View Full Version : Help Defining Perspective

 Kansai04 April 2005, 01:11 AMHey all I feel at times I have a little trouble defining perspective of real life situations. So i wondered if i could get some help from you guys out there to see what you think. I got this pic from www.macdesktops.com (http://www.macdesktops.com) I think its a 2point perspective feel free to leave your opions on what you feel the perspective is in the shot or create some guide lines in photoshop to help me understand thanx for your help credit for the photo goes to Dirk Schober from www.macdesktops.com (http://www.macdesktops.com) (http://javascript%3Cb%3E%3C/b%3E:mailto%28%27dschober%27,%27mac.com%27,%27feedback%27,%27macdesktops.com%27,%27DSchicago%27,null%29)
Kanga
04 April 2005, 01:29 AM
Well its 3 point cause the camera angle is lower then the tops of the buildings.
Perspective and its rules are really simple, they are an aproximation as no line is visualually straight, they are all curved but to draw them we use a ruler and a set of simple rules. These rules you can find in any book or on the web (google).

What exactly are your problems with perspective? Maybe we can help you out better if we know what they are.

TheDweller
04 April 2005, 01:56 AM
Yep, 3 point perspective. Look at the buildings on the sides, and you see they lean inward. Eventually they would meet at a point in space far above.

What might be confusing you is that things have to be running parallel to use the same vanishing point. For example, the buildings are assumed to be all going straight up, so they will all share the same vanishing point above. The buildings on the left are all parallel to each other running down the street, and so appear to shoot for the same vanishing points there too. However, the building on the right (Chicago Sun Times) is across some water, and could very well not be "square" to the other street. It looks to me like it uses it's own vanishing points. I wish I had a different way to explain this so it made sense, but I'm afraid I'm probably not being very clear.

csDevil
04 April 2005, 02:01 AM
To define the perspective points, there MUST be straight lines, like the central and left buildings tops. Then you simply continue drawing them infinitely (theoretically) or until it meets the horizon. These are the points for lines that are parallel to the ground/horizon.
For fish-eyes scene, you can have 3 or 4 points. Just draw the vertical lines until they meet each other.

This scene has 3: 1 up and 2 in the horizon

Ordibble-Plop
04 April 2005, 02:05 AM
Camera lens distortion will also cause anomalies when it comes to trying to define vanishing points from photographs.

Kansai
04 April 2005, 03:30 AM
Hey all thanx for the replies. But I did a little photoshop work in hopes to show you all what I thought was th correct perspective. see attached image

DrFx
04 April 2005, 12:02 PM
The line that goes to the right is really VERY discrepant to the real building edge! The vanishing point is thus much further to the right.

Ilikesoup
04 April 2005, 09:43 PM
The line that goes to the right is really VERY discrepant to the real building edge! The vanishing point is thus much further to the right.

Or the horizon line (as drawn) is too low. But I think Kansai gets the idea. Now any horizontal line that your draw should start at a point in space and, if extended far enough, will connect with one of the two vanishing points. Horizontal lines above the horizon line will slope downward toward the vanishing point and horizontal lines below the horizon will slope upward.
Hope that makes sense.

CGTalk Moderation
04 April 2005, 09:43 PM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.

1