GB2316591A

GB2316591A - Producing isometric view from manipulated plual planar views in CAD system

Info

Publication number: GB2316591A
Application number: GB9711465A
Authority: GB
Inventors: Nobuhiro Seki; Yoshiyuki Otsuka
Original assignee: INT TECHNICAL PUBLICATION CO L; International Technical Publication Co Ltd
Current assignee: INT TECHNICAL PUBLICATION CO L; International Technical Publication Co Ltd
Priority date: 1996-07-05
Filing date: 1997-06-04
Publication date: 1998-02-25
Anticipated expiration: 2017-06-04
Also published as: KR980010880A; GB9711465D0; KR100232278B1; GB2316591B

Abstract

To obtain an isometric view on the basis of the data of plan view, the main input means 300 enters designated planar view, plane stand point Pa to be specified in relation to the designated planar view above and the direction of the planar view by a simple manipulation on the display 100, together with display standard point P10 for the desired isometric view obtained through the operating means 20. Then the model projection plane input means 300 enters designated plane of the three model projection planes composing the isometric view and the direction of the designated plane in the same manner. A table is equipped, which contains ratio of the major axis and minor axis of each projection planare obtained, depending on the angle of each projection. The operating means 20 overlaps the system of coordinates of 45' rotation of the planar view on the system of coordinates of the major axis and minor axis of the ellipse on the projection plane, and obtains a projection view by operating by multiplying by the ratio a/b of the major axis (a) and minor axis (b) in the major axis direction and minor axis direction, and thus obtained projection view is matched with the plane standard point P10 on the planar view at the display standard point Pa, and the isometric view is displayed on display 100 so that the direction on the planar view may coincide with the direction of the model projection plane. A projection view which corresponds with rotating angle of model projection plane 1 currently on show on the display 100 is obtained. By means of the angle input means 400, the rotating angle of model projection plane 1 is entered and after this procedure the angle operating means 30 computes the ratio of the major and minor axes of each projection plane. The model projection planes are displayed in rotation about at least one of the basic three axes for composing the model projection planes. Hence, the model projection planes corresponding to the inclination of the planar view to be projected appear on the display 100.

Description

TITLE OF THE INVENTION Apparatus of drawing a cubic view TECHNICAL FIELD OF THE INVENTION The present invention relates to an apparatus of drawing a cubic view. and more particularly to an apparatus of drawing a cubic view by using data of plan view.

Fig. 12 shows an exanple of a known CAD system. This kind of system basically possesses the following functions for drawing a straight line, a circle, an ellipse, etc.

(a) Straight line I: Indicates the start point and end point of a desired straight line by a mouse 12 and a cursor.

II: Indicates the start point of a desired straight line, and enters the angle and length from an operation board 11.

(b) Circle I: Indicates the center point by the nouse 12 and the cursor, and enters the radius from the operation board 11.

II: Indicates two points corresponding to the diameter by the mouse 12 and the cursor.

(c) Ellipse I: Indicates the center point by the mouse 12 and the cursor, and enters the direction of the major axis, length of the najor axis, and length of the minor axis.

Moreover, this CAD system can move and copy thus drawn graphic elements or a figure drawn by combining these graphic elements.

(d) nove I: Indicates the move object figure and move source standard point, and indicates the nove destination standardpoint. As a result, the figure or graphic element moves to the move destination standard point.

II: Indicates the move object figure and moving direction (indicates a straight line), and enters the moving distance.

(e) Copy The operating procedure is exactly same as in the move, except that the original figure remains at the original position.

Moreover, the present applicant proposed, in U.S. Patent No.

5,115,494 (Japanese Patent No. 1883355), a nethod of displaying model projection planes (for example, standard numeral 1 in Fig. 1) drawing standard direction and standard length of a cubic view and ellipses of standard size on each projection plane for composing the cubic view, and drawing the cubic view through the medium of the model projection planes. That is, displaying three model projection planes in a displaying apparatus, when drawing a line segment in the standard direction, first the start point of the segment is designated, and any one of standard axes (x-axis, y-axis, z-axis) is designated in the procedure of direction designation. Then the length is entered. When drawing an ellipse, the center point of the ellipse is designated, and the ellipse drawn on a specific plane of the model projection plane is designated, and the dianeter of the circle on the plan view to be projected is entered from the operation board. In this way, the ellipse corresponding to the diameter of the circle in which the designated direction (for example, direction of the standard line) is the basis of the ellipse can be drawn. Each standard axis of the model projection plane shown in Fig. I is drawn in the isometric direction, and hence the ellipse has also the isoietric direction and the ratio of najor axis and minor axis.

