Usage: gdal_footprint [--help] [--long-usage] [--help-general]
                      [-b <band>]... [-combine_bands VAR]
                      [[-ovr <index>]|[-srcnodata "<value>[ <value>]..."]]
                      [-t_cs VAR] [-t_srs <srs_def>] [-split_polys]
                      [-convex_hull] [-densify <value>] [-simplify <value>]
                      [-min_ring_area <value>] [-max_points <value>|unlimited]
                      [--quiet] [-oo <NAME>=<VALUE>]... [-of <output_format>]
                      [[-location_field_name <field_name>]|[-no_location]]
                      [-write_absolute_path] [-lco <NAME>=<VALUE>]...
                      [-dsco <NAME>=<VALUE>]... [-lyr_name <value>] [-overwrite]
                      <src_filename> <dst_filename>

Note: gdal_footprint --long-usage for full help.