10 ms·

The longest straight line in Great Britain without crossing a public road

154 points by samwillis 4y ago

cdaringe 4y ago
Loved it. Seemed like it was discovered by manual search
bediger4000 4y ago
> Crown copyright and database rights 2023. Do i, as a US citizen, have to respect Crown Copyright? I mean, the USA originated in a revolt against that very same crown. The USA is by constitution and temperament forbidden from giving out titles and such. We respect free markets, content creators and their successors in interest here.
- lljk_kennedy 4y ago
  Technically, legal proceedings could be taken against you in the UK. Realistically - most of the stuff covered by Crown Copyright falls under the Open Government License and is free to use once attributed. https://www.cla.co.uk/crown-copyright https://www.cla.co.uk/crown-copyright https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/ https://www.nationalarchives.gov.uk/doc/open-government-lice...
- matthews2 4y ago
  The United States is party to the Berne Convention, so yes.
- bigdollopenergy 4y ago
  In as much as anyone has to respect the copyright coming from any jurisdiction they are not in. Which for the most of the world generally means that, yes, you do have to respect it. It being the UK and your historical reasoning isn't very relevant. One of the main things that allows global trade to happen as freely as it does, is countries cooperating so that copyright can be legally enforced across them. The resulting court cases are likely to be less actionable if you have no presence there, but you can be sued in that country for breach of copyright and have a judgement placed upon you. It's bilateral, a Brit may wonder the same thing about the US or any other country and the answer would be the same.
  - InCityDreams 4y ago
    The Pirate Bay disagrees. They rather splendidly told the usa to gtfo, as did kim dotcom. Ymmv.
- Doctor_Fegg 4y ago
  > We respect free markets, content creators That’s awesome. Please respect the content creators at the Ordnance Survey then.
- swarnie 4y ago
  Since the US don't extradite even for serious offences You can probably just ignore it and be tried in absentia if caught and prosecuted. You'll have to join the 66% of your countrymen who can't travel abroad however.
  - deleted 4y ago
    [deleted]
  - ledauphin 4y ago
    this is an interesting statistic. I'd love to have a reference!
    - killjoywashere 4y ago
      Seems there are some stats running around about the number of US citizens who hold passports. https://www.statista.com/statistics/804430/us-citzens-owning-a-passport/ https://www.statista.com/statistics/804430/us-citzens-owning...
    - pacaro 4y ago
      https://today.yougov.com/topics/travel/articles-reports/2021/04/21/only-one-third-americans-have-valid-us-passport https://today.yougov.com/topics/travel/articles-reports/2021... Apparently only 37% of Americans have a valid current passport
      - ghaff 4y ago
        Even assuming that includes passport cards for Canada/Mexico, unless someone lives near the border, an international trip is a relatively big deal for a lot of families. The US is big and has a lot of variety for travel. It's really not surprising that a (sizable) minority don't have near-term plans to travel internationally.
        pacaro 4y ago
        Absolutely agree. The socio-economic breakdown of the research backs this up. It's very strongly correlated with household income
- Woeps 4y ago
  Uhm, kinda, it depends. Overall Copyright is all mushed together under some kind of global agreement right? Because must I remind you, of your post of an hour ago: "property rights are paramount." ;)
- Veen 4y ago
