4 ms·

> where should I buy a house if I care about these four parameters? A lot of this data exists, and is freely available. I used to work for a startup where we

by tpxl 4y ago

> where should I buy a house if I care about these four parameters? A lot of this data exists, and is freely available. I used to work for a startup where we tried to accurately predict the amount of sun a particular plot of land would get. You can pretty much get a 3d map of the world with 5m accuracy (or even more granular, but the datasets get ridiculously big at that point), then render a 360° view from any location in the world and simulate the sun movement. You can even get 3d models of some cities to take buildings into account (the earth model is ground only). The startup eventually failed for Covid reasons. Satellite data is available for most of the world for things like wind speed, cloudiness, vegetation, ... If you live in a decent country you may be able to freely get data for zoning, power lines, internet, building density, public transport... You can build a really good dataset to evaluate a particular plot of land if you combine all this data. Anyway, hit me up if you ever get that FU money, because I'd also like to do something like this :)

paganel 4y ago
> You can pretty much get a 3d map of the world with 5m accuracy ( Related, maybe OT, but you seem a person that knows a lot more about this than I would know: more exactly I wanted to ask you if you know of a decent enough method to get the height of a building based on GoogleStreetView. Meaning, I'm "inside" GoogleStreetView, I'm looking at a "building" from outside on the street, I know the geo coordinates of the camera that took the photo, I know the geo coordinates of the building, so that I know the distance between the photo camera and the building, I can "count" (for lack of a better word) the building's size in screen pixels (or some other unit/reference? which one?), and based on all that I'm curious if one can get the real height in meters of said building. From what I could found around on some other forums there were people mentioning the aperture of the GoogleStreetView photo camera being part of the "equation" to compute it all, and that would be a problem because we do not know the values for the aperture. I have no idea though if all that discussion was on the subject or not.
- Waterluvian 4y ago
  The images need to be rectified or else, yes, the lens distortion messes up the measurements. Really you just need a length and an angle to complete the triangle. The length is easy: measure distance from base of building to any point where you know the angle. But getting the angle from a point to the top of the building is tricky. I don’t know if any clever way to estimate that without stereo imagery. A lot of this stuff is automatically calculated when a digital surface model (DSM) is generated from stereo pairs of images. So you might be able to just look it up in Google Earth. This is the data (probably blended with many other sources such as LiDAR and ground survey data) Google uses to extrude buildings into 3D models. P.S. this was an assignment in 1st year for me. Estimate the height of the CN Tower from some aerial photos. I feel like I should remember more.
- sorenjan 4y ago
  I took a shot at this. If you assume flat terrain between you and the base of the building, the problem can be simplified to basically the distance to the building from your current position times the tangent of the angle from the horizontal plane to the top of the building, from the definition of the tangent function[0]. To find the distance you can plug in your current coordinates and the buildings coordinates in a great circle distance calculator, like this one: [1], or just use the distance measure feature in Google maps. To find the angle you can zoom in on the top of the building in street view mode, and in the URL you'll have the pitch angle as a number between 1 and 179, ending in t [2] (so for instance 150.1t is a pitch angle of 150.1 degrees). Conveniently you'll also have the coordinates of the street view position in the same URL. To get the angle from the horizontal plane you have to subtract 90, since 0 pitch is straight down. I tried it with a tall building (Turning Torso in Malmö), and got 199 m on my first attempt and 195 on my second. The correct height is 190.4 m, so pretty close. The first attempt was 100 m away, the second more than 1.2 km. I then tried it with the Chrysler building from the other side of East river about 1.5 km away, and got 274 m which is close to the actual 282 m. You can probably use more sophisticated methods that downloads the 360 image as a stereographic projection and extracts the pitch angle from there, but for something that's a close enough one off I think this works ok. [0] https://en.wikipedia.org/wiki/Trigonometric_functions#Right-angled_triangle_definitions https://en.wikipedia.org/wiki/Trigonometric_functions#Right-... [1] https://www.gpsvisualizer.com/calculators https://www.gpsvisualizer.com/calculators [2] https://www.trekview.org/blog/2020/decoding-google-street-view-urls/ https://www.trekview.org/blog/2020/decoding-google-street-vi...
