Identifying Urban Sprawl in Plymouth

Map showing urban sprawl over last 25 years in the areas surrounding Plymouth

Map showing urban sprawl over last 25 years in the areas surrounding Plymouth

Nowadays you can answer a wide range of environmental questions yourself using only open source software and free remote sensing satellite data. You do not need to be a researcher and by acquiring a few skills you can the analysis of complex problems at your fingertips. It is amazing.

I’ve been based at Pixalytics in Plymouth, over the last few months, on an ERAMUS+ placement and decided to use Plymouth to look at one of the most problematic environmental issues for planners: Urban Sprawl. It is well known phenomenon within cities, but it can’t be easily seen from ground level – you need to look at it from space.

The pressure of continued population growth, the need for more living space, commercial and economic developments, means that central urban areas tend to expand into low-density, monofunctional and usually car-dependent communities with a high negative ecological impact on fauna and flora associated with massive loss in natural habitats and agricultural areas. This change in how land is used around cities is known urban sprawl.

As a city Plymouth suffered a lot of destruction in World War Two, and there was a lot of building within the city in the 1950s and 1960s. Therefore, I decided to see if Plymouth has suffered from urban sprawl over the last twenty-five years, using open source software and data. The two questions I want to answer are:

  1. Is Plymouth affected by urban sprawl? and
  2. If it is, what are Plymouth’s urban sprawl trends?

1) Is Plymouth affected by urban sprawl?
To answer this question I used the QGIS software to analysis Landsat data from both 1990 and 2015, together with OpenStreetMap data for natural areas for a 15 kilometre area starting from Plymouth’s City Centre.

I then performed a Landscape Evolution analysis, as described in Chapter 9 of the Practical Handbook of Remote Sensing, written by Samantha and Andrew Lavender from Pixalytics. Firstly, I overlaid natural areas onto the map of Plymouth, then added the built up areas from 2015 shown in red and finally added the 1990 built-up areas in grey.

Detailed map showing the key urban sprawl around Plymouth over last 25 years

Detailed map showing the key urban sprawl around Plymouth over last 25 years

The map, which has an accuracy of 80 – 85%, shows you, no major urban development occurred in the city of Plymouth and its surroundings in the last 25 years – this is of course about to change the development of the new town of Sherford on the outskirts of the city.

However, as you can see in the zoomed in version of the map on the right, there is a noticeable urban development visible in the north west of the city and a second in Saltash in Cornwall on the east of the map. The built up area in the 15km area around Plymouth increased by around 15% over the 25 year period. The next question is what are the trends of this sprawl.

2) What are Plymouth urban sprawl trends?
A large amount of research tries to categorize urban sprawl in various types:

  • Compact growth which infill existing urban developments, also known as smart growth, and mainly occurs in planning permitted areas
  • Linear development along main roads
  • Isolated developments into agricultural or wildlife areas in proximity with major roads.

These last two have a bad reputation and are often associated with negative impacts on environment.

Various driving forces are behind these growth types, creating different patterns for cities worldwide. For example, rapid economic development under a liberal planning policy drives population growth in a city which then is expands and incorporates villages located in near or remote proximity over time. This is fragmented approach, and results in a strong land loss.

But this is not the case for Plymouth which in the last 25 years showed a stable development in the extend permitted by planning policies with a predominant infill and compact expansion, a smart growth approach that other cities could take as an example.

These conclusions can be taken following only a few simple steps- taking advantage of free open source software and free data, without extensive experience or training.
This is a proven example of how you can make your own maps at home without investing too much time and money.

This is the end my internship with Pixalytics, and it has been one of my best experiences.

Blog written by Catalin Cimpianu, ERASMUS+ Placement at Pixalytics.

The Road To Success….

Danube river crossing The Great Romanian Flood Plain. Image acquired by Sentinel-2A on the 3rd December 2015. Data courtesy of ESA.

Danube river crossing The Great Romanian Flood Plain. Image acquired by Sentinel-2A on the 3rd December 2015. Data courtesy of ESA.

‘On the road, you will face many stumbling blocks, twists, and turns… You may never know how far the road will take you.’ **

In my case, the road brought me to Plymouth, a city on the south coast of Devon, England, a magical place with great history and outstanding views.

What I am doing here? Well, I am pursuing my dream of becoming a GIS and Remote Sensing Specialist by doing an internship through the Erasmus + programme at a local company called Pixalytics. My mentor is Dr. Samantha Lavender, is a great professional with vast experience in this field, She is also the Chairman of the British Association of Remote Sensing Companies and former Chairman of the Remote Sensing & Photogrammetry Society. For me, this is about more than just getting a grade, earning credit, or making money; this is an opportunity to learn, ask questions, and impress with my eagerness.

Finding this internship was easy for me. With a short search on Google I found this Pixalytics blog, where a previous student here had posted her impressions and thoughts on the company. I immediately said “This worth trying!” In the next moment I opened my email started writing, I sent wrote emails to multiple addresses, to make sure my message reached the target. After just two days, I received an answer from Mr. Andrew Lavender and it was positive!

I was very happy and because I knew the departure papers would take over a month to be completed, I immediately started doing them. All of this happened at the end of September. After my papers were done, I bought my flight ticket to Luton Airport, then a bus to London and then onto Plymouth. I arrived on December 5th and so, like the previous student, here I am posting my own impressions and thoughts on the Pixalytics blog page.