  The Crown isn't really the monarchy when used in this sense and it doesn't have much to do with titles and such. It's a synecdoche used to refer to the UK government (and the governments of some commonwealth countries). Crown Copyright is the copyright the government holds in the material it creates. In this case, the Ordnance Survey, which is a UK government agency. Whether you have to respect that copyright is a different matter, although it may be unwise to use Ordnance Survey mapping data for commercial purposes without a license.
  - dragonwriter 4y ago
    > The Crown isn't really the monarchy when used in this sense and it doesn't have much to do with titles and such. It's a synecdoche used to refer to the UK government That’s also the Crown the US was revolting against, so...
- eertami 4y ago
  I think it's actually the US which is more likely to take issue with you for breaking the copyright, than the UK would. Considering the US publishes an annual report on copyright/IP rights enforcement about it's trading partners that it deems to be insufficient[0]. [0]: https://ustr.gov/sites/default/files/USTR-2016-Special-301-Report.pdf https://ustr.gov/sites/default/files/USTR-2016-Special-301-R...
- dukeyukey 4y ago
  No need to be edgy. Crown copyright is just the phrase used for copyright created when the UK (And Canada, and Australia, and others) create copyrighted content. It's nothing special.
shrx 4y ago
I see a new GeoWizard [1] series covering this in the future [1] https://www.youtube.com/watch?v=M7w986ni7_g https://www.youtube.com/watch?v=M7w986ni7_g
- sixothree 4y ago
  Even before I finished reading the headline, I assumed this was part of his work.
- neom 4y ago
  Was just coming here to comment about GeoWizard. Probably my favorite YouTuber, straight line challenge is awesome, how not to cross American is my favorite YouTube series by a long shot.
  - eCa 4y ago
    The ”How not to travel America” playlist: https://youtube.com/playlist?list=PL_japiE6QKWrCfn7NFL86bRSWez5DTDWt https://youtube.com/playlist?list=PL_japiE6QKWrCfn7NFL86bRSW... Don’t miss the similarly named Europe trip either, for anyone new to GeoWizard.
- spuz 4y ago
  Along those lines, someone else whose attempts I've really enjoyed watching is Ally who recently uploaded the first part of his attempt to cross Scotland in a straight line: https://youtu.be/_Lcu6qL7NWs https://youtu.be/_Lcu6qL7NWs
- yreg 4y ago
  He had one where he wasn't allowed to use roads[0]. But crossing them is fine, the man can teleport across railroads anyway[1]. [0] - https://youtu.be/pDU9BOtX80A https://youtu.be/pDU9BOtX80A [1] - https://youtu.be/QkLDThED4T4?t=2195 https://youtu.be/QkLDThED4T4?t=2195
justinator 4y ago
Being an avid hill walker, I love to see how far away from civilization I can get in Colorado on my hikes. I should be able to get really out there, right? My State is 1/3 public, undeveloped land! The farthest summit from a road is about 6 miles. Kinda made me sad inside. That's how remote you can get from a car. I have gone on farther trips without crossing a paved road - one being 120 miles that took 6+ days (tough terrain!) by following the crest of an entire mountain range - quite difficult. As the crow flies, that's about 70 miles point to point. If you stretch the theoretical limit between paved roads - encapsulating this entire mountain range, it's about 78 miles. There's about 3 rough 4WD tracks that you can use to cross it - but that's it, in that entire range, any other point across you have to traverse by foot (and there's only a few trails to do so too). Hope it stays that way. But again, it's still always <6 miles to where you can drive a car. I've been to more "remote" places, such as Alaska, with vast Wilderness- but they let you fly planes into there, which seems somewhat like cheating.
- bombcar 4y ago
  Part of the issue is that the vast western BLM land in the USA is mostly some variation of desert; and that desert is very VERY easy to put a road down on, if all the road is a slightly graded path. I assume you've seen https://www.projectremote.com/remote-statistics/ https://www.projectremote.com/remote-statistics/ (updated from defaced/hacked domain)
