[HN Gopher] Learning About the GeoTIFF File Format with a Hex Ed...
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Learning About the GeoTIFF File Format with a Hex Editor (2018)
Author : oldpatricka
Score : 71 points
Date : 2021-05-05 16:42 UTC (6 hours ago)
(HTM) web link (medium.com)
(TXT) w3m dump (medium.com)
| ivanhoe wrote:
| speaking of this, what hex editor would community recommend for
| examining (potentially quite large) binaries?
| redrobein wrote:
| ImHex
| gspr wrote:
| I haven't gotten my hands dirty with it myself yet, but Poke
| looks super interesting!
|
| https://www.jemarch.net/poke
|
| https://media.ccc.de/v/ASG2019-127-gnu-poke-an-extensible-ed...
|
| Actually, it sounds like a fun weekend task to redo this
| GeoTIFF writeup in Poke :-)
| MontagFTB wrote:
| On the Mac, I cannot recommend Hex Fiend enough:
| https://hexfiend.com/
| punnerud wrote:
| Could we build a static "Google Maps" using really big GeoTIFF
| files and downloading part of them with the section of a file
| functionality.
|
| Just like the SQLite example:
| https://news.ycombinator.com/item?id=27025829
| gregsadetsky wrote:
| I think that you meant to link to
| https://news.ycombinator.com/item?id=27016630 instead which was
| the recently posted SQLite/SQL.js/HTTP range library
|
| And there was a specific sub-thread in the conversation that
| mentioned using this for maps too!
|
| https://news.ycombinator.com/item?id=27020372
| punnerud wrote:
| Thank you, a bit too fast there
| kylebarron wrote:
| You could, you'd just have to be wary of how large the header
| metadata would be. If you had a single Cloud-Optimized GeoTIFF
| of the world with internal tiles up to zoom 14, the header
| metadata could be a few MB, which wouldn't be ideal to load in
| every client.
| kylebarron wrote:
| See also: https://github.com/pangeo-data/cog-best-
| practices/issues/9
| simonw wrote:
| Sad to say it but these days loading a few MB to a client is
| par for the course. I don't think it's a reason not to try
| and get this working - the range header trick does sound
| particularly relevant to this format.
|
| UPDATE: Just read https://kylebarron.dev/blog/cog-
| mosaic/overview which is excellent and clearly you're already
| very on top of the range request mechanism!
| gregsadetsky wrote:
| The posts on this topic on your site are really fascinating!
|
| https://kylebarron.dev/blog/cog-mosaic/overview
|
| https://kylebarron.dev/blog/cog-mosaic/naip
| kylebarron wrote:
| Thanks! The text is still relevant but those demos are a
| little old. If you're curious these demos are from last
| week (using Cloud-Optimized GeoTIFFs under the hood to
| serve image data quickly):
|
| - https://studio.unfolded.ai/public/9a2c5cd8-f0f0-43ce-b231
| -78...
|
| - https://studio.unfolded.ai/public/96c70224-dd89-431f-ae7a
| -0a...
|
| - https://studio.unfolded.ai/public/af792fd8-1990-4cdc-
| bf2b-99...
| kylebarron wrote:
| This is a good hex editor overview, but also the part about
| Cloud-Optimized GeoTIFFs is quite good. In the past couple of
| years COGs have really revolutionized the satellite imagery
| industry. Even USGS has seen this is the future and publishes the
| official Landsat data in Cloud-Optimized GeoTIFF format [0].
|
| I've been leveraging COGs recently to quickly bring satellite
| imagery into the browser for analysis [1].
|
| [0]: https://www.usgs.gov/core-science-
| systems/nli/landsat/landsa...
|
| [1]: https://www.unfolded.ai/blog/2021-04-28-raster-layer/
| alleycat5000 wrote:
| We use COGs at work with mapserver (and GDAL's /vsis3/ magic)
| to serve up imagery internally for qa/qc:
|
| https://github.com/pedros007/mapserver-docker
|
| Literally saves hundreds of thousands of dollars a year by
| avoiding having to stage the imagery locally before serving it
| out!
| darekkay wrote:
| I recently did something similar with Foobar 2000's playlist
| format [1]. It was a fun learning experience :)
|
| [1] https://darekkay.com/blog/foobar2000-playlist-index-format/
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(page generated 2021-05-05 23:00 UTC)