Three Exciting Ways to Protect Forests With Remote Sensing

Forests cover one third of the Earth’s land mass and are home to more than 80% of the terrestrial species of animals, plants and insects. However, 13 million hectares of forest are destroyed each year. The United Nations International Day of Forests took place recently, on 21st March, to raise awareness of this vital resource.

Three remote sensing applications to help protect forests caught our eye recently:

Two scans show the difference between infected, on the right, and uninfected, on the left, patches of forest. Image Courtesy of University of Leiceste

Identifying Diseased Trees
In the March issue of Remote Sensing, researchers from the University of Leicester, (Barnes et al, 2017), published a paper entitled ‘Individual Tree Crown Delineation from Airborne Laser Scanning for Diseased Larch Forest Stands’. It describes how the researchers were able to identify individual trees affected by larch tree disease, also known as phytophthora ramorum.

This fungus-like disease can cause extensive damage, including the death, and diseased trees can be identified by defoliation and dieback. Airborne LiDAR surveys were undertaken by the company Bluesky at an average altitude of 1500 m, with a scan frequency of 66 Hz that gave a sensor range precision within 8 mm and elevation accuracy around 3–10 cm.

Remote sensing has been used to monitor forests for many years, but using it to identify individual trees is uncommon. The researchers in this project were able to successfully identify larch canopies partially or wholly defoliated by the disease in greater than 70% of cases. Whilst further development of the methodology will be needed, it is hoped that this will offer forest owners a better way of identifying diseased trees and enable them to respond more effectively to such outbreaks.

Monitoring Trees From Space
An interesting counterpoint to work of Barnes et al (2017) was published by the journal Forestry last month. The paper ‘Estimating stand density, biomass and tree species from very high resolution stereo-imagery – towards an all-in-one sensor for forestry applications‘ written by Fassnacht et al (2017).

It describes work undertaken to compare the results of very high resolution optical satellite data with that of airborne LiDAR and hyperspectral data to provide support for forestry management. The team used WorldView-2 images, of a temperate mixed forest in Germany, with a 2m pixel size, alongside a LiDAR DTM with a 1 m pixel size. This data was then used to estimate tree species, forest stand density and biomass.

They found  good results for both forest stand density and biomass compared to other methods, and although the tree classification work did achieve over eighty percent, this was less than achieved by hyperspectral data over the same site; although differentiation of broadleaved and coniferous trees was almost perfect.

This work shows that whilst further work is needed, optical data has the potential to offer a number of benefits for forestry management.

Monitoring Illegal Logging
Through the International Partnership Programme the UK Space Agency is funding a consortium, led by Stevenson Astrosat Ltd, who will be using Earth Observation (EO) data to monitor, and reduce, illegal logging in Guatemala.

The issue has significant environmental and socioeconomic impacts to the country through deforestation and change of land use. The Guatemalan government have made significant efforts to combat the problem, however the area to be monitored is vast. This project will provide a centralised system using EO satellite data and Global Navigation Satellite Systems (GNSS) technology accessed via mobile phones or tablets to enable Guatemala’s National Institute of Forestry (INAB) to better track land management and identify cases of illegal logging.

Overall
The protection of our forests is critical to the future of the planet, and it’s clear that satellite remote sensing can play a much greater role in that work.

Catching Wavelength 2017

Remote sensing, like GIS, excels in integrating across disciplines and people. Whilst no one ever said being a multi-disciplinary scientist was going to be easy, for the ‘thirsty’ mind it challenges, cross pollinates ideas and looks at problems with new eyes. A diverse group of people connected by a common thread of spatial and remotely sensed data found themselves doing all these things and more in London last week at the Wavelength 2017 conference.

The talks and posters took us on whirlwind tour through the ever varying landscape of remote sensing. We moved through subject areas ranging from detecting ground ice, vegetation and overall land cover, through to earth surface movement and 3D imaging, and onto agriculture yield and drought. We also covered the different vertical scales from which remotely sensed data is collected, whether from satellites, planes, drones or cameras operated from ground level. On top of this focus we also had some great key note talks, running through the varied career of a remote sensing scientist (Groeger Ltd), as well as in depth data assimilation of remote sensing imagery in models (UCL) and commercial developments in airborne camera work (Geoxphere Ltd).

