Monday, October 26, 2020

Using CloudCompare to determine a 3D rotation matrix's euler angles and vice versa

Working with 3D transformation matrices and Euler angles can be a little confusing with all that complex mathematical calculations. I found the Apply Transformation tool in CloudCompare to be useful in helping to calculate the Euler angles i.e. roll, pitch, and yaw given the transformation matrix, or vice versa. 

To use the tool the find the roll, pitch and yaw, you can do the following:

  1. Start up CloudCompare. Load a point cloud file and select it in the tree pane.

  2. Next, select Edit > Apply transformation.

    The Apply transformation dialog box appears.

  3. Type in the transformation matrix you want to determine the Euler angles.

  4. Then click the Euler angles tab.

    The calculated angles are displayed as Phi (yaw), Theta (pitch) and Psi(roll).

To determine the transformation matrix from the Euler angles, just type in the yaw, pitch, and roll values in the Phi, Theta and Psi fields. Then click the Matrix 4x4 tab. 

Monday, October 19, 2020

WebApp to convert an Applanix smooth best estimated trajectory (SBET) binary file to comma-separated value (CSV) file

An Applanix ( smooth best estimated trajectory (SBET) binary file is a common file you may encounter when working in field LiDAR, and aerial photo data collection. It is basically a refined trajectory of the real time navigation of the path taken in the field data collection process.

I wrote an online WebApp tool ( to convert an SBET file (typically with an extension *.out) to a comma-separated value (CSV) file, and compressed to a ZIP file for easier transportation. The extraction, conversion and compression processes take place inside a Web browser locally only; there is no requirement to upload to a web server so that will save on the time and data connection costs.

To use this converter, simply visit the web site with any modern web browser.

Then, just drag and drop an SBET file, e.g. SBET.OUT onto the indicated area. Or click the Browse button and select the SBET file. Then click Open.

A process indicator will be displayed while the conversion is taking place. After the conversion has completed, a download link will appear as shown below.


Click the link to download the zip file and extract out the converted CSV file. An example of the result of the conversion is shown below.