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

An Applanix (https://www.applanix.com) 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 (https://dominoc925-pages.appspot.com/webapp/sbetcsv/default.html) 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 https://dominoc925-pages.appspot.com/webapp/sbetcsv/default.html 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. 

 

C# code snippet to read an Applanix SBET file

The smoothed best estimated trajectory (SBET) file of an air survey flight created and exported by the Applanix PosPac software is a simple binary format. The SBET file is just a series of records with the following double fields, as described by the C# code below:

public class SbetRecord

{

    public double time;    //GPS seconds of week

    public double latRad;    //latitude in radians

    public double lonRad;    //longitude in radians

    public double alt;    //altitude

    public double xVel;    //velocity in x direction

    public double yVel;    //velocity in y direction

    public double zVel;    //velocity in z direction

    public double roll;    //roll angle

    public double pitch;    //pitch angle

    public double heading;    //heading angle

    public double wander;    //wander

    public double xForce;    //force in x direction

    public double yForce;    //force in y direction

    public double zForce;    //force in z direction

    public double xAngRate;    //angular rate in x direction

    public double yAngRate;    //angular rate in y direction

    public double zAngRate;    //angular rate in z direction

}

Then just use a BinaryReader to open up the file and read in the fields as doubles as shown in the code snippet below.

SbetRecord rec = new SbetRecord();

// Open an SBET file for reading...

BinaryReader reader = new BinaryReader(File.Open(@"C:\Temp\sbet1.out", FileMode.Open, FileAccess.Read));

// ...read a record...

rec.time = reader.ReadDouble();

rec.latRad = reader.ReadDouble();

rec.lonRad = reader.ReadDouble();

rec.alt = reader.ReadDouble();

rec.xVel = reader.ReadDouble();

rec.yVel = reader.ReadDouble();

rec.zVel = reader.ReadDouble();

rec.roll = reader.ReadDouble();

rec.pitch = reader.ReadDouble();

rec.heading = reader.ReadDouble();

rec.wander = reader.ReadDouble();

rec.xForce = reader.ReadDouble();

rec.yForce = reader.ReadDouble();

rec.zForce = reader.ReadDouble();

rec.xAngRate = reader.ReadDouble();

rec.yAngRate = reader.ReadDouble();

rec.zAngRate = reader.ReadDouble();

// ... etc ...