In parallel, we were taken on a grand tour covering the temperate UK, parts of the Middle East, the tundra in North America, the central belt of Africa, and even onto the moon and Mars! In many cases we heard talks from scientists from these countries (though not the moon or Mars …). Some are based at the universities in the UK, whilst, others came specifically to talk at the conference.

I found myself transfixed by the far flung places. Listening to how the dark side of the moon is being mapped, a place that never sees daylight and is incredibly ‘chilly’ and traps ice in these shadowed lands. I also heard about the CO2 that precipitates out of the atmosphere on Mars as snow and forms a 1m blanket. Working in places like Africa started to feel really quite local and accessible!

Possibly the most intriguing aspect of the conference for me, was the advancements that have been made in photogrammetry and how multiple photos are now being used to produce highly intricate 3D models. We saw this applied to cliff morphology and change detection, as well as the 3D point clouds that are produced when modelling trees and vegetation generally.

The 3D models aren’t totally complete due to line of sight and other issues. The model visualisations look like an impressionist painting to me, with tree leaves without trunks or clumps of green mass suspended in mid air. However, this does not matter when calculating leaf volume and biomass, as these discrepancies can be worked with and lead to some very useful estimates of seasonality and change.

Setting this up is no small feat for the organiser, and PhD student, James O’Connor. He delivered an interesting programme and looked after the delegates well. I can truly say I haven’t been to such a friendly conference before. It was also unique in providing ample time to discuss aspects of material presented, both from talks and posters, and sharing technical know-how. This felt of real value, especially to the PhD students and young professionals this conference is geared towards, but equally myself with experience in only certain fields of remote sensing.

I would highly recommend Wavelength, and look forward to seeing what they are planning for 2018!

Blog written by Caroline Chambers, Pixalytics Ltd.

Remote Sensing Goes Cold

Average thickness of Arctic sea ice in spring as measured by CryoSat between 2010 and 2015. Image courtesy of ESA/CPOM

Remote sensing over the Polar Regions has poked its head above the ice recently.

On the 8th February The Cryosphere, a journal of the European Geosciences Union, published a paper by Smith et al titled ’Connected sub glacial lake drainage beneath Thwaites Glacier, West Antarctica’. It described how researchers used data from ESA’s CryoSat-2 satellite to look at lakes beneath a glacier.

This work is interesting from a remote sensing viewpoint as it is a repurposing of Cryosat-2’s mission. It’s main purpose is to measure the thickness of the ice sheets and marine ice cover using its Synthetic Aperture Radar (SAR)/Interferometric Radar Altimeter, known as SIRAL, and it can detect millimetre changes in the elevation of both ice-sheets and sea-ice.

The team were able to use this data to determine that the ice of the glacier had subsided by several metres as water had drained away from four lakes underneath. Whilst the whole process took place between June 2012 and January 2014, the majority of the drainage happened in a six month period. During this time it’s estimated that peak drainage was around 240 cubic metre per second, which is four times faster than the outflow of the River Thames into the North Sea.

We’ve previously highlighted that repurposing data – using data for more purposes than originally intended – is going to be one of the key future innovation trends for Earth Observation.

Last week, ESA also described how Sentinel-1 and Sentinel-2 data have been used over the last five months to monitor a crack in the ice near to the Halley VI research base of the British Antarctic Survey (BAS). The crack, known as Halloween Crack, is located on the Brunt ice Shelf in the Wedell Sea sector of Antarctica and was identified last October. The crack grew around 600 m per day during November and December, although it has since slowed to only one third of that daily growth.

Since last November Sentinel-2 has been acquiring optical images at each overflight, and this has been combined with SAR data from the two Sentinel-1 satellites. This SAR data will be critical during the Antarctic winter when there are only a few hours of daylight and a couple of weeks around mid-June when the sun does not rise.

