need a little help with perspective cube

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Old 08 August 2006   #1
Unhappy need a little help with perspective cube


hi there- ive been studying perspective and none of the books ive read show how to do this so im wondering if its possible and if so how to do it.

it the above pic. the green dots marked vp1 and vp2 are the two vanishing points for a cube with its cornor facing out towards the viewer. by drawing the solid red line to establish the middle (cornor) and connecting to the vanishing points i can easily determine the hight of the cube as it diminishes into the distance. however now im stuck, the dotted red lines are estimations of where i think the cube ends for thoese faces. is there any method fo exactly calculating the distance of these lines from the middle cornor so it makes a perfect cube? i am completely stumped - please help

rat

Last edited by rattsang : 08 August 2006 at 10:22 AM.
 
Old 08 August 2006   #2
Get this book:

The Theory and Practice of Perspective


This is the best book on perspective that I've seen.

spnhead
 
Old 08 August 2006   #3
sorry that book does not help- i need an answer to the specific question only
thanks

rat
 
Old 08 August 2006   #4
Hmm, would like to know how to do it myself. One workaround for the problem would be to project a square onto the "floor" and use it as the base of your cube in 3D, don't remember how exactly that was done, though, but I'm sure you can google it up.
 
Old 08 August 2006   #5
Talking Easiest way I've learnt.

Back in Grade 7 or 8, our teacher taught us to draw the object first then draw circle diagonally from the object that you have drawn. Draw a cube then draw a dot diagonally from the cube then connect the cube's points to the dot. I hope that helps.
 
Old 08 August 2006   #6
You have to project the box down, like this:
http://forums.cgsociety.org/attachm...id=100198&stc=1
(if the image doesn't show up sorry it's my first time putting an image in)
edit: hope this helps you^^
p.s. If you don't get it, i copied it from a book i have so maybe i can explain it for you if need be.
Attached Images
File Type: jpg projected-box.jpg (22.8 KB, 48 views)
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Last edited by Just Call Me Bruce! : 08 August 2006 at 02:47 AM.
 
Old 08 August 2006   #7
Originally Posted by DeathArtist: Back in Grade 7 or 8, our teacher taught us to draw the object first then draw circle diagonally from the object that you have drawn. Draw a cube then draw a dot diagonally from the cube then connect the cube's points to the dot. I hope that helps.


hi deathartist- that isnt very clear could you post an image and explain each line that is in it.

just call me bruce, i know this method and it isnt very accurate and causes masssive distorsion as you can probably see from your pic thanks anyway.

thanks
rat
 
Old 08 August 2006   #8
maybe something like a dimetric projection. if not matbe you could be a little more specific, like what you need if for?
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Old 08 August 2006   #9
Originally Posted by spnhead:
Get this book:

The Theory and Practice of Perspective


This is the best book on perspective that I've seen.

spnhead


Thank you so much for this link!
I cannot stop reading, and I am sure it will be a great deal of help for my future drawings.

cheers

//edit:
After some reading I think it might even answer the OP's question. Look for pages 30-53 in the book.

Last edited by wormee : 08 August 2006 at 11:48 PM.
 
Old 08 August 2006   #10
Your intuition was right. Your cube is correct, you just have a very "wide angle" lens. The positioning of your vanishing points determines this.
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Old 08 August 2006   #11
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