The curvilograph is a drawing aid that I came up with recently. The idea started with the need to be able to have a reliable vanishing point located outside the paper/canvas/board, without having to put a screw or a nail in the table every time. The curvilograph does a lot more than that, though, as it lets you create a curvilinear perspective.
The basic curvilograph consists of four support platforms that either have a simple pin to support a straight ruler or have a little clamp to hold a flexible ruler. The pins or clamps act as vanishing points and can be moved, while the supports are attached to a drawing board or a canvas.
To create a curvilinear perspective, i.e. ‘bend’ perspective lines, one clamps a flexible ruler onto the little clamps. By increasing the tension (or the amount of flexible ruler pushed between the two clamps), a natural curve is formed because the material of the ruler has to go somewhere. By repeating this step over and over, each following line of the perspective grid can be traced onto the image.
The image below shows how the perspective in Triptych was created. Currently I’m using a steel ribbon (used for packaging) as a ruler, but as you can see in the pictures, metal has a tendency to deform permanently. For the next version I’m planning to use some sort of plastic.