This work hit the headlines as BAS decided to evacuate their base for the winter, due to the potential threat. The Halley VI base, which was only 17km from the crack, is the first Antarctic research station to be specifically designed to allow relocation to cope with this sort of movement in the ice shelf. It was already planned to move the base 23 km further inland, and this was successfully completed on the 2nd February. Further movement will depend on how the Halloween Crack develops over the winter.

Finally, the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) project was announced this week at the annual meeting of the American Association for the Advancement of Science. Professor Markus Rex outlined the project, which will sail a research vessel into the Arctic sea ice and let it get stuck so it can drift across the North Pole. The vessel will be filled with a variety of remote sensing in-situ instruments, and will aim to collect data on how the climate is changing in this part of the world through measuring the atmosphere-ice-ocean system.

These projects show that the Polar Regions have a lot of interest, and variety, for remote sensing.

Supporting Chimpanzee Conservation from Space

Gombe National Park, Tanzania. Acquired by Sentinel-2 in December 2016. Image courtesy of ESA.

Being able to visualise the changing face of the planet over time is one of the greatest strengths of satellite remote sensing. Our previous blog showed how Dubai’s coastline has evolved over a decade, and last week NASA described interesting work they’re doing on monitoring habitat loss for chimpanzees in conjunction with the Jane Goodall Institute.

Jane Goodall has spent over fifty years working to protect and conserve chimpanzees from the Gombe National Park in Tanzania, and formed the Jane Goodall Institute in 1977. The Institute works with local communities to provide sustainable conservation programmes.

A hundred years ago more than one million chimpanzees lived in Africa, today the World Wildlife Fund estimate the population may only be around 150,000 to 250,000. The decline is stark. For example, the Ivory Coast populations have declined by 90% within the last twenty years.

One of the key factors contributing to this decline is habitat loss, mostly through deforestation; although other factors such as hunting, disease and illegal capture also contributed.

Forests cover around 31% of the planet, and deforestation occurs when trees are removed and the land has another use instead of being a forest. In chimpanzee habitats, the deforestation is mostly due to logging, mining and drilling for oil. This change in land use can be monitored from space using remote sensing. Satellites produce regular images which can be used to monitor changes in the natural environment, in turn giving valuable information to conservation charities and other organisations.

In 2000 Lilian Pintea, from the Jane Goodall Institute, was shown Landsat images comparing the area around the Gombe National Park in 1972 and 1999. The latter image showed huge deforestation outside the park’s boundary. The Institute have continued to use Landsat imagery to monitor what is happening around the National Park. In 2009 they began a citizen science project with local communities giving them smartphones to report their observations. Combining these with ongoing satellite data from NASA has helped develop and implement local plans for land use and protection of the forests. Further visualisation of this work can be found here. The image at the top was acquired Sentinel-2 in December 2016 and shows the Gombe National Park, although it is under a little haze.

The satellite data supplied by NASA comes from the Landsat missions, which currently have an archive of almost forty-five years of satellite data, which is freely available to anyone. We also used Landsat for data in our Dubai animation last week. Landsat captures optical data, which means it operates in a similar manner to the human eye – although the instruments also have infrared capabilities. However, one drawback of optical instruments is that they cannot see through clouds. Therefore, whilst Landsat is great for monitoring land use when there are clear skies, it can be combined with synthetic aperture radar (SAR), from the microwave spectrum, as it can see through both clouds and smoke. This combination enables land use and land change to monitored anywhere in the world. Using the freely available Landsat and Sentinel-1 SAR data you could monitor what is happening to the forests in your neighbourhoods.

Satellite data is powerful tool for monitoring changes in the environment, and with the archive of data available offers a unique opportunity to see what has happened over the last four decades.

Have you read the top Pixalytics blogs of 2016?

