7 ms·

Mapping the Shadows of New York City

129 points by baron816 9y ago

pavement 9y ago
It'd be interesting to see a composite of reflected sunlight included around the builings with highly reflective exteriors.
- Bartweiss 9y ago
  This strikes me as a definite perk of the glass-and-steel skyscraper design. Older brick and stone designs seem to waste a lot more light, especially as they get dirty and lose albedo.
  - twobyfour 9y ago
    Brick and stone buildings have mostly been kept clean the last 15 years or so, and they don't darken as quickly as they did in the 20th C when both transportation and industry produced far more soot. That said, I've seen buildings that were nearly black with 100 years of accumulated soot at the end of the 1980s undergo deep cleaning (sandblasting) in the 90's and come out off-white. It's pretty remarkable. 25 years later, those same buildings are now almost exactly the same color they were immediately after the cleaning, without any further maintenance.
    - Bartweiss 9y ago
      It is a pretty stunning difference. Honestly, I think I'm mostly thinking of a handful of black stone buildings (famously, American Radiator) and buildings which haven't been cleaned since the '70s or '80s.
amichal 9y ago
Very cool. The explaination of "shadow accumulation" would have been a bit closer to reality if they had used hours in their example. shadows don't move anywhere near that far in 1 minute.
QuelqueChose 9y ago
Is this the first time somebody's constructed an interactive map of every single building in the greater NYC metropolitan area? It's really the part of the article that I find most impressive.
- jannes 9y ago
  Probably not. You can download the footprints of the buildings here: https://data.cityofnewyork.us/browse?q=buildings&provenance=official https://data.cityofnewyork.us/browse?q=buildings&provenance=... Other uses of this data: https://nycopendata.tumblr.com/post/156085577820/one-dataset-three-ways https://nycopendata.tumblr.com/post/156085577820/one-dataset...
- pokemongoaway 9y ago
  Seems like a good opportunity to sell data to those in real estate. For example, why would someone pay the same for two different apartments on the same floor when one gets direct sunlight door 30% of the day, and the other gets none!
  - pavel_lishin 9y ago
    For that matter, you can market both of those as advantages. Apt A: "Save hundreds on air-conditioning in the summer - this apartment never feels the full brunt of the scorching sun!" Apt B: "Wake up every morning to a New York sunrise - the best way to beat those winter blues." Just gotta know what the tenant is looking for.
    - rdnt02 9y ago
      Almost always you want Apt B. Bright sunlight can be controlled with electronic transition glass, curtains and other methods. You can't reproduce sunlight in your apartment.
      - yathern 9y ago
        I find it surprising you mentioned electronic transition glass - I had thought it's not used pretty much anywhere as of yet, and prohibitively expensive.
shrx 9y ago
Pretty awesome visualization. Does anyone know if the authors published a paper on the "shadow computation that is 10 to 15 times faster than older methods"? I couldn't find it on their websites [1-3]. [1] https://vgc.poly.edu/~fmiranda/ https://vgc.poly.edu/~fmiranda/ [2] https://vgc.poly.edu/~csilva/ https://vgc.poly.edu/~csilva/ [3] http://www.harishd.com/home/ http://www.harishd.com/home/
- theoh 9y ago
  It sounds like a way to take larger simulation steps by linearising the movement of projected points on shadow outlines. I'm guessing a bit, but the idea of figuring out how to take larger steps is an established trick for speeding up simulations (e.g. the Siggraph paper "Large Steps in Cloth Simulation") "Instead of explicitly tracking the movement of the sun, which is how shadow accumulation is usually measured, the researchers are tracking the movement of the shadows. Using the key insight that shadows move linearly within a short time range, they designed an efficient algorithm that performs an order of magnitude faster than those used in existing approaches. “This also allows users to interactively compute and explore shadows over different time ranges and allows them to quickly test multiple scenarios,” said Doraiswamy."
solarspeed 9y ago
Huh, just yesterday I tried something like this, but lacking elevation data for NY I settled for most of Europe: https://i.imgur.com/b7h3ulR.jpg https://i.imgur.com/b7h3ulR.jpg (I downscaled the resulting 198'000x126'000 image to 4'950x3'150.) And some more high resolution ones, e.g. Salt Lake City https://i.imgur.com/R352z2l.jpg https://i.imgur.com/R352z2l.jpg Using an extremely fast tool built by coworkers.
- Shengbo 9y ago
  It's really cool to see the natural borders of countries in much higher contrast than a regular elevation map. Especially the Alps walling off Northern-Italy from the rest of the continent and the way the Carpathian basin is surrounded by terrain that made it hard to invade. Makes sense that it was such a heavily contested area around the 9th century.
piyush_soni 9y ago
Awesome work!
key8700 9y ago
"It is said that the sun rises in the east and sets in the west. But at New York’s latitude, that’s not quite the case. On the summer solstice, the sun rises in the northeast and sets in the northwest, while on the winter solstice, the angle changes and the sun rises in the southeast and sets in the southwest. " I thought the sun's path was always south of due East-West for locations north of the Tropic of Cancer at all times of the year.
- rz2k 9y ago
  Above the tropic of cancer, the sun is south of you at noon even in the summer, but rises and sets a little in the north because the earth is more spherical than cylindrical. I think http://www.suncalc.org http://www.suncalc.org is a useful site for seeing where the sun will be at different times of the year. Zoom out the map, then move the dynamic icon north and south in June and December.
coldcode 9y ago
Don't think I could live there, I like sunshine. Some people love living in the city because of all the amazing stuff you can do there, but it's too big (and dark in many places) for me. I wonder what NYC will look like in 200 years. Can you build higher?
- pavel_lishin 9y ago
  > it's too big (and dark in many places) for me. I don't know about "too big" - that's pretty subjective - but it's plenty bright right now. Summer sun means it's hot and sunny, and will probably be that way most places you live - unless you happen to live in Midtown or Fidi, you'll be walking in the sun every day. And remember, just because you're not in direct sunlight doesn't mean it's dark - most things around you will reflect light, especially the windows on buildings. Apartments, however, are a much bigger toss-up. I've lived in places where most of our windows faced the sun (not particularly fun in the summer), and I've lived in basement/garden apartments where even when the sun did peek over the neighboring rooftop to strike our windowsill, the trees above us filtered most of it out.
  - deleted 9y ago
    [deleted]
- NathanKP 9y ago
  As much as I like the interactive map the truth is it makes things look way more shadowed than they actually are because its showing the averages of shadows from all time of the year and all times of the day. The reality is that most of the streets have a shady side and sunny side at all times of the year. It's shady on one side of the street in the morning and shady on the other side in the afternoon. This is actually great because you can choose the side of the street to walk on. If you are too hot in the summer you can go walk on the shaded side, or if you are too chilled in the spring/fall/winter you can walk on the sunny side. During the summer it is actually very nice to have a long stretch of tall buildings where you can cool off by walking on the shady side of the street. It's kind of like enjoying walking down a street that is shaded by a lot of trees, although sadly the buildings don't absorb as much heat as the trees do, and in some cases glass buildings actually seem to reflect the heat harshly.
hammock 9y ago
Some cool accompanying photos. I also enjoyed seeing the buildings' shadows projected onto the Hudson River
baron816 9y ago
New York NIMBYs often refer to shadows when trying block the construction of a new building. But as covered in shadows as New York is, it doesn't have a shadow problem. It has an affordability problem. Lots of people are willing to spend crazy amounts of money there (many of whom could live anywhere in the world) because it's still an amazing place to live. More people would love to live there, but there is, of course, a shortage of affordable housing...

