Traffic4cast 2019: What do three channels mean respectively?

[fangyh09]

Hi, could you explain a bit more for data(“array”: shape (288, 495, 436, 3))? What do three channels mean respectively?

[Ali Soleymani]

Hi fangyh09,
Thank you for your interest in our competition.
Regarding the shape of the data (288, 495, 436, 3):
288 is the number of 5-mintues bins per day – basically from 00:00 to 23:55 there are 288 bins.
495, 436 is the size of the data (height, width) and 3 is the number of the channels (volume, speed and heading)

Volume is the number of probe points (capped above and below) recorded in each 100*100 meters grid cell.
Speed is the average speed from the collected probe points in each grid cell.
Heading: Each probe point records the heading direction (values from 0 to 359). The points are binned in four heading directions of North-East (0-90), South-East (90-180), South-West (180-270) and North-West (270-0). The raw heading values [0-359] are mapped to four distinct values of [1,85,170,255] in the order of [NW,NE,SW,SE] and the major heading bin, i.e. the bin with the highest number of points is selected.

I hope this help.
Thanks again for your interest.

• This reply was modified 3 years, 10 months ago by Michael Kopp.

[fangyh09]

Thanks a lot.

I want to know a bit more about volume and speed. How are they normalized?

[Ali Soleymani]

Both Volume and Speed are first capped at Volmax and Speedmax values to remove noisy readings and the volume is also cut off at Volmin. Then the Volume values are normalized from [Volmin-Volmax] to [1-255] and Speed values from [0-Speedmax] to [0-255].

Hope this helps!

• This reply was modified 3 years, 10 months ago by Michael Kopp.

[Christian Eichenberger]

Closing this 2019 thread.

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