How to use Google Earth for Research and Recording

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Puffin
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How to use Google Earth for Research and Recording

Post by Puffin »

Every now and then someone asks a question about Google Earth, http://earth.google.com/ which is normally answered within the forum. It was then suggested that an article may be of permanant use, so here goes.

What is Google Earth and how can we use it as metal detectorists?

Well for those that don't know what Google Earth is, it's a fantasic downloadable tool for looking at the surface of the earth from above. You can zoom in and out, rotate and generaly fly around the landscape of your choice. But once you have been playing with it for a while, you realise that much more can be achived. Contory to a common believe, Google Earth is not made up of satalite images, but high quality photographs taken from an airplane flying a set pattern. These are updated on a regular basis so if you spot something worth looking at, save the image to your hard disc, because it will disappear.

The images on Google Earth can show up some interesting archeological features that are not seen from ground level, so this is a real bonus when looking for possible detecting sites to ask premission for. However, once you have permission to detect an area, what other benefits do you get from using Google Earth. Well I'll tell how I use it, others will do things differently and no doubt you will find a way to use it for you own benefit.
Fields without overlay.jpg
Fields without overlay.jpg (137.23 KiB) Viewed 6051 times
What about comparing 19th century OS maps with present day data?

First I look up a website called, http://www.british-history.ac.uk/map.aspx?pubid=270 This site has a series of free 19th century OS map images which can be saved to your hard drive, I select the area I want, zoom in and save a small section of map. Zoom level "HIGH", right click, "SAVE PICTURE AS", then save to your hard drive. Open up Google Earth, go to the area of interest, click "ADD" at the top of the page and click on "IMAGE OVERLAY", this will open up your hard drive, click on "BROWSE", find the map image that you want to overlay, click on it and it will be loaded over the top of the view you have on Google Earth. You have to then rotate, using the green diamond, Scale, stretch and pull the map image using the green corner lines and move the map image using the cross at the centre of the image. At the side of the image overlay, there is a "Proporties Box" which you can use to edit the file details along with displaying the corner coordinates of the overlay, there is also a slide control so that you can slowly make the map image transparent this lets you see the Google Earth image underneath. This way you can directly compare the two images, that modern crop mark turns out to be a 19th century hedge line or cart track, always worth looking at with your detector.
With oldmap overlay.jpg
With oldmap overlay.jpg (94.11 KiB) Viewed 6061 times
You can permently save the overlay, which can be turned on and off or re-edited. On the tool bar at the top of the page, you will see a small rectangle icon. white on the left and blue on the right. Click this, this brings up a "drop down" on the left side of the screen. If you look here you will see "PLACES" under which you will find your map image overlay file name. Left click to highlight, then right click. After a little while a dialogue box pops up, go to the bottom of this, to "PROPORTIES" click here. This re-opens the "Control Box" and allows you to edit and reposition your image overlay. (green corners reappear).

A couple of overlay possibilities have cropped up on a resent thread. Leeolitina kindly gave us a link to this site. http://www.brock-family.org/gavin/google-earth/ brilliant, once loaded, as you roam you get a permenant OS map overlay that follows you. The problem is it only displays OS maps at 1:50,000 and street map scales. The more useful 1:25,000 scale that shows hedge lines and footpaths, does not display. I've found out that the OS still have not released the 1:25,000 maps for free distribution. Sadly it means paying for them.

After a little Googling I found http://www.Anquet.co.uk where you down load a programme onto your PC. This programme allows you to purchase and download 1:25,000 scale OS maps. Minimum order £10.00 for a reasonable area. But because Anquet only allows you a personal License you can only use the downloaded map within the Anquet programme. You can print it out and transfer the map to a small range of smart phones and PDA's with GPS built in. So how do you get the Anquet Map file format onto Google Earth? Well you don't, not directly. Using a small programme called MapCapt http://users.skynet.be/hofinger/MapCapt.html you can capture an area off the screen and save it as a .jpg file. Get where I'm going? Hope so!
25000 overlay.jpg
25000 overlay.jpg (94.16 KiB) Viewed 6062 times
First load MapCapt and minimise, then load Anquet and the map your interested in, enlarge the area until you have at least 2 by 6 OS grid squares depending on your monitor size/shape. The smaller the area enlarged, the better, as the resulting saved image is a lowish resolution and it is easier to aline the saved .jpg image in Google Earth without too much distortion. Restart MapCapt then select the two opposite corners of the area you want and save the resulting file. You can configure MapCapt to remember the corners of different map viewers, which can be called back up later.

Close both programmes and start Google Earth. Go to the area you are interested in. Click "ADD", "IMAGE OVERLAY", "BROWSE", find the saved .jpg, click. A box will show on Google Earth which you can stretch, rotate and pull until it fits the area. To help you do this, there is a slider control in the dialogue box, which fads the image in and out, so you can see under the image. There you have it, reasonable quality OS 1:25,000 map overlays in Google earth. Which will be more useful then the 1:50,000 maps. Whatever overlay you play with, it's always useful to print out the image from within Google or save it to your Hard Drive or back it up elsewhere just in case.