This CAD system can draw a cubic view on the basis of the data of plan views stored in the memory means. Fig. 11 and Fig. 12 are flow diagrams showing the procedure. First, as shown in a schenatic diagram in Fig. 10 (a), the top view, botton view, front view, back view, right side view, and left side view are drawn in individual views, and the position of the plan view drawn in each view is designated. From this state, consequently, the correspondence between each side of the plan view and each projection plane of the cubic view to be drawn is related.

That is, as shown in Fig. 10 (a), when the top view PV, front view B, rear view A, right side view R, left side view L, and bottom view C are drawn in each view, the nenu screen displays right side, left side/front, rear/top, bottom. In response, the operator selects either right or left side, either front or rear, either top or bottom, and selects any one of the combinations in Fig. 10 (b). Herein, only the menu of "right side, left side/front, rear/top, bottom" is displayed1 but the die-shaped figure shown in Fig. 10 (b) is not displayed.

The upper line exanples in Fig. 10 (b) are initially set so that the top surface may be disposed on the top surface of the cubic view (in the lower line examples, the botton surface corresponds to the bottom surface on the cubic view), but it is also possible to designate otherwise for disposing other surface than the top surface (botton surface) in the top surface (botton surface) of the cubic view.

Fig. 11 (a) shows an example of drawing individual views in a practical drawing, and according to this drawing, hereinafter, the procedure of drawing a cubic view in the prior art is described.

As shown in Fig. 11 (b), origin Pa on the plan view is designated by the system of coordinates of the plan view (in this case, the front view), and display origin Pb is designated, and it is so set that the origin Pa on the plan view nay be positioned on the display origin Pb when a projection drawing corresponding to the plan view is drawn. Afterwards, the scale and other necessary items are entered.

In consequence, as indicated by thick line in Fig. 12 (b), designating elements to be projected (straight line, circle), or a set of elements, a section line La drawn in other view corresponding to the surface is designated. As a result, the projection plane is displayed so that the plane standard point Pa on the plan view may coincide with the display standard point Pb. Further, as indicated by thick line in Fig. 12 (c), designating other elements to be projected or a set of elenents, section line Lb is designated. Still more, when drawing the right side upper left part n in a cubic view, the elenents for composing the portion are designated as shown in Fig. 12 (b), and section Lc is designated. By sequentially repeating in this procedure, a cubic view is drawn.

In the conventional method, it is necessary to clarify the corresponding relation of elements appearing on each plan view, and the views nust be prepared by disposing each drawing composing the plan view at specified position, and at this time it is not permitted to dispose each drawing in other place than the specified position.

To determine the corresponding relation of each drawing of plan view and each surface for composing the cubic view, it cannot be judged visually on the screen, and the description of the manual shown in Fig.

10 (b) is indispensable. The invention is devised in the light of the above conventional background, and it is hence an object thereof to present an apparatus of drawing a cubic figure easily by manipulation on the screen only without having to prepare views.

SUMMARY OF THE INVENTION When drawing a cubic view on the basis of the data of plan view, as shown in Fig. 9, the system of coordinates v, w by 45. rotation (Fig.

9 (b), origin Pa) of the plan view to be projected is overlapped with the system of coordinates u. w of major axis and minor axis (Fig. 9 (c), origin PO) of the ellipse drawn in a specific plane in the projection plane (X plane, Y plane, Z plane shown in Fig. 9 (a)) for composing the cubic view (Fig. 9 (d)), and the plan view is multiplied by the ratio a/b of the major axis and minor axis in the major axis direction and minor axis direction (Fig. 9 (d) to (e)). For the ease of understanding, in Fig. 9, these two systems of coordinates are displayed so as to be matched in the origin, but in this invention, as described later, the projection plane obtained by calculation is designed so that the display standard point P10 designated separately may coincide with the plane standard point on the plan view, for example, the origin of the coordinates (origin Pa).

Conforming to such basic principle, in this invention, the model projection drawing is used as described below.

