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Coordinate Reference Systems

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spk578
What does the "2000" mean at the end of the coordinate system names in the Solar System folder?   You can also find reference to the number in the details of the *.prj file itself.   GEOGCS["GCS_Jupiter_2000",DATUM["D_Jupiter_2000", SPHEROID["Jupiter_2000_IAU_IAG", 71492000.0,15.41440275981026]], PRIMEM["Reference_Meridian",0.0],… (Show more)
asrujit_pb
I'm trying to figure out why my raster image does not match its spatial extent. For example, the bottom-left corner of the image is supposed to be at (1033596, -526063) (see attachment "projection info"), but this point (green dot) does not line up with the bottom-left corner of the raster (see attachment "raster"). I've set the coordinate system… (Show more)
spk578
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spk578
Planetary Coordinate Reference Systems There is an interesting but perhaps little-used folder of *.prj files called “Solar System”. As someone interested in geodesy and its application it is particularly intriguing how scientists have constructed coordinate reference systems for planetary bodies other than the Earth.   First off let’s have a look… (Show more)
in Coordinate Reference Systems
spk578
In 2022, the National Spatial Reference System (NSRS) is scheduled to be modernized, with new reference frames replacing North American Datum (NAD) 83(2011), NAD 83(PA11) and NAD 83(MA11), or the NAD 83 system.   The North American Vertical Datum (NAVD) 88, which provides the vertical datum used in the United States, will also be replaced. One of… (Show more)
in Coordinate Reference Systems
spk578
Vincenty's Formulae are two methods named after Thaddeus Vincenty a Polish-American geodesist who lived during the 20th Century. During his career, he devised his formulae as well as contributing to major projects such as the NAD 83 where he introduced three-dimensional Earth-centered coordinates. Vincenty's formulae were published in 1975 and it… (Show more)
in Coordinate Reference Systems
spk578
"CAD lives in a world of one-centimeter grids. GIS lives, at best, in a world of one-meter grids. So you have this really interesting change in accuracy where the construction world's incredibly accurate but not scalable. The GIS world is very scalable, but not incredibly accurate."   Read the interview here: DM Exclusive: Chris Anderson, CEO of… (Show more)
in Coordinate Reference Systems
CathyUGIS
I am a little gunshy as we have had some problems with WA State NAD 83 Harn transformation to WGS for a Statewide 911 dataset merge.  Do you have time to talk to me this morning?
in Coordinate Reference Systems
spk578
Distance calculations using longitude and latitude on the ellipsoid.   Haversine or Vincenty? The choice depends on the resolution needed.  This thread on Computing Distances reminded me that I had the latter kicking around and Bruce Harold's Reverse Geocoding uses it.     So I thought I would throw the reference in the Py..Links so I/we don't… (Show more)
spk578
I decided to look into some of the mathematics that makes it possible to calculate distances considering 3D space, for example, calculating distance on a sphere. You can find our more on geodesic distances from the previous blog (Geodesic distances: How long is that line again? ).   The Earth is round but big, so we can consider it flat for short… (Show more)
in Coordinate Reference Systems
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