What else can you do in Google Earth?

Well, I also record my find spots and walking/detecting route on Google Earth. I use a personal GPS unit to do this. An eTrex Personal Navigator, see the April 2008 issue of the Searcher for an article on Garmin GPS units, which I used to use on a lanyard around my neck. However I was having problems with the signal dropping out with intermitant track recording. I got around this by using a belt mounted camera case to house the GPS unit, making sure the screen faces away from my body, as the GPS signal receiver is under the screen. I still use the lanyard to attach the GPS to the case, preventing losing it in the middle of the field. The information I gather consists of Track Data and Waypoints. It's a basic machine, but you can set it to automatically record you position either on a timed basis or distance travelled. Basically a track is a digital dot to dot. I've set mine to record every 10 feet, which after 7 hours of detecting, accounts for about 20% of the units memory. To record a find spot, press a button on the GPS which records a "Waypoint", issuing a number on the display, this is then manually transfered onto a clip top fines bag with a date, using a Sharpie water proof marker pen. Takes about half a minute to do in the field. Sometimes it takes me a week or two to catalogue the finds, hence the date. If I numbered every find I would end up creating masses of useless data, ring pulls and scrap ali etc. are not recorded.

I had to buy extra cables to down load the stored data, as the cheaper units don't come with them, a Garmin data cable which is an older serial connector and a serial to USB Converter from Maplins. If you go to http://www.gpsu.co.uk and download and register the GPS Utility, a programme that will down load, convert and save the data to .kml the default Google file formate. A cracking programme that does lots of other stuff, including uploading your own Waypoints to the GPS unit. Say you see a feature on google earth, note its lat. and long. input it into GPSU then upload. When in the field, just navigate to within 5m of the feature which may not be visible on the ground. I then just go into Google Earth, load the file .kml, via "FILE", "OPEN", and Google Earth displays the Waypoints and the Track. These can be edited further within Google Earth using the same method to open "PLACES", "PROPERITIES" above, you can edit the Waypoint Icons, changing the referance numbers, colours, attaching pictures or add a description. So when you click on the icon/waypoint you can see and read about the find. As I date and number both the find bag and Google file with the same date, I can cross referance them together at a later date. GPSU can also be set up to convert the GPS units Lat. Long. data to OS grid referances to 10 digits plus Alpha prefix. At this point I should say, I also keep a handwritten note book recording these details as a hardcopy backup.

While in the "PLACES" section you can Drag and Drop the files into folders to order them, otherwise you will end up in a mess, I like to give each field a number and Parish referance. E.G. W14-001, this translates as Walsall field 14 object number 001. So I've got a folder called Walsall within which I have a number of folders for each field, that way I place each days detecting data in the right field folder. Easier to track the files. You can do the same thing with the individual map overlays. You can also turn the overlays "ON" or "OFF" by "CHECKING" the box next to the file name in the "PLACES" section. This unique number is also written on a new, clean bag with the cleaned find ready for storage.

I've read about a number of other ways of recording your finds in Google Earth. One is to print out a copy of the field map, record the approximate position of the find with a pen, while in the field. When you get back home you can manually transfer the data into Google Earth by centering the find spot on screen, then click the "PUSH PIN" Icon on the tool bar, A short while later a "Proporties dialogue box" opens. You can move the "Push Pin" to the right location then asign a description in the Proporties Box, then "SAVE" it.

PhilD, has also come up with this link, http://maps.google.co.uk/maps/mpl?modul ... applet.xml which allows you to pin point your find spot on Google Earth then get an OS grid referance for your FLO when you record your find with the PAS. I'm sure that there is a ton of things that you can do with Google Earth, just Google "Google Earth Hacks" for a selection of them.

If you do the same field on a regular basis, you can start to build up a pattern or profile for the area covered. I use different coloured track lines for each trip, white icons for coins and square icons for PAS recorded finds. It surprised me just how little of an area I really cover per trip, I average according to the GPS, about 3 miles per day. A year down the line, when you next get to go on that field again, as least you can see the areas that need double checking or missed the first time around.

Thanks to the power of Google Earth.

Have fun, Puffin.
Deus, XP GMP, CS 4Pi, Canon 450d, Garmin GPS, PAS Self Recorder.
Hamster Count 55. Then so far this year 0 to the Deus.
Denarius Count 7. Then so far this year 0.

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bodvoc
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Re: How to use Google Earth for Research and Recording

Post by bodvoc »

Wow, that was a great post puffin. I am totally in the stone age when it comes to this excellent style of site mapping. Definately food for thought.
Professionally aimless wandering.

seDEUSed

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