In order to achieve above-mentioned objective, the invention is composed as shown in Fig. 1. By means of the main input means 300, designated plan view, plane stand point Pa to be specified in relation to the designated plan view above and the direction of the plan view are entered by a simple manipulation on the display 100, together with display standard point P10 which displays a cubic view obtained through the operating means 20, as below.

Then by means of the model projection plane input means 300, designated plane of the three model projection planes composing the cubiv view and the direction of the designated plane are entered by a simple manipulation on the display 100.

A table is equipped, which contains ratio of the major axis and minor axis of each projectioan plane obtained, depending on the angle of each projection.

Furthermore, the operating means 20 overlaps the system of coordinates of 45. rotation of the plan view on the system of coordinates of the major axis and minor axis of the ellipse on the projection plane, and obtains a projection view by operating by multiplying by the ratio a/b of the major axis (a) and minor axis (b) in the major axis direction and minor axis direction, and thus obtained projection view is matched with the plane standard point P10 on the plan view at the display standard point Pa, and the cubic view is displayed on display 100 so that the direction on the plan view may coincide with the direction of the model projection plane.

The above procedure makes it possible to obtain a projection view which corresponds with rotating angle of model projection plane I currently on show on the display 100.

Furthermore, by means of the angle input means 400, the rotating angle of model projection plane 1 is entered and after this procedure the angle operating means 30 computes the ratio of the major and ninor axes of each projection plane. The nodel projection planes are displayed in rotation about at least one of the basic three axes for composing the model projection planes. Hence, the model projection planes corresponding to the inclination of the plan view to be projected appear on the display 100.

Alternatively, by displaying a plural sets of the model projection planes, and setting the basic three axes at nutually different angles, it may be designed to cope with inclination angles of plural plan views at the same time.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a conceptual diagram showing the principle of the invention; Fig. 2 is a conceptual diagran of an input screen of model projection planes and their projection angles; Fig. 3 is a conceptual diagram showing the relation of plan views and cubic view of the invention; Fig. 4 is a flowchart showing the procedure of drawing a cubic view from plan views shown in Fig. 3; Fig. 5 is a flowchart showing the procedure of drawing a cubic view from plan views shown in Fig. 3; Fig. 6 is other conceptual diagram showing the relation of plan views and cubic view; Fig.7 is a flowchart showing the procedure of drawing the cubic view in Fig. 6; Fig. 8 is a conceptual diagram showing the relation of direction of plan view and direction of cubic view; Fig. 9 is a conceptual diagram showing basic pipe diameters of plan views and cubic view; Fig. 10 is a conceptual diagram of a prior art; Fig. 11 is a flowchart showing the procedure of drawing a cubic view by prior art; and Fig. 12 is a flowchart showing the procedure of drawing a cubic view by prior art.

DETAILED DESCRIPTION OF THE INVENTION [Embodixent 1] Fig. 1 is a conceptual diagram showing the principle of the invention and Fig. 2 shows indications appearing on the display at the initial stage of the process involving the invention.

First, as shown in Fig. 2, a model projection drawing 1 appears on the display 100 by isonetric projection drawing method which is obtained by calcualtion in the angle operation means as described below.

This model projection drawing 1 can be rotated about the x-axis, y-axis. or z-axis, and this point is described later1 and herein the x-axis, y-axis, and z-axis are supposed to be facing the isometric direction. At this time, as shown in Fig. 1, on a table 10 installed at a specified area of memory means, the ratio of major axis and minor axis of the ellipse in the isometric drawing is written individually for X, Y, and Z planes.

In this case, supposing the length of the major axis to be 1, the ratio of minor axis/major axis is 1/C2, and the minor axis direction is nultiplied by the contraction rate of 1/ ;'2. To the contrary, supposing the minor axis to be 1, the ratio of major axis/minor axis is i'3, and hence the major axis direction is multiplied by the enlargement rate of T3.

In Fig. 1 and 2, however, the length in the isometric standard direction (each axial direction of x, y, z) is supposed to be 1, and it shows an example of enlarging by T3/2 in the major axis direction, and contracting by 1/#2 in the minor axis direction. Meanwhile, the model projection plane operating means 31 administers enlarging and contracting process.

In such state, an actual example of drawing a cubic view in Fig.

