# 3D Geometry and projection

#### SahandAp

##### New member

The picture above is taken with a camera in a room which is 3 meters high and other dimensions are 4 and 6. The camera is 1.5 meters above the roof and no more data is given.
Find the distance between the camera and the center of the room.

#### Dr.Peterson

##### Elite Member
View attachment 21626
The picture above is taken with a camera in a room which is 3 meters high and other dimensions are 4 and 6. The camera is 1.5 meters above the roof and no more data is given.
Find the distance between the camera and the center of the room.
Should that be 1.5 meters above the floor??

Please show what you have tried, as we request:

It will also be helpful if you tell us what you have learned that might be applied to this problem, even if you don't see how. Context is very important. I'm guessing that the only measurements from the picture that will be useful are the angles, so I expect you to list some theorems concerning angles in a projection.

#### SahandAp

##### New member
Should that be 1.5 meters above the floor??

Please show what you have tried, as we request:

It will also be helpful if you tell us what you have learned that might be applied to this problem, even if you don't see how. Context is very important. I'm guessing that the only measurements from the picture that will be useful are the angles, so I expect you to list some theorems concerning angles in a projection.
I'm afraid you're right and i made a mistake, it must be 1.5 meters above the floor.

And about the necessary formulas, I think using vectors may be helpful (and no specific formula is needed) but i have no other idea how to solve this problems.

#### Dr.Peterson

##### Elite Member
This tells me something; I know at least that you have heard of vectors. I suppose you are thinking of dot and cross products, and so on.

But, again, please tell us what you have learned about projections, specifically. There must be something, at least a definition of the kind of projection you are assuming. How it has been presented to you can make a difference in how I would suggest approaching the problem. I have not made any attempt to solve it myself, since the goal is to help you do it, which requires using methods available to you.