  - justinator 4y ago
    hmm, I think though there's a reason that the road exists - even in the desert? Probably to mine or a mine town originally? Same with all the roads in the mountains. Resource extraction and motor vehicles kinda go hand in hand.
    - bombcar 4y ago
      Most of the ones I've encountered in the high desert have things like ancient mining claims or tiny towns somewhere, but others appear to simply be 4WD trails that have been used "enough". According to the link; Wyoming has the furthest at 21 miles from a road (which is a circle containing 1385 sq miles). Since distance from a road is a circle, the sq miles needed to get far from it go fast quickly, even six miles is 113 sq mile, and since it's likely a road alongside one edge, you're talking a square of land at least 144 sq mile. The only things that big are usually parks/nature reserves of some kind, and they often have fire roads or other accesses built for reasons (including people camping, etc).
gooseyman 4y ago
Even cooler when you consider the right to roam https://en.m.wikipedia.org/wiki/Freedom_to_roam https://en.m.wikipedia.org/wiki/Freedom_to_roam I live in a state that has very little public land, which would make any attempt to walk it incredibly difficult
sixothree 4y ago
I remember talking to a group of people about the "vastness of America" and mentioned that no matter where you go you're never really more than 20 miles from a road. Not a single person believed me. I never did follow up with investigation. But I do sometimes ask people this question. Ultimately, people seem to think there are these great patches of untouched land on a vast scale where it simply doesn't exist.
- adrianpike 4y ago
  Yep, even the furthest spot in Wyoming in the Thorofare wilderness complex is something like 19 miles out from a road. One thing to keep in mind is that only a few miles over rugged terrain can be a _lot_. A few miles away from a remote forest road in the wrong direction and you might not see any people for years and years. I do search and rescue out here, and even with helicopters it's pretty vast; https://www.peakbagger.com/map/bigmap.aspx?t=W&l=CT&d=9&cx=-123.601&cy=47.7711&rad=13.58&minx=-123.893&miny=47.5746&maxx=-123.309&maxy=47.9676&hj=0 https://www.peakbagger.com/map/bigmap.aspx?t=W&l=CT&d=9&cx=-...
  - technocratius 4y ago
    > A few miles away from a remote forest road in the wrong direction and you might not see any people for years and years. This is essentially what happened to this McCandless guy in Alaska. That book about him -Into The Wild, by Krakauer - is super well written and a very interesting story. The movie based on the book is also quite well produced.
- hgsgm 4y ago
  I found a reference at http://remotefootprints.org/ http://remotefootprints.org/ linked from BBC, but it looks like the site was hacked by a Bitcoin/crypto scammer. Anyway, they claim that in USA rhat 22miles is the farthest you can get from a road of any kind that supports a vehicle, and still be in "developable" terrain. That would exclude mountains, lakes, floodplains, and maybe or maybe not forests (because they could be cut down?)
  - 4y ago
ryandrake 4y ago
Not entirely clear from the article, but it looks like it might be a "straight" line on a Mercator-projected map, in other words, a rhumb line[1]. So that technically doesn't answer the question "what (and where) is the longest distance you can walk in a straight line [...]??" When you are walking in reference to a compass (let's simplify and assume it references True North), you are actually making a gradual turn to stay aligned with your angle to the meridians. Especially at high latitudes like in Great Britain. Instead, he should be looking for the longest Great Circle[2] line from point to point, which may, in reality, be in a very similar location because for short distances, great circles often line up very closely with rhumblines. The author is a founder of a mapping company, so he very likely knows this, and the article is aimed at a more layman audience who likes to play around with Google Maps and such. 1: https://en.wikipedia.org/wiki/Rhumb_line https://en.wikipedia.org/wiki/Rhumb_line 2: https://en.wikipedia.org/wiki/Great_circle https://en.wikipedia.org/wiki/Great_circle