3 (b) from plan views shown in Fig. 3 (a) is described. When the plan view shown in Fig. 3(a) is shown on the display 100, as illustrated in Fig. 4, by means of main input means 200 (a main input means comprises display 100, cursor L, to be described below, and input control means, which doesn't appear in the figure), a group of straight lines corresponding to the foremost surface of the front view in the plan views shown in Fig. 4 (a) is designated (as a result, for example, the designated group of straight lines is indicated by a color different from other lines or in a lightness different from other lines, and in the following example, it is explained that the lightness is heightened). Consequently, as shown in Fig. 4 (b), the plane standard point P1 (indicated as Pa in Fig. 3) on the front view is designated by the cursor. In consequence, the operating means 20 acquires the elenents for composing the plan view, that is, the data such as start end of line segnent, length direction, size and center of circle and others, from main memory means 50 storing the data. At the sane tine, the position of the plane standard point P1 is entered into the operating means 20. When the plan standard point P1 is specified, the cursor appears in an inverted L forn, and by the direction of the inverted L forn, as described below, the direction of the plane is also indicated.

Successively, when a specific plane (in this case, Y plane Cx) of the model projection drawing 1 is also designated (Fig. 4 (c)) on the display 100, the plane specified by model projection plane input means 300 as well as the direction of the plane, details of which will be described below, are entered into the operating means 20, as shown in Fig. 4(c). Furthermore, the display standard point P10 is indicated on the display as the standard for projecting the designated plan view of the specified plane. The position of this display standard point P10 enters into the operating means 20 via main input means 200.

With this procedure, the designated plan view may be displayed in the state projected on the specific plane of the projection drawing as mentioned above. As a result, it is instructed that the designated plan view be adhered to the Y plane of the projection drawing, and hence the operating means 20 acquires data necessary for calculation, such as the ratio corresponding to the designated plane from the memory means 10 storing the ratio as described above. At this time, the standard point (projection standard point) PO on the cubic view is initially set at the right shoulder corner of Y plane, and the meaning of this projection standard point is explained later.

In this state1 on this plan view, the operating means 20 operates by multiplying by the ratio to obtain the projection drawing corresponding to the plan view, and the corresponding position of the standard point P1 on the projection drawing is displayed in coincidence with the display standard point P10 (Fig. 4 (c)), and thus obtained data relating to the projection drawing is stored in a specified region in the main menory means 50.

The problem here is the direction of gluing the front view to the Y plane, and two axes (herein x-axis and z-axis) having the apex on standard point PO on the cubic view when displaying the Y plane corresponding to the direction of bottom L1 and base L2 of the L-shaped cursor appearing when the plane standard point P1 on the plan view is instructed appear as change of color or lightness. Then, in a state of conversion from plan view to cubic view, the plan view is disposed so that the direction of bottom L1 and direction of x-axis, and direction of base L2 and direction of z-axis may coincide with each other.

Similarly, as shown in Fig. 4 (d), of the elements for composing the right side view, the element of the foremost plane is designated on the display 100, and when the plane standard point P2 is designated on the display 100, the elements composing the right side view, the position of the plane standard point P2, and the desired projection direction of the right side view, which is specified by the L-shaped cursor when the plane standard point P2 is specified, are entered into the operating means 20 by means of the main input means 200.

Successively when a specific projection plane (in this case X plane Cx) of the model projection drawing 1 is designated, specified plane and its direction( which is determined automatically when the display standard point PO is specified as below) are entered into the operating means 20 by means on the model projection plane input means 300 Furthermore, after a display standard point P20 is designated, the position of the display standard point P20 is entered into the operating means 20 by means of the main input means 200 At this time, the projection standard point PO is set automatically at the right shoulder of the X plane by designating the X plane of the model projection plane 1. With the projection standard point PO as the apex, the lightness of the y-axis and z-axis becomes high, and the right side view is projected in the coinciding direction of the bottom L1 direction'and y-axis direction, and base L2 direction and z-axis direction at the time of L of the cursor shown in Fig. 4 (e).

Moreover, the display standard point P20 is designated as above, and the display standard point P20 at this time is the point that should be present on the cubic view, and it is easy to understand for drawing to select the point present on the projection drawing corresponding to the front view drawn already on the Y plane. In this case, it is the point corresponding to the lower right corner of the front view, and the same point as the display standard point P10 on the front view is taken (Fig. 4 (d) to (e) to (f)).

When the above procedure is over, same operation as above is calculated in the operating means, and the desired projection drawing is obtained, and displayed so that the plane standard point P2 and display standard point P20 may coincide with each other.

