GB2252753A

GB2252753A - Perspective drawing aid

Info

Publication number: GB2252753A
Application number: GB9103195A
Authority: GB
Inventors: Edward Adrian Barclay
Original assignee: Individual
Current assignee: Individual
Priority date: 1991-02-14
Filing date: 1991-02-14
Publication date: 1992-08-19
Anticipated expiration: 2011-02-14
Also published as: GB2252753B; GB9103195D0

Abstract

A perspective drawing aid which facilitates making two point perspective drawings comprises a body (1) carrying first (F) and second (S) rotatable means each adapted to produce arcuate movement of the drawing aid when it is moved over a flat surface. Each has a straight edge (5, 7) associated therewith, a projection of which gives a notional vanishing point for each rotatable means. The notional vanishing point for the first and second rotatable means are different. A third rotatable means (T) is configured to draw parallel lines. The body is triangular in cross-section with the rotatable means projecting from a respective side thereof and with the associated straight edge defined by a respective apex of the body. <IMAGE>

Description

Title: Perspective drawing aid DESCRIPTION The present invention relates to a perspective drawing aid.

By perspective drawing aid we mean an instrument that enables a series of lines to be drawn which, if projected, would converge at a common vanishing point.

When making a two point measured perspective drawing the resultant image takes up a comparatively small area of the available paper when compared with the geometric construction that brought it about. This is because the two vanishing points have to be placed relatively far away from the centre line of vision in order to achieve a realistic representation. In order to avoid such geometric construction and the inherent disadvantages, a perspective drawing aid has been proposed comprising a conical roller or equivalent and an associated straight edge. The effect of such a conical roller is to produce an arcuate movement of the drawing aid when it is moved over a flat surface with the roller in engagement therewith such that the associated straight edge can be used to draw a series of lines which converge at a common vanishing point.The roller can be represented by wheels of different diameter spaced on a common axis and the apparatus can be set to produce closer or more distant vanishing points by adjusting the relative spacing of the two wheels. Examples of such prior art devices are disclosed in U.S. Patent 4586285 and British Patent Specification Nos. 1094483 and 1083104.

The present invention is particularly concerned with providing a perspective drawing aid for use in teaching perspective drawing where the emphasis is more on ease of use and convenience than on the ability to select a wide range of vanishing points.

It is an aim of the present invention to provide a perspective drawing aid which facilitates making two point perspective drawings in a simple and convenient manner.

Accordingly, the present invention provides a perspective drawing aid comprising a body carrying first and second rotatable means each adapted to produce arcuate movement of said perspective drawing aid when it is moved over a flat surface with a selected one of the rotatable means in engagement therewith and each having -an axis of rotation and a straight edge of or associated therewith, a projection of which straight edge gives a notional vanishing point for each rotatable means, and wherein the notional vanishing point for the first and second rotatable means are different or where adjustable may be set differently.

The two point perspective drawings may have their vanishing points set at a common distance from a centre line of vision and, in such a case, the difference may be in terms of direction, eg. to left or right relative to the orientation of the drawing aid. More usually however, the vanishing points will be at different distances from the centre line of vision. Convenience and ease of use is achieved by providing the device with means providing two different vanishing points. The vanishing points of the first and second rotatable means may be to the same side of the apparatus but more preferably are directed to opposite sides for further ease of use. Identification means is provided to ensure correct orientation of the device.

It is preferred for the straight edge to be disposed parallel with the notional edge of the conical surface of revolution of the rotatable means.

Alternatively it may be on a line which intersects with the vanishing point for the rotatable means with which it is associated or even parallel with the axis of rotation of the rotatable means. The straight edge carries a positioning line described further hereinafter.

In a preferred embodiment the body also carries a third rotatable means adapted to produce parallel movement of said perspective drawing aid when it is moved on a flat surface with the third rotatable means in engagement therewith to permit drawing parallel lines along a straight edge of or associated therewith.

A particularly convenient embodiment results when the body is triangular in cross-section defining three sides through which a respective one of the rotatable means projects for contact with the flat surface and defining a respective edge associated with each of the rotatable means.

The present invention will now be described further by way of example only with reference to the accompanying drawings, in which: Figure 1 is a perspective view of one embodiment of drawing aid in accordance with the invention, Figure 2 shows an end view of the drawing aid of Figure 1 and a view in each of the directions A, B and C, and Figures 3 and 4 illustrate the theory that underlies the operation of the drawing aid.

