as this plane polygon；A space plane polygon being likely to comprise lagoon island can be obtained through the two step, the reconstruction in this face will be completed after its trigonometric ratio；

C the identification of () hollow inner cylinder and hollow polygon facet and reconstruction: for any one connecting line, if it is connected to two circular cavities, then the two hole is actually formed an interior curved surface of column, will complete the reconstruction in this face after its trigonometric ratio.