Changing Your Position

In Partiview, there are two ways to change your position, either fly to a specified location, or use the jump command to instantly go to a point (x, y, z).

Determining your Position

In order to see information on your current position, the where command generates a report to the Console Window. By typing

where

Partiview generates 4 lines of information describing your position. These are

camera at x y z looking to jump x y z Rx Ry Rz scale c2w: a_xx a_xy a_xz 0 a_yx a_yy a_yz 0 a_zx a_zy a_zz 0 x y z 1

where x, y, z are the values of your current position, $\hat{{x}}$ , $\hat{{y}}$ , $\hat{{z}}$ are unit vectors that describe the forward direction vector, Rx, Ry, Rz are the rotation angles about the x, y, and z axes, and the c2w a_ij coefficients describe a transformation matrix from camera (your view) to world coordinates.

If we look at Partiview without any data and only the Point of Interest marker in our view, we can explain some of these numbers. The red axis points in the + x direction, the green axis points in the + y direction, and the blue axis points in the + z direction. The $\hat{{x}}$ , $\hat{{y}}$ , $\hat{{z}}$ values are unit vectors (add to 1) that describe your forward vector. For example, if you line up squarely on the red axis, so that you're looking down the red axis and the blue and green axes form a plane parallel to your viewing plane, then, the forward direction is just about all in the negative x direction, so $\hat{{x}}$ should be very close to -1, with very small components in the y and z directions. Similarly, flip 180^o and $\hat{{x}}$ would be +1. Position yourself at a 45^o angle in all directions, and $\hat{{x}}$ $\sim$ $\hat{{y}}$ $\sim$ $\hat{{z}}$ .

Resetting the Camera Position

You can reset the camera position using the keyboard shortcut keys cw in the Graphics Window (type the letter c, then w in the Graphics Window). This transports you to this location (as reported by where):

(x, y, z) = (0, 0, 3) (,,) = (0, 0, - 1) (Rx, Ry, Rz) = (0, 0, 0)

looking down the + z axis from 3 distance units away with the + x axis pointing to the right and the + y axis pointing up.

Jumping to a new position

If you'd like to jump to some point in the data, you may use the jump command to specify an x, y, z and Rx, Ry, Rz of your choosing. Let's define these rotation angles Rx, Ry, Rz more throughly. If you reset the camera position (with the cw keys), then the rotation angles are all zero. In Rotate Flight Mode, rotate with the right mouse button so that the x (and y) axis is about 45^o from where it was after resetting. Now, issue the jump command with no arguments and you will see that the value of Rz is around 45^o. You have rotated about the z axis (which is pointing directly at you) by about 45^o.

Reset the camera position again. Now, in the Orbit Flight Mode, rotate about the x axis by placing the mouse at the top of the y (green) axis and pulling down along this axis with the left button pressed. This should keep the x axis stationary. Now, we expect the value of Rx to change since we're rotating about the x axis. Does jump prove us right?

As another example, if you'd like to go 10 units out the x axis and look back on the Point of Interest, you will need to set (x, y, z) = (10, 0, 0) and (Rx, Ry, Rz) = (0, 90, 0). Why must Ry = 90^o and not 0^o? Well, reset the camera position using the cw keys. Now, imagine increasing your x position by 1 unit (i.e., moving in a direction parallel to the + x axis by one unit). What will happen? The Point of Interest will move to the left 1 unit since we've moved the camera to x = 1. Using jump first inspect your current position: (x, y, z) = (0, 0, 3). Now, move one unit out the x axis (maintaining your z position) using this command:

jump 1 0 3

The rotational angles will remain the same if they are unspecified. As you see, the Point of Interest has moved off to the left and we have not changed the direction we're looking. We only moved a few steps to the right, without moving our head.

Digital Universe Atlas

Partiview User's Guide

Changing Your Position