Artist's rendition of a satellite - paulfleet/123RF Stock Photo

Artist’s rendition of a satellite – paulfleet/123RF Stock Photo

As this is the final blog of the year we’d like to take a look back over the past fifty-two weeks and see which blog’s captured people’s attention, and conversely which did not!

It turns out that seven of the ten most widely viewed blogs of the last year weren’t even written in 2016. Four were written in 2015, and three were written in 2014! The other obvious trend is the interest in the number of satellites in space, which can be seen by the titles of six of the ten most widely read blogs:

We’ve also found these blogs quoted by a variety of other web pages, and the occasional report. It’s always interesting to see where we’re quoted!

The other most read blogs of the year were:

Whilst only three of 2016’s blogs made our top ten, this is partly understandable as they have less time to attract the interest of readers and Google. However, looking at most read blogs of 2016 shows an interest in the growth of the Earth Observation market, Brexit, different types of data and Playboy!

We’ve now completed three years of weekly blogs, and the views on our website have grown steadily. This year has seen a significant increase in viewed pages, which is something we’re delighted to see.

We like our blog to be of interest to our colleagues in remote sensing and Earth observation, although we also touch on issues of interest to the wide space, and small business, communities.

At Pixalytics we believe strongly in education and training in both science and remote sensing, together with supporting early career scientists. As such we have a number of students and scientists working with us during the year, and we always like them to write a blog. Something they’re not always keen on at the start! This year we’ve had pieces on:

Writing a blog each week can be hard work, as Wednesday mornings always seem to come around very quickly. However, we think this work adds value to our business and makes a small contribution to explaining the industry in which we work.

Thanks for reading this year, and we hope we can catch your interest again next year.

We’d like to wish everyone a Happy New Year, and a very successful 2017!

Perspectives from the 12th Appleton Space Conference

Sam presenting at the 2016 Appleton Space Conference. Image courtesy of Deimos UK.

Sam presenting at the 2016 Appleton Space Conference. Image courtesy of Deimos UK.

Last week I attended the 12th Appleton Space Conference, it was the first time I’d been to one of these conferences, and I was excited to be giving a talk. It was hosted by RAL Space at the Harwell Campus.

After the welcome, the day started with a talk from Ross James (Deputy CEO at the UK Space Agency). He’s new to the space community, and so has enjoyed learning to understand it more fully. It was interesting to hear him reinforce the conclusion that the space industry’s value-added multiplier is two, but also that the industry needs to be more regionally and user focused.

Talks then followed by members of European Centre for Space Applications and Telecommunications (ECSAT, the UK’s ESA centre) and the Harwell Campus. I was surprised hear the comparison that the Harwell Campus site is roughly equivalent to the size of the City of London. Whilst Harwell doesn’t yet have any of the iconic tall buildings of the City, it does mean it has plenty of space to grow – with plans to increase the campus to 5 500 jobs by 2020; although it was acknowledged that an upgrade of the underpinning infrastructure would be needed to support this.

Sam presenting at the 2016 Appleton Space Conference. Image courtesy of Sara Huntingdon, Space for Smarter Government Programme.

Sam presenting at the 2016 Appleton Space Conference. Image courtesy of Sara Huntingdon, Space for Smarter Government Programme.

After the break we swapped to the topics of growth and innovation. The Autumn Statement had a strong focus on creating an environment for backing winners, with Innovation UK targeted on turning scientific excellence into economic input and scaling up high potential businesses. Two quotes from Tim Just (Innovate UK) that particularly resonated with me:

  • Research is the transformation of money into knowledge; and
  • Innovation transforms it back again.

There was also a debate on whether the space industry is reaching the threshold for a tipping point as outlined in Malcolm Gladwell’s criteria – i.e., where a slow moving trend reaches critical mass and causes a larger change such as the use of space applications and technologies becoming the everyday norm. The last two talks before lunch were on the development of new instruments – including the recently launched Sentinel-3 mission.

