Terrestrial remote sensing toolkit

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BRG The University of Queensland
Fundamentals

- Main page
- Pre-processing
- Field data collection
- Mapping approaches
- Change and trends
  - About
  - Image requirements
  - Mapping change
  - Trend detection
  - Example time series
  - Example change maps
- Delivery

# What is change and trend detection?

Image-based maps of biophysical properties of marine environments or their composition can be analysed to identify the location, magnitude and type(s) of change occurring between the times of image acquisition.

This application is one of the fundamental advantages of remote sensing for mapping and monitoring environments, it provide a spatially and temporally explicit means to map changes in specific environment features.

Before any remotely sensed images, or image based map products are used for change or trend detection, it is absolutely essential that the image or image maps meet certain requirements in terms of their geometric and radiometric properties. These requirements are to ensure that any changes detected are due to environmental changes, and not image artefacts.

Change detection algorithms typically use two images of the same area collected in sequence and show the difference between the two dates.

Trend detection algorithms apply time series analysis techniques to image series of at least 10 images, either at individual pixel or some aggregate line or area, and identify periodicities and trends.