129 points by baron816 9y ago

It'd be interesting to see a composite of reflected sunlight included around the builings with highly reflective exteriors.

Bartweiss 9y ago
This strikes me as a definite perk of the glass-and-steel skyscraper design. Older brick and stone designs seem to waste a lot more light, especially as they get dirty and lose albedo.
- twobyfour 9y ago
  Brick and stone buildings have mostly been kept clean the last 15 years or so, and they don't darken as quickly as they did in the 20th C when both transportation and industry produced far more soot. That said, I've seen buildings that were nearly black with 100 years of accumulated soot at the end of the 1980s undergo deep cleaning (sandblasting) in the 90's and come out off-white. It's pretty remarkable. 25 years later, those same buildings are now almost exactly the same color they were immediately after the cleaning, without any further maintenance.
  - Bartweiss 9y ago
    It is a pretty stunning difference. Honestly, I think I'm mostly thinking of a handful of black stone buildings (famously, American Radiator) and buildings which haven't been cleaned since the '70s or '80s.

amichal 9y ago

Very cool. The explaination of "shadow accumulation" would have been a bit closer to reality if they had used hours in their example. shadows don't move anywhere near that far in 1 minute.

QuelqueChose 9y ago

Is this the first time somebody's constructed an interactive map of every single building in the greater NYC metropolitan area? It's really the part of the article that I find most impressive.

jannes 9y ago
Probably not. You can download the footprints of the buildings here: https://data.cityofnewyork.us/browse?q=buildings&provenance=official https://data.cityofnewyork.us/browse?q=buildings&provenance=... Other uses of this data: https://nycopendata.tumblr.com/post/156085577820/one-dataset-three-ways https://nycopendata.tumblr.com/post/156085577820/one-dataset...
pokemongoaway 9y ago
Seems like a good opportunity to sell data to those in real estate. For example, why would someone pay the same for two different apartments on the same floor when one gets direct sunlight door 30% of the day, and the other gets none!
- pavel_lishin 9y ago
  For that matter, you can market both of those as advantages. Apt A: "Save hundreds on air-conditioning in the summer - this apartment never feels the full brunt of the scorching sun!" Apt B: "Wake up every morning to a New York sunrise - the best way to beat those winter blues." Just gotta know what the tenant is looking for.
  - rdnt02 9y ago
    Almost always you want Apt B. Bright sunlight can be controlled with electronic transition glass, curtains and other methods. You can't reproduce sunlight in your apartment.
    - yathern 9y ago
      I find it surprising you mentioned electronic transition glass - I had thought it's not used pretty much anywhere as of yet, and prohibitively expensive.

