The picture to the right shows an example of a GPS track. Note that the arrows point in the direction of travel. This track was plotted with the following spreadsheet values:
This spreadsheet is included in the sample data.
The column IconHeading specifies how many degrees to rotate the icon. IconHeading can be a number, the word "line", or the word "line" plus or minus a number.
For example, Icon 222 is Google's airplane icon. It looks like this on Google Earth.
If a value of 90 is entered into the IconHeading column, the icon is rotated 90 degrees to the right.
If a value of -90 is entered into the IconHeading column, the icon is rotated 90 degrees to the left.
If the word "line" is entered into the IconHeading column, the airplane is rotated to point in the direction of travel. That is, the airplane looks like it is flying along the line.
If the value "line-180" is entered into the IconHeading column, the airplane is lined up with the direction of travel, then spun around 180 degrees. The airplane looks like it is flying backwards.
"line-180" is quite useful when using Icon 196, Google's arrow icon. Notice that by default the arrow points down, not up. If we specified a value of "line" in the IconHeading column, the arrow would point in the wrong direction.
To fix this, use a value of "line-180" (or "line+180"), which flips the arrow around 180 degrees and points it in the right direction.
Another problem is that the arrow is hard to see because it is just an outline. Use IconColor to add color to any icon. Yellow looks like this:
This combination of IconHeading and IconColor gives us the GPS track illustrated at the beginning of this article.