||[Mar. 26th, 2007|05:03 am]
To spare you from finding vanishing points that occur waaay off the page, a diagram by Paul Rivoche:
When subdividing those vertical lines on each side (Step 3), I find it best to divide them into 10 equal parts, using centimeters. (Metric is just easier to use when plotting out page dimensions, since it makes the math easier.) So: a 6cm line on one side becomes ten 6mm segments, while a 16cm line on the other side becomes ten 16mm segments. Then you join the ten segments on one side to the ten on the other side (a la the broken lines in the diagram). This gives you a mathematically simple but thorough grid to work from. If you want more grid lines: mark twenty 3mm segments, and twenty 8mm segments.
To find lengths on each side that are easily divisible (such as my examples of 6 and 16), bridge your initial pair of perspective lines with your ruler and move it along them until you find two distances (one at the narrow end and one at the broad end) that are each made up of a divisible number of centimeters. If you can't find divisible distances where you need them, mark where the nearest divisible distance would be, and simply adjust one of the initial perspective lines to meet it. Your initial perspective line was just an estimate anyway, and keeping the numbers divisible will save you from tricky math.
Note that the subdivided vertical lines should always be perpendicular to the horizon line. So for "dutched" camera angles, when your horizon line is diagonal (instead of parallel to the top and bottom of your page), make sure the subdivided lines are perpendicular to that angled horizon line, instead of being parallel to the sides of the page as they usually are.
For more perspective tips, see this entry.
Now that I read/see this, it's so simple, I feel like an idiot for all the times I've had strings taped to yardsticks taped to my drafting table... or have done perspective work on a panel in tiny, tiny form--then blown it up and lightboxed it back onto the bristol board.
Thanks for posting...
I've been using this method for quite some time but I actually take it further. The main problem with any type of ruled perspective grid is that the resulting drawing is often quite stiff. Perspective, of course, is a method for representing what a 3D world in a 2D space. And reality is not nearly as stiff as a ruled page often depicts. Stiffness - not good.
My approach is to do perspective grids freehand. I use the same method as you describe but I "eyeball" it instead of ruling. It's far simpler than what you're describing and far quicker. And, best of all, it's far more natural. Especially for outdoor scenes. And, if I make a mistake, then it's pretty simple to adjust it.
Your mileage may vary, of course.
2008-12-20 10:34 am (UTC)
Or you can do what I do, and just scotch tape typing paper temporarily to the sides of your boards and put the vanishing points there. This method looks 100 times more complicated and less accurate.
Von -- Sorry for the tardy reply, but I'd love to see some examples of your hand-drawn approach.
Anonymous -- Yeah, when the points are within a foot of the page (as in your typing paper method), I just draw 'em right on my drawing table, and erase later. The method described above is for when the points are off the drawing table (or board). Which is often, unless you're drawing really severe angles all the time.
It looks complicated at first blush, but it's simple once you get the hang of it. I can lay down a grid in a few minutes, and it saves all that time and hassle of aiming yardsticks off the board. (I once drew a comic's worth of backgrounds consisting of nothing but Alcatraz, and this method saved my bacon.)
I don't know precisely how accurate it is, but it's accurate enough that no one can tell the difference.