Google Earth Engine: how to export a sloping image without zero patch

Question

I want to export a strip image in GEE, and the image I want to export looks like:

The export code is:

    Export.image.toDrive({
      image: img,
      description: descp,
      scale: 30,
      folder: folder,
      fileFormat: 'TFRecord',
      region: img.geometry(),
      formatOptions: {
        'patchDimensions': [256, 256],
        maxFileSize: 104857600,
        compressed: true,
      },
      skipEmptyTiles: true,
    });

However, when I read the exported tfrecord files, I still get a lot of image patches which are full of zero values. So I'm wondering how can I avoid this kind of situation?

Answer 1

Regardless of your roi shape the export happens with the bounding box of your roi with everything outside given value of masked value, 0 in most cases. In case of exporting to TFRecords exports it even adds a few padding to make all the patches consistent so that you don't end up with a 256x10 patch somewhere around the edges. So, its done to follow the data standard and is not something that should be "avoided". This actually ensures that your data remains geo-referenced as TFRecords (and TIFs as well) are actually just matrix of data with the coordinate information on another file (or in metadata for geo-tifs).