1 Introduction

This guide is intended to introduce the basics of running LandTrendr (LT) in Google Earth Engine (GEE). It describes the LT conceptual framework, what is required to run LT-GEE, how to run it, what the outputs are, and how they are formatted. It also provides three example scripts, a series of user interfaces to LT operations, and an API for opinionated, but easy use.

LandTrendr is set of spectral-temporal segmentation algorithms that are useful for change detection in a time series of moderate resolution satellite imagery (primarily Landsat) and for generating trajectory-based spectral time series data largely absent of inter-annual signal noise. LT was originally implemented in IDL (Interactive Data Language), but with the help of engineers at Google, it has been ported to the GEE platform (porting paper; GEE overview; GEE paper). The GEE framework nearly eliminates the onerous data management and image-preprocessing aspects of the IDL implementation. It is also light-years faster than the IDL implementation, where computing time is measured in minutes instead of days.

We assume that you have a GEE account, that you are somewhat familiar with the GEE JavaScript API, and have a basic understanding of LandTrendr (method, application).