ArtSpots Forum Topic - Vanishing points in 3-point perspective?

Tym

Fri, 18 Jul 2008 01:04:52 -0000

Those are all great ideas...honestly the way i've done it - as far as setting up my points (and this works best if you've got a drawing surface much bigger than the final drawing) is to draw the horizon line, then place your two v.p.s there, then dot the third vp somewhere else, above or below. the mathy-stuff really only (to my mind) comes in for the actual drawing part. plus, the only times you'll need 3pt is when you're looking wayyyy up or wayyyyy down, usually at the corner of a big-city building. most of the rest of the time, the distortion is pretty minor [on a side note, i've experimented with a sort of 4-point ocular perspective, based on the premise that the eye's surface is curved, so perspective ought to curve and bulge, with the bulge being in the middle and space "curving" away towards distant points, as though you were staring straight at a gridded ball. thus, the four points are left & right on the horizon, then above and below the centerpoint. I only used this one for an architectural shot showing the middle-heights of a city of towers. i wanted to accentuate the vertical thrust (up AND down) as well as have the view taper off to either side realistically...it worked ok (it was just a sketch on a bus in Italy, after all)]

Metsys

Tue, 13 May 2008 16:28:42 -0000

There's another option: cheating. Make a simple 3D mock up of your scene, render it, and then paint on top of that. From the rendering you can identify the 3 vanishing points so you can paint other things in perspective too. To help with perspective in Photoshop, there's a trick I learned from Donald Yatomi (http://www.donaldyatomi.com/) where you use paths as guides for your perspective lines, using the direct select tool to change the position of the end point of the line so the other end is still at the VP, and box selecting to move the VPs (see attached image). The paths layer can also be hidden, and it's never exported or printed if it isn't. You can also go an extra step with cheating by adding light sources to your 3D mock up to help with painting shadows, reflected light, etc. It's usually not practical for characters though, but it's handy for easy things like vehicles and architecture. I do recommend adding a few floating spheres where characters would be as clues to how the lighting should look. Now, I started using these tricks years ago because I was a 3D guy new to illustration, and knew that I could cut corners with my 2D projects that way, but I'm seeing it becoming more and more common for artists with a 2D-only background, who do understand 3-point perspective, to start learning things like Maya just so they don't have to spent as much time worrying about perspective and lighting in the first stages of painting.

Nocte

Tue, 13 May 2008 11:14:25 -0000

Thanks for the tip! I've checked it out, and they do have a chapter showing you how to construct a drawing once you already have your vanishing points. But they don't tell you where to place the VPs to begin with. (Other than that the first two are "somewhere" on the horizon, and the third one is "somewhere far away".)

techmon

Sat, 10 May 2008 05:05:13 -0000

Try the book "How To Draw Comics The Marvel Way." It is mentioned there and might answer your question.

hollietree

Wed, 03 Oct 2007 00:28:24 -0000

i suppose for those of us who aren't super mathematicians, we'll just have to do it by eye :P

Nocte

Tue, 06 Feb 2007 22:51:00 -0000

Calculating the VPs is indeed not practical. I'm getting the impression there's no documented method for constructing 3 VPs armed with only a ruler and a compass. But I've come up with something myself, based on the viewpoint folding method documented on Handprint for 2PP. I'll explain it shortly here, just in case somebody is interested. While not as easy as in 2-point perspective, it is considerably easier than using trigonometry and a calculator. The trick is to fold it once for the bottom VP and the horizon, and another time for the other two VPs. You start with the viewing direction and a 90° field of view. α is the up-down angle, β is the left-right angle. You start at point 1 by drawing two perpendicular lines. The intersections with the meridian are the bottom VP and the horizon (point 2). With point 2 as the center, circle off point 1 to find 3 (the second folded viewpoint). The other two VPs can be found on the horizon by drawing perpendicular lines from point 3. So yeah, I have no idea if this method has been described anywhere before. If you're not sure it is correct, you can check it by finding the orthocenter of the triangle between the VPs, which is the same as the viewing direction, the middle of the circle, and more or less the middle of your paper as well. Handprint.com also shows how to use a circle of Thales to find back the 90° field of view.

Rousseau Cheetah

Tue, 06 Feb 2007 18:26:22 -0000

Nope. =) It involves some pretty complicated maths for complete accuracy. As far as I know, though, the first two vanishing points are pretty much the same as those in 2-point, while the third will be somewhere either above or below the horizon, depending on your point of view. As to find the exact location of the third vinishing point, I'm afraid I can't help much. There are books that explain in detail, but they do require some heavy calculus, from what I could tell. 0__0

Nocte

Mon, 22 Jan 2007 22:07:10 -0000

I hope this is the right place to ask this. It's not a tutorial, but I'm working on one, and I need a bit of help. ;) And perhaps others have wondered the same thing. In 2-point perspective, it's easy to find your vanishing points for a given angle. I'm sure most of you have used it to find the diagonal VP for your cube once. (Handprint.com has a thorough explanation of it.) Is there a similar method for 3-point perspective?