Re: CRS Issues [SEC=UNCLASSIFIED]

Sorry that I was not able to participate in the call.

Two CRS issues:

_CRS Definition_

Most of the discussion to date on this thread appears to have related to just horizontal CRS. Issues relating to both vertical and temporal CRS have also been discussed in a number of emails.

Are these CRS also covered by 1. Below.



_Default CRS_

Issues relating to the assumption that data is based on a default CRS have been raised from memory. For many use cases, this assumption can be quite dangerous and can have unforeseen consequences.

See also my related post on 'misuse of spatial data'.

I'm trying to find some citable references that effectively illustrate the issue of 'misuse', but have limited time. I'll keep going though, as this is an important, but typically overlooked issue, as people just strive for a map as a 'pretty picture'. 

Bruce



________________________________
From: Ed Parsons <eparsons@google.com>
Sent: Thursday, 2 July 2015 12:14 AM
To: SDW WG Public List; sdwwg@lists.opengeospatial.org
Subject: CRS Issues

Thanks for you input everyone on the call today.. Here is where we stand on the combined issues raised by Frans.

1)The CRS Definition requirement<http://w3c.github.io/sdw/UseCases/SDWUseCasesAndRequirements.html#CRSDefinition> currently in the UCR document should be rephrased. This is what ISSUE-10<https://www.w3.org/2015/spatial/track/issues/10> is about. The proposal for new wording is "There should be a recommended way of referencing a CRS with a HTTP URI, and to get useful information about the CRS when that URI is dereferenced."

Agreed and accepted slight modified wording removing "recommended".

2)In the course of discussing CRS requirements a new BP requirement was introduced: Default CRS<http://w3c.github.io/sdw/UseCases/SDWUseCasesAndRequirements.html#DefaultCRS>. No issues have been raised with regard to this requirement yet.

New issue created but not a new formal requirement.

3)In the course of discussing CRS requirements a possible new BP requirement has come up. ISSUE-29 (Add a requirement for linking geometry to CRS)<https://www.w3.org/2015/spatial/track/issues/29> was raised to enable further discussion and/or decision-making.

Agreed a new requirement

4)Whether 'a recommend way' is the best expression to be used in requirements is something that is discussed in the thread Use of the word 'standard' in the UCR document<https://lists.w3.org/Archives/Public/public-sdw-wg/2015Jun/0211.html>.

Agreed that the appropriate term should be "Advice", rather than recommended way or standard, so the BP should offer Advice as needed.


Ed


--
Ed Parsons
Geospatial Technologist, Google
Mobile +44 (0)7825 382263
www.edparsons.com<http://www.edparsons.com> @edparsons

Received on Wednesday, 1 July 2015 21:34:57 UTC