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  • G-STEP with EURISY Conference: Growth and competitiveness using satellite applications- practical approaches for non-space SMEs

    November 2011

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  • Satellite Data Apps: Funding and Protecting Your Innovation

    National Space Centre

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FAQs

Who is Earth Observation Technology for?

There is no ‘typical’ Earth Observation user or industry. A vast amount of data is collected and there are many different ways the same data can be processed. Take a look at our case studies to see Earth Observation data being applied in agriculture, risk assessment, construction and urban planning amongst others.

What is Earth Observation Technology?

Earth Observation technology includes satellites, aerial monitoring and ground based sensors. These technologies gather remotely sensed data about land, marine and atmospheric variables.

We are all familiar with satellite acquisitions presented as images – Google Maps and Google Earth - however the raw digital data can be processed with computer software in many different ways to extract information relevant and specific for end user requirements.

What can Earth Observation Technology do for you?

Acquiring the most reliable, detailed and up-to-date information available is undoubtedly the most crucial requirement of good business and effective government. Earth Observation provides a whole new dimension of information ready to be exploited. Data has been collected for over 30 years by an increasingly extensive network of satellites, and a considerable amount is freely available. G-STEP training is designed to highlight the free data and processing software already accessible.

Why G-STEP?

Although some of the data is freely available, negotiating what is useful to you, where to find it and how to process it is a specialist task. G-STEP can help through access to the University of Leicester’s Earth Observation Science Research - dedicated to interpreting this data in a meaningful way to reveal important information about the world we live in. Alternatively we are able to provide free, tailored training packages giving you the freedom to process the data in order to create a product as individual as your business.

Where can I get the data from?

Most data can be accessed and downloaded online. Contact us to find out more.

How much does the data cost?

The cost of the data depends on three things: the spatial resolution of the sensor, whether the sensor is commercial or non-commercial and the level of processing the data has undergone i.e. whether it is raw data or a product such as the heat maps shown below.

UK heat data

What difference does the resolution make?

The spatial resolution of the sensor essentially controls the level of detail available, as illustrated in the images below. The resolution you require controls the choice of satellite and the cost of acquiring the data. Even if you require high resolution images for your analysis it is important to remember that low cost low spatial resolution images are useful for pinpointing the exact area beforehand.

satellite data
With all satellite data, a trade off must be made between how much surface detail can be collected - the spatial resolution, and how much area can be observed at a given time - the spatial coverage.

What funding opportunities are available?

There are opportunities to gain funding for staff training and equipment, claim tax relief for research and development activities and many more. Contact us to discover the funding your business could be eligible for.

What kind of processing software is required to use the data?

G-STEP has a database of image processing and GIS software (FOSS and licensed) suitable for viewing, processing and analysing earth observation data. Contact us to discuss your requirements further.

What is a GIS?

A GIS (Geographical Information System) is a system of computer hardware, software and procedures to facilitate the management, manipulation, analysis, modelling, representation and display of data that is linked to location in order to solve complex problems regarding planning and management of resources.


The data in a GIS is geographically referenced (georeferenced) to a common coordinate system, making it possible to overlay layers or themes of geospatial data – such as land use, elevation, census data etc. This allows analysts to query the GIS spatial relational database, to combine queries and to produce new maps.


Essentially a GIS is a tool to assist in decision-making and management of attributes that need to be analysed spatially.

What is the difference between Free Open Source Software (FOSS) and licensed or proprietary software?

Proprietary software is computer software licensed under exclusive legal right of its owner. An individual or company purchases a license that gives the right to use the software under certain conditions, but restricted from other uses, such as modification, further distribution, or reverse engineering. Examples include ArcGIS and Envi.

Free Open Source Software is not necessarily free of charge but in practice this is often the case. It is software that is liberally licensed to grant the right of users to use, study, change, and improve its design through the availability of its source code.

G-STEP offers training in both types of software – all of our FOSS training utilises packages that are available free of charge. Contact us to discuss your requirements further.

What is remote sensing?