shrx 9y ago

Pretty awesome visualization. Does anyone know if the authors published a paper on the "shadow computation that is 10 to 15 times faster than older methods"? I couldn't find it on their websites [1-3]. [1] https://vgc.poly.edu/~fmiranda/ https://vgc.poly.edu/~fmiranda/ [2] https://vgc.poly.edu/~csilva/ https://vgc.poly.edu/~csilva/ [3] http://www.harishd.com/home/ http://www.harishd.com/home/

theoh 9y ago
It sounds like a way to take larger simulation steps by linearising the movement of projected points on shadow outlines. I'm guessing a bit, but the idea of figuring out how to take larger steps is an established trick for speeding up simulations (e.g. the Siggraph paper "Large Steps in Cloth Simulation") "Instead of explicitly tracking the movement of the sun, which is how shadow accumulation is usually measured, the researchers are tracking the movement of the shadows. Using the key insight that shadows move linearly within a short time range, they designed an efficient algorithm that performs an order of magnitude faster than those used in existing approaches. “This also allows users to interactively compute and explore shadows over different time ranges and allows them to quickly test multiple scenarios,” said Doraiswamy."

solarspeed 9y ago

Huh, just yesterday I tried something like this, but lacking elevation data for NY I settled for most of Europe: https://i.imgur.com/b7h3ulR.jpg https://i.imgur.com/b7h3ulR.jpg (I downscaled the resulting 198'000x126'000 image to 4'950x3'150.) And some more high resolution ones, e.g. Salt Lake City https://i.imgur.com/R352z2l.jpg https://i.imgur.com/R352z2l.jpg Using an extremely fast tool built by coworkers.

Shengbo 9y ago
It's really cool to see the natural borders of countries in much higher contrast than a regular elevation map. Especially the Alps walling off Northern-Italy from the rest of the continent and the way the Carpathian basin is surrounded by terrain that made it hard to invade. Makes sense that it was such a heavily contested area around the 9th century.

piyush_soni 9y ago

Awesome work!

key8700 9y ago

"It is said that the sun rises in the east and sets in the west. But at New York’s latitude, that’s not quite the case. On the summer solstice, the sun rises in the northeast and sets in the northwest, while on the winter solstice, the angle changes and the sun rises in the southeast and sets in the southwest. " I thought the sun's path was always south of due East-West for locations north of the Tropic of Cancer at all times of the year.

rz2k 9y ago
Above the tropic of cancer, the sun is south of you at noon even in the summer, but rises and sets a little in the north because the earth is more spherical than cylindrical. I think http://www.suncalc.org http://www.suncalc.org is a useful site for seeing where the sun will be at different times of the year. Zoom out the map, then move the dynamic icon north and south in June and December.

coldcode 9y ago

Don't think I could live there, I like sunshine. Some people love living in the city because of all the amazing stuff you can do there, but it's too big (and dark in many places) for me. I wonder what NYC will look like in 200 years. Can you build higher?

pavel_lishin 9y ago
> it's too big (and dark in many places) for me. I don't know about "too big" - that's pretty subjective - but it's plenty bright right now. Summer sun means it's hot and sunny, and will probably be that way most places you live - unless you happen to live in Midtown or Fidi, you'll be walking in the sun every day. And remember, just because you're not in direct sunlight doesn't mean it's dark - most things around you will reflect light, especially the windows on buildings. Apartments, however, are a much bigger toss-up. I've lived in places where most of our windows faced the sun (not particularly fun in the summer), and I've lived in basement/garden apartments where even when the sun did peek over the neighboring rooftop to strike our windowsill, the trees above us filtered most of it out.
- deleted 9y ago
  [deleted]
NathanKP 9y ago
As much as I like the interactive map the truth is it makes things look way more shadowed than they actually are because its showing the averages of shadows from all time of the year and all times of the day. The reality is that most of the streets have a shady side and sunny side at all times of the year. It's shady on one side of the street in the morning and shady on the other side in the afternoon. This is actually great because you can choose the side of the street to walk on. If you are too hot in the summer you can go walk on the shaded side, or if you are too chilled in the spring/fall/winter you can walk on the sunny side. During the summer it is actually very nice to have a long stretch of tall buildings where you can cool off by walking on the shady side of the street. It's kind of like enjoying walking down a street that is shaded by a lot of trees, although sadly the buildings don't absorb as much heat as the trees do, and in some cases glass buildings actually seem to reflect the heat harshly.

hammock 9y ago

Some cool accompanying photos. I also enjoyed seeing the buildings' shadows projected onto the Hudson River

baron816 9y ago

New York NIMBYs often refer to shadows when trying block the construction of a new building. But as covered in shadows as New York is, it doesn't have a shadow problem. It has an affordability problem. Lots of people are willing to spend crazy amounts of money there (many of whom could live anywhere in the world) because it's still an amazing place to live. More people would love to live there, but there is, of course, a shortage of affordable housing...