Re: BP document FROZEN - vote next Monday [SEC=UNCLASSIFIED]

Hi Jeremy,

I’m not going to get the time to review this BP within the timeframe required by SDWWG.

I’ll send you what I have to date. You may be able to do something with it.

5. Spatial Things

  *   I recall that there was some discussion on imprecisely defined locations. Where did we get to with this.   Some examples:

     *   The Mara-Serengeti ecosystem
     *   The Great Barrier Reef
     *   Dogger Bank
     *   West of the Black Stump
     *   The Sahara
     *   the coastline
     *   The Western Australian Greenstone belt
     *   The Mary River floodplain

  *   These could also be considered 'Spatial Things’, we just can’t reliably define their locations with crisp vector boundaries.

6. Coverages

  *   I note the statement about coverages not being a 'spatial thing’.

     *   This is quite constraining and implies that only vector data can be a 'spatial thing’.

     *   Following on from my comments in response to 2 above, many of these features are best represented with imprecise ‘fuzzy’ boundaries. A coverage is a good way of handling this.

On  5. Spatial Things  and  6. Coverages

  *   I don’t like the artificial delineation between ‘spatial things’ and Coverages.

     *   Both are conceptually ‘Spatial Things’

     *   We are just talking about vector and raster data in different terms.

     *   A ‘Spatial Thing’ could be represented using both raster and vector representations, depending on the context of what the representation is to be used for.

     *   This is probably where a discussion on how ‘spatial things’ are conceptualised as ‘objects’/features/coverages etc could be useful. It could bring in discussions on scale, precision, accuracy, intended use etc.

  *   I do like the the linkage between a real world concept and multiple representations of that concept. It will allow us to overcome a long term issue inherent in spatial data modelling.

7.  Spatial Relations

  *   Topological Relations

     *   Topology is more about the connectedness of features e.g.:

        *   Network trace, upstream, downstream
        *   Left of, right of
        *   Etc

     *   The examples given are conflating topology with spatial overlay functions, e.g.

        *   Intersects, Overpaps, Point in poly, Buffer, etc

  *   Perhaps a brief discussion on 'spatial joins’ may be also appropriate here, where the attributes of one feature can potentially be assumed by another feature due to their spatial co-location, e.g.:

     *   'this building’ is located in 'this census district', therefore I infer that the census attributes for 'this census district’ apply to the residents of ’this building'

8. CRS

  *   See my comments in the related email. They are still relevant as noted by Byron in his email of 4 April.

10. SDI

  *   This document takes an overly pessimistic and narrow view of SDIs.

  *   SDIs are more than just a Discovery Metadata catalogue.

  *   They are defined as "the base collection of technologies, policies and institutional arrangements that facilitate the availability of and access to spatial data”. See the SDI Cookbook [1], Chapter 1, SDI.

  *   Discovery metadata records *can* be very useful for determining the content of a given spatial dataset and its intended use. They are very useful to use to determine if it is appropriate to use the data set for a purpose other than that for which it was created.

  *   What would be useful is if a way could be found to make these metadata records within the catalogues indexable, together with a way of linking the Discovery Metadata record to the Spatial Data Service(s) that provide access to this data. This is where there is considerable potential for linked data. And yes these services could be configured to provide GUID’s for spatial things, just don’t throw the baby out with the bathwater.

Sorry, that is all that I’ve been able to get to.

Kind regards,



From: Linda van den Brink <<>>
Date: Thursday, 16 March 2017 at 20:04
To: "SDW WG (<>)" <<>>
Subject: BP document FROZEN - vote next Monday
Resent-From: <<>>
Resent-Date: Thursday, 16 March 2017 at 20:04

Hi all,

The BP document is FROZEN and ready for people to read/review at

A massive amount of work has been done during this sprint. To summarize:
- Section 8 CRS, BP1, BP3, BP6, BP8, BP9, BP10, BP11, BP14, BP17 updated
- BP2, BP12, BP13, BP15, BP16, Section 12.8 (Dealing with large datasets), Section 14 Narrative removed

A full account of the changes is in the sprint plan[1].

VOTE is scheduled for MONDAY 20-3-2017 during the face to face meeting in Delft.

Special thanks to Andrea, Josh, Clemens, Bill, Ed, and Byron for putting in the hours this sprint!

Linda & Jeremy


Received on Thursday, 13 April 2017 05:23:22 UTC