- rootusrootus 4y ago
  If it were to get technical enough to differentiate between rhumb and great circle, then maybe it should factor in elevation changes too.
  - 0_____0 4y ago
    If you include elevation then you have to include tolerance for deviation. I live in an old house, so I can't even walk across the room without a vertical deviation of some sort :) Edit: My point here is that if you try to plot a literal straight line through 3D space, it will be necessary to allow some amount of deviation in one axis. Else your longest 3D line will be the distance between your first two points.
  - crznp 4y ago
    He does: 75.9km on the map, 77.0km when accounting for elevation. With the caveat: "Well, it's never as much as I'd think and it depends upon the accuracy of your terrain model"
    - 4y ago
karaterobot 4y ago
This is neat. I pretty easily found a 183km straight line through central WA, from Wenatchee/Cashmere, NNW up to the Canadian border. I can only visually confirm (via Google Earth) that it doesn't cross paved roads though.
- chihuahua 4y ago
  Since Route 20, a state highway, goes all the way across the state, from west to east, and it's between Wenatchee and the Canadian border, it seems to me that your straight line would have to end when it intersects Route 20 somewhere near Diablo.
  - karaterobot 4y ago
    Yep, you're right. So, at most 148km.
- legitster 4y ago
  Uh, that can't be right. Highway 20 would cut through that in the middle. Perhaps the software is a bit confused because the highway closes during winters? Also, the terrain profile of this straight line would make the Scottish line look like a mini-golf course!
corwinstephen 4y ago
This would be a cool metric to use in various analyses. It's a number that's guaranteed to be shrinking fast in today's world and I'd bet there's a quality-of-life benefit to be had by trying to optimize for growing it rather than shrinking it.
regularjack 4y ago
> 'a paved surface for vehicular use' The author is assuming that all "restricted access" roads are unpaved, which I think is unlikely to be true. I wonder if there's data about which roads are paved. Regardless, very interesting stuff, and great analysis.
- pornel 4y ago
  In the UK even "public" roads deep in the countryside are often unpaved.
jkaptur 4y ago
It looks like the author found this line using manual inspection, but it seems possible to automate the search: https://github.com/BradleyWood/Longest-Line-In-Polygon/blob/master/README.md https://github.com/BradleyWood/Longest-Line-In-Polygon/blob/.... It might even be sufficiently fast, despite the O(n^3) running time, because the 'n' is the number of points per polygon, not total, and you can operate on each polygon in order of "wingspan" (you can't stop once you find the longest straight line in the longest polygon, but you can once your best line is greater than the wingspan of the remaining polygons).
ks2048 4y ago
This is mainly about getting getting the correct roads data, but I would be more interested in the algorithmic question: given a roads network, how do you find the longest line not crossing a road? The linked blog post mentioned they "calculated the areas of all the polygons to identify the largest ones". Just drawing some lines on a plane, there are not necessarily any polygons. And they say start and end points must be on vertices, but I'm not sure why. So it's not very clear.
- OscarCunningham 4y ago
  This paper https://arxiv.org/abs/1804.07389# https://arxiv.org/abs/1804.07389# uses an algorithm called 'branch-and-bound'.