Referring to the drawings, perspective drawing aid comprises a body -1 having three sides, 2, 3 and 4, which meet at edges 5, 7 and 9. The body carries first, second and third rotatable means, (F, S, T) only the first and second of which are illustrated in Figure 1.

Each of the rotatable means comprises an axle journalled for rotation in the body and in the illustrated embodiment comprises spaced wheels which in the case of the first and second rotatable means are of different diameter to define the respective notional vanishing points Vpl, Vp2. A small portion of the periphery of the wheels projects through the respective sides so that the apparatus can be moved over a flat surface on which it is placed. In the illustrated embodiment the edge 5 is parallel with the axis of rotation of the first rotatable means and the edge 7 is parallel with the axis of rotation of the second rotatable means. This simplifies the construction of the apparatus.

The third rotatable means has spaced wheels of equal diameter and edge 9 is parallel to the axis of rotation of the third rotatable means so as to act as a parallel rule when said rotatable means is placed on a flat surface.

Edges 5 and have associated alignment marks 11, 13 for use in setting the apparatus for drawing lines which converge at the vanishing points and which marks are disposed on an adjacent side of the apparatus (eg.

sides 3 and 4 respectively) so as to be visible when the first or second rotatable means is positioned for use.

Thus in setting up the apparatus to draw lines converging at the notional vanishing point of the first rotatable means, the line 11 is aligned with the centre view point, with the edge 5 on a horizontal axis.

Thereafter movement of the apparatus results in the apparatus moving in an arcuate fashion with the edge aligned with the vanishing point Vpl. Drawing lines which converge with the vanishing point Vp2 of the second rotatable means calls for alignment of mark 13 with the centre view point with the edge 7 on a horizontal axis, whereafter movement of the apparatus follows the arcuate path and enables the desired perspective lines to be drawn. Vertical lines can be drawn using the third rotatable means by way of edge 9.

Figures 3 and 4 show how the conical surface of revolution enables lines to be drawn which would intersect with the notional vanishing point Vp.

In the illustrated embodiment, the first and second rotatable means have a fixed vanishing point which is particularly convenient for a perspective drawing teaching aid and the size of the apparatus and the positioning of the vanishing points is chosen to suit drawings on the most common size of paper - say A2 or A3.

The triangular configuration is advantageous in providing a ruling edge for each of the rotatable means as well as convenience of holding the body is preferably constructed of plastics and may be colour coded to identify and correlate the edge which is to be used with a particular rotatable means, and ensure correct orientations.

Claims

1. A perspective drawing aid comprising a body carrying first and second rotatable means each adapted to produce arcuate movement of said perspective drawing aid when it is moved over a flat surface with a selected one of the rotatable means in engagement therewith and each having an axis of rotation and a straight edge of or associated therewith, a projection of which straight edge gives a notional vanishing point for each rotatable means, and wherein the notional vanishing point for the first and second rotatable means are different or where adjustable may be set differently.

2. A perspective drawing aid as claimed in claim 1 in which the vanishing points of the first and second rotatable means are different in that they are directed to opposite sides of the apparatus.

3. A perspective drawing aid as claimed in claim 1 or 2 in which the vanishing points of the first and second rotatable means are disposed at different distances from the centre line of vision.

4. A perspective drawing aid as claimed in claim 1, 2 or 3 in which the straight edge is disposed parallel with the notional edge of the conical surface of revolution of the rotatable means.

5. A perspective drawing aid as claimed in claim 1, 2 or 3 in which the straight edge is disposed on a line which intersects with the vanishing point for the rotatable means with which it is associated.

6. A perspective drawing aid as claimed in any preceding claim in which the straight edge of or associated with the first and second rotatable means carries a positioning line for alignment with the centre line of vision in positioning of the apparatus for use.

7. A perspective drawing aid as claimed in any one of the preceding claims and further comprising a third rotatable means adapted to produce parallel movement of said perspective drawing aid when it is moved on a flat surface with the third rotatable means in engagement therewith to permit drawing parallel lines along a straight edge of or associated therewith.

8. A perspective drawing aid as claimed in claim 7 in which the body is triangular in cross-section defining three sides through which a respective one of the rotatable means projects for contact with the flat surface and wherein the respective straight edge associated with each of the rotatable means is defined by an apex of the triangular body.

9. A perspective drawing aid constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.