In this procedure, all elements on the top view are designated, and the plane standard point P4 and projection plane (in this case, Z plane Cz), and display standard point P40 are specified. At this time, the projection standard point PO is set automatically to the right shoulder on the Z plane by designating the Z plane of the model projection plane 1. With the projection standard point PO as the apex, the lightness of the x-axis and y-axis becomes high, and the top view is projected in the coinciding direction of the bottom L1 direction and x-axis direction, and base L2 direction and y-axis direction at the time of L of the cursor shown in Fig. 4 (h).

Moreover, as the display standard point P40 at this time, the nearest corner on the cubic view is designated. When this procedure is over, same operation is calculated by the operating means 20, and the desired projection drawing is obtained and displayed so that the plane standard point P4 and display standard point P40 may coincide with each other (Fig. 4 (g) to (h) to (i)).

In succession, the right side view appears, and by designating all elements for composing a mounting hole n located at an inner position from the foremost plane of the right side view, projecting on specified position (plane standard point P6, display standard point P60) (Fig. 4 (j) to (k) to 1)), and further designating only the corner R1 of the right side view of the mounting hole n, the plane standard point PS on the plan view is matched with the standard point PSO on the cubic view, and the corner R1 is projected on the cubic view (Fig. 5 (m) to (n) to (o)). Afterwards, oblique line L11 on the plan view is drawn as oblique line L12 on the cubic view (this is merely to draw a straight line L12) (Fig. 5 (p) to (q) to (r)), or unnecessary portion is erased, so that the cubic view is completed (Fig. 5 (s) to (t)).

[Embodiment 2] Referring then to an example of drawing a cubic view in Fig. 6 (b) from plan views in Fig. 6 (a), projection processing at other angle than isometric is described.

From the top view in Fig. 6 (a), it is known that this drawing is rotated 15. from the ordinary plan view. In this invention, as shown in Fig. 2, at the first step of the procedure, an angle input screen 40 appears on the display 100 for input of angle of rotation, together with model projection planes 1. When the operator designates to rotate the specified standard axis (in this case, z-axis) by 15. (type in 15, after the phrase "rotation angle of z axis = ), the typed-in angle is entered into angle operating means 30 by means of the angle input means 400. Then the angle operating means 30 calculates the ratio of the major axis and minor axis on each plane and length of standard line (ratio supposing the isometric direction to be 1) according to a rule of geometry, results are written into the table 10 installed in memory means. And at the same time, the model projection plane 1, which is rotated by 159 about the z-axis and has standard line each having the length of side calculated at the obtained ratio, is aquired and displayed on the display 100. (see Fig. 7).

As explained in Embodiment 1, at the stage when the rotated model projection plane is displayed, the elements composing a plane, a plane standard point and direction of the plane are entered by means of the main input means 200, and then the designated model projection plane and its direction are entered by means of the model projection plane input means 300, and furthermore, display standard point is entered into the operating means 20 by means of the main input means 200 . Consequently, the operating means 20 executes calculation to produce a projection drawing. Detailed descriptions on the respective input means 200 and 300 are eliminated from the explanation below.

In this state, first all elements on the top view are designated, and the plane standard point P101 on the plan view is designated same as above. In succession, when line Ld as the standard for coinciding the direction of the drawing and the direction of the cursor is designated, the axis of ordinates L2 of the cursor coincides with the standard line Ld (this function is presented by the CAD system in which this invention is applied). As a result of this, data corresponding to the elements of the top view, the position of the standard point P101, and the direction of the specified plane are entered into the operating means 20.

In this stage when the projection plane (Z plane) is designated, the plane and its direction (see below) are entered in the operating means 20, and when a display standard point P110 is designated, the position of the display standard point P110 is entered into the operating means 20. In this process, a projection drawing of the top view on the Z plane is obtained (Fig. 7 (a) to (b) to (c)). Still nore, also herein, the standard point PO on the cubic view is initially set at the right end corner of the Z plane, and the lightness of the x-axis and y-axis varies with the standard point PO as the apex. Therefore, the direction of the projection drawing appears so that the bottom L1 of the L-shaped cursor may coincide with the x-axis direction, and the base L2 with the y-axis direction.

Consequently, by designating the elements for composing the side view, designating the plane standard point P102,and rotating the cursor (matching straight line Lf with L-shaped base L2 of the cursor), the lower line of the side view and the bottom L1 of the cursor are natched, and further the X plane Cx of the model projection plane is designated (Fig. 7(d) to (e) to (f)).

