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Big-Life-Lab / PHES-ODM

The Public Health Environmental Surveillance Open Data Model (PHES-ODM, or ODM). A data model, dictionary and support tools for environmental surveillance.
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Include projection for coordinates / polygons #176

Closed sorinsion closed 2 years ago

sorinsion commented 3 years ago

Please include a Projection or EPSG column in tables dealing with coordinates or polygons. Ottawa's coordinates are Lat/Long 45°15'1.591"/-75°48'3.895" in EPSG:4326 WGS 84 but they become X/Y 1508475.41/-190710.50 in EPSG:3978 NAD83 / Canada Atlas Lambert and if you don't know the projection these numbers are useless.

NielsNicolai commented 3 years ago

Should the model allow for different projections, or do we fix the reference system and people should adhere to this? The former is definitely more generic but it may lead to confusion for non-GIS experts?

sorinsion commented 3 years ago

Let's put as little pressure as possible on the users and let them use whatever projection suits them. I can help with a conversion module that will take whatever coordinates or polygons and reproject them to, let's say, EPSG:4326 WGS 84. The only thing that should be mandatory would be for them to specify the EPSG code for each of the coordinates or polygons, if it's different from 4326. This should be made clear in the documentation.

mathew-thomson commented 2 years ago

The Polygon table now has a geoEPSG field for version 2. lat and long are only found in the site table, however. Should lat and long also be recorded in the Polygon table?

mathew-thomson commented 2 years ago

@sorinsion @DougManuel @jeandavidt - do we think that lat and long need to be added to the Polygon table as well, or are geoEPSG and geoWKT sufficient?

jeandavidt commented 2 years ago

lat and long can only hold one coordinate, whereas polygons, by definition, need at least three. geoWKT lets people enter a long string of coordinates in a standardized format. geoWKT (for the coordinates themselves) and geoEPSG (to indicate how the coordinates should be interpreted) are enough.

mathew-thomson commented 2 years ago

Amazing - thanks, @jeandavidt . I will close this issue for now then.