Monday, May 16, 2022

Convert Geoids from BYN to GTX format with this WebApp

This WebApp came about because I wanted to use some Geoid files for some vertical datum corrections with Proj (which uses .gtx format) but could only find Geoid files in Natural Resources Canada's .byn format.

  1. To convert Geoid BYN files to GTX, open up a browser to the following url:

    The WebApp is loaded.

  2. Click the Add File button.

    The File Upload dialog appears.

  3. Browse and select a .byn file e.g. EGM96.byn. Click Open.

    The Geoid file is displayed in a list and the Convert button is enabled.
    Note: the Geoid .byn is loaded locally to the browser and not transferred to some server on the Internet.

  4. Click the Convert button.

    The Geoid file is converted into .gtx format and the Process log and Save As icons are enabled.

  5. Optional. To view the process log, click the Show Process Log icon.

    The process log messages are displayed.

  6. To save the converted .gtx Geoid locally, click the Save Converted File icon.

    The Geoid file is saved.

  7. Optional. If necessary, you can use a GIS software like QGIS to display the converted .gtx file, as shown below.


Monday, May 2, 2022

Time Converter App for time conversion in the browser developed with Flutter

I recently learned Flutter ( - a cross platform SDK for building native Android, IOS, Windows, Linux, Web, and MacOS applications with a single code base. For practice, I built a simple application - a Time Converter App for converting time values from various formats to other formats. The formats include GPS time, Julian date, Unix epoch, and UTC date time.

Using the Time Converter App

  1. To use the application, open up a browser and go to

    The app page is loaded.

  2. In the Convert from drop down field, select the source time format e.g. gps.


  3. In the to format drop down field, select the destination time format e.g.  utc.

  4. In the entry fields, click the clock icon to use the current system time values. Or type in the values e.g. 2207 as shown below.

  5. Click the blue Convert button.

    If the input values are valid, then the converted time value will be shown in the Output field.