From 207194f67bbfc8571239372b16228a6124de22bd Mon Sep 17 00:00:00 2001
From: Scott Staniewicz <scott.j.staniewicz@jpl.nasa.gov>
Date: Mon, 2 Dec 2024 21:43:17 -0500
Subject: [PATCH] 'Use `nearest` resampling for merging temporal coherence
 (#508)

Closes #144

The `lanczos` filter was leading to pixels above 1 in the merged
temporal coherence image, despite the max being 1.0 per burst.

This is also likely the reason for negative coherences, though
we can reopen if any new instances are spotted (hasn't been seen in a
year)
---
 src/dolphin/workflows/stitching_bursts.py | 34 +++++++++++++----------
 1 file changed, 20 insertions(+), 14 deletions(-)

diff --git a/src/dolphin/workflows/stitching_bursts.py b/src/dolphin/workflows/stitching_bursts.py
index eff0bdfb..f93aef3c 100644
--- a/src/dolphin/workflows/stitching_bursts.py
+++ b/src/dolphin/workflows/stitching_bursts.py
@@ -132,6 +132,7 @@ def run(
             temp_coh_file_list,
             outfile=stitched_temp_coh_file,
             driver="GTiff",
+            resample_alg="nearest",
             out_bounds=out_bounds,
             out_bounds_epsg=output_options.bounds_epsg,
         )
@@ -157,28 +158,33 @@ def run(
             amp_dispersion_list,
             outfile=stitched_amp_disp_file,
             driver="GTiff",
+            resample_alg="nearest",
             out_bounds=out_bounds,
             out_bounds_epsg=output_options.bounds_epsg,
         )
         repack_raster(stitched_temp_coh_file, keep_bits=10)
 
     stitched_shp_count_file = stitched_ifg_dir / "shp_counts.tif"
-    stitching.merge_images(
-        shp_count_file_list,
-        outfile=stitched_shp_count_file,
-        driver="GTiff",
-        out_bounds=out_bounds,
-        out_bounds_epsg=output_options.bounds_epsg,
-    )
+    if not stitched_shp_count_file.exists():
+        stitching.merge_images(
+            shp_count_file_list,
+            outfile=stitched_shp_count_file,
+            driver="GTiff",
+            resample_alg="nearest",
+            out_bounds=out_bounds,
+            out_bounds_epsg=output_options.bounds_epsg,
+        )
 
     stitched_similarity_file = stitched_ifg_dir / "similarity.tif"
-    stitching.merge_images(
-        similarity_file_list,
-        outfile=stitched_similarity_file,
-        driver="GTiff",
-        out_bounds=out_bounds,
-        out_bounds_epsg=output_options.bounds_epsg,
-    )
+    if not stitched_similarity_file.exists():
+        stitching.merge_images(
+            similarity_file_list,
+            outfile=stitched_similarity_file,
+            driver="GTiff",
+            resample_alg="nearest",
+            out_bounds=out_bounds,
+            out_bounds_epsg=output_options.bounds_epsg,
+        )
 
     if output_options.add_overviews:
         logger.info("Creating overviews for stitched images")