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Does anyone have a video or a tutorial about how to rotate the cube?

Inignem

Pro-death amateur drawer
I want to rotate the cube in every degree to understand how angles change as the figure moves. However I have been unable to find videos that show how the cube rotates.


I have seen this video http://youtu.be/50EjlzVsQM8 but I am under the idea that since the cube is an object where every side is equal, then when rotating the aparent lenght should be reduced during the first degrees of rotation when the deeper side of the cube still does not trespass the first parallel. In this video indeed the cube is slightly smaller in that instant, but in some other videos it is bigger.

Also, in some videos the deeper sideof the cube is drawn proportionally bigger or smaller than the front side of the cube. Some tutorials about the vanishing point seem kinda innacurate.

Can somebody help me prrrrrllllllleeeeasssseeeee?
 

Taralack

Hit 'em right between the eyes
I'm not sure what exactly you're asking for here to be honest. Have you considered maybe downloading a 3d program, creating a cube in it, and see how it looks?
 

Inignem

Pro-death amateur drawer
I'm not sure what exactly you're asking for here to be honest. Have you considered maybe downloading a 3d program, creating a cube in it, and see how it looks?


What I want is to be able to accurately draw a cube in every possible degree.
 

Taralack

Hit 'em right between the eyes
Then my first suggestion would be the way to go. Or even better, get a cube like object in real life and draw from that.
 

Inignem

Pro-death amateur drawer
Then my first suggestion would be the way to go. Or even better, get a cube like object in real life and draw from that.

Problem is, I cant see the deep side of the cube, and borders will be irregular.
 
Get a transparent cube?

What do you mean by "the borders will be irregular?" Perspective does that, it's kind of important to be able to make something to look naturally 3D.
 

DrGravitas

Member
I don't think you're going to find may videos of 3D cubes to learn proper perspective off of. I'm not sure what Vanishing Point tutorials you've tried, but perhaps you should consider a book instead. This one, Perspective Made Easy, I found to be quite straight forward and useful, if a bit light on content. Certainly the price was right.

Outside of that, investigate techniques like "Clock angles". Basically, you hold a straight-edge at arms length perpendicular to your line of sight at an object (A physical cube really would serve better here than a video of one.)
This page from Empty Easel seems to be a decent introduction to the technique. Although, I first read about it in a book: "Drawing from Observation."

If I have the time, I might be able to whip you up some still-shots of a cube. But, I don't think I understand precisely what your looking for. Perspective and even the focal length of the 3D camera will affect how the cube is perceived, as in this .gif:

Orthographic_camera_distance_focal_length.gif


from wikipedia's article on Graphical Projection
 

Inignem

Pro-death amateur drawer
I don't think you're going to find may videos of 3D cubes to learn proper perspective off of. I'm not sure what Vanishing Point tutorials you've tried, but perhaps you should consider a book instead. This one, Perspective Made Easy, I found to be quite straight forward and useful, if a bit light on content. Certainly the price was right.

Outside of that, investigate techniques like "Clock angles". Basically, you hold a straight-edge at arms length perpendicular to your line of sight at an object (A physical cube really would serve better here than a video of one.)
This page from Empty Easel seems to be a decent introduction to the technique. Although, I first read about it in a book: "Drawing from Observation."

If I have the time, I might be able to whip you up some still-shots of a cube. But, I don't think I understand precisely what your looking for. Perspective and even the focal length of the 3D camera will affect how the cube is perceived, as in this .gif:

Orthographic_camera_distance_focal_length.gif


from wikipedia's article on Graphical Projection

I have traind myself to rcognize the 360 angles around a point, so thats not the problem (still unable to be precise however)

first id like to know how big the bottom face of the cube must be in comoarision with the frontal one.

the secondone is, how much the cube seems to incrase or decrease its size during the rotation on a side.
 

DrGravitas

Member
There are no simple, standard ratio between the sizes of the faces of a cube. It is dependent on too many factors. My geometry skills are a bit rusty, but I could probably dig up a formula to describe it. However, I doubt that would be of much use. As has been said, even with 3D programs these things will be dependent upon the type of perspective used and other parameters.

Consider this image:
Perspective-foreshortening.png

Again, from wikipedia (Perspective (graphical)) which depicts the same stack of cubes but drawn using perspective methods with two different styles of foreshortening: oblique parallel projection foreshortening (left) and perspective foreshortening.

Obviously, perspective foreshortening is what your looking for, but even this is dependent upon other factors. In my opinion, your best bet is stick with the vanishing point tutorials. That book I linked also goes into 3-point perspectives and even focuses mostly on cube shapes.

Even with some quick Cubes, I don't think you will get much use out of them. Consider these two below. Even just a shifting the camera along a single plane is going to dramatically change the ratio between the faces.
HyxAe69.png

T6cUdQy.png


EDIT: Whoops, those images were quite a bit bigger than I thought. Oops. I can downsize them if requested.
 

Inignem

Pro-death amateur drawer
Hmm, would hou kindly post images of a cube rotating, taking any side as axis, starting where any square is completely visible until it dissappears after the first 1/4 revolution? If you could give nine shots, one per each ten grades rotated, I would love you forever and be your internet bodyguard in this forum, forever.
 

DrGravitas

Member
Hmm, would hou kindly post images of a cube rotating, taking any side as axis, starting where any square is completely visible until it dissappears after the first 1/4 revolution? If you could give nine shots, one per each ten grades rotated, I would love you forever and be your internet bodyguard in this forum, forever.

Ehhhh, if you really think these cubes will help, then I'll do it despite thinking otherwise...

Uploaded as an album on Imgur so as to save on forum space:
One cube, viewed head-on using a perspective viewpoint with a camera focal length of 35 (I forget what units Maya uses...). The cube is rotated 90 degrees (1/4 of a total 360 revolution) in nine images, each incrementing 10 degrees.

Although, I should point out that only the first 5 rotations actually present any unique information. The last four rotations are mirror images of the first four, in reverse order. But, I posted all 9 anyways. Let me know if you have trouble viewing the album.
 
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Inignem

Pro-death amateur drawer
Ehhhh, if you really think these cubes will help, then I'll do it despite thinking otherwise...

Uploaded as an album on Imgur so as to save on forum space:
One cube, viewed head-on using a perspective viewpoint with a camera focal length of 35 (I forget what units Maya uses...). The cube is rotated 90 degrees (1/4 of a total 360 revolution) in nine images, each incrementing 10 degrees.

Although, I should point out that only the first 5 rotations actually present any unique information. The last four rotations are mirror images of the first four, in reverse order. But, I posted all 9 anyways. Let me know if you have trouble viewing the album.

Wow, just wow. Thanks a lot. Words are not enough to express how much I love you. Thanks!

you know what? Fuck it. Ill give you a free ticket to request me anything. I can draw anything for you. Just request, please. (Just dont ask me scat, but I can do pretty much anything!)
 
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DrGravitas

Member
Wow, just wow. Thanks a lot. Words are not enough to express how much I love you. Thanks!

you know what? Fuck it. Ill give you a free ticket to request me anything. I can draw anything for you. Just request, please. (Just dont ask me scat, but I can do pretty much anything!)

Hmmm... OK! Please accurately draw a tesseract from a four-point perspective worm's eye-view, with appropriate foreshortening.
 
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