Alisson Steffens



Shoreline monitoring system

About the project

CASSIE is an open source web tool for automatic shoreline mapping and analysis using satellite imagery (

It was built in JavaScript, using the Google Earth Engine (GEE) API, and can be applied to any coastal region on Earth where there is a boundary between land and water.

CASSIE uses Landsat and Sentinel-2 satellite imagery, freely available from GEE, and implements automatic shoreline detection using normalized differential water index (NDWI) together with the Otsu image segmentation algorithm.

Satellite-derived shorelines are analyzed for a set of user-defined transects along which various statistical analyzes are performed. Comparisons of CASSIE-derived shorelines and rate of change with state-of-the-art methods show that the products of this tool are sub-pixel accurate. The new concept of big data storage and cloud computing (GEE) platform, combined with a user-friendly interface and high level of automation make CASSIE a complete tool to support a wide variety of studies and applications where the knowledge of the behavior of the line coast is essential.

My involvement

In this project, I worked as a developer, where I developed the web interface, the integration with the Google Earth Engine API and the implementation of the automatic coastline detection algorithm. In addition, I also worked as a researcher, where I developed the methodology for automatic shoreline detection and the statistical analysis of transects.


During my time at Cassie, I coordinated the development of a version of the project called C-Squeeze, focused on mangrove squeeze detection. The project was approved and financed by Grupo Fundação Boticário, and is currently being developed by the other members of the project.


  • react
  • Redux
  • Google Earth Engine