fingerlocks 4y ago
> You can pretty much get a 3d map of the world with 5m accuracy I'm having trouble locating high res DEM files. I can easily find arc second granular data (~30m accuracy at my latitude), but beyond that, it appears it's locked down for academic use or by request only. Where are you getting these freely available datasets? I'm not a GIS person, I dabble in map stuff for personal use, so forgive me if I'm missing something obvious somewhere.
- qwertox 4y ago
  The lack of high res DEM files angers me a lot as well. 30m simply isn't enough and then there are projects like TanDEM-X where it isn't clear why they can't share the 12m x 12m data with the public if it's mostly payed through public funding.
- orbisvicis 4y ago
  Yes, I agree that data balkanization represents a significant hindrance for further development of openstreetmap. Fifteen or so years ago I was experimenting with importing DEM files from the US into Blender for landscaping, and finding the data was frustrating. Sometimes the data was available at a state website, other times at a federal website, sometimes also available on the website of some mapping program/project. Surveys within a given geopolitical constraint would be found on the website of whichever department provided the funding. I understanding that, even if ignoring legal realities, merging this data into a single "ground" (heh) truth would be a herculean task, scientifically. But there was no common database or delivery method. Some departments would link to FTP sites, other would provide arcgis downloads via an interactive web tool. I'd have to depend on user-maintained blog posts to even find the data. And the best data was always locked away behind secure portals that I couldn't get access to. Nowadays openstreetmap is running into the same problem at the municipality level. In the US, if I understand correctly, publicly-funded geographic surveys are under copyright to whichever governing entity and not eligible for import into openstreetmap. Take for example the excellent app Every Door (https://github.com/Zverik/every_door https://github.com/Zverik/every_door) with a focus on easily adding building information. In the US, openstreetmap has no address information. Either that or very little address information - but none in my area. So it'd be easy for me to add building nodes with house numbers but I won't be doing that. Not only is it a massive commitment, but the data is already available at openaddresses.io. The catch? It's "probably" license-compatible with openstreetmap. Before merging, all that data would have to be reviewed by a team of lawyers. That's not something a software developer can help with. In existing threads here, a top complaint about OsmAnd is that lack of address information. Try planning a route without addresses, and without constantly switching to Google Maps to convert addresses to coordinates. Not very user friendly! Opensupermaps (https://github.com/pnoll1/osmand_map_creation https://github.com/pnoll1/osmand_map_creation) is a user-maintained merge of openstreetmaps and openaddresses.io, but it doesn't integrate with OsmAnd's data update system. And that's how data balkanization is breaking openstreetmap, right now.
mistrial9 4y ago
energy-generating systems will always attract money, since they produce something that sells, by definition. Unfortunately you are therefore out of luck.. there will be an endless line of new entries to do what you already did.. on the other side of the coin, is water, flooding and tides. Oceans are rising, many storms are more intense and flood events are increasing. Take your 3D knowledge and apply it to safety for floods and water events. No one wants that work, it is tedious and data-heavy. Yet, that is what is needed for many people who will not or cannot do it themselves. good luck
larsiusprime 4y ago
Is it possible to calculate what the view looks like from any arbitrary coordinate on the planet? At the very least, if there is a view of water, or of trees, or an unobstructed view of the horizon? And quantify that in some simple way?
- kvdveer 4y ago
  All the data is there, the ability to quantity it in some simple way is not.
- tpxl 4y ago
  It's not possible with 100% accuracy, but you might get close. You can model the land easily, but not trees or buildings. If you're standing on a barren rock it's easy, since there are no obstructions. If it's a forested area (you get this info from satellite images), you probably can't see water, even though there's no land between you and it, except if you're standing on a cliff or something, so the trees don't bother you. If it's an urban area, you probably won't be able to determine whether you can see water, since there aren't really models for buildings available.

