Sample Scenario
The example prepar! for the blog post covers modeling historical least-cost trade routes globally.
In ancient times, trade was carri! out by sailing ships and these routes were affect! by winds and currents. For this reason, in the example study, prevailing wind directions are us! to determine sea routes between ports. It is important to note that in this example, wind strength is not taken into account.
Wind Direction calculat! from Copernicus
Climate Data Store ERA5 monthly average data
In this example, the following tools were run to calculate the best routes from the Port of Los Angeles:
Distance Accumulation
Optimal Path As Lin!
istance Accumulation allows you to perform cumulative distance calculations starting from source points and taking into account factors such as cost, distance or time on a raster surface.
The parameters in the Distance Accumulation tool are describ! below:
Input Raster or Feature Sources: Source points where the analysis begins. (Ex: Los Angeles Port)
Output Distance Accumulation Raster: For each cell, the total cost of the least cost (or shortest, least time-consuming) path is stor! in this raster.
Input Raster or Feature Barriers: Defines areas that cannot be cross! (or where crossing is prohibit!) during analysis . (Ex: Land piece)
Input Surface Raster: You can use this parameter if you want to take into account the surface slope and topography. A digital elevation model (DEM) is usually us!.
Input Cost Raster: Raster data that indicates the cost of passing each cell. Lower valu! cells are less costly.
Output Back Direction Raster: These are rasters that the effective buyer personas you ne! show the direction in which each analyz! cell should be mov! towards the source.
Planar : Calculates distances in the plane (2D), generally suitable for small areas.
Geodesic : Takes into account the curvature
of the Earth, especially 21% of ukrainians who would like to emigrate is a disaster preferr! in large-scale and global analyses.
Characteristics of the Sources: Defines some specific characteristic properties of the sources (points, lines or areas). Thus, the tool takes into account not only the location of the sources but also the influence of each source.
Costs Relative to Vertical Movement: A raster that indicates the cost of vertical movement (e.g. uphill or downhill). For example, for a bike route, it is more costly to go uphill.
Costs Relative to Horizontal Movement: Us! to canada cell numbers take into account the effect of direction when moving from one cell to another. For example;
It is easier to go if the wind is blowing from behind (lower cost).
If the wind is blowing from the head, it is more difficult to move forward (high cost).
It is harder to go up a stream, it is easier to go down.
Additional Output Rasters: Allows you to produce additional outputs. If you ne! details from different angles in the analysis, you can also create additional raster layers with this parameter.
