# Yaw, Pitch, Roll and Omega, Phi, Kappa angles

Yaw, Pitch, Roll and Omega, Phi, Kappa angles define the orientation of the drone or the camera during the image acquisition.

The main difference between the two sets of angles is:

• Yaw, Pitch, Roll angles define the rotation of a body, for example, aircraft or a drone with respect to its navigation coordinate system. Mostly used by drone manufacturers.
• Omega, Phi, Kappa angles define the rotation between the image coordinate system and a projected coordinate system. Mostly used in photogrammetry software.

## Yaw, Pitch, Roll definition

Yaw, Pitch, Roll angles define the relation between the navigation coordinate system and the body coordinate system. The coordinate systems and rotations are defined as:

### Example

Assuming that the camera is mounted such that the camera looks down and the top of the image points to the front of the aircraft, the yaw, pitch, roll angles are defined as follows:

Yaw

• If yaw = 0° and the camera is looking to the ground (i.e. nadir), it means that the top of the image points to the north.
• If yaw = 90° and the camera is looking nadir, it means that the top of the image points to the east.
• If yaw = 270° and the camera is looking nadir, it means that the top of the image points to the west.

Pitch

• If pitch = 0°, it means that the camera is looking down (i.e. nadir).
• If pitch = 90°, it means that the camera is looking forward.

Roll

• If using a gimbal, this value is usually 0°.

Some more examples:

• yaw = 0°, pitch = 0°, roll = 0° means: the camera is nadir (looking down perpendicular to the ground), the top of the image points to the north.
• yaw = 0°, pitch = 90°, roll = 0° means: the camera is looking forward from the aircraft, towards north.
• yaw = 90°, pitch = 0°, roll = 0° means: the camera is nadir (looking down perpendicular to the ground), the top of the image points to the east.

## Omega, Phi, Kappa definition

The omega, phi, kappa angles are defined as the angles used in order to rotate a (X, Y, Z) geodetic coordinate system and align it with the image coordinate system. The rotations are applied in the following order:

• Omega (ω), the rotation around the Χ axis.
• Phi (φ), the rotation around the Y axis.
• Kappa (κ), the rotation around the Z axis.
 Rotation around the X-axis (Omega) Rotation around the Y-axis (Phi) Rotation around the Z-axis (Kappa) Exterior orientation rotations/angles.

More information about the coordinate system definition see the How are the Internal and External Camera Parameters defined? article.

Note: The sense of the angle is defined by the right hand rule. A positive rotation means that if the thumb of the right hand is pointed along the positive direction of the rotation axis, then the fingers curl in the positive direction, i.e. counterclockwise.

## How to convert Yaw, Pitch, Roll to Omega, Phi, Kappa

Successfully converting from Yaw, Pitch, and Roll to Omega, Phi, and Kappa depends on several factors, including the camera's position on Earth.

There are many ways to convert Yaw, Pitch, and Roll to Omega, Phi, and Kappa. Pix4D's method is described in the attached documents:

## Using Omega, Phi, Kappa and Yaw, Pitch, Roll angles in Pix4D

### Importing angle values into Pix4D

Most drone manufacturers write angle values directly in the EXIF tags of the images. If the EXIF tags are available, the values will be automatically converted to Omega, Phi and Kappa when importing the images into Pix4D Desktop. For more information see Specifications of xmp.camera tags article.
Since the definition of Yaw, Pitch, and Roll may vary for different UAV manufacturers, it is not possible to guarantee that Omega, Phi, and Kappa can be calculated accurately for all UAVs.

Pix4D has worked with a number of UAV partners to automatically calculate Omega, Phi, and Kappa using Yaw, Pitch, and Roll stored in a flight log that belongs to any of our listed UAV manufacturers: Input files.

### Processing options

Accurate angle values can be incorporated to accelerate processing time and produce more accurate results using the Accurate Geolocation and Orientation Calibration Method: Menu Process > Processing Options... > 1. Initial Processing > Calibration.

It is possible to test the accuracy of the initial Omega, Phi, and Kappa values according to the variance (RMS) which appears in the Quality Report or compare the initial orientation with the optimized orientation calculated by Pix4Dmapper.

To test the accuracy of the initial Omega, Phi, and Kappa values apply Standard or Alternative Calibration Method: Menu Process > Processing Options... > 1. Initial Processing > Calibration.

Pix4Dmapper calculates the optimized orientation during Step 1. Initial Processing.

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### Article feedback (for troubleshooting, post here)

• kvsro silchar

Hello,

is it possible with Pix4D to plan a mission for corridor mapping with curves and stuff so the flight direction would copy the polygon?

It wouldn't have just straight flight lines but curved (following a road for example?

• Teodora (Pix4D)

Hi,

You could use Pix4Dcapture for flight planning. Depending on the object/surface to be mapped, you can perform polygon, grid, circular or free flight missions. More information can be found here: https://www.pix4d.com/product/pix4dcapture. You could also share your questions with other interested users and we strongly recommend using our online community

Cheers,

Teodora