# Orientation Vector

A description of Viam’s orientation vector method.

Viam’s orientation vector is a method for describing the orientation of an object in 3D space. It is part of a Pose which also includes the position in 3D space.

## Basics

Orientation vectors are composted of 4 attributes.

- RX, RY, RZ - define a vector from the center of the object to another point in the reference frame. This defines the direction something is pointing in.
- Theta - describes the angular position around that vector.

## Examples

### Configuring frame for a camera

- You have a room with a camera.
- The corner of the room is (0,0,0).
- You want to configure the camera into the frame system, so you need to know where in the room the camera is, and where it’s pointing.
- This requires a Pose.
- X, Y, Z are simply the measurements from the corner of the room.
- Now to figure out the orientation vector:
- To figure out RX, RY, RZ first take a picture with the camera.
- Determine the point in the very center of the image.
- Measure the X, Y, Z of that point from the corner (call them X2, Y2, Z2, respectively).
- RX, RY, RZ become the difference between X, Y, Z (the camera’s position) and X2, Y2, Z2 (that point’s position).
- Theta is determined by looking at the picture and changing Theta’s value until down is correct, likely 0, 90 or 180.
- To do this, take a picture
- Determine if the orientation is correct
- If not, add 90 to Theta, and try again

## Why we like it

- Easy to measure in the real world
- No protractor needed
- Rotation is pulled out (as Theta) which is often used independently and measured independently.