by tpxl 4y ago

paganel 4y ago

> You can pretty much get a 3d map of the world with 5m accuracy ( Related, maybe OT, but you seem a person that knows a lot more about this than I would know: more exactly I wanted to ask you if you know of a decent enough method to get the height of a building based on GoogleStreetView. Meaning, I'm "inside" GoogleStreetView, I'm looking at a "building" from outside on the street, I know the geo coordinates of the camera that took the photo, I know the geo coordinates of the building, so that I know the distance between the photo camera and the building, I can "count" (for lack of a better word) the building's size in screen pixels (or some other unit/reference? which one?), and based on all that I'm curious if one can get the real height in meters of said building. From what I could found around on some other forums there were people mentioning the aperture of the GoogleStreetView photo camera being part of the "equation" to compute it all, and that would be a problem because we do not know the values for the aperture. I have no idea though if all that discussion was on the subject or not.

Waterluvian 4y ago
The images need to be rectified or else, yes, the lens distortion messes up the measurements. Really you just need a length and an angle to complete the triangle. The length is easy: measure distance from base of building to any point where you know the angle. But getting the angle from a point to the top of the building is tricky. I don’t know if any clever way to estimate that without stereo imagery. A lot of this stuff is automatically calculated when a digital surface model (DSM) is generated from stereo pairs of images. So you might be able to just look it up in Google Earth. This is the data (probably blended with many other sources such as LiDAR and ground survey data) Google uses to extrude buildings into 3D models. P.S. this was an assignment in 1st year for me. Estimate the height of the CN Tower from some aerial photos. I feel like I should remember more.
sorenjan 4y ago
I took a shot at this. If you assume flat terrain between you and the base of the building, the problem can be simplified to basically the distance to the building from your current position times the tangent of the angle from the horizontal plane to the top of the building, from the definition of the tangent function[0]. To find the distance you can plug in your current coordinates and the buildings coordinates in a great circle distance calculator, like this one: [1], or just use the distance measure feature in Google maps. To find the angle you can zoom in on the top of the building in street view mode, and in the URL you'll have the pitch angle as a number between 1 and 179, ending in t [2] (so for instance 150.1t is a pitch angle of 150.1 degrees). Conveniently you'll also have the coordinates of the street view position in the same URL. To get the angle from the horizontal plane you have to subtract 90, since 0 pitch is straight down. I tried it with a tall building (Turning Torso in Malmö), and got 199 m on my first attempt and 195 on my second. The correct height is 190.4 m, so pretty close. The first attempt was 100 m away, the second more than 1.2 km. I then tried it with the Chrysler building from the other side of East river about 1.5 km away, and got 274 m which is close to the actual 282 m. You can probably use more sophisticated methods that downloads the 360 image as a stereographic projection and extracts the pitch angle from there, but for something that's a close enough one off I think this works ok. [0] https://en.wikipedia.org/wiki/Trigonometric_functions#Right-angled_triangle_definitions https://en.wikipedia.org/wiki/Trigonometric_functions#Right-... [1] https://www.gpsvisualizer.com/calculators https://www.gpsvisualizer.com/calculators [2] https://www.trekview.org/blog/2020/decoding-google-street-view-urls/ https://www.trekview.org/blog/2020/decoding-google-street-vi...

fingerlocks 4y ago

> You can pretty much get a 3d map of the world with 5m accuracy I'm having trouble locating high res DEM files. I can easily find arc second granular data (~30m accuracy at my latitude), but beyond that, it appears it's locked down for academic use or by request only. Where are you getting these freely available datasets? I'm not a GIS person, I dabble in map stuff for personal use, so forgive me if I'm missing something obvious somewhere.

qwertox 4y ago
The lack of high res DEM files angers me a lot as well. 30m simply isn't enough and then there are projects like TanDEM-X where it isn't clear why they can't share the 12m x 12m data with the public if it's mostly payed through public funding.
orbisvicis 4y ago
Yes, I agree that data balkanization represents a significant hindrance for further development of openstreetmap. Fifteen or so years ago I was experimenting with importing DEM files from the US into Blender for landscaping, and finding the data was frustrating. Sometimes the data was available at a state website, other times at a federal website, sometimes also available on the website of some mapping program/project. Surveys within a given geopolitical constraint would be found on the website of whichever department provided the funding. I understanding that, even if ignoring legal realities, merging this data into a single "ground" (heh) truth would be a herculean task, scientifically. But there was no common database or delivery method. Some departments would link to FTP sites, other would provide arcgis downloads via an interactive web tool. I'd have to depend on user-maintained blog posts to even find the data. And the best data was always locked away behind secure portals that I couldn't get access to. Nowadays openstreetmap is running into the same problem at the municipality level. In the US, if I understand correctly, publicly-funded geographic surveys are under copyright to whichever governing entity and not eligible for import into openstreetmap. Take for example the excellent app Every Door (https://github.com/Zverik/every_door https://github.com/Zverik/every_door) with a focus on easily adding building information. In the US, openstreetmap has no address information. Either that or very little address information - but none in my area. So it'd be easy for me to add building nodes with house numbers but I won't be doing that. Not only is it a massive commitment, but the data is already available at openaddresses.io. The catch? It's "probably" license-compatible with openstreetmap. Before merging, all that data would have to be reviewed by a team of lawyers. That's not something a software developer can help with. In existing threads here, a top complaint about OsmAnd is that lack of address information. Try planning a route without addresses, and without constantly switching to Google Maps to convert addresses to coordinates. Not very user friendly! Opensupermaps (https://github.com/pnoll1/osmand_map_creation https://github.com/pnoll1/osmand_map_creation) is a user-maintained merge of openstreetmaps and openaddresses.io, but it doesn't integrate with OsmAnd's data update system. And that's how data balkanization is breaking openstreetmap, right now.

mistrial9 4y ago

energy-generating systems will always attract money, since they produce something that sells, by definition. Unfortunately you are therefore out of luck.. there will be an endless line of new entries to do what you already did.. on the other side of the coin, is water, flooding and tides. Oceans are rising, many storms are more intense and flood events are increasing. Take your 3D knowledge and apply it to safety for floods and water events. No one wants that work, it is tedious and data-heavy. Yet, that is what is needed for many people who will not or cannot do it themselves. good luck

larsiusprime 4y ago

Is it possible to calculate what the view looks like from any arbitrary coordinate on the planet? At the very least, if there is a view of water, or of trees, or an unobstructed view of the horizon? And quantify that in some simple way?

kvdveer 4y ago
All the data is there, the ability to quantity it in some simple way is not.
tpxl 4y ago
It's not possible with 100% accuracy, but you might get close. You can model the land easily, but not trees or buildings. If you're standing on a barren rock it's easy, since there are no obstructions. If it's a forested area (you get this info from satellite images), you probably can't see water, even though there's no land between you and it, except if you're standing on a cliff or something, so the trees don't bother you. If it's an urban area, you probably won't be able to determine whether you can see water, since there aren't really models for buildings available.