OGC WKT-CRS reference

[markh]

In reviewing the draft for CF 1.7, up to ​https://github.com/cf-convention/cf-conventions/commit/cf93c126736fe943adc4843cd31984e1eaa87ee0 (Jul 18th 2017)

I note that the references to Well Known Text Coordinate Reference Systems (WKT_CRS)

link to an OGC resource, OGC_CTS ​http://www.opengeospatial.org/standards/ct which does not define WKT_CRS or the encodings for that standard.

With regard to the OGC, the definition of Coordinate Reference Systems should refer to ​http://www.opengeospatial.org/standards/wkt-crs as an OGC information page, or ​http://docs.opengeospatial.org/is/12-063r5/12-063r5.html (currently the latest version)

Indeed, this standard is a joint OGC - ISO standard, defining WKT_CRS and has been in the public domain for some time. It is also defined by ISO as ISO19162.

There is a push from the OGC to ensure that reference to this standard is taking place, not to previous, unmaintained cross references. I have recently been asked to follow up on this by our local OGC representative, following their last technical committee meeting, as an explicit action.

I propose that the references to OGC_CTS in the document be replaced with references to OGC_WKT_CRS and refer to the joint ISO, OGC standard, via the OGC who put the standard into the public domain, able to be read by all.

​http://www.opengeospatial.org/standards/wkt-crs

I think that it would be helpful to link to the maintained WKT_CRS standard before the CF1.7 document is published.

I am marking this as a defect, I will prepare a github change to reflect this, once we have established that this is a useful course of action.

Given the imminent nature of CF 1.7, please may I request a fairly swift response on whether this approach is deemed suitable by document maintainers?

many thanks

mark

[davidhassell]

Hi Mark,

Thanks for this - your suggested web site looks fine to me.

All the best,

David

[painter1]

Section 5.6.1 states that Example "5.12 also represents a slightly modified version of the WKT example shown in section 7.4 of [OGC_CTS]". I haven't been able to find such an example. Could someone point out where it is, or should we simply delete that statement?

[markh]

Replying to painter1:

Section 5.6.1 states that Example "5.12 also represents a slightly modified version of the WKT example shown in section 7.4 of [OGC_CTS]". I haven't been able to find such an example. Could someone point out where it is, or should we simply delete that statement?

There does not appear to be any such example in the up to date CRS-WKT document, and I cannot find a similar example in the OGC_CTS document as published.

I think that we should simply delete that statement, it does not add much in any case.

[markh]

in replying to painter1:

I have had cause to examine the details of the use of WKT_CRS in examples in the text. I have noted that the updates to WKT-CRS in ISO19162 are not reflected in the CF document. There is extensive use of the older syntax, for example GEOGCS rather than GEODCRS.

This is not surprising, as the CF edits were made prior to the publishing of ISO19162. Indeed numerous on line resources continue to use the older syntax and there is provision within ISO19162 to recognise this syntax.

So, whilst there is no issue with the text in is current state (barring the reference to an example we cannot find, as noted above) I do wonder whether putting the up to date syntax into the CF document within the examples might add some value.

I have put together a change which would deliver this, for your consideration. If it is worthwhile, you are welcome to adopt it.

​https://github.com/cf-convention/cf-conventions/pull/122

This includes the deletion of the "5.12 also represents a slightly modified version of the WKT example shown in section 7.4 of [OGC_CTS]" sentence, but this change could clearly be provided as an individual change if preferred, it is a simple deletion.

I do not consider this to be a show stopper issue, the adoption of the WKT syntax updates are taking time and backwards compatibility in tools is expected. It may even be viewed that this is an exercise better approached in a future publication of CF, rather than this one.

all the best mark

[davidhassell]

Hello,

I'd like to favour the first choice: "simply delete that statement". I think that the scope for delay in 1.7 is too great, otherwise.

Thanks, Mark, and all the best,

David

[markh]

Replying to davidhassell:

Hello,

I'd like to favour the first choice: "simply delete that statement". I think that the scope for delay in 1.7 is too great, otherwise.

Thanks, Mark, and all the best,

David

That is fine by me, I will close ​https://github.com/cf-convention/cf-conventions/pull/122

we can revisit it at a later date. I do not think it is good to risk delay to 1.7 for this

[markh]

However, I have just gone to do this and noted that ​https://github.com/painter1

merged this at the end of last week

so I cannot close it, as it has been merged

looks like this ticket is complete now, I am happy for this to be closed