I use GEE to create temporal composites from Landsat imagery (right now using Landsat 8 Collection 2, but same issue with Collection 1 or Landsat 7) for a particular island. I noticed that parts of my composite were getting weird pixel values. When I investigated further, I found that one of my islands of interest is at the intersection of overlapping Landsat paths (WRS Path 83 & 84) where one path (84) only overlaps at the bottom corner of the path/row and only covers about half the island. Now path 83 covers the entire island. If I create a median temporal composite (find all images over a 4 year period, remove all clouds, then use a reducer (50th percentile) on the image collection) on images from both paths (aka all available images that might overlap my area of interest), I get compositeAll which looks a bit weird in the north western corner of the island. If I create a temporal composite ONLY using path 83 or path 84 (composite83 or composite84) I get a very different image. Here is the composite 84:
and for all images compositeAll . All the above images are visualized with the same parameters to highlight the different pixel values present in the two paths. Any idea how to correct this other than manually only using one path? I would rather be able to use all available images for a given location...but clearly my code is not correcting the images fully?
Here is a chart showing the mean pixel values in an area of the north western side of the lagoon of the island for all three composites for bands 1-8. you can see that the pixel values for the composite from Path 84 is much higher than composite 83 and is not the same across the different bands. This means that the composite using both path 83 & 84 gets weird looking pixel values. I'm attaching the code. I've