Overlaying Historic Maps in Google Earth

Ever since I was little, I spent my summers up in the Sequoia Nat'l Forest running around the old fireroads and visiting all the touristy spots like Hume Lake, Buck Rock and Stony Creek. After seeing a coffee table book called They Felled the Redwoods, by Hank Johnston, I caught a glimpse of the history of logging of the Giant Sequoia and I was hooked! I looked up the book at the local library and was able to find it at my own Fresno State University. I spent a solid two hours reading through and marveling at their ingenuity, engineering skills and all the archival photos. I highly recommend the read to anyone interested in Sequoia history, logging history, and the like. Johnston also includes maps of the day with the old logging roads and historic sites all nicely labeled. When I saw these maps I immediately wondered if I could compare these maps to current ones, that way I could find the historic places and visit them -maybe even finding old relics. I scanned these maps and opened them up on my computer. The first step I had to do digitally was to remove the white background from these scans. A simple Google search and I found an online background remover that didn't need me to enter my email, create an account or buy a subscription.

Before removing background

After removing background

I saved these new images as PNG image files and then set to overlay them on Google Earth. If you don't have Google Earth by now, what are you doing reading this? Google Earth is one of my favorite tools for mapping the backcountry and visualizing the terrain before going there, something not always easy to do with topo maps. In GE the first thing I did was to bring up the general area of the photo I was going to overlay on the map. I then went to the top toolbar, clicked New, then went down to Overlay Image.

After selecting the image to overlay I just had to adjust the ratios until it lined up. This took some finagling until I got it just right, by keeping the center center while adjusting the edges as needed. After getting it where I like I saved it as a KML file.

From there I was able to adjust the transparency of the image as I liked. I also was able to transfer the points on the overlay and save them as GPX points, which I could open in CalTopo or transfer to my GPS to use when out on the trail. Now that these old maps are overlaid onto new maps, I can also note how the fireroads used today stem from those original ones over 100 years ago. In the future I may change the black color of the map to white or yellow in order to see better against the green of the forest. I'm sure I could do this using a free photo editor of some sort with very little prior knowledge.

EDIT: While thinking about changing the color I decided to just do it. All I did was go to Online Image Editor and invert the color before removing the transparency and voila! a white map that is now easier to read against the green background.

How about that!?!