7 ms·

Nearly two decades of satellite images available in Nasa’s Worldview

206 points by eaguyhn 8y ago

pul 8y ago
Here's the link to what this article is referring to: https://worldview.earthdata.nasa.gov/ https://worldview.earthdata.nasa.gov/
- stinos 8y ago
  Nice. Is there a simple explanation somewhere of what the different bands mean? E.g. I'm looking at my place now and we have this spot on our property where the vegetation is quite different and this exact spot shows up clearly on the NDVI layer. Houses etc do as well so could be temperature?
  - agcopenhaver 8y ago
    NDVI is a well established vegetation index that takes advantage of the relatively unique spectral qualities of vegetation, in that it absorbs large amounts of red light and reflects large amounts of infrared. It is the normalized difference of a sensor's near infrared band and its red band. There are numerous band combinations available to highlight certain materials within a scene. Here is a link describing some additional indices: http://www.harrisgeospatial.com/docs/AlphabeticalListSpectralIndices.html http://www.harrisgeospatial.com/docs/AlphabeticalListSpectra... Additionally, here is a brief description of different individual bands and how they can be used: https://gisgeography.com/spectral-signature/ https://gisgeography.com/spectral-signature/
    - stinos 8y ago
      Thanks for this, very helpful!
- sp332 8y ago
  Is this a web-based version of World Wind, or a separate project? https://en.wikipedia.org/wiki/NASA_World_Wind https://en.wikipedia.org/wiki/NASA_World_Wind
  - noiv 8y ago
    Different interfaces - data sources mostly overlap as they are in the public domain.
throwawaymath 8y ago
This is great news for a project I'm currently working on: https://news.ycombinator.com/item?id=17237445 https://news.ycombinator.com/item?id=17237445. I'll be sure to look into this and see what's new compared to what's already out there. There is a lot of public satellite imagery. That said, I wouldn't be surprised if this isn't actually the first surfacing of this particular dataset. My experience is that most data of this kind (satellite, land station, oceanic/marine, balloon, radar, etc...) is already available online. It's unfortunately mired in a sea of complexity, filled with shifting departments, confusing acronyms, funding depletion and musical chairs. Here is my favorite example. The NOAA works directly with NASA for much of this kind of data, and stewards it online here: https://www.ncdc.noaa.gov/data-access https://www.ncdc.noaa.gov/data-access. Observe that the URL indicates the department is the NCDC (National Climatic Data Center). As it turns out, the website informs us that the NCDC no longer exists, and is now known as the NCEI (National Centers for Environmental Information). But let's put that detail aside. Now we go to the page listed for satellite datasets: https://www.ncdc.noaa.gov/data-access/satellite-data/satellite-data-access-datasets https://www.ncdc.noaa.gov/data-access/satellite-data/satelli.... Lots of acronyms - acronyms for everything! Let's try the OISST (Optimum Interpolation Sea Surface Temperature) dataset: http://www.ncdc.noaa.gov/sst/ http://www.ncdc.noaa.gov/sst/. Whoops, that 404s. It also doesn't tell us what the acronym stands for. Fortunately we can find the canonical page by Googling for it. Okay, let's try another dataset back on that first page. How about the SSM/I-SSMIS (Special Sensor Microwave/Imager and Special Sensor Microwave Imager Sounder): https://www.ncdc.noaa.gov/ssmi https://www.ncdc.noaa.gov/ssmi? Well, we're told we have to go to http://www.class.noaa.gov/ http://www.class.noaa.gov/ to get that data. Now the first thing we see on that page is an "urgent notice" that URLs are breaking, and anyone using the current ones (for e.g. FTP access) has to migrate to a slightly different URL with a choice of subdomains appended. Moving past that initial notice, if we actually try to find the SSMI dataset, we find out that it's actually listed as the DMSP (Defense Meteorological Satellite Program): https://www.bou.class.noaa.gov/saa/products/search?datatype_family=DMSP https://www.bou.class.noaa.gov/saa/products/search?datatype_.... Now to download this data, we're presented with this wacky interface: https://www.bou.class.noaa.gov/saa/products/psearchDMSP