> For the complete documentation index, see [llms.txt](https://docs.ceruleansonar.com/c/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.ceruleansonar.com/c/surveyor-240-16/coordinate-frames.md).

# Coordinate Frames

### Surveyor Internal Coordinate frame

In order to process Surveyor data without SonarView, you will need to know the coordinate frame used by the device. Here is an image of the Surveyor coordinate frame.

<figure><img src="/files/RRJzEjObyEcE8TG95XvQ" alt=""><figcaption></figcaption></figure>

In the image above, the Z-Axis is going into the face of the device. With the transducers pointing down, the blue arrow will be pointing up.

### SonarView Mounting Offsets

To process data correctly, SonarView needs the mounting offsets from your position sensor to the Surveyor, expressed in the forward-right-down (FRD) coordinate frame.

* Forward, Right, Down offsets should be entered FROM your position source TO the Surveyor.
* Yaw offset is not supported, so the Surveyor’s X-axis must be aligned with your yaw source.
* Roll offset is visual only (used to orient the vehicle model correctly), but it still follows the right-hand rule: point your thumb along the Surveyor’s X-axis; the direction your fingers curl is positive roll.

The image below shows where to measure to for the mounting offsets:

<figure><img src="/files/1XZjThTu92f7R4IhhLSu" alt=""><figcaption></figcaption></figure>