154 points by samwillis 4y ago

Loved it. Seemed like it was discovered by manual search

> Crown copyright and database rights 2023. Do i, as a US citizen, have to respect Crown Copyright? I mean, the USA originated in a revolt against that very same crown. The USA is by constitution and temperament forbidden from giving out titles and such. We respect free markets, content creators and their successors in interest here.

lljk_kennedy 4y ago
Technically, legal proceedings could be taken against you in the UK. Realistically - most of the stuff covered by Crown Copyright falls under the Open Government License and is free to use once attributed. https://www.cla.co.uk/crown-copyright https://www.cla.co.uk/crown-copyright https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/ https://www.nationalarchives.gov.uk/doc/open-government-lice...
matthews2 4y ago
The United States is party to the Berne Convention, so yes.
bigdollopenergy 4y ago
In as much as anyone has to respect the copyright coming from any jurisdiction they are not in. Which for the most of the world generally means that, yes, you do have to respect it. It being the UK and your historical reasoning isn't very relevant. One of the main things that allows global trade to happen as freely as it does, is countries cooperating so that copyright can be legally enforced across them. The resulting court cases are likely to be less actionable if you have no presence there, but you can be sued in that country for breach of copyright and have a judgement placed upon you. It's bilateral, a Brit may wonder the same thing about the US or any other country and the answer would be the same.
- InCityDreams 4y ago
  The Pirate Bay disagrees. They rather splendidly told the usa to gtfo, as did kim dotcom. Ymmv.
Doctor_Fegg 4y ago
> We respect free markets, content creators That’s awesome. Please respect the content creators at the Ordnance Survey then.
swarnie 4y ago
Since the US don't extradite even for serious offences You can probably just ignore it and be tried in absentia if caught and prosecuted. You'll have to join the 66% of your countrymen who can't travel abroad however.
- deleted 4y ago
  [deleted]
- ledauphin 4y ago
  this is an interesting statistic. I'd love to have a reference!
  - killjoywashere 4y ago
    Seems there are some stats running around about the number of US citizens who hold passports. https://www.statista.com/statistics/804430/us-citzens-owning-a-passport/ https://www.statista.com/statistics/804430/us-citzens-owning...
  - pacaro 4y ago
    https://today.yougov.com/topics/travel/articles-reports/2021/04/21/only-one-third-americans-have-valid-us-passport https://today.yougov.com/topics/travel/articles-reports/2021... Apparently only 37% of Americans have a valid current passport
    - ghaff 4y ago
      Even assuming that includes passport cards for Canada/Mexico, unless someone lives near the border, an international trip is a relatively big deal for a lot of families. The US is big and has a lot of variety for travel. It's really not surprising that a (sizable) minority don't have near-term plans to travel internationally.
      - pacaro 4y ago
        Absolutely agree. The socio-economic breakdown of the research backs this up. It's very strongly correlated with household income
Woeps 4y ago
Uhm, kinda, it depends. Overall Copyright is all mushed together under some kind of global agreement right? Because must I remind you, of your post of an hour ago: "property rights are paramount." ;)
Veen 4y ago
The Crown isn't really the monarchy when used in this sense and it doesn't have much to do with titles and such. It's a synecdoche used to refer to the UK government (and the governments of some commonwealth countries). Crown Copyright is the copyright the government holds in the material it creates. In this case, the Ordnance Survey, which is a UK government agency. Whether you have to respect that copyright is a different matter, although it may be unwise to use Ordnance Survey mapping data for commercial purposes without a license.
- dragonwriter 4y ago
  > The Crown isn't really the monarchy when used in this sense and it doesn't have much to do with titles and such. It's a synecdoche used to refer to the UK government That’s also the Crown the US was revolting against, so...
eertami 4y ago
I think it's actually the US which is more likely to take issue with you for breaking the copyright, than the UK would. Considering the US publishes an annual report on copyright/IP rights enforcement about it's trading partners that it deems to be insufficient[0]. [0]: https://ustr.gov/sites/default/files/USTR-2016-Special-301-Report.pdf https://ustr.gov/sites/default/files/USTR-2016-Special-301-R...
dukeyukey 4y ago
No need to be edgy. Crown copyright is just the phrase used for copyright created when the UK (And Canada, and Australia, and others) create copyrighted content. It's nothing special.

shrx 4y ago

I see a new GeoWizard [1] series covering this in the future [1] https://www.youtube.com/watch?v=M7w986ni7_g https://www.youtube.com/watch?v=M7w986ni7_g

sixothree 4y ago
Even before I finished reading the headline, I assumed this was part of his work.
neom 4y ago
Was just coming here to comment about GeoWizard. Probably my favorite YouTuber, straight line challenge is awesome, how not to cross American is my favorite YouTube series by a long shot.
- eCa 4y ago
  The ”How not to travel America” playlist: https://youtube.com/playlist?list=PL_japiE6QKWrCfn7NFL86bRSWez5DTDWt https://youtube.com/playlist?list=PL_japiE6QKWrCfn7NFL86bRSW... Don’t miss the similarly named Europe trip either, for anyone new to GeoWizard.
spuz 4y ago
Along those lines, someone else whose attempts I've really enjoyed watching is Ally who recently uploaded the first part of his attempt to cross Scotland in a straight line: https://youtu.be/_Lcu6qL7NWs https://youtu.be/_Lcu6qL7NWs
yreg 4y ago
He had one where he wasn't allowed to use roads[0]. But crossing them is fine, the man can teleport across railroads anyway[1]. [0] - https://youtu.be/pDU9BOtX80A https://youtu.be/pDU9BOtX80A [1] - https://youtu.be/QkLDThED4T4?t=2195 https://youtu.be/QkLDThED4T4?t=2195