The first afternoon session was on understanding scientific advances. We started off by discussing exoplanets (a planet which orbits a star outside the solar system), followed by detecting signals using ground based radars and then understanding gravitational waves. My own talk on harnessing the increasing volumes of Earth Observation (EO) data came at the end of this session. I focused on discussing how there has been a massive change in the amount of available EO data with the need to bring the abilities of computers and humans together to best use this wealth of information.

The slides from my presentation can be found here. It was interesting to see some of the messages people took away from my talk on Twitter such as:

  • The availability of free satellite data is revolutionising remote sensing
  • We have to make the most out of the large quantity of data made available by Earth Observation

After lots of people coming to talk to me during coffee it was great to see Paul Jerram from e2V showing what EO sensors look like, ranging from much larger version of the snapshot imagers found in smart phones to time delay imagers that collect the signal over a period of time so we can have very high resolution imagery. For example, the planet Mars is being imaged at 30 cm resolution. Prof Martin Wooster (Kings College London) focused on biomass burning emissions. Research has shown that the Malaysian fires in 2015, linked to El Nino, contributed to 15% of the global carbon dioxide increases that year but also to thousands of deaths due to the air pollution they caused.

Our day of talks concluded with a keynote lecture by Tim Peake, giving a personal insight into his mission into Space onboard the International Space Station (ISS). As an afternoon speaker I had a front row seat, and so I’m easily spotted on Tim’s room selfie! It was interesting to hear that Tim found adjusting to gravity back on Earth more difficult than weightlessness in space. How much he enjoyed his time on the ISS was obvious when he said he’d be happy to go again as the journey into space was particularly exhilarating.

Whilst aboard the ISS Tim used his limited amount of spare time on Sundays to take photographs of the Earth. Anyone who followed Tim on Twitter will have seen some of these, but he has also now brought out a book of these pictures titled ‘Hello, is this planet Earth? My View from the International Space Station’. An interesting footnote, although not from the conference, is that the UK has just purchased the capsule Tim used to get to, and from, space and it will go on display in the Science Museum next year.

Overall, it was a fantastic day jam packed with interesting, exciting and inspiring discussions about space!

Small Satellites Step Forward

Artist's concept of one of the eight Cyclone Global Navigation Satellite System satellites deployed in space above a hurricane. Image courtesy of NASA.

Artist’s concept of one of the eight Cyclone Global Navigation Satellite System satellites deployed in space above a hurricane. Image courtesy of NASA.

We’re all about small satellites with this blog, after looking at the big beast that is GOES-R last week. Small satellites, microsatellites, cubesats or one of the other myriad of names they’re described as, have been in the news this month.

Before looking at what’s happening, we’re going to start with some definitions. Despite multiple terms being used interchangeably, they are different and are defined based around either their cubic size or their wet mass – ‘wet mass’ refers to the weight of the satellite including fuel, whereas dry mass is just the weight of satellite:

  • Small satellites (smallsats), also known as minisats, have a wet mass of between 100 and 500 kg.
  • Microsats generally have a wet mass of between 10 and 100 kg.
  • Nanosats have a wet mass of between 1 and 10 kg.
  • Cubesats are a class of nanosats that have a standard size. One Cubesat measures 10x10x10 cm, known as 1U, and has a wet mass of no more than 1.33 kg. However, it is possible to join multiple cubes together to form a larger single unit.
  • Picosats have a wet mass of between 0.1 and 1 kg
  • Femtosats have a wet mass of between 10 and 100 g

To give a comparison, GOES-R had a wet mass of 5 192 kg, a dry mass of 2 857 kg, and a size of 6.1 m x 5.6 m x 3.9 m.

Small satellites have made headlines for a number of reasons, and the first two came out of a NASA press briefing given by Michael Freilich, Director of NASA’s Earth science division on the 7th November. NASA is due to launch the Cyclone Global Navigation Satellite System (CYGNSS) on 12th December from Cape Canaveral. CYGNSS will be NASA’s first Earth Observation (EO) small satellite constellation. The mission will measure wind speeds over the oceans, which will be used to improve understanding, and forecasting, of hurricanes and storm surges.

