Google Earth, Toporama and Aerial Archaeology...

[Steve]

I've been a big fan of Google Earth for over two years now. For those who've yet to discover it, Google Earth is software that allows the user to view any location on Earth from above, at any height and at any angle. It features a combination of aerial photography and satellite imagery and the user can also choose to turn on (or off) a wide range of "layers", which will overlay such things as roads, borders, points of interest, 3D structures, etc.

Now, Google Earth is not only great fun, it's also capable of revealing a very great deal of information about the world aournd us. Because it's world wide, you can visit places you might never be able to visit in person; want to visit the pyramids of Egypt? Just zip over and zoom in... But, this applies locally as well; on the ground, we're all limited to some extent to where we can travel. In part, this can be due to things like terrain considerations (plowed fields are hard to tromp through in March...), or maybe private property (not everyone wants you tromping through their fields...). Google Earth eliminates those limitations. In a place like Lambton County, with it's gridwork of roads, the spaces between these roads can be hard to access and resources like Google Earth, topographical maps and aerial imaging, in general, can help us see and explore areas we may not be able to visit in person.

But, there's far more available and this is where I'd like to talk about Aerial Archaeology. What is it? Well, let's break it down. Merriam-Webster defines archaeology as "the study of the material remains of past human life and activities". So, "aerial archaeology" just means performing that study from the air, or more accurately, from above (for a bit more detailed definition, read this). Doing so allows us to see things from a perspective that we don't have while viewing from ground level. How? Well, here's an excerpt from an "Introduction to Aerial Archaeology" at the University of Vienna's Aerial Archive:

The terms "aerial" or "remotely sensed information" already indicate, how aerial archaeology works: it uses the distant view. Archaeological sites show up on the ground surface, depending on their state of preservation, by light-shadow-contrasts (shadow marks), tonal differences in the soil (soil marks) or differences in height and color of the cultivated cereal (crop marks). In that way, settlements, graveyards, fortifications etc. produce specific structures, that can be identified easier from a high viewpoint.
In principle, you could see an archaeological feature also while standing on it, but like a cat on the carpet, you would not be able to realize any pattern, that could give you a bit more information about WHAT this site could be like. If You choose a more distant viewpoint (even if it´s only a ladder or a building), the structures become clearer to you and the pattern becomes understandable.

As you can see, aerial archaeology has been around for a long time, but it's the advent of the Internet and tools like Google Earth that's made it accessible to the general public and allows us amateur enthusiasts to join in the fun and perform our own research...

Before I bring this down to our local level and see what we can do with it, I first need to introduce you to another powerful tool available online; Toporama is Natural Resources Canada's topographic map server (read more about it here). Here you can view 'topo' maps of all of Canada, right down to quite detailed 1:50 000 scale. When used in conjunction with imaging sources like Google Earth, you have a very powerful combination of tools for discovering and studying Lambton County from above.

In my next post, I'll demonstrate the power of aerial archaeology by showing you an example of actual research that's dear to my heart: finding the route of an abandoned railway...

In the meantime, why not download Google Earth* and familiarize yourself with Toporama, so you can follow along with my example and maybe find something I missed...



* Google Earth can take a lot of computer power to run smoothly. Be sure to check the minimum requirements needed to run it and if your computer doesn't meet them, you can always use Google Maps instead. Just type in the location you want and then switch to the Satellite view, which uses the same images as Google Earth, but without all the extra navigation and layer features.

[Steve]

For over 3 years now, I've been keeping a close eye on Google Earth, in anticipation of high resolution (hi-res) imagery updates covering Lambton County. Hi-res coverage should reveal a great deal more info about Lambton's 'back 40' and it's past history, such as abandoned rail lines, etc. that are now, almost invisible from ground level. It will also help us plan our explorations and provide modern data for comparison to historical aerial imagery. (See my post on Aerial Archaeology...)

Previously, the only hi-res imagery covering Lambton County was a thin strip along the St. Clair River, on the western edge of the county. This imagery was likely overlap of hi-res satellite imagery of Michigan and it covered from Lake Huron in the north, to just north of Wallaceburg, in the south and it extended only as far east as Kimball/Modeland Road.

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Here is a perspective view in Google Earth of Lambton County showing the hi-res area along the St. Clair (brownish rectangular strip). In the distance, you can see the new hi-res area over Sarnia (whitish area). Everything to the east (left) of the hi-res is still low resolution imagery (as of April 2008).


Well, it's not the large update I was hoping for, but there is some new high resolution imagery in Google Earth covering Sarnia!

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This new imagery extends the existing hi-res coverage to the east, as far east as Mandaumin Rd and south, to just south of Churchill Ln. It appears to be somewhat higher resolution imagery than the former hi-res imagery over Sarnia. It looks to have been taken about two years ago, in the late spring (based on foliage) and in the late morning (based on shadows). The previous imagery was at least 3 years old, based on construction previously in evidence at Venetian Village in Point Edward.

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Here's a view of Mandaumin showing the transition from hi-res to low-res to show the huge difference in detail. Of course, you can zoom in much closer than this, as seen below...

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The cool thing about winter, or spring time imagery is that you can see things on and in the ground (such as houses, or long filled stream beds, etc.) that become obscurred as the summer foliage and crops grow.

Sooner or later, all of Lambton will get hi-res coverage, as has much of central Ontario. I can hardly wait!

[Steve]

I just discovered that there is some new higher resolution imagery of Lambton in Google Earth. I don't know exactly when it was added, as I haven't looked at G. E. lately. Some of it, I'll call "medium" resolution, as it's higher resolution than before, but not quite as detailed as what's currently covering the Sarnia area. Other areas are very high res.

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The coverage is patchy and covers mostly the north part of the county, with some missed areas, in Plympton, Warwick and Bosanquet (Lambton Shores) townships. It's in various resolutions, in large blocks and taken at different times of the year.

The extreme northern tip with Grand Bend is still low res and although Arkona is just outside the new imagery and still low res, Rock Glen and most of the Ausable River valley are now high res. By turning on Google Earth's terrain feature, you can fly through the Ausable Gorge in high resolution 3D!

We'll have to wait for more updates until Petrolia and most of the south is covered, but there is one large block of high res in Dawn and Euphemia that takes in Florence and a good section of the east branch of the Sydenham River.

On the natural side, Kettle Point is neat to look at, as are the dunes and blind channels of the Ausable River around Port Franks and the Pinery. I've already mentioned the river valleys of the Ausable and Sydenham and by changing the verticle exaggeration on Google Earth's terrain setting, you can make our otherwise flat county look pretty dramatic in 3D perspective views...


I'm sure I'll be finding stuff for ages to come, but here's a couple of examples I've been waiting for...

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Here's one of the more dramatic examples of Lambton's extant built heritage. This is the old Grand Trunk Railway bridge over the Ausable River, just east of Thedford. Trying to go see this bridge on the ground is not easy. You need to do some fairly difficult hiking, through ever-thickening vegetation, along the abandoned railbed. Now, for the first time, you can visit it in Google Earth.

Here's another view from one of my visits in 2006...

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