View Full Version : VPs of 2 cubes at different angles?
Playdo 09 September 2011, 09:40 PM I think this is the correct forum to post this in. If not, then please move it.
How do you draw 2 cubes that are at different angles, in 2 point perspective?
If the 2nd cube is rotated, both its VPs will change. The 1st VP can be set anywhere, but how do you work out its 2nd VP so that it gives the correct perspective?
Thanks


psage
09 September 2011, 05:16 PM
Use the same horizon line and choose another vanishing point on it.
Maybe someone else can expound on that for you (I don't have a diagram to show). Hope that gives you an idea to try, though.
Playdo
09 September 2011, 07:56 PM
Hi Psage. Good to get a reply on this.
If I was doing 1point perspective, then I would set a different VP1 and that would be it.
I'm talking about 2point perspective. So I choose a different VP1 for the second cube (that's fine). If I randomly put VP2 anywhere on the horizon then the perspective of the two cubes looks out of place to one another. So how do you work out where to put VP2?
I've had an intense search look through the net but haven't found an answer on this.
joshbailey
09 September 2011, 10:23 AM
Vanishing points are not decided by the object but by the camera or person viewing so they would still both use the same VPs. Just draw a cube around the angled one that points to that vanishing point then rotate the other one inside of it so your proportions are in perspective. Hope this helps
Quadart
09 September 2011, 11:07 AM
If you’re asking that question, then you probably did not determine the placement of your first set of VPs on a top view plan of your first object.
The image below is a clear example of how it’s done.
http://www.lems.brown.edu/vision/people/leymarie/Refs/VisualArt/Figs/2ptp1.jpg
image from here:
http://www.lems.brown.edu/vision/people/leymarie/Refs/VisualArt/DrawPerspective.html
You might also want to look through this invaluable source (found in the stickies above, 3rd sticky down):
http://handprint.com/HP/WCL/tech10.html#index
joshbailey
09 September 2011, 12:26 PM
great resources
Playdo
09 September 2011, 12:35 PM
@joshbailey: I was getting conflicting information on the thread below (see image half way through), stating that, once rotated, the VPs change. If you have time to sketch out an example of your method, that'd be really appreciated.
http://www.conceptart.org/forums/showthread.php?p=3055611&mode=linear#post3055611
@Quadart: You're right, I didn't set them up using a plan view. I'm looking for a solution for quick sketching, rather than an exact, time consuming method. I'll have a look through that link, but I think I'll get bogged down by the mathematics of it all.
Quadart
09 September 2011, 12:50 PM
I'm looking for a solution for quick sketching, rather than an exact, time consuming method.
You can use the diagram, or one like it, to get an idea of how it’s done. Then you can wing it, freehand, from there.
BlankM
07 July 2012, 03:19 AM
Sorry to revive this thread but it greatly confuses me. A lot of information I find tells me to use multiple vanishing points.
My basic question is this: How would I determine the correct proportions for two cubes when one cube's parallels no longer vanish into the same point because of its rotation?
I'm currently going through Norling's "Perspective Made Easy" and this is the one piece that baffles me. If the answer is in the handprint website I am looking for it but I find it quite hard to digest.
BlankM
07 July 2012, 06:49 AM
Edit: Double post
DanielBrown
09 September 2012, 04:17 PM
2 point perspective describes a situation where there is no convergence in the z axis (This occurs in only on the horizon, but its close enough for visuals most of the time.)
That handy fact is what solves our problem. The two cubes share the z axis. We can use a one point projection system to compare height to distance from the horizon. I am assuming that you have the following things figured out :
First cube (vanishing points on the horizon, location of the cube relative to the horizon, I find height very tricky to link to width & length in 2 point perspective I usually steal it from a 3 point perspective.)
Second cube (Vanishing points, location relative to the horizon.)
To solve the height of the second cube, draw rays from a vanishing point through the top and bottom corners of the first cube. Place your second cube, draw a line parallel to the horizon through one of the corners of the cube & intersecting the rays to the vanishing point. Without taking your pen from the paper, draw a vertical to intersect with the other ray, draw a horizontal line back to the second cube. Now close the rectangle by drawing in the vertical height of that part of the second cube.
MisterS
12 December 2012, 01:20 AM
This setup is quite straight forward. I'm assuming you're starting with a blank sheet and your first cube will be rotated 45 degrees to picture plane...
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