The constellation will consist of eight small satellites in low Earth orbits, which will be focussed over the tropics rather than the whole planet. Successive satellites in the constellation will pass over the same area every twelve minutes, enabling an image of wind speed over the entire tropics every few hours.

Each satellite will carry a Delay Doppler Mapping Instrument (DDMI) which will receive signals from existing GPS satellites and the reflection of that same signal from the Earth. The scattered signal from the Earth will measure ocean roughness, from which wind speed can be derived. Each microsatellite will weigh around 29 kg and measure approximately 51 x 64 x 28 cm; on top of this will be solar panels with a span of 1.67 m.

The second interesting announcement as reported by Space News, was that NASA is planning to purchase EO data from other small satellite constellation providers, to assess the quality and usability of that data. They will be one-off purchases with no ongoing commitment, and will sit alongside data from existing NASA missions. However, it is difficult not to assume that a successful and cost effective trial could lead to ongoing purchases, which could replace future NASA missions.

It’s forecast that this initiative could be worth in the region of $25 million, and will surely interest the existing suppliers such as Planet or TerraBella; however, in the longer term it could also attract new players to the market.

Finally in non NASA small satellite news, there was joint announcement at the start of the month by the BRICS states (Brazil, Russia, India, China and South Africa) that they’d agreed to create a joint satellite constellation for EO. No further detail is available at this stage.

Once again, this shows what a vibrant, changing and evolving industry we work in!

GOES-R Goes Up!

Artist impression of the GOES-R satellite. Image courtesy of NASA.

Artist impression of the GOES-R satellite. Image courtesy of NASA.

On Saturday, 19th November, at 10.42pm GMT the Geostationary Operational Environmental Satellite-R Series (GOES-R) is due to be launched from Cape Canaveral in Florida, USA.

The GOES-R is a geostationary weather satellite operated by the National Oceanic & Atmospheric Administration (NOAA) Department of the US Government. It will the latest in the NOAA’s GOES series of satellites, and will take the moniker GOES-16 once it is in orbit, joining the operational GOES satellite constellation comprising of GOES-13, GOES-14 & GOES-15.

It will be put into a geostationary orbit at around 35 800 km above the Earth which will allow it to match the Earth’s rotation, meaning that it will effectively stay over a specific point on the Earth. It will be located approximately at 137 degrees West longitude, and through the constellation will provide coverage for North, Central and South America together with the majority of the Atlantic and Pacific Oceans.

Artists impression GOES-R satellite and its instruments. Image courtesy of NASA.

Artists impression GOES-R satellite and its instruments. Image courtesy of NASA.

The instrument suite aboard the satellite has three types: Earth facing instruments, sun facing instruments and space environment instruments.

Earth Facing Instruments: these are the ones we’re most excited about!

  • Advanced Baseline Imager (ABI) is the main instrument and is a passive imaging radiometer with 16 different spectral bands: two visible bands – Blue and Red with a spatial resolution of 0.5km, four near-infrared with spatial resolutions of 1 km; and ten infrared bands with a spatial resolution of 2 km. As its in a geostationary orbit its temporal resolution is extremely high with the full mode being where the Western Hemisphere is imaged every 5 – 15 minutes, whereas in its Mesocale mode (providing a 1000 km x 1000 km swath) the temporal resolution is only 30 seconds.
  • Geostationary Lightning Mapper (GLM) is, as the name suggests, an instrument that will measure total lightning, and both in-cloud and cloud-to-ground lightning across the Americas. It is an optical imager with a single spectral band of 777.4 nm which can detect the momentary changes in the optical scene caused by lightning. The instrument has a spatial resolution of approximately 10 km.

Sun Facing Instruments

  • Extreme Ultraviolet and X-ray Irradiance Sensors (EXIS) instrument has two sensors to monitor solar irradiance in the upper atmosphere; these are the Extreme Ultraviolet Sensor (EUVS) and the X-Ray Sensor (XRS).
  • Solar Ultraviolet Imager is a telescope monitoring the sun in the extreme ultraviolet wavelength range.

