[Geotools-devel] GEOS Geostationary Satellite projection with sweep

[Kurt S. <sc...@gm...>]

Hi all,

I'm trying to figure out how to correctly handle projecting GEOS 16 / 17
data with GeoTools.

My initial attempt was via data imported through gdal_translate, so I
started asking here:

https://lists.osgeo.org/pipermail/proj/2019-June/008675.html
<https://www.google.com/url?q=https://lists.osgeo.org/pipermail/proj/2019-June/008675.html&sa=D&usg=AFQjCNHQlTTVWYkpwMESXvRpXiYzhNm5lw>

Source rasters:
gsutil cp
gs://gcp-public-data-goes-17/ABI-L1b-RadC/2019/151/21/OR_ABI-L1b-RadC-*_G17_s20191512131197_*.nc
.

Earth Engine screen shots:
https://photos.app.goo.gl/sW1upk1iZ9p62MuY9
https://photos.app.goo.gl/UAGccF2rjPDfenS27

However, I can bypass to write any WKT into the raster's info on the
GeoTools side.  Is there anything I can add to do the same thing as the
proj extension that Even has via the NetCDF gdal driver?  e.g.

EXTENSION["PROJ4","+proj=geos +lon_0=-137 +h=35786023 +x_0=0 +y_0=0
+ellps=GRS80 +units=m +no_defs  +sweep=x"]]

Looking
through GeostationarySatellite.java, GEOS.txt, GeostationarySatelliteTest.java,
I don't see any mention of sweep

I see adapted from: https://github.com/OSGeo/proj.4/blob/4.9/src/PJ_geos.c
I don't see the 2012 / 2013 initial changes for sweep axis.
<https://github.com/geotools/geotools/blob/master/modules/library/referencing/src/main/java/org/geotools/referencing/operation/projection/GeostationarySatellite.java>So
I presume not the changes since that are now it:
https://github.com/OSGeo/PROJ/blob/master/src/projections/geos.cpp

I presume that we would need to add sweep support and some mechanism to
support setting it, yes?

https://github.com/geotools/geotools/blob/master/modules/library/referencing/src/main/java/org/geotools/referencing/operation/projection/GeostationarySatellite.java
https://github.com/geotools/geotools/blob/master/modules/library/referencing/src/test/resources/org/geotools/referencing/test-data/scripts/GEOS.txt
https://github.com/geotools/geotools/blob/master/modules/library/referencing/src/test//java/org/geotools/referencing/operation/projection/GeostationarySatelliteTest.java

I happen to be using GeoTools 19, but I'm fine back porting things if
necessary.

Thanks!
-kurt