def get_itersecting_DEM_tile_names(index, geometry):
    """
    Find the DEM tiles that intersect the geometry and extract the
    filenames from the index. NOTE: the geometries need to be in the 
    same CRS!
    
    Parameters
    ----------
    index : dtype=GeoDataFrame
        DEM tile index.
    geometry : shapely geometry object
        polygon of interest.

    Returns
    -------
    fname
        file name of tiles of interest.
    """    
    # sometimes points are projected to infinity
    # this is troublesome for intestections
    # hence remove these instances
    out_of_bounds = index['geometry'].area.isna()
    index = index[~out_of_bounds]
    
    mask = index.intersects(geometry)
    index = index[mask]
    return index['CPP filename']