Perspective - multiple vanishing point sets

[HJRS]

Hi Guys,
I've recently started reading up on perspective and have noticed that in just about every tutorial and book i've read all objects in a scene are parallel to each other and so share the same set of vanishing points. In some sites it's been mentioned that objects that don't face the same direction will use their own sets of vanishing points but they dont really go into how to find them. What i'm stuck on (in 2 point perspective) is finding the second VP or more specifically the distance required between them. The second dot point in this link http://www.artlearn.org/courses/Basi...on_Rockman.pdf says that each set of vanishing points just need to have the same distance between them. Can someone confirm if this is acurate? Other sites have alluded to other methods (making sure both angles make up 90 degrees being one) so i'm not sure what to believe.

Hope this makes sense.

Cheers,
Harley.

[[email protected]]

The second dot point in this link http://www.artlearn.org/courses/Basi...on_Rockman.pdf says that each set of vanishing points just need to have the same distance between them. Can someone confirm if this is acurate?

No, it is not. The distance between vanishing points across the horizon is pretty meaningless. It is minimal if the directions are both at 45 degrees, and grows towards infinity if one direction approaches 0 degrees, in a one-point perspective.

Learn to construct vanishing point from your eye point, stationary point or whatever it is called.

[arenhaus]

Research the "architect's method" of building perspectives from plans. It includes a very practical way of finding the VPs.

[vineris]

What I do is sketch out a thumbnail that looks approximately like what I want and then make sure all lines parallel to one another go to the same vanishing point. I have *some* sort of idea about what I want the cube or building or car to look like, so why not work backwards from that?

[HJRS]

Thanks for the replies guys.
@[email protected]: I didn't really think it could be right, just seemed to easy lol. I'll look into constructing VP's from the stationary point, when trying to construct simple scenes i've pretty much just put the VP's in arbitrary locations (usuallly just to the edge of the page).

@arenhaus: I'm familiar with the architects method of using floor/elevation plans and that's what i'll use if there isn't another way. I could also use measuring points as well.

@vineris: i guess i'm trying to find out how to construct the objects/cubes as accurately as possible. As i'm pretty inexperienced with perspective i dont trust my estimations as this stage.

For those interested i came across these links last night which will achieve what i want. If anyone else knows of any other ways I'd love to know.
http://mysite.pratt.edu/~jwenner/ima...ate_cube_1.jpg
http://mysite.pratt.edu/~jwenner/ima...ate_cube_2.jpg


Cheers,
Harley.

[armando]

The distance changes depending on how far you expect people to be from your picture when they look at it. A small pic that people look at in a book will have closer vp's than one you expect them to look at from a wall. The simplest way I've heard of to calculate this is just to hold out your arms perpendicularly then just walk closer or farther to the picture depending on where you want the points to hit.



But what really matters is that it look cool.

[Charlie D]

Download Successful Drawing from here

http://escapefromillustrationisland....ion-downloads/

[Kamber Parrk]

No, it is not. The distance between vanishing points across the horizon is pretty meaningless. It is minimal if the directions are both at 45 degrees, and grows towards infinity if one direction approaches 0 degrees, in a one-point perspective.

Learn to construct vanishing point from your eye point, stationary point or whatever it is called.

This is correct.

Was that DEBORAH Rockman!?! as the source of the PDF? (hope not. . .)

Christ!

There's a lotta crap on the interwebs. . . .

[HJRS]

Thanks again for the replies ppl.

For those that are interested, while reading a section on ellipses from an eBook on perspective, I think i've worked out another way to find where the second vanishing point would lie: If you drew a square (ie 4 equal sides) in perspective on a plane and then drew a circle (in perspective) inside the square, the minor axis of the circle/ellipse would point to the other vanishing point. (please correct me if i'm wrong!).

I realise this probably isn't the easiest or most efficient way of setting up a scene however i was just curious if/how this could be done and couldn't let it rest until i found out

[[email protected]]

For those that are interested, while reading a section on ellipses from an eBook on perspective, I think i've worked out another way to find where the second vanishing point would lie: If you drew a square (ie 4 equal sides) in perspective on a plane and then drew a circle (in perspective) inside the square, the minor axis of the circle/ellipse would point to the other vanishing point. (please correct me if i'm wrong!).

You're wrong. First, you construct your vanishing points, then you construct your square in perspective and, finally, you construct your cicle in perspective. There is no way to automagically get square and circle in perspective to get a vanishing point...

[Erayo]

http://www.handprint.com/HP/WCL/tech10.html
this link should be posted to any perspective related question... 100% mathematically accurate and well explained.
The short answer for the question is that most perspective "tutorials" will only use parallel objects since it is much easier and you don't have to do many calculations to get it right.
When drawing a complicated scene unless you must have it 100% accurate, just try and make it look right. making sure all parallel lines get to the same vanishing point will help.

[HJRS]

@eezacque: Seems like there's a lot of misinformation out there on perspective then which is getting a little frustrating. constructing VP's from ellispses was also in the Gnomon basic perspective dvd (unless i misunderstood what he said). Also after reading further in the eBook i mentioned there is a similar method used. So not sure what to think there.

@Erayo thanks for the link, looks like a good read. I don't need 100% accuracy but i figure if i can understand the theory behind it, it will help me when constructing scenes.

[Koji Bryant]

I don't need 100% accuracy but i figure if i can understand the theory behind it, it will help me when constructing scenes.

Relying on theory for answers is doing it the hardway in my opinion. Multiple vanishing points off the top of your head??? aye ya yuy

Learn free sketchup or any other 3d programs to rough out your scene (you can just use boxes, cylinders, etc.). Use resulting vanishing lines as drawing guides. Profit. You can print out the screen as a guide for your sketchbook if you're not into digital.

And you can actually learn theoritical perspective better and faster after using 3d a lot as a time saving tool. My experience anyway.

But if you like maths...