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Adopt WKT for CRS #3796
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I have prepared a sample data file which illustrates the use of the This is a CDL file, to aid readability. The nD variables are left unspecified, saving space.
will create a binary netCDF file with these unspecified variables encoded as missing data. The CDL specification for the example file is:
|
I agree that users will probably want this soon, and this is a really useful start. However the new, multiple form of the "grid_mapping" attributes is I think better handled as a separate issue. Let's by all means cross-couple them, but I think the effects relating to "crs_wkt" are only a minor aspect in that context. |
Hi @pp-mo I agree with your assessment:
The The capability that is missing in Iris and limiting here is the Bearing this ticket in mind whilst addressing the enhanced So a solution that preserves the order of terms, and handles the references such that this order can be used is the important factor here.
So implementing #3388 in an unordered fashion could meet the scope of #3388 as currently stated, but would be a real limiting factor for addressing this capability request. I hope this is useful confirmation and clarification of your perspective. |
In order to maintain a backlog of relevant issues, we automatically label them as stale after 500 days of inactivity. If this issue is still important to you, then please comment on this issue and the stale label will be removed. Otherwise this issue will be automatically closed in 28 days time. |
I think that this would still be a useful extension of Iris, despite that the more general question dealt with in #3388 was closed. |
We have [mistakenly] conducted a detailed conversation on the pull request, not the issue - see #4719. It has basically been decided that this overlaps enough with #3388 that #3388 will also be required before this work is considered completed. See the tasklist at the top of this issue for more detail. |
Feature Request: Support
crs_wkt
grid_mapping syntax (CF1.8) in Iris.As of version 1.8 of the CF Conventions, the use of Well Known Text for Coordinate Reference Systems encodings with standardised variable referencing is supported for CF netCDF files.
The adoption of the ISO/OGC standard for CRS definitions is a major step forward for CF, enabling enhanced interoperability and providing new capabilities.
It would be beneficial for Iris to support this capability effectively to enhance users' ability to effectively provide referencing information for coordinates.
The OGC publishes the joint ISO/OGC standard in the public domain at:
http:https://docs.opengeospatial.org/is/18-010r7/18-010r7.html
It is worth noting that recent version of Proj support WKT, including parsing of WKT CRS strings.
The use of WKT CRS strings is easily supported, as it just involves the use of the CF attribute name
crs_wkt
on a variable.There are minor issues to note on escape characters, particularly the need to escape
"
characters within the string as\"
. This is likely easy to handle in software.The challenge for Iris is the enhancements made to the
grid_mapping
data variable attribute to enable the references between the data variable, and by implication the associated coordinates.This enhanced syntax is detailed in the CF Conventions:
http:https://cfconventions.org/Data/cf-conventions/cf-conventions-1.8/cf-conventions.html#grid-mappings-and-projections
Iris does not recognise this syntax and does not interpret any coordinate reference system referencing where it is used.
The enhanced syntax has particular value to users using Iris to create data sets in CF-netCDF for sharing with wider communities.
The adoption of the CF syntax for these relations and their interpretation in the Iris data model brings valuable opportunities for improved referencing by coordinates and coordinate reference system definitions for data specification.
Please may we develop this ticket into a full enhancement proposal and aim to plan work to deliver this capability in an Iris release?
Tasks
Cube
CoordSystem
s easier #6030The text was updated successfully, but these errors were encountered: