I would like to then use the hedgerows by bringing it into QGIS as a layer. I need to know what software to use and the method to make such a layer?

I would like to use a google earth image in Grass and do a supervised classification on it for the Wigan, Bolton, Manchester and Salford area (England) They join up as a square and it is in this area I need to identify where hedgerows are located if possible. I have access to QGIS, Grass and Arc. ( I could also use free to download software).

Does anyone know of a way to achieve this?

closed as too broad by PolyGeo Oct 22 '15 at 21:59

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • 3
    This question is rather broad since it deals with a lot of sub-questions: Do you mean a Google Maps map or satellite images, as displayed in Google Earth? Do you know how to export these from Google Maps/Earth, since there are no classification tools in this software? What software/tools do you have access to, which might be able to do supervised classification (GIS software, Python, R,...)? What is the nature of your training data, I assume you have since you want to employ supervised learning? Can you please edit your question and be a bit more specific? – Kersten Jul 20 '15 at 10:48
  • Hello sorry , I mean a Google Earth image of the Wigan, Bolton, Manchester, Warrington area (England) where I would like to be able to classify hedgerows. I think the only way to do this is by supervised classification. I have access to QGIS and Grass. I am doing a habitats academic project and want a hedgerows layer to indicate green corridors so I need all the hedgerows as a layer I can put into QGIS. (I hope this is enough information). Thank you – Abigail Jul 20 '15 at 11:00
  • My university does give me access to arc as well @Kersten – Abigail Jul 20 '15 at 11:12
  • Just a sidenote, because it hasn't mentioned yet: You should carefully read googles licensing terms. They explicitly forbid you to "trace" a map using their images or alter any content based on google imagery sources. You so you know if you want to publish sth. made from google content. google.com/permissions/geoguidelines.html – Curlew Jul 20 '15 at 12:47
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    In September the Environment Agency will be releasing Lidar data for England you will be able to see hedgerows and use GIS to extract them for your project. see environmentagency.blog.gov.uk/2015/06/16/… "From September 2015 all our LIDAR data will become Open Data and everyone will be able to use it for free." – Mapperz Jul 20 '15 at 13:40

You will likely have poor success using pixel-based supervised classification techniques, especially if you only have 3 spectral bands (Red, Green, Blue) from a GE screen capture. You may be able to get at the hedgerows if you had imagery with the near-infrared band. One common technique for supervised classification is to generate a vegetation index such as NDVI and include this information band in with the spectral bands prior to doing the classification. This method will likely not work is because there will be significant pixel confusion resulting in a noisy classified product.

Alternatively, try using object-oriented feature extraction methods, which tend to produce more accurate results for your type of problem. Since hedgerows are usually linear features, you may want to try edge extraction techniques in QGIS's Morpheo toolbox. There is a good blog on Image Processing Using Orfeo Toolbox in QGIS to help get you started.

  • Thanks for suggesting this I will try it, but how do I install the Orfeo toolbox on QGIS? I haven't used python before, I'm a little lost as I'm a beginner user. Thanks – Abigail Jul 20 '15 at 12:24
  • The Orfeo toolbox is packaged with the latest version of QGIS. Even better, these are GUI based tools, so no programming required. – Aaron Jul 20 '15 at 12:28
  • So do I go on plugins and manage/install plugins? Sorry I just cant locate it – Abigail Jul 20 '15 at 13:24
  • Thank you everyone for your answers. I am going to close this question as I cannot use the Google Earth/maps image for what I want to do. – Abigail Jul 20 '15 at 13:38

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