Hacker News Reader

Comment by patrickyeon | Hacker News Reader

(I used to work at planet, this is my recollection of what was the case then)

Usually, for ocean-sized bodies of water, we'd stop imaging entirely to reduce power load and align the solar panels with the sun. Effectively all of the ocean had nothing going on on the surface that we could image anyway.

When Planet gets the imagery, they have a fairly good sense of where it is, but it is still processed to get it to align with ground truth, which is called rectification and relies on matching visible features to known ground features. If the entire image is clouds, this can't work and they don't publish the image because they can't say exactly where it is. Also, there's not really usable information in that imagery I guess.

View on HN

You could track container ships, in fact they're probably so easy to detect you could run a small computer vision model on the satellite and only transmit those photos.

Obviously the most interesting container ships are the ones that you can see from space but don't show up on marine trackers. Although I don't know how you turn that information into money.

Actually someone must already be doing this, Airbus sponsored a Kaggle competition for detecting ships in satellite imagery https://www.kaggle.com/c/airbus-ship-detection and maybe that's how they caught that Iranian oil tanker last month.

Planet & others are listening to AIS transponder signals from space which I imagine takes out a lot of the need for a bandwidth-heavier computer vision approach. Ships turn off their AIS sometimes when they're doing naughty things, but from what I understand they're usually relatively close to shore when they do that.

You could possibly spot container ships at one instance in a day (the constellation only goes over any point twice a day, ~10.30 AM (local) and 12 hours later (no sunlight)). To what end? You are roughly tripling your power, data storage, and downlink costs, with a loss on your power production (and orbit control, because the Doves use differential drag for phasing) for a poor product that doesn't really have customers.

If you want to track ships that want to be seen, basically everybody has AIS receivers up there (although I understand that's not trivial to sort out from space). If you want to track ships that aren't broadcasting, use radar.

Reply on news.ycombinator.com