Densify the geostationary bounding polygon before reprojecting in AreaSlicer#729
Open
lorenzo-cingano wants to merge 1 commit into
Open
Conversation
…aSlicer AreaSlicer.get_polygon_to_contain builds the bounding polygon of a geostationary source disk and reprojects it into the destination projection to compute the source slice. When the source is a partial disk (rapid scan or region of interest data), clipping the disk to its area extent introduces straight chord edges with only two vertices. Those chords are not straight in the destination projection, so the reprojected polygon cuts the corner and the source slice comes out too small, leaving part of the destination without data. Densify the polygon with segmentize before reprojecting it, so the chord edges keep enough vertices to follow their true shape in the destination projection.
Member
|
Thanks for this PR! I just wanted to let you know that we're not ignoring you, but most of us are on vacation or (like me) don't have time to review this right now. I hope to review it next week though. |
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## main #729 +/- ##
=======================================
Coverage 93.68% 93.69%
=======================================
Files 89 89
Lines 13715 13725 +10
=======================================
+ Hits 12849 12859 +10
Misses 866 866
Flags with carried forward coverage won't be shown. Click here to find out more. ☔ View full report in Codecov by Harness. 🚀 New features to boost your workflow:
|
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
AreaSlicer.get_polygon_to_containbuilds the bounding polygon of a geostationary source disk and reprojects it into the destination projection to compute the source slice. When the source is a partial disk (rapid scan or region of interest data), clipping the disk to its area extent introduces straight chord edges with only two vertices. Those chords are not straight in the destination projection, so the reprojected polygon cuts the corner and the source slice comes out too small, leaving part of the destination empty. A full disk source is unaffected, because its whole boundary is the densely sampled disk arc.This densifies the polygon with
segmentizebefore reprojecting it, so the chord edges keep enough vertices to follow their true shape in the destination projection. The problem was found in satpy when resampling MSG rapid scan data to a polar stereographic area withgradient_search.segmentizeneeds shapely 2.0 or newer. shapely is currently unpinned in the dependencies, so ashapely>=2.0pin can be added if you want it explicit.