RE: BP: CRS intro

I made a couple of small suggestions and submitted pull-request.

From: Linda van den Brink [mailto:l.vandenbrink@geonovum.nl]
Sent: Tuesday, 10 January, 2017 02:17
To: SDW WG (public-sdw-wg@w3.org) <public-sdw-wg@w3.org>; Byron Cochrane <bcochrane@linz.govt.nz>
Subject: BP: CRS intro

Hi all,

I've incorporated a text Ed sent me for the CRS intro in the BP, as per his action-247.

@Byron, this is important for you because you have an action to work on BPs 3 and 18, also on coordinate ref systems.

See the CRS intro section in the editor's draft at http://w3c.github.io/sdw/bp/#CRS-background

Ed has restructured the section and has left some things out, focusing less on trying to explain everything about CRS and more on what you need to know to publish or work with spatial data on the web - really the 101 on CRS.

Consequently, some parts that were in this section before have been left out:

-          The explanation of geoids and ellipsoids and how there are different ellipsoids that give a good approximation of different parts of the earth. There is still some info on ellipsoids but less than previously.

-          The explanation of map projections, again, only a little bit left. I did add a reference to http://thetruesize.com

-          Information on how to reference a CRS and how to describe a CRS. I imagine this could be part of BP18, instead.

-          Information on open source coordinate ref conversion tools. This could also be part of a BP (also 18 I think).
Byron, perhaps you could take a look at the text that's NOT in the CRS intro anymore (check the latest WD) and decide if it should be in one of the BPs instead?

I don't know if you want to merge BP3 and BP18, by the way. There is something to say for this, but on the other hand I see them as having different key recommendations. BP3 is about using an appropriate CRS for high precision use cases, and BP18 is about specifying the CRS of location data.

Linda


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Linda van den Brink
Adviseur Geo-standaarden

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