Remote sensing is the science of observing and studying the earth, its land surface, the oceans, atmosphere and its dynamics without physical contact. Information transfer is accomplished by the use of electromagnetic radiation; therefore the electromagnetic spectrum is fundamental to remote sensing systems.

Instruments for remote sensing outside the visible wavelengths of the electromagnetic spectrum can give access to additional information about the physical world surrounding us.


Remote sensing systems make use of the electromagnetic spectrum in two ways, by collecting the radiation that is reflected, emitted or scattered by a target (passive systems) or by illuminating a target with a pulse or beam of radiation and collecting the signal that is reflected or diffracted back to the sensor (active systems).

What is optical remote sensing?

Optical remote sensing is a passive technique that utilises the principle that everything on the Earth’s surface absorbs and reflects solar electromagnetic radiation. Different materials reflect and absorb different wavelengths in the electromagnetic radiation spectrum, which gives them a spectral reflectance signature.

Spectral imaging sensors record the reflectance data in different spectral bands, image processing software or a GIS can then be used to view different band combinations or to assign false colour to certain wavelengths in order to make differences in spectral reflectance more obvious.

What do we mean by ‘true’ and ‘false’ colour images?

True colour images use reflectance data in the visible wavelengths – red, green and blue – as our eyes would see them. A false colour image is generated when ‘red’, ‘green’ or ‘blue’ colours are applied to other wavelengths in the electromagnetic spectrum. Usually this is to make visible the reflectance data in wavelengths such as infra red and near infra red.

text

What is RADAR?

RADAR (Radio Detection And Ranging) is an active remote sensing technique that operates in the microwave or radio wave region of the electromagnetic spectrum. The radar emits electromagnetic pulses (A), which are focused by the antenna into a beam (B), and measures how long it takes for the reflected signal (C) - known as backscatter - to return from the target.

It is possible to identify the range, altitude, direction, or speed of both moving and fixed objects such as aircraft, ships, motor vehicles, weather formations, and terrain. Radar is able to detect objects at ranges where other emissions from the target object, such as sound or visible light, would be too weak to detect.


Radar sensors are not impeded by cloud cover, dust, haze or time of day – all of which are limitations in optical remote sensing. Radar sensors can be both spaceborne and airborne.

What is SAR?

SAR (Synthetic Aperture Radar) is a form of RADAR remote sensing. The radar antenna is attached to a moving aircraft or spacecraft that emits a series of pulses as it travels, therefore it produces a series of reflected signals (backscatter) that can be combined. Effectively it takes advantage of the motion of the satellite or aircraft along its orbital track to mathematically reconstruct (synthesise) an operationally larger antenna and therefore provide high-spatial-resolution imaging capability (3m from aircraft and 25m from satellites) while maintaining high spatial coverage.


For example, in the diagram below the target (A) remains in the radar beam for the distance in which the plane travels (B). Therefore the length of the synthesized antenna is equivalent to the distance (B).

What is InSAR? (Also known as IfSAR)

InSAR (Interfereometric Synthetic Aperture Radar) is an analysis technique that uses repeat pass SAR imagery – essentially two or more SAR images of the same area at different times. The differences in the reflected signals are analysed to produce an interferogram – an image that reveals changes in the elevation of a landscape to a very high level of detail.

The coloured bands seen in a given InSAR image, like the one below, can be regarded in a similar way to contour lines on map except on a vastly reduced scale.

INSAR text

What is LiDAR? (Also known as ALS – Airborne Laser Scanning)

LiDAR (Light Detection And Ranging) is an active remote sensing technique that operates in the UV, visible or infrared wavelengths of the electromagnetic spectrum. Laser pulses are emitted from an aircraft (A), which are focused by the antenna into a beam (B) and the distance to an object or surface is determined by measuring the time delay between transmission of a pulse and detection of the reflected signal (C) – known as backscatter. Once processed LiDAR data provides accurate height information for both terrain and surface features.

LiDAR sensors are not impeded by cloud cover, dust or haze – all of which are limitations to in optical remote sensing.