justinator 4y ago

Being an avid hill walker, I love to see how far away from civilization I can get in Colorado on my hikes. I should be able to get really out there, right? My State is 1/3 public, undeveloped land! The farthest summit from a road is about 6 miles. Kinda made me sad inside. That's how remote you can get from a car. I have gone on farther trips without crossing a paved road - one being 120 miles that took 6+ days (tough terrain!) by following the crest of an entire mountain range - quite difficult. As the crow flies, that's about 70 miles point to point. If you stretch the theoretical limit between paved roads - encapsulating this entire mountain range, it's about 78 miles. There's about 3 rough 4WD tracks that you can use to cross it - but that's it, in that entire range, any other point across you have to traverse by foot (and there's only a few trails to do so too). Hope it stays that way. But again, it's still always <6 miles to where you can drive a car. I've been to more "remote" places, such as Alaska, with vast Wilderness- but they let you fly planes into there, which seems somewhat like cheating.

bombcar 4y ago
Part of the issue is that the vast western BLM land in the USA is mostly some variation of desert; and that desert is very VERY easy to put a road down on, if all the road is a slightly graded path. I assume you've seen https://www.projectremote.com/remote-statistics/ https://www.projectremote.com/remote-statistics/ (updated from defaced/hacked domain)
- justinator 4y ago
  hmm, I think though there's a reason that the road exists - even in the desert? Probably to mine or a mine town originally? Same with all the roads in the mountains. Resource extraction and motor vehicles kinda go hand in hand.
  - bombcar 4y ago
    Most of the ones I've encountered in the high desert have things like ancient mining claims or tiny towns somewhere, but others appear to simply be 4WD trails that have been used "enough". According to the link; Wyoming has the furthest at 21 miles from a road (which is a circle containing 1385 sq miles). Since distance from a road is a circle, the sq miles needed to get far from it go fast quickly, even six miles is 113 sq mile, and since it's likely a road alongside one edge, you're talking a square of land at least 144 sq mile. The only things that big are usually parks/nature reserves of some kind, and they often have fire roads or other accesses built for reasons (including people camping, etc).

gooseyman 4y ago

Even cooler when you consider the right to roam https://en.m.wikipedia.org/wiki/Freedom_to_roam https://en.m.wikipedia.org/wiki/Freedom_to_roam I live in a state that has very little public land, which would make any attempt to walk it incredibly difficult

sixothree 4y ago

I remember talking to a group of people about the "vastness of America" and mentioned that no matter where you go you're never really more than 20 miles from a road. Not a single person believed me. I never did follow up with investigation. But I do sometimes ask people this question. Ultimately, people seem to think there are these great patches of untouched land on a vast scale where it simply doesn't exist.

adrianpike 4y ago
Yep, even the furthest spot in Wyoming in the Thorofare wilderness complex is something like 19 miles out from a road. One thing to keep in mind is that only a few miles over rugged terrain can be a _lot_. A few miles away from a remote forest road in the wrong direction and you might not see any people for years and years. I do search and rescue out here, and even with helicopters it's pretty vast; https://www.peakbagger.com/map/bigmap.aspx?t=W&l=CT&d=9&cx=-123.601&cy=47.7711&rad=13.58&minx=-123.893&miny=47.5746&maxx=-123.309&maxy=47.9676&hj=0 https://www.peakbagger.com/map/bigmap.aspx?t=W&l=CT&d=9&cx=-...
- technocratius 4y ago
  > A few miles away from a remote forest road in the wrong direction and you might not see any people for years and years. This is essentially what happened to this McCandless guy in Alaska. That book about him -Into The Wild, by Krakauer - is super well written and a very interesting story. The movie based on the book is also quite well produced.
hgsgm 4y ago
I found a reference at http://remotefootprints.org/ http://remotefootprints.org/ linked from BBC, but it looks like the site was hacked by a Bitcoin/crypto scammer. Anyway, they claim that in USA rhat 22miles is the farthest you can get from a road of any kind that supports a vehicle, and still be in "developable" terrain. That would exclude mountains, lakes, floodplains, and maybe or maybe not forests (because they could be cut down?)
- 4y ago