https://www.bou.class.noaa.gov/saa/products/psearchDMSP. This is basically why I decided to work on my current project to consolidate, document and organize all of this data in a public search engine. It feels like so much climate data is only public in the absolute minimum sense of the word, because trying to access it (or even make sense of all of it) transports me back to 2006. There's a very real sense that the right hand doesn't know what the left is doing here. Clearly these organizations are aware that accessing the data is difficult, and they must have good intentions by going through the effort to document it and host it in FTP servers. But there are so many conflicting names and acronyms for the "stewards" for overseeing this or that data, which redirect you to various "portals" for searching it, which tell you to add data to your "cart" to "order" in some sort of contrived interface. It's maddening. Well, there ends my rant for the day. If anyone has any good ideas for working on this, please feel free to get in touch.
hanselot 8y ago
Someone has to keep the UFO hunters busy.
noiv 8y ago
ESA's Sentinel fleet offers similar images with much higher spatial but lower temporal resolution, here's a two days old nearly cloud free view of San Francisco: https://apps.sentinel-hub.com/eo-browser/#lat=37.7504&lng=-122.3142&zoom=12&time=2018-06-09&preset=1_TRUE_COLOR&datasource=Sentinel-2%20L1C https://apps.sentinel-hub.com/eo-browser/#lat=37.7504&lng=-1...
waffle_ss 8y ago
A project I wish existed is an open source competitor to Google Earth's automatic generation of 3D models from satellite images. Their generator is pretty smart and even generates pretty good approximations of trees, bushes, streetlights, and so on. This is very useful when you need to figure out 360° line-of-sight from a point in space (i.e. a viewshed) for things like planning where to put RF antennas as topographic maps don't take vegetation or other obstructions into account. Google Earth even has built-in viewshed generation which uses their 3D model data (works great), but unfortunately the 3D model layer only seems to exist for fairly populated areas (probably because it's computationally expensive) - so doing RF planning in rural areas requires more traditional legwork. So it would be cool for a project to provide similar functionality for OpenStreetMap using this public satellite data. OpenStreetMap does have 3D modeling support but last time I looked it seemed pretty focused on buildings and people hand-editing the data.
- jakecopp 8y ago
  I don't think it would be in scope of OpenStreetMap itself, but it would be an incredible service alongside it. Even just for tracing non-existing building outlines in OpenStreetMap - it would be a huge help. Much of the work for Humanitarian OpenStreetMap Tasker (https://tasks.hotosm.org/ https://tasks.hotosm.org/) is building tracing - it would be a huge help. If someone is good with machine learning please build this!!
  - toomuchtodo 8y ago
    I’d argue that we shouldn’t be so quick to say what isn’t in OSMs scope. To me, OSM should be the open Source Of Truth for all worldwide GIS data, a way to refer to our entire cartographic world in a digital format. Perhaps now it’s restricted to mapping data, but I would love to see the steering committee bring additional products out (temporal layers, the mapping you mention, and so on). If OSM is important to you, there’s an open executive position advertised on the last HN Who’s Hiring post.
    - rmc 8y ago
      > If OSM is important to you, there’s an open executive position advertised on the last HN Who’s Hiring post. That position is only for the "OpenStreetMap US" local chapter, not OSM globally. OSM is quite large outside the US, so if you get that job, don't expect to be able to shape the OSM community & project, which can be like herding cats... The best way to affect change like this in OSM, is to become active and respected in the project. It's quite a do-ocracy.
gizmodo59 8y ago
Is it me or the level of detail is not good in some regions even compared to Google Earth? https://worldview.earthdata.nasa.gov/ https://worldview.earthdata.nasa.gov/
- noiv 8y ago
  Where available GE has images taken from planes updated after several years. WorldView's images are updated every day and taken from satellites.
deleted 8y ago
[deleted]

