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RE: Area of spatial objects

From: Car, Nicholas (L&W, Dutton Park) <Nicholas.Car@csiro.au>
Date: Wed, 7 Nov 2018 12:54:55 +0000
To: Frans Knibbe <frans.knibbe@geodan.nl>, "public-sdwig@w3.org" <public-sdwig@w3.org>
Message-ID: <ME2PR01MB38921CA3C1C56B984D438002E7C40@ME2PR01MB3892.ausprd01.prod.outlook.com>
Hi Frans,

What if I wanted to publish Features’ areas without also publishing geometries? What about features with a point geometry and an area, no polygon. Also, I have data where an area is given and also a polygon but I don’t know for sure if the area was calculated from the polygon. In fact I have data with an area and an Albers area and a geometry and don’t really know what happened to make which.

So, I want to be able to represent area as a spatial property of a feature, independently of any geometry. For this I will try using Observations and Measurements-style mechanics for this.

I think I might use subclassing of a sosa:ObservableProperty (https://www.w3.org/TR/vocab-ssn/#SOSAObservableProperty) to express spatial properties such as area and then relate then to a geo:Feature which would also, by SOSA logic, be a sosa:FeatureOfInterest. I may invent modelling to relate that spatial property to a geometry, but this wouldn’t be required, just nice to have if known.



From: Frans Knibbe <frans.knibbe@geodan.nl>
Sent: Monday, 5 November 2018 6:22 PM
To: public-sdwig@w3.org
Subject: Re: Area of spatial objects

Hi Nick,

I wonder: Doesn't the fact that multiple areas for a single spatial thing are published mean that the areas are calculated from different geometric representations of that spatial thing? That would logically make the area a property of a geometry. Besides, the geometry instance could be used to link to the CRS (e.g. Albers), ideally by URI.

CRS data linked to a geometry could also give access to the basic unit of the CRS (e.g. meter) and through that provide information on the units of properties derived from the geometry (like the area), but that would demand a fair amount of reasoning on the part of the data consumer.



Received on Wednesday, 7 November 2018 12:55:27 UTC

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