Herein, the projection standard point PO of the X plane is the right shoulder, and when projection is instructed in this state, the bottom L1 of the L-shaped cursor coincides with the y-axis direction, the base L2 with the z-axis direction, and thereby the plane standard point P102 is located at point P111 of the right upper shoulder shown in Fig. 7 (c), which is inconvenient.

In this case, when projected on the X plane, the plane standard point P102 on the side view should coincide with the display standard point P110 shown in Fig. 7 (c).

Accordingly, by making use of the fact that the side views are symmetrical both vertically and laterally, the following processing is done. That is, after designating the plane standard point P102 as stated above, the X plane is designated. Then, by designating the point Pc of the lower left angle of the X plane, the lightness of the y-axis and z-axis varies with the Pc at the apex. As a result, the direction of the bottom L1 of the L-shaped cursor is designated to be inclined to the y-axis direction, and the direction of the base L2 to the z-axis direction. In this state, further, the lower left angle of the plan view (appearing before the middle in the projection drawing) P110 already projected as the display standard point is designated.

As a result, the plane standard point P102 on the plan view is overlapped with the display standard point P110 (Fig. 7 (d) to (e) to (f) to (g).

Incidentally, with the lower right point P103 of the plan view as the reference point on the plan view, the initially set projection standard point PO can be directly used as the display standard point, and the display standard point as the right shoulder point P111 of the projected plan view, so that the same results as above can be obtained.

The drawing on the plan view to be projected on the Y plane is a front view, and naking use of the fact that the front view and right side view are identical, the entire right side view is designated again.

Next, as the plane standard point, point 1043 at lower right corner is designated, and the Y plane of the model projection plane is designated, and the display standard point P110 corresponding to the lower right corner of the already projected to view is designated, so that the desired projection drawing is plotted (Fig. 7 (h) to (i) to (j)). When processed in this procedure, the lines L10, L11, L11, L12 are overlapped by two each. and they are erased to be one line each (Fig. 7 (h)).

This embodiment shows that the angle of the model projection planes can be freely changed, and also that the cubic view can be drawn only from a plan view and one side view, and it means that a cubic view can be drawn even from incomplete plan views (if all six planes are not available).

Fig. 8 shows a mode of initial setting of standard points P1 to Pd on the cubic view. That is, the corners of the planes for composing the cubic view are preliminarily related as shown in Fig. 8 (a). In this state, for example, when point Pa is selected, each corner indicated by thick lines 1 to 4 in Fig. 8 (c) becomes the standard point P0 on the cubic view, and two sides enclosing each corner (combination of two axis out of x, y, z axes) coincide with two sides L20, L21 of the cursor shown in the plan view in Fig. 8 (b),

Claims

What is claimed is:

I. An apparatus for drawing a cubic view on the basis of the data of plan view, which comprises; main input means for entering designated plan view, designated plane standard point, to be determined in relation to the plan view, the direction of the plan view, and display standard point which specifies the cubic view obtained through operating means, on a display, model projection plane input means for entering the designated plane of the three model projection planes composing the cubic view, and direction of the designated plane, on a display, table containing ratio of the major axis and minor axis of each projection plane obtained, depending on the angle of each projection, operating means wherein a system of coordinates of 45 o rotation of the plan view is overlapped with a system of coordinate of major axis and ninor axis of an ellipse of the projection planes, a projection drawing is obtained by multiplying the major axis direction and minor axis direction by the ratio of a/b of the major axis (a) and the minor axis (b) obtained projection drawing is matched with the display standard point at the plane standard point, and the direction on the plan view and the direction of the model projection plane are matched to be displayed.
2. An apparatus for drawing a cubic view of claim 1, wherein the direction on the model projection plane is set initially.
3. An apparatus for drawing a cubic view of claim 1, comprises; angle input means for entering the angle of inclined plan view to be projected, angle operating means wherein the ratio of major axis and minor axis of each projected plane is calculated after performing input procedure with angle input means, model projection plane is rotated and displayed about at least one of the basic three axes for composing the model projection plane, depending on the inclination of the plan view to be projected.
4. An apparatus of drawing a cubic view of claim 3, wherein a plural sets of model projection planes are displayed, and any one of three basic axes is set at a mutually different angle.