The Garret Tree
Saturday, September 02, 2006
  What if there had been a satellite image of the River Kwai railway?
What if there had been satellites at the end of the Second World War?

From that random thought, I was inspired for a rainy day Labour Day Saturday project.

That idea is only realistic if the war had continued for many years longer and the rockets under development, eventually, as they did almost 20 years later, were able to launch satellites into orbit. (A subject for what science fiction calls an "alternative world" and now that academics have gotten into that form of speculation, "counterfactual history." )

On this Labour Day weekend in Toronto, with what is now tropical depression Ernesto pouring rain down on the city, while I was checking my e-mail, I decided, as my mind wandered, to complete a task that had been low on my to do list for months. Find a satellite image of the area on the Burma Thailand Railway where F Force, the subject of my book, built a section of the railway and road just south of the Burma border.

I did find the image. And then inspired again I decided to see if I could marry that image with a copy of what is likely the only war time extant map of the railway. The result is the picture posted on this blog.

Now a bit of background. As a photo editor, I have been working with Photoshop for more than 10 years. And for the past four or so years, I have used many satellite images from different sources in my job at the Canadian Broadcasting Corporation. So, while with some luck, I was able to finish this in about a hour, there are years of experience behind the operation.

The satellite image

At CBC, we often use satellite images supplied by the NASA/MODIS project that is based at the Goddard Space Flight Center. These images are most often of hurricanes, typhoons, forest fires, other natural phenonomen and often just gorgeous images. NASA/MODIS did help the CBC recently when the National broadcast from the Northwest Passage, and as part of that I created a photo gallery of satellite images of the area of the National's broadcast.

There were no suitable images in the main NASA/MODIS gallery so I then searched through what NASA/MODIS calls its subsets. The probem was to find an image where there was little cloud cover. And as I found when I went looking, although there many images that show Thailand clear, the mountains that mark the border were often cloud covered. I eventually found one, Pimai subset image, 200605, taken on January 5, 2006.

On this image, the upper valley of the Kwai is perfectly clear, and you can see the route of the river down from the mountains, to the lake created by the Khao Lem reservoir and then the river valley as it flows south. Three Pagoda Pass also stands out, a yellow-brown streak among the green mountains.

The map

I discovered the map during my research on F Force for The Sonkrai Tribunal. It is an air force navigation chart (there are no markings to indicate whether it was Royal Air Force or United States Air Force, both bombed the Burma Thailand Railway). I believe it is the only wartime extant map of the railway because it does show the route but with the disclaimer "alignment approximate." (The better known maps drawn by former POWs were created after the war for war crimes investigation or historical records)

Fun with Photoshop

I had downloaded the satellite image and enlarged it by about 30 per cent using the tools in Photoshop CS2, which is about as far as you can go without losing the integrity of the image.

It was only then that I was inspired to see if I could match it with the image of the map. I used a small section of the map I created as a reference for the F Force area. Checking image size of both in Photoshop I saw that they were approximately the same size already, I made a small adjustment to the map and luckily it was a perfect match on the first try.

I then spent some time trying to opitmize the image for best display. at first the satellite image was the background layer, with the map as the second layer.

The air navigation map was pink and that diminished the greens from the true colour satellite image. So I desaturated the map to a neutral gray.

I then tried an number of experiments with opacity to find the best way of bringing out the information on the map while maintaining the beauty of the satellite image. Eventually I created a duplicate layer for the satellite image, made the map the background layer (dropping the original satellite background layer) and tweaked the opacity on the satellite image.

Finally I made a copy, merged the layers and used curves to create what I hope is the optimum for the images. (I used both RGB curves and then the green curve to enhance the greens a bit)

Both the original NASA image and the map cover a much larger area, but at this point I have no plans to go further and create a second image.

But the result shows, allowing for the "alignment approximate" and the fact the Khao Lem dam and reservoir has drowned much of the route, how a satellite image of the Burma Thailand Railway might have looked.

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I write in a renovated garret in my house in a part of Toronto, Canada, called "The Pocket." The blog is named for a tree can be seen outside the window of my garret.

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Name: Robin Rowland
Location: Toronto, Canada

I'm a Toronto-based writer, photographer, web producer, television producer, journalist and teacher. I'm author of five books, the latest A River Kwai Story: The Sonkrai Tribunal. The Garret tree is my blog on the writing life including my progress on my next book (which will be announced here some time in the coming months) My second blog, the Wampo, Nieke and Sonkrai follows the slow progress of my freelanced model railway based on my research on the Burma Thailand Railway (which is why it isn't updated that often) The Creative Guide to Research, based on my book published in 2000 is basically an archive of news, information and hints for both the online and the shoe-leather" researcher. (Google has taken over everything but there are still good hints there)

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    A River Kwai Story
    A River Kwai Story
    The Sonkrai Tribunal