def init(cls, typ, class2type):
        """
        Defines custom fields in the value factory so that the importer can find them
        @param typ
        @param class2type
        """
        field = typ.getField(cls.FIELD_NAME)
        class2type.put( StrStrHashMap , typ )
        typ.setComponentType( StrStrHashMap )
        typ.setImportExportHelper( StrStrHashMapSerializer(typ, field))
        typ.putValidator(field, Validator_object.get(1))
        typ.lock()
def _read_16bits_png_with_flow_and_valid_mask(file_name):

    flow_and_valid = _read_png_16(file_name).to(torch.float32)
    flow, valid_flow_mask = flow_and_valid[:2, :, :], flow_and_valid[2, :, :]
    flow = (flow - 2 ** 15) / 64  # This conversion is explained somewhere on the kitti archive
    valid_flow_mask = valid_flow_mask.bool()

    # For consistency with other datasets, we convert to numpy
    return flow.numpy(), valid_flow_mask.numpy()