Remote Sensing and Image Processing Training
Responding to the momentum of MOOCs Massive Online Open Courses
See end of this article for links to free remote sensing resources.
Remote sensing is taking land or water surface images from satellites, planes, helicopters and from unmanned airborne systems, and image processing is making some sense of all the light spectral data within those images, using computer algorithms developed to quickly process huge amounts of data.
Remote sensing and image processing has practical application in areas such as natural hazards (eg fire, floods, cyclones), coastal environments such as mangrove reduction or restoration, mapping the spread of weeds, savanna fires, marine and benthic habitat mapping, and ocean colour indicating water quality.
Disaster management entails the stages of response, recovery, reduction, readiness, by the public and emergency services. Remote sensing is often used in the response stage to supply images and information from satellite or airborne data.
It can also be powerful in building resilience within the community in the reduction and readiness stages, by building up people’s awareness of their environment, such as fire fuel, fire weather and fire action plans or flood risk and evacuation plans.
In the recovery stage, which can go on for years, it is used for example, as eucalypt bushland re-sprouts from epicormic meristems or recovery buds after fire. The new growth can be seen and compared in time series analysis, eg regular satellite images.
Another on ground application concerns how ecosystems and environments are recovering or degrading, for example the amount of woody vegetation in respect to grazing and fire. In images vegetation can show as red against a background of blue/green colour.
Image data comes from the colour and also the shadow, the contrast of objects to their surroundings and the shape of the feature.
In order to know the spectral features of surfaces, a field spectrometer is used to measure the light wavelength reflected off of an object, this is done on site, that is, in the field and is a matter of point and record, in the same manner as a satellite.
For example, in a coral reef along the edges we may find deeper water with brown branching coral and massive and plate coral, then rock and rubble pounded by waves but protecting the inner reef, and within the reef may be a lagoon with mats of bacteria on sand giving a green brown colour, coral and rock together giving a dark colour, clear sand patches light and areas of algae dark.
Each surface is giving off a different spectral signature measured and recorded on site with a field spectrometer. The visible light spectrum is used as this generally gets through the water. The term spectral signature implies it is unique to a particular surface but it is worth noting that there is so much variability in nature, eg between trees or a leaf, that it may not be entirely unique.
To find this spectral data within the pixels of a satellite image, algorithms are applied which estimate the percentage of a land cover, in our case the percentage of coral, compared to sand, rock or algae. Coral is the important factor we are looking for in reef health. It is useful to know about the environments we are investigating, for example when coral is killed, by crown of thorn starfish or by bleaching it quickly becomes covered in algae, this can be used as an indicator of damage or threat to the reef.
Training in image processing and field validation are both equally important when using remote sensing.
Free remote sensing resources:
To develop foundational understanding of remote sensing, like a textbook Remote Sensing Lab
Introduction to remote sensing with Karen Joyce, Remote Sensing Educational Resources (2012) Education — KEJOYCE.COM
How to be lazy: Getting Remote Sensing and Image Processing to do the Work For You. With Karen Joyce (2014) (41) How to be lazy: Getting Remote Sensing and Image Processing to do the Work For You — YouTube
Interactive online tools for enhancing student learning experiences in remote sensing (2014) (PDF) Interactive online tools for enhancing student learning experiences in remote sensing (researchgate.net)
What is Google Earth Engine? https://goo.gl/n5Gh5Q
