Google Earth as a GIS

Contents:

Looking at Change over time in Google Earth Downloading Maps from emapsite Creating Overlays in Google Earth

Graeme Eyre, Anglo European Schooleyreg@aesessex.co.uk

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Looking at Change over Time in Google Earth

The amount of different images you have available will depend on the region you are looking at.

1. Open Google Earth.

2. Zoom to your chosen destination.

3. Click on the ‘show historical imagery button’ ( )

4. You can then use the slider to move between different dates.

The best area that I have found to explore this is The Bird’s Nest Stadium In China. Type ‘National Stadium, Beijing in the search box.

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Accessing OS Maps from ‘eMapSite’ under the ‘Map Pilot’

1. Go to the website: http://www.emapsite.com/mapshop/

2. Click on the ‘My Emapsite’ button in the top right hand corner of the page.

3. Login using your email address and password.

4. You will then return to the homepage but your name and organisation should appear in the top right hand corner.

5. In the large search box on the website type in the name of the location you wish to get an OS map for, e.g. the town name. Then press ‘go’

6. If multiple options for that town name is found you will need to select the one that you meant.

7. When given the choice between ‘mapshop’ or ‘plans ahead’ select ‘mapshop’

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8. You can now use the map window to select the area that you wish to down load your map of. I suggest you use the rectangle tool. You then need to select the map type that you want using the check boxes on the left.

NOTE: Only the map types listed as part of the ‘Map Pilot’ will be free, the cost will be set as zero when you progress to the shopping basket. If you choose another type of map you will need to pay for them.

9. Click on the ‘Add Selection to basket and view’

10. You will then be taken to the shopping basket page. Change the format from ‘tif’ to ‘jpg’. The cost should be £0.00; then click on ‘buy’

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11. When you get to the choose project option, keep the default ‘no project’ and click ‘next step’.

12. Select the check box to say you accept the license. Then click ‘Next Step: Payment Options’

13. Put in a purchase order/job reference number for this order (it does not matter what you put it down is; it is purely so you can download the map. Then click ‘next step’

14. You will then see a screen telling you your order is being processed. For a small area this will typically take 30-45 seconds.

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15. After waiting about a minute click on ‘Account Summary’ and then select the ‘downloads tab’

16. You can then download your map to your computer / user area. To do this click on the download link in ‘your downloads’. Then save it somewhere in your user space.

17. The file you downloaded is a ‘zip’ file; before importing it into Google Earth you will need to unzip it.

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Adding Images as Overlays in Google Earth

In this example this is adding an OS Map over the top of the Google Earth Image.

1. Open ‘Google Earth’

2. Navigate to the approximate area that your overlay will cover.

3. Go To Add> Image Overlay or click the Add Image Overlay Button ( )7

4. Type in a title and navigate to the image you want to overlay using the ‘browse button’. Then the image should appear in the centre of the window overlaid over the Google Earth base image. Use the slider to make the image slightly opaque so that you can position it correctly.

5. Move the ‘Google Earth- New Image Overlay’ box out of to one side, but do not click on OK at this point. Then use the green handles to position the image by twisting it and resizing it so it lines up with the base mapping as best as possible. Once you are happy with the image’s position click ‘OK’.

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6. You have now created a new overlay in Google Earth.

7. If you ever want to adjust that layer after clicking okay you can open the properties box, which allows you to make adjustments as if you had just added the layer.

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Saving Google Earth Placemarks / Overlays

Google Earth automatically keeps all the place marks / overlays you have created in a session in the ‘Places’ bar on the right hand side. If you want to be able to access them next time you log on, or from a different computer, or allow other people to use them you need to save them.

1. Create a folder in ‘My Places’ Right click on my places, then Add -> Folder.

2. A Box will appear and you will need to give your new folder a name. Once you have given your folder a name click on ‘OK’

3. You now need to drag any files / place marks into that folder.

4. Once everything you want saved is in the folder, right click on the folder and choose ‘Save Place As’

5. Choose the destination of your file (where you want to save it), and the file name; keep the ‘Save as Type’ as Kmz.

6. You will then be able to open and view your place marks on any computer with Google Earth Installed.

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APPENDIX ONE: GOOGLE EARTH FILE FORMATS

When saving Google Earth objects you can save them in two formats KML or KMZ.

Google Earth objects include place marks, and overlays.

Most of the time you want to save things as KMZ

KML – Keyhole Mark-up Language

KML files link to the files elsewhere; i.e. when opening a KML file in Google Earth the image is then opened from a another location; either a location somewhere on the computer, a networked location, or somewhere via the internet.

This is useful when using live updated data, e.g. live earthquake maps.

The problem is if the remote information is moved then the KML file will not work.

KMZ – Keyhole Mark-up Language-Zipped

KMZ files are self-contained and all the image data required is included within the file itself.

This creates bigger file sizes but means that all the required elements are within one file. If you are creating a file for teaching this would usually be the file type you would use.

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APPENDIX TWO: MAP TYPES INCLUDED IN THE SCHOOLS MAP PILOT

1:250 000 Scale Colour Raster

1:250 000 Scale Colour Raster combines roads, railways, all cities, towns and many villages, and will be familiar to many as the mapping used for the OS Travel Map – Road series. With a gazetteer of over 25 000 names, 53 tiles cover the country, each 100 km by 100 km.

1:50 000 Scale Colour Raster

1:50 000 Scale Colour Raster provides a complete digital view of the popular paper OS Landranger Map series. A total of 812 tiles cover the country, each 20 km by 20 km.

1:10 000 Scale Raster

Ordnance Survey's 1:10 000 Scale Raster map data provides more detailed mapping, including fences, field boundaries, road names and buildings, and is s upplied in 5 km by 5 km edgematched tiles.

OS Street View ™

Ordnance Survey's OS Street View is street-level, backdrop map data that is specifically designed for online applications, as it has a quick download time. Shows clear street-level detail, including building outlines, woodland and water. OS Street View is supplied in 5 km by 5 km tiles.

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OS Mastermap ® Topography Layer

OS Mastermap is the largest-scale map data. The Topography Layer has nine themes, representing land area classifications; buildings; roads, tracks and paths; rail; water; terrain and height; heritage and antiquities; structures; and administrative boundaries. File sizes are very large and schools wanting data for direct download are advised to restrict an initial order to an area of 2 km by 2 km for urban areas.

OS Mastermap ® Integrated Transport  Network ™ (ITN) Layer

The ITN Layer is the definitive geographic reference for Great Britain’s road structure. It represents all navigable roads across Great Britain, from motorways to alleyways, and road routing information.

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APPENDIX THREE: Unzipping Zip Files in Windows XP

Before you use the map data image in Google Earth you need to ‘unzip’ the zip file.

1. Open ‘My Documents’ or wherever the file was saved.

2. Double Click on the Zipped Folder you wish to unzip.

3. On the folder tasks box click on ‘Extract all Files’

4. A box will come up, just click next on all the boxes accepting all the defaults. The extraction process will then run and you will be told the extraction process was successful.

5. You will then find your map images in a folder next in the same directory that your zip file was in.

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