What is the updirection property of a camera?

What is the updirection property of a camera?

• Kristian PD

  quite clear explaination.

  Thank you, David

  
  
  

• H.Ashok

  Describing the orientation of an object in three dimensions is a non-trivial matter -- in fact there are many different methods of describing a single 3D orientation.
  
  In this case, instead of a camera, imagine you're moving your head around in 3D space. Imagine that Camera.Position corresponds to the center of your head. After specifying where your head is located, you need decide what direction you're looking in -- Camera.ForwardDirection. But there's a problem -- these two pieces of information don't uniquely specify an orientation. You could rotate your head on the axis specified by the ForwardDirection without changing its position and you'd still satisfy both of these criteria. To see an example of this, sit on a swiveling chair and look straight up in the air. Now spin the chair and keep looking straight up. If you can do this without throwing up, you'll notice that the (x,y,z) position of your head isn't changing, and your ForwardDirection (the direction you're looking in, a vector which would be (0,1,0) -- straight up -- in this example) isn't changing either.
  
  So you need one more piece of information to describe this 3D orientation unambiguously, and that's the UpDirection. Once you've decided which direction the top of your head is pointing in (visualize an arrow sticking out the top of your head) your orientation will be unambiguously described.
  
  Keep in mind that Position is a Point3D, whereas ForwardDirection and UpDirection are both Vector3Ds.
  
  Hope that helps ,
  David
  
• What is the updirection property of a camera?