The Colorful Zebra and Zero Priorities

October 6th, 2021 | by Marius Dupuis

(2 min read)

Once you are caught by the very ideas of geodata and operation of autonomous vehicles, you have a hard time seeing the world and not being impressed by all the oddities that might pose interesting challenges to the machine.

Colorful Zebra

Colorful pedestrian crossing… (Graz, image by Marius Dupuis)
…even more confusing in greyscale

A recent encounter was with a pedestrian crossing in Graz, Austria. For the human eye (left picture) it is clear that the fundamental pattern is the one of a zebra crossing. But what would a camera see, especially if it was looking at the whole thing in the intensity domain only (right picture)? The optical sensors of humans and automated drivings systems might work the same way but the interpretation of the scene is totally different.

The lighting adds to the disturbing impression, and the fact that the colorful stripes seem to provide more specular reflections than either the road or the white stripes, doesn’t make the perception and classification task any easier. We already saw “camouflage abstract art attack” that lead to repeatable misclassification of traffic signs (and a stop sign mutates into a speed limit sign). But isn’t it the role of art to challenge normal life? In this case it certainly does.

So, in this case, you really depend on this situation being part of a system’s Operational Design Domain (ODD). And unless there is additional sensor input or signage available or the crossing is clearly marked in an underlying navigation database and tagged as “special”, it might only be recommended for the brave pedestrians to use this crossing while an autonomous vehicle is approaching.

Zero Priorities

Yield to the yielding (near Tegernsee, image by Marius Dupuis)

Tell me when you think it’s your turn. This road next to the beautiful lake “Tegernsee” in Bavaria is shared between cyclists and the occasional local vehicle – and it might lead to very interesting traffic situations.

I had a hard time figuring out when I would be allowed to go if there was traffic on any of the branches of this little road “network”. I could only come up with two solutions: first, as a cyclist I might just apply a tendency to act “flexibly” in terms of unclear situations; second, this is a “first-past-the-post” game and the one who makes it first past the yield sign is automatically on the priority road.

Therefore, don’t feel challenged. Just make it a competition.

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