ryandrake 4y ago

Not entirely clear from the article, but it looks like it might be a "straight" line on a Mercator-projected map, in other words, a rhumb line[1]. So that technically doesn't answer the question "what (and where) is the longest distance you can walk in a straight line [...]??" When you are walking in reference to a compass (let's simplify and assume it references True North), you are actually making a gradual turn to stay aligned with your angle to the meridians. Especially at high latitudes like in Great Britain. Instead, he should be looking for the longest Great Circle[2] line from point to point, which may, in reality, be in a very similar location because for short distances, great circles often line up very closely with rhumblines. The author is a founder of a mapping company, so he very likely knows this, and the article is aimed at a more layman audience who likes to play around with Google Maps and such. 1: https://en.wikipedia.org/wiki/Rhumb_line https://en.wikipedia.org/wiki/Rhumb_line 2: https://en.wikipedia.org/wiki/Great_circle https://en.wikipedia.org/wiki/Great_circle

rootusrootus 4y ago
If it were to get technical enough to differentiate between rhumb and great circle, then maybe it should factor in elevation changes too.
- 0_____0 4y ago
  If you include elevation then you have to include tolerance for deviation. I live in an old house, so I can't even walk across the room without a vertical deviation of some sort :) Edit: My point here is that if you try to plot a literal straight line through 3D space, it will be necessary to allow some amount of deviation in one axis. Else your longest 3D line will be the distance between your first two points.
- crznp 4y ago
  He does: 75.9km on the map, 77.0km when accounting for elevation. With the caveat: "Well, it's never as much as I'd think and it depends upon the accuracy of your terrain model"
  - 4y ago

karaterobot 4y ago

This is neat. I pretty easily found a 183km straight line through central WA, from Wenatchee/Cashmere, NNW up to the Canadian border. I can only visually confirm (via Google Earth) that it doesn't cross paved roads though.

chihuahua 4y ago
Since Route 20, a state highway, goes all the way across the state, from west to east, and it's between Wenatchee and the Canadian border, it seems to me that your straight line would have to end when it intersects Route 20 somewhere near Diablo.
- karaterobot 4y ago
  Yep, you're right. So, at most 148km.
legitster 4y ago
Uh, that can't be right. Highway 20 would cut through that in the middle. Perhaps the software is a bit confused because the highway closes during winters? Also, the terrain profile of this straight line would make the Scottish line look like a mini-golf course!

corwinstephen 4y ago

This would be a cool metric to use in various analyses. It's a number that's guaranteed to be shrinking fast in today's world and I'd bet there's a quality-of-life benefit to be had by trying to optimize for growing it rather than shrinking it.

regularjack 4y ago

> 'a paved surface for vehicular use' The author is assuming that all "restricted access" roads are unpaved, which I think is unlikely to be true. I wonder if there's data about which roads are paved. Regardless, very interesting stuff, and great analysis.

pornel 4y ago
In the UK even "public" roads deep in the countryside are often unpaved.

jkaptur 4y ago

It looks like the author found this line using manual inspection, but it seems possible to automate the search: https://github.com/BradleyWood/Longest-Line-In-Polygon/blob/master/README.md https://github.com/BradleyWood/Longest-Line-In-Polygon/blob/.... It might even be sufficiently fast, despite the O(n^3) running time, because the 'n' is the number of points per polygon, not total, and you can operate on each polygon in order of "wingspan" (you can't stop once you find the longest straight line in the longest polygon, but you can once your best line is greater than the wingspan of the remaining polygons).

ks2048 4y ago

This is mainly about getting getting the correct roads data, but I would be more interested in the algorithmic question: given a roads network, how do you find the longest line not crossing a road? The linked blog post mentioned they "calculated the areas of all the polygons to identify the largest ones". Just drawing some lines on a plane, there are not necessarily any polygons. And they say start and end points must be on vertices, but I'm not sure why. So it's not very clear.

OscarCunningham 4y ago
This paper https://arxiv.org/abs/1804.07389# https://arxiv.org/abs/1804.07389# uses an algorithm called 'branch-and-bound'.