Space Environment Monitoring Instruments

  • Space Environment In-Situ Suite (SEISS) consists of four sensors:
    • Energetic Heavy Ion Sensor (EHIS) to measure the proton, electron, and alpha particle fluxes at geostationary orbit.
    • Magnetospheric Particle Sensor (MPS) is a magnetometer measuring the magnitude and direction of the Earth’s ambient magnetic field; and has two sensors the MPS-LO and MPS-HI.
    • Solar and Galactic Proton Sensor (SGPS) will, as the name indicates, measure the solar and galactic protons found in the Earth’s magnetosphere.
  • Magnetometer will measure of the space environment magnetic field that controls charged particle dynamics in the outer region of the magnetosphere.

The ABI instrument is the most interesting to us in terms of Earth observation, and it will produce a remarkable 25 individual products including Aerosol Detection, Cloud and Moisture Imagery, Cloud Optical Depth, Cloud Particle Size Distribution, Cloud Top Measurements, Derived Motion Winds & Stability Indices, Downward Shortwave Radiation at the Surface, Fire/Hot Spotting, Hurricane Intensity Estimation, Land Surface Temperature, Moisture & Vertical Temperature Profiles, Rainfall Rate, Reflected Shortwave Radiation at the Top Of Atmosphere, Sea Surface Temperature, Snow Cover, Total Precipitable Water and Volcanic Ash. If you want to look at the details of specific products then there are Algorithm Theoretical Basis Documents (ABTDs) available, which are like a detailed scientific paper, and can be found here.

The GOES-R is the first in a series of four satellites to provide NOAA with improved detection and observation of environmental events. It is not a cheap series of satellite, with the cost of developing, launching and operating this series estimated to be around $11 billion. However, this will provide observations up to 2036.

We’re excited by this launch, and are looking forward to being able to utilise some of this new generation weather information.

Ten Top Tips Learnt Working for a Small Remote Sensing Company

Artist's rendition of a satellite - mechanik/123RF Stock Photo

Artist’s rendition of a satellite – mechanik/123RF Stock Photo

I am approaching the end of my year at Pixalytics, and this blog is summary of what I’ve learnt from working for a small commercial remote sensing company.

The work itself has been a real blessing for me. Remote sensing product development was just the role I had been looking for, so I took it on with relish. During the year I have spent time researching, and supporting the product development of, flood mapping using SAR imagery, vegetation time series and light pollution.

I’ve learnt a huge amount over the past twelve months, and here are my top ten tips on researching & developing remote sensing products:

  1. Keep in mind who your stakeholders are and exactly what they require.
  2. Ensure your ground site is really covered by the satellite image, as coverage tends to be diagonal rather than straightforward latitude and longitude square and can miss a site altogether.
  3. Practise program version control at all times!
  4. Check the images you are using are the best ones for your requirements, i.e., not 16 day composites when daily images are more suitable and available; stopping you wasting a day downloading the wrong images!
  5. Write down problem solving routines, so next time you can do it for yourself!
  6. It’s always important to run pilots and streamline programming. This will save time and effort, and help verify that your end product is statistically robust.
  7. Write down what you find and keep good records of your algorithms and programming, so that you don’t duplicate work.
  8. Write technical notes on your work, so that programs can be easily shared, reviewed and run by others.
  9. Allow sufficient time before deadlines for reviewing and reworking.
  10. Make notes on the data you are using as you go along, including source, dates, locations and any company/organisation credits needed.

These are all lessons I’ll be taking with me when I leave, whether in commerce or academia.

It’s also been an insight into how a business is run, via these activities and hearing (one side!) of Sam’s teleconferences. Plus I’ve been involved in valuable encounters with the Environment Agency on products and have attended conferences, and given a presentation at one, on behalf of Pixalytics.

Plymouth has also been fun to explore. I’ve enjoyed visiting the various arts venues all over the city together with the galleries and museums, festivals and excellent cuisine.

Many thanks to Sam and Andy at Pixalytics for giving me this opportunity. I’m sad to leave and have enjoyed my time here.