My first day at Pixalytics started pretty badly, I got lost and arrived a little late. I now remind myself each morning to turn left, not right, when I get off the bus. I got a short introduction to the building where the company is located, and my office for the next three months, which by the way looks very good. The office has a professional, but relaxed, atmosphere and I soon started working, one of my first tasks being the downloading of Sentinel-2A data, which proved a very difficult one due to slow data speeds and functionality of the ESA Data Hub.

Over the next three months, I am expecting to assist Pixalytics in developing their agritech products, explore the potential of Sentinel-2A data and I will be doing my own research into Urban Sprawl in Romania. I am hoping to have the opportunity to present my research at a conference during my placement.

It has been over a week now since I came to Plymouth and I feel great, working at Pixalytics is a great opportunity for my career and I will take full advantage of this. I strongly recommend all students who want to burst their work experience and who want to see what it is like to be in a professional business environment, to search for Erasmus+ placement offers as I did. You will not regret it!

Blog written by Catalin Cimpianu

** Quote is by Tony Hassini, from ‘The Road To Success’

Practical Handbook of Remote Sensing

Book ArrivalOur first book is out now!!! A dull and damp Saturday afternoon was spectacularly brightened by a deliveryman’s knock at the door, who handed over our first copies of the Practical Handbook of Remote Sensing – as you can see in the picture. It was the first time we’d got the finished paperback in our hands. Very exciting!

The book was written by us, Samantha Lavender and Andrew Lavender, and is published by CRC Press of the Taylor & Francis Group. It is a general how-to guide for anyone wanting to use remote sensing, guiding inexperienced individuals through the principles and science of remote sensing, and giving them the skills to undertake practical remote sensing at home with just a computer and free-to-access desktop software.

It’s a book Sam has wanted to write for many years: something which we hope opens up the exciting field we work in to new people. However she quickly realised that if she was writing an ‘idiots guide’, she needed an idiot – which she says is where I came in! Personally, I prefer the publisher description of me as a non-expert navigating the subject for the first time.

The first half of the book begins with the basic principles and history of remote sensing, next we have the science behind remote sensing and image processing and finally the first half is finished off with chapters on practical remote sensing and image processing with a variety of example exercises. The second half is focussed on applications of remote sensing within both land and marine environments, with details on the applications, scientific theory of the remote sensing techniques and associated practical exercises.

We aimed to make the book practical, readable and easy to understand. The principle we used was that if I couldn’t understand a section of the book, it had to be rewritten until I could understand it! We have also based it on open source software, using ESA’s Sentinel Application Platform (SNAP) and QGIS as our remote sensing and geographical information systems software. The default dataset we’ve used is Landsat; again as it is freely accessible, although a number of other datasets are also included.

We’d also like to start to build a community of ‘new’ remote sensors and so we launched a complementary website last weekend, www.playingwithrsdata.com – designed and written by the excellent i-Create Design and Square Apple. The website will keep the book users updated on any changes to software or data used in the book, provide additional exercises and a forum for people to ask questions and continue their learning.

We’re both very excited and proud about having our first book published, and we hope that people will enjoy reading it and working through the exercises to gain new skills. What’s that? You want to know where you can immediately get hold of a copy of the Practical Handbook of Remote Sensing. Well, clicking on this link will take you to our wonderful publishers who can make that happen!

Pixalytics is growing!

Practical Handbook of Remote Sensing CoverThe last week has seen two significant firsts for Pixalytics!

  • Our first book, Practical Handbook of Remote Sensing, has gone on presale!
  • Our first full time employee joined the company!

Right at the outset of establishing Pixalytics, we put down the DNA of the company we wanted to develop. Science is at the heart of Pixalytics, and we use our scientific knowledge to undertake research and development, provide products and services and to promote the scientific education and knowledge.

As part of that educational strand, we’ve written a book this year. It’s a book Sam has wanted to write for a long time, and takes people without any prior knowledge through the basic principles and science of remote sensing, gives them practical skills to undertake basic remote sensing at home and demonstrates the various applications where remote sensing can be used.

Sam quickly recognised that if she was going to write a general how-to book, she needed someone who knew nothing about the subject, which is where I came in. So together we co-wrote the book combining Sam’s 20 years of experience with my non-expert perspective of navigating through remote sensing for the first time. I have proof-read, tested and applied everything in the book; and so if I can learn remote sensing from it, anyone can!!

The book uses open source software as we wanted it to be as accessible as possible, and will be supported by a website offering news, updates, a learning forum and further exercises for people who’ve bought the book.

The book, Practical Handbook of Remote Sensing, is published by CRC Press of the Taylor & Francis Group. It went on pre-sale last week, and the actual paper copies are due to be shipped later this month. If you are interested you can order a copy here, or if you have any questions, please get in touch.

The second first for us is that we now have a full time employee, Dr Louisa Reynolds! Up until now Pixalytics has just been Sam and I, we’ve had the occasional short-term Erasmus student, PhD student, MSc placements and work experience people along the way, but not a full time employee. We’ve steadily grown the business over the last few years and we’ve reached the point where Sam no longer has enough hours in the day to do the work we have; although, Sam might say we reached that point a little while ago!

Hence, on Monday Louisa joined Pixalytics as an Earth Observation Scientist and brings with her strong skills in remote sensing, image processing, astrophysics, atmospheric and ocean physics. She will be providing support to Sam on all aspects of our Earth Observation and remote sensing work. This will significantly increase the capacity and capability of the company, which will hopefully lead to exciting new work in the future.

Overall, these are both major milestones for us and we’re delighted to welcome both Louisa and the Practical Handbook of Remote Sensing to Pixalytics.