6 ms·

's/(human|desktop)/smartphone/g'

by moeny 4y ago

untech 4y ago
Using two 32 bit numbers for coordinates, each record would take 8 bytes, which is 64 gigabytes for 8 billion population. Don’t think many smartphones have this RAM today.
- cellis 4y ago
  Don't you need 3 numbers? Unless you believe in a flat earth ;). Also you need some slack space for metadata. Let's call it 100GB all in.
  - toast0 4y ago
    Lat long and assuming at ground gets you most of the way there.
    - Dylan16807 4y ago
      "Add it all up, and the US has around 340 billion square feet of building stock[3]. This is about 12,200 square miles, or 0.00032% of US land area" Judging by that, you need a negligible increase in the number of locations you can represent to handle everywhere stable and off the ground someone could be. Much less than one bit per person. If you want to deal with people currently in airplanes then you could give them an extra couple bytes. It's less than a million people so it won't affect your total storage at all.
  - withinboredom 4y ago
    GPS altitude is notoriously bad via consumer devices. It's better to store altitude as less than 2 bytes with the range from being a few km below sea level to the maximum altitude consumer devices will report (3,000 km -- though maybe less because there is also a speed limit at which they will stop reporting too so you can't just buy a GPS device and build a guided missile).
  - ilyt 4y ago
    Most people don't live in caves or in the sky city, 2 is enough. And in places you care (multi-floor buildings) you aren't getting GPS signal inside anyway...
- Dylan16807 4y ago
  The planet has 2^47 square meters of surface, so more like 6 bytes. Plus you can group together people in the same area and/or sort positions as integers and store only the deltas between them, so you can probably get down to 2-3 bytes per person. And you can get dozens of models of smartphone with 16GB of RAM right now. So there might be a gap there but it's a very small gap. The phone of tomorrow will have the RAM. Edit: Thinking about it more, with 2^33 people and 2^47 locations the average delta would be 2^14, and it's pretty easy to guarantee that fits into 2 bytes per person. And with a more accurate world population count you'd free up at least a gigabyte for your phone to actually operate with.
- renonce 4y ago
  You can build that phone. Phones made an engineering decision to put more battery rather than more RAM, and it's just a matter of putting more LPDDR5 chips onto the circuit board.

's/(human|desktop)/smartphone/g'

by moeny 4y ago

's/(human|desktop)/smartphone/g'

Using two 32 bit numbers for coordinates, each record would take 8 bytes, which is 64 gigabytes for 8 billion population. Don’t think many smartphones have this RAM today.

cellis 4y ago
Don't you need 3 numbers? Unless you believe in a flat earth ;). Also you need some slack space for metadata. Let's call it 100GB all in.
- toast0 4y ago
  Lat long and assuming at ground gets you most of the way there.
  - Dylan16807 4y ago
    "Add it all up, and the US has around 340 billion square feet of building stock[3]. This is about 12,200 square miles, or 0.00032% of US land area" Judging by that, you need a negligible increase in the number of locations you can represent to handle everywhere stable and off the ground someone could be. Much less than one bit per person. If you want to deal with people currently in airplanes then you could give them an extra couple bytes. It's less than a million people so it won't affect your total storage at all.
- withinboredom 4y ago
  GPS altitude is notoriously bad via consumer devices. It's better to store altitude as less than 2 bytes with the range from being a few km below sea level to the maximum altitude consumer devices will report (3,000 km -- though maybe less because there is also a speed limit at which they will stop reporting too so you can't just buy a GPS device and build a guided missile).
- ilyt 4y ago
  Most people don't live in caves or in the sky city, 2 is enough. And in places you care (multi-floor buildings) you aren't getting GPS signal inside anyway...
Dylan16807 4y ago
The planet has 2^47 square meters of surface, so more like 6 bytes. Plus you can group together people in the same area and/or sort positions as integers and store only the deltas between them, so you can probably get down to 2-3 bytes per person. And you can get dozens of models of smartphone with 16GB of RAM right now. So there might be a gap there but it's a very small gap. The phone of tomorrow will have the RAM. Edit: Thinking about it more, with 2^33 people and 2^47 locations the average delta would be 2^14, and it's pretty easy to guarantee that fits into 2 bytes per person. And with a more accurate world population count you'd free up at least a gigabyte for your phone to actually operate with.
renonce 4y ago
You can build that phone. Phones made an engineering decision to put more battery rather than more RAM, and it's just a matter of putting more LPDDR5 chips onto the circuit board.