206 points by eaguyhn 8y ago

pul 8y ago

Here's the link to what this article is referring to: https://worldview.earthdata.nasa.gov/ https://worldview.earthdata.nasa.gov/

stinos 8y ago
Nice. Is there a simple explanation somewhere of what the different bands mean? E.g. I'm looking at my place now and we have this spot on our property where the vegetation is quite different and this exact spot shows up clearly on the NDVI layer. Houses etc do as well so could be temperature?
- agcopenhaver 8y ago
  NDVI is a well established vegetation index that takes advantage of the relatively unique spectral qualities of vegetation, in that it absorbs large amounts of red light and reflects large amounts of infrared. It is the normalized difference of a sensor's near infrared band and its red band. There are numerous band combinations available to highlight certain materials within a scene. Here is a link describing some additional indices: http://www.harrisgeospatial.com/docs/AlphabeticalListSpectralIndices.html http://www.harrisgeospatial.com/docs/AlphabeticalListSpectra... Additionally, here is a brief description of different individual bands and how they can be used: https://gisgeography.com/spectral-signature/ https://gisgeography.com/spectral-signature/
  - stinos 8y ago
    Thanks for this, very helpful!
sp332 8y ago
Is this a web-based version of World Wind, or a separate project? https://en.wikipedia.org/wiki/NASA_World_Wind https://en.wikipedia.org/wiki/NASA_World_Wind
- noiv 8y ago
  Different interfaces - data sources mostly overlap as they are in the public domain.

throwawaymath 8y ago

This is great news for a project I'm currently working on: https://news.ycombinator.com/item?id=17237445 https://news.ycombinator.com/item?id=17237445. I'll be sure to look into this and see what's new compared to what's already out there. There is a lot of public satellite imagery. That said, I wouldn't be surprised if this isn't actually the first surfacing of this particular dataset. My experience is that most data of this kind (satellite, land station, oceanic/marine, balloon, radar, etc...) is already available online. It's unfortunately mired in a sea of complexity, filled with shifting departments, confusing acronyms, funding depletion and musical chairs. Here is my favorite example. The NOAA works directly with NASA for much of this kind of data, and stewards it online here: https://www.ncdc.noaa.gov/data-access https://www.ncdc.noaa.gov/data-access. Observe that the URL indicates the department is the NCDC (National Climatic Data Center). As it turns out, the website informs us that the NCDC no longer exists, and is now known as the NCEI (National Centers for Environmental Information). But let's put that detail aside. Now we go to the page listed for satellite datasets: https://www.ncdc.noaa.gov/data-access/satellite-data/satellite-data-access-datasets https://www.ncdc.noaa.gov/data-access/satellite-data/satelli.... Lots of acronyms - acronyms for everything! Let's try the OISST (Optimum Interpolation Sea Surface Temperature) dataset: http://www.ncdc.noaa.gov/sst/ http://www.ncdc.noaa.gov/sst/. Whoops, that 404s. It also doesn't tell us what the acronym stands for. Fortunately we can find the canonical page by Googling for it. Okay, let's try another dataset back on that first page. How about the SSM/I-SSMIS (Special Sensor Microwave/Imager and Special Sensor Microwave Imager Sounder): https://www.ncdc.noaa.gov/ssmi https://www.ncdc.noaa.gov/ssmi? Well, we're told we have to go to http://www.class.noaa.gov/ http://www.class.noaa.gov/ to get that data. Now the first thing we see on that page is an "urgent notice" that URLs are breaking, and anyone using the current ones (for e.g. FTP access) has to migrate to a slightly different URL with a choice of subdomains appended. Moving past that initial notice, if we actually try to find the SSMI dataset, we find out that it's actually listed as the DMSP (Defense Meteorological Satellite Program): https://www.bou.class.noaa.gov/saa/products/search?datatype_family=DMSP https://www.bou.class.noaa.gov/saa/products/search?datatype_.... Now to download this data, we're presented with this wacky interface: https://www.bou.class.noaa.gov/saa/products/psearchDMSP https://www.bou.class.noaa.gov/saa/products/psearchDMSP. This is basically why I decided to work on my current project to consolidate, document and organize all of this data in a public search engine. It feels like so much climate data is only public in the absolute minimum sense of the word, because trying to access it (or even make sense of all of it) transports me back to 2006. There's a very real sense that the right hand doesn't know what the left is doing here. Clearly these organizations are aware that accessing the data is difficult, and they must have good intentions by going through the effort to document it and host it in FTP servers. But there are so many conflicting names and acronyms for the "stewards" for overseeing this or that data, which redirect you to various "portals" for searching it, which tell you to add data to your "cart" to "order" in some sort of contrived interface. It's maddening. Well, there ends my rant for the day. If anyone has any good ideas for working on this, please feel free to get in touch.

