@classmethod
def direct_studies(cls):
    """Options for direct studies.

        In particular this classmethod will set options below:
        irradiance_calc (-I) = True
        ambient_bounces (-ab) = 0
        direct_certainty (-dc) = 1
        direct_threshold (-dt) = 0
        direct_jitter (-dj) = 0
        direct_sec_relays (-dr) = 0
        """
    cls_ = cls()
    cls_.I = True
    cls_.ab = 0
    cls_.dc = 1
    cls_.dt = 0
    cls_.dj = 0
    cls_.dr = 0
    return cls_
