Recall the picture from the deep dive into the isochrone details, of the area surrounding the start of the solution.
How wide is the search?
Before the isochrone algorithm arrives at your target point it does not know what the fastest path will end up being.
In the example above, you may wonder, when starting in Hawaii, why is the algorithm expanding the isochrones which are heading directly away from Neah Bay? Isn’t that wasteful? Wouldn’t it be faster to only consider isochrone points which are, at least, heading generally toward the destination?
There are several answers to this.
Sometimes, the best, or only, path between two points can only be found by first heading away from it. Consider this path generated between London and Bristol:
In order to create a successful path to Bristol, the solver must first head directly away from it. This solution works in LuckGrib without changing any settings. In fact, there are no settings in LuckGrib to control how wide the search is. LuckGrib always performs the widest search possible.
Some systems reduce the search space in a variety of ways, in order to speed up their calculation. LuckGrib is fast enough for this not to be necessary.
Improved understanding.
A second reason for creating a large solution space (the set of isochrones created) is that, when used with the weather routing analysis image algorithms, it is possible to greatly improve your understanding of the weather conditions surrounding the path generated.
Recall this pair of images from the Isochrone introduction:
Just as a meteogram can show you the values, at a point, for the weather conditions through time, these images show you some of the conditions you can expect across the isochrone solution space, through time.
As there is uncertainty in all weather forecasts, you are not only interested in the weather conditions found exactly on the optimized path. You will also be interested in the conditions in the surrounding regions. Weather forecasts change over time, and what may be happening off of your path today may move toward your path in the future. It is important to be aware of the overall conditions in the forecast.
Remember, the goal of this system is to improve your understanding of the weather systems. Simply presenting a path may not improve your understanding.