The Earthplough spreadsheet does a nice job of touring rectangular areas, but not all areas are rectangles. If we are looking at an area such as an island or even a bay, there is often a whole lot of water visible within our rectangle. This water takes time to tour and also uses up our memory cache allocation.
Here are some examples of caching where we are able to reduce the tour time and also reduce our cache size, while still loading all of the data that we need.
An Island. Here we have an island (Koh Samui, Thailand). I have already created a path that will cover the island, but it also covers a lot of the sea.
Select your path and edit its properties. Start at the beginning of the path. Remove unwanted lines by left clicking on a point and press delete. Repeat the process at the end of the path, working backwards. Shorten the vertical lines by dragging the endpoints to follow the island more closely. Taking a few minutes to shorten a path is a good investment of your time. The length of your path will reduce and so shorten your ‘play tour’ time. As you are not scanning so much ocean, your used cache size will also be significantly lower. Below is my edited path of Koh Samui.
So what is the point in using the spreadsheet to create a path when you could have just drawn this path by hand? The hardest part of drawing a manual path is being able to set your vertical lines at just the right width for your camera height. Placing the lines too far apart will result in missing data; too close together will mean the path is unnecessarily long, which wastes your time. The spreadsheet does this bit for you and on large areas it will save a lot of time.
Sometimes you only want to scan the coast of an area (many islands do not have much inland and all roads and towns are close to the coastline) – in this situation you may be better off just drawing a path manually and following the coast. If you want to go further inland, draw second and third lines that follow your first line. If you are unsure about how far apart to make your lines then create a quick Earthplough path on the area to gauge how apart to make your lines. Match the distance between vertical lines to be approximately the same as the Camera height in Google Earth tour. 5000m for larger regions, 1000m for cites and 2500m for somewhere in between. Below is a part of the east coast of Madagascar. I drew this path manually.
How about a Bay area? For our next example we see the area around Manila, Philippines. This has a large area of water in the center that we don’t want to scan in any detail. The Earthplough spreadsheet creates vertical lines for the path and these do not adapt well to this particular scenario.
Often the easiest way to reduce the path size is to use our Earthplough path as a template. Just draw a new path over the top, skip the bits that are ocean. That way your vertical lines are still the correct width apart.
For another alternative, I have chosen to copy the manila path from the Google Earth temporary places to My places. I did this twice and renamed the paths M1 and M2. Then I changed the color properties of each path to distinguish them. Sometimes the most efficient way to scan is to create more than one path, but the drawback is you have to be there when the first scan finishes to start the next scan (in order to make best use of your time if you happen to be in a hurry).
Path M1 has had its lines shortened to cover the upper area of the bay. Path M2 covers the lower area; I also deleted a large section of the path M2, as it was already covered by M1 (an overlap). This leads us to a question; does running a tour over an area you have already toured increase the cache size? The answer is no. The cache is already loaded with the information and so the total memory size will only increase when you tour a new area. But do keep in mind that if you try and load beyond your cache size, some of the older information will be deleted and lost.
That’s the final lesson over. You have graduated. Well done, email me for your certificate!
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