In order to display the dispersal of pollen effectively, the ellipse is created at the tree location with following parameters
- Ellipse size : related to time of the year that the size will be bigger in the high pollen season and smaller in the non-pollen season.
- Ellipse position: related to the tree location.
- Ellipse direction: related to the wind direction.
- Ellipse color: related to the tree type.
- Ellipse opacity: related to pollen density.
In total, three ellipses will be generated at each tree location. Firstly, the ellipse center position (xe1, ye1 in case of small ellipse), semi-major and semi-minor axis (a1, b1 in case of small ellipse) have to be computed by the table below.
|Ellipse size||Compute distance l||Semi-major axis “a”||Semi-minor axis “b”|
|Small ellipse||l1 = (100) * (Fs)||a1 = (200) * (Fs)||b1 = (100) * (Fs)|
|Medium ellipse||l2 = (150) * (Fs)||a2 = (300) * (Fs)||b2 = (150) * (Fs)|
|Big ellipse||l3 = (250) * (Fs)||a3 = (500) * (Fs)||b3 = (250) * (Fs)|
For all equations, the second coefficient (Fs) is the “Factor of seasonal blooming” of each tree in the specific month which has value in range of 0 to 1. Then, the first coefficient had been applied due to the former researches about pollen dispersal distance showing tat pollen has high concentration approximately within 500 – 1000 meters along the wind direction. Thus, in our application, we applied the value of these coefficients as shown in the table above.
For example, in case of the peak blooming season, the small, medium and big ellipse will have the far most distance from the tree location equal to 300, 450 and 750 meters respectively as shown in the following table.
|The longest distance between||Calculation Example|
|Tree location||small ellipse||l1+a1 = [100 * 1] + [200*1] = 300|
|Tree location||medium ellipse||l2+a2 = [150 * 1] + [300*1] = 450|
|Tree location||big ellipse||l3+a3 = [250 * 1] + [500*1] = 750|