GIS novelties from Agile and Blue Marble

Agile’s Python Shapefile tutorial. Time-based NATRF2022 framework - GIS meets plate tectonics.

Agile Scientific’s Matt Hall has published a really useful utility for reading and writing Esri shapefiles which doubles as an excellent tutorial on the subject. Shapefiles encode points, lines and polygons along with their attributes in what Hall describes as a ‘slightly weird’ format which is in fact a collection of files, one of which is the SHP file. Hall’s post walks through reading a shape file, changing its CRS*, tweaking some attributes and writing it back.

Speaking of CRSs, a Blue Marble blog post introduces the four new geographic reference frames that the US National Geodetic Survey (NGS) is to introduce starting in 2022. NATRF2022, the North American terrestrial reference frame introduces new frames for the Continental US/Canada/Mexico, the Mariana tectonic plate, the Pacific plate and the Caribbean. NATRF2022 will replace NAD83 which, it appears, is not as ‘geocentric’ as intended. It is actually off-center by about two meters. Moreover, plate motion since NAD83’s definition has aggravated the situation. The new frames will be time-based to accommodate future plate motion. As Blue Marble says, ‘This is going to require a new mindset for a lot of GIS users.’ Incidentally, a similar issue was reported at the NDR2017 Stavanger meet from the New Zealand NDR following the 2011 Christchurch earthquake that moved parts of the country by tens of meters!

* Coordinate reference system.

This article originally appeared in Oil IT Journal 2017 Issue # 7.

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