Difference between Perspective, Isometric, Oblique and Orthographic Drawing.

Perspective Drawing

Perspective Drawing is the technique used to represent three-dimensional images on a two-dimensional plane.

- http://www.artyfactory.com/perspective_drawing/perspective_index.htm

What do you mean by that? First of all, let's take a look at perspective drawing's processes. The first part of the process is called 'linear perspective drawing'. Linear perspective drawing actually means to draw the 'outline' of the items in the drawing as shapes first. An example would be this:

Only the shapes are outlined, together with the structure. Also, a blind spot is presented within the drawing (the little red dot with lines coming out of it.)

This basically forms the 'backbone' of the drawing, in which the next part comes in.

Aerial perspective drawing is more of the color and texture and less of shapes. When we look at a linear perspective drawing, it barely soothes the eye. And so, this is the next part: to add a flourish of colors and textures to the first linear perspective drawing. This is the example of the picture above after the aerial perspective drawing process:

Get the picture? (get it? picture?)

So now, I've basically summarized Perspective drawing. (All information with thanks to ArtyFactory.com though no copying was done)

Isometric Drawing

If you've played Who Has The Biggest Brain on Facebook, or taken the New South Wales Maths Assessment, isometric drawing should not be a new thing. Isometric drawing is drawn using rulers to ensure accuracy of the drawing. (normally, cubes) Also, all vertical lines in an isometric drawing is kept vertical, but the horizontal line are 30 degrees horizontal.

Take a look at this example taken from BBC (Information also rephrased from the same website):

Isometric drawings are also easier to scale from plain view.

Oblique Drawing

Oblique drawings show a 3-dimensional view of an object, the difference from isometric drawing is: oblique drawings show you what is in between the objects. Take a look at this diagram, taken from Thinkquest.org's Library (information also abstracted from that site) to see the different steps to draw an oblique drawing:

Firstly, draw a tic-tac-toe-like diagram. That will be your diagram's backbone. Second, make your 'backbone' three-dimensional by making it look like a cube with lines inside it. Third, draw the thing in which you want to draw (let's say, a smaller cube, or a stair-like shape) and outline it, then erase the original cube, and, lastly, add the measurements.

One more thing about oblique drawing: calivier, normal and cabinet obliques.

Calivier Oblique = Full measurement used in drawing (which means, if you want to draw the stairs, you need a very big piece of paper)

Normal Oblique = Depth 3/4 of real measurement

Cabinet Oblique = Depth half of real measurement

Orthographic Drawings

Related to isometric drawings. Orthographic drawings are of those done by designers. From all views top, bottom, side to side. This is an example of a 'rough' orthographic drawing:

This 'box' if so called cut, it would look like this:

As you can see, there are six sides: front, top, rear, bottom, left-side and right-side view.

And now, the 'box' is made into a car, and it comes out like this:

That is why I said it was like a designer's drawing, cause we look from every side of the object: to get the feeling of 3-D out.

With help from http://www.cdli.ca/depted/g7/ortho.htm

That concludes my explanation and comparing of all the different types of drawings listed.

-Pasakorn