Google Earth Useful Tip

Definitely a really useful trick! I have found pictures taken in February and March to be the best views for measuring such spots.

Here's another, and I assume many people do this: if you're measuring along a road you may want to toggle the road names on and off-- on to make sure you're on the right road, off so you can measure without those annoying superimposed lines. You also want to zoom in (to see crucial details like corners) and out (so you can see spr).

Pete sent me a couple different course paths from people who measured this course with google earth. I opened those up in GE in order to compare to my path. Below is a small section of that


My path is shown and blue. I was very surprised to see my path not follow the corners at all. Around one corner I'm in the grass, and around the other I'm out in the middle of the road. Then I remembered that I used an older image when I drew my path. Below is the same paths on the winter imagery of 2012.


The measurements from these 3 paths were within a few feet of each other, so using either the 2013 or the 2012 imagery results in a good measurement. Apparently the image is just shifted slightly between the two. But the lesson learned here is that you should pick one image for your path measurement and stick to it, rather than switching back and forth on different corners.

I have data from 4 measurers so far, closely grouped. I found that practice makes perfect, and learned some tricks.

Here is how I think the best measurement evidence will be generated:

1. Using Google Earth, begin with a virgin map with nothing on it.
2. Using previous data, put a mark at the start and finish.
a. The Start is 616.42 feet north of the center of road T-549
b. The Finish is 128.9 feet north of the center of the driveway to the park. There is a very faint paintmark at the proper location, visible by squinting or using Street View.

3. With Start and Finish marked, measure the course in one go. When you are done, save the file as a GE .kmg file.

a. Click on the measure line and read the length in feet.

b. Use high magnification when needed at corners.

c. If path is obscured, go back in time, and get an unobscured view. This will not interrupt a measurement that you may have in progress.

d. If you make a "bad click" which is way off the line you want, just give it a right-click. Each right click will erase the last point entered. You don't have to start over!

The more times you do this the shorter will be the resultant measurement. Measure as tight as you can, but do not leave the road surface. Pretty soon you will see that you cannot improve significantly. You will have measured the SPR.

If you are satisfied that you have got it as good as you can, let me know and send me the kmg file. Remember - only one measure line in the file!

I have noticed that if I collect kmg’s in my GE program, clicking on one of them will sometimes give me the wrong kmg. So I store them in another folder, and save nothing in the GE program.

I haven’t seen it discussed in this topic, but you can open a saved GE kmz file for additional work or modifications. It is helpful to rework an old course or continue on a current route. I used it often in development of the new Huntsville marathon route.

Open the saved file and right click on the path to show the measured points. You can then add, delete or move the points in a similar way as in the initial layout.

For us old timers, GoogleEarth is the best thing since "sliced bread"
I remember "PGED" (pre GoodEarth Days) when we would spend days measuring roads just to create a course. Now we can do it in minutes (or hours)in the comfort of our homes!
And let's not forgot the stacks of US Gov topo maps many of us have used to determine elevation.