Hello Suryaa
Le 2025-02-11 à 20 h 09, Suryaa Charan Shivakumar a écrit :
I'd like to store non-standard CRS. Is there any way to do it
currently or is it in the plans?
Yes, it is possible. First, we need to choose an "authority" name. Let's
take "MyAuthority" for this email. Then, the additional CRS can be
specified in a WKT file like this one:
https://sis.apache.org/apidocs/org.apache.sis.referencing/org/apache/sis/io/wkt/doc-files/ESRI.txt
Note: the above example uses an SIS-specific syntax, which is to declare
fragments of WKT with something like "SET WGS84=...", then reuse these
fragments with the dollar sign. For example, "$WGS84" is substituted
with the value of "SET WGS84=...". This syntax can reduce a lot the
amount of duplications when there is many CRS to define, but is specific
to Apache SIS. If you want portable WKT definitions, this part of
above-cited example file needs to be ignored.
It is important that each CRS definition contains an "ID["MyAuthority",
xxxx]" WKT element, where "MyAuthority" is the authority name chosen for
the custom CRS. Then, create a subclass of WKTDictionary as documented
there (substitute "MyAuthority" by the chosen authority name):
https://sis.apache.org/apidocs/org.apache.sis.referencing/org/apache/sis/io/wkt/WKTDictionary.html#example-heading
Register your custom implementation in META-INF/services or
module-info.java, depending on whether you are using Java modules
system. After all those steps have been completed, the method which was
used for fetching EPSG code (e.g. CRS.forCode("EPSG:4326")) should
recognize also the custom CRS (e.g. CRS.forCode("MyAuthority:1234")).
Martin