hanselot 8y ago

Someone has to keep the UFO hunters busy.

noiv 8y ago

ESA's Sentinel fleet offers similar images with much higher spatial but lower temporal resolution, here's a two days old nearly cloud free view of San Francisco: https://apps.sentinel-hub.com/eo-browser/#lat=37.7504&lng=-122.3142&zoom=12&time=2018-06-09&preset=1_TRUE_COLOR&datasource=Sentinel-2%20L1C https://apps.sentinel-hub.com/eo-browser/#lat=37.7504&lng=-1...

waffle_ss 8y ago

A project I wish existed is an open source competitor to Google Earth's automatic generation of 3D models from satellite images. Their generator is pretty smart and even generates pretty good approximations of trees, bushes, streetlights, and so on. This is very useful when you need to figure out 360° line-of-sight from a point in space (i.e. a viewshed) for things like planning where to put RF antennas as topographic maps don't take vegetation or other obstructions into account. Google Earth even has built-in viewshed generation which uses their 3D model data (works great), but unfortunately the 3D model layer only seems to exist for fairly populated areas (probably because it's computationally expensive) - so doing RF planning in rural areas requires more traditional legwork. So it would be cool for a project to provide similar functionality for OpenStreetMap using this public satellite data. OpenStreetMap does have 3D modeling support but last time I looked it seemed pretty focused on buildings and people hand-editing the data.

jakecopp 8y ago
I don't think it would be in scope of OpenStreetMap itself, but it would be an incredible service alongside it. Even just for tracing non-existing building outlines in OpenStreetMap - it would be a huge help. Much of the work for Humanitarian OpenStreetMap Tasker (https://tasks.hotosm.org/ https://tasks.hotosm.org/) is building tracing - it would be a huge help. If someone is good with machine learning please build this!!
- toomuchtodo 8y ago
  I’d argue that we shouldn’t be so quick to say what isn’t in OSMs scope. To me, OSM should be the open Source Of Truth for all worldwide GIS data, a way to refer to our entire cartographic world in a digital format. Perhaps now it’s restricted to mapping data, but I would love to see the steering committee bring additional products out (temporal layers, the mapping you mention, and so on). If OSM is important to you, there’s an open executive position advertised on the last HN Who’s Hiring post.
  - rmc 8y ago
    > If OSM is important to you, there’s an open executive position advertised on the last HN Who’s Hiring post. That position is only for the "OpenStreetMap US" local chapter, not OSM globally. OSM is quite large outside the US, so if you get that job, don't expect to be able to shape the OSM community & project, which can be like herding cats... The best way to affect change like this in OSM, is to become active and respected in the project. It's quite a do-ocracy.

gizmodo59 8y ago

Is it me or the level of detail is not good in some regions even compared to Google Earth? https://worldview.earthdata.nasa.gov/ https://worldview.earthdata.nasa.gov/

noiv 8y ago
Where available GE has images taken from planes updated after several years. WorldView's images are updated every day and taken from satellites.

deleted 8y ago

[deleted]