Blog written by Dr Louisa Reynolds.

Remote Sensing: Learning, Learned & Rewritten

Image of Yemen acquired by Sentinel-2 in August 2015. Data courtesy of ESA.

Image of Yemen acquired by Sentinel-2 in August 2015. Data courtesy of ESA.

This blog post is about what I did and what thoughts came to mind on my three-month long ERASMUS+ internship at Pixalytics which began in July and ends this week.

During my first week at Pixalytics, after being introduced to the Plymouth Science Park buildings and the office, my first task was to get a basic understanding of what remote sensing is actually about. With the help of Sam and Andy’s book, Practical Handbook of Remote Sensing, that was pretty straightforward.

As the words suggest, remote sensing is the acquisition of data and information on an object without the need of being on the site. It is then possible to perform a variety of analysis and processing on this data to better understand and study physical, chemical and biological phenomena that affect the environment.

Examples of programming languages: C, Python & IDL

Examples of programming languages: C, Python & IDL

I soon realized that quite a lot of programming was involved in the analysis of satellite data. In my point of view, though, some of the scripts, written in IDL (Interactive Data Language), were not as fast and efficient as they could be, sometimes not at all. With that in mind, I decided to rewrite one of the scripts, turning it into a C program. This allowed me to get a deeper understanding of satellite datasets formats (e.g. HDF, Hierarchical Data Format) and improve my overall knowledge of remote sensing.

While IDL, a historic highly scientific language for remote sensing, provides a quick way of writing code, it has a number of glaring downsides. Poor memory management and complete lack of strictness often lead to scripts that will easily break. Also, it’s quite easy to write not-so-pretty and confusing spaghetti code, i.e., twisted and tangled code.

Writing C code, on the other hand, can get overly complicated and tedious for some tasks that would require just a few lines in IDL. While it gives the programmer almost full control of what’s going on, some times it’s just not worth the time and effort.

Instead, I chose to rewrite the scripts in Python which I found to be quite a good compromise. Indentation can sometimes be a bit annoying, and coming from other languages the syntax might seem unusual, but its great community and the large availability of modules to achieve your goals in just a few lines really make up for it.

It was soon time to switch to a bigger and more complex task, which has been, to this day, what I would call my “main task” during my time at Pixalytics: building an automated online processing website. The website aspect was relatively easy with a combination of the usual HTML, Javascript, PHP and CSS, it was rewriting and integrated the remote sensing scripts that was difficult. Finally all of those little, and sometimes not quite so little, scripts and programs were available from a convenient web interface, bringing much satisfaction and pride for all those hours of heavy thinking and brainstorming. Hopefully, you will read more about this development in the future from Pixalytics, as it will form the back-end of their product suite to be launched in the near future.

During my internship there was also time for events inside the Science Park such as the Hog Roast, and events outside as well when I participated at the South-West England QGIS User Group meeting in Dartmoor National Park. While it is not exactly about remote sensing, but more on the Geographic Information System (GIS) topic it made me realize how much I had learned on remote sensing in my short time at Pixalytics, I was able to exchange my opinions and points of view with other people that were keen on the subject.

A side project I’ve been working on in my final weeks was looking at the world to find stunning, interesting (and possibly both) places on Earth to make postcards from – such as one at the top of the blog. At times, programming and scientific research reads can get challenging and/or frustrating, and it’s so relaxing to just look at and enjoy the beauty of our planet.

It is something that anyone can do as it takes little knowledge about remote sensing. Free satellite imagery is available through a variety of sources; what I found to be quite easy to access and use was imagery from USGS/NASA Landsat-8 and ESA Sentinel-2. It is definitely something I would recommend.

Finally, I want to say “thank you” to Sam and Andy, without whom I would have never had the opportunity to get the most out of this experience, in a field in which I’ve always been interested into, but had never had the chance to actually get my hands on.

Blog written by Davide Mainas on an ERASMUS+ internship with Pixalytics via the Tellus Group.