World coordinates of objects

Question

How do I see the object's world coordinates. I want to build a scene, view this scene with cameras at different locations and analize what I see. For this purpose, I want to be able to see where my camera and my objects are in the world and how far apart they are. Hence, I need their respective world coordinates and also it might be nice to be able to display the units/meters in the grid. When I select an object, the location and rotation are all (0,0,0). This must be relative to some starting position of the object but not from the point (0,0,0) in the world.

So:

1. Where can I see an object's world coordinate?
2. Can I display units in the grid?
3. How would I be able to systematically change the position and orientation of the camera with discrete steps in some predefined intervals? Would that be done using animations?

Thanks in advance!

Answer 1

The location of an object is determined by the location of it's Origin. Most likely all your object origins are at 0,0,0, and not in the centers of your objects.
To move the origins to your objects, select everything (A) and press CtrlShiftAltC> Origin to geometry.

I don't think there is any native way to display units on the grid.

I'm not quite sure what you mean by "systematically", but you could try snapping.

Answer 2

Gandalf3 has done a good job of answering your questions, but I'll share a work-around I developed for the challenges the second question posed: I use "helper geometry". Helper geometry consists of objects I use as an aid to making a particular model. These objects include place markers, label holders, and modeling tools. Place markers and label holders are self explanatory; an example of a modeling tool would be in the circumstance where I want two objects to be a designated distance apart, say 8.235 blender units, but the distance is not parallel to the x, the y, or the z axis. In this instance I might create a plane mesh that is 8.235 blender units in one dimension, place it so that one edge of the plane is at the first point, and orient the plane in the direction I want to measure the distance, and then locate the other object at the edge opposite the first.

To help me remember the locations of objects in the grid, I'd create an object of suitable size. In the case of an object to remember the location of camera 1, it would probably be a cylinder of very small diameter, named "camera1location". As long as I don't apply the location transformation to helper geometry, I can read the co-ordinates of the item in the properties window, object tab.

To keep my modeling projects orderly, I place all cameras and lamps in layer 1; all helper geometry in layer 2, and do my modeling in layers 3 through 20.