Spec direct power
This controls the direct specular power. Essentially, this is how strongly surfaces that are perpendicular to the ray drawn from the camera are rendered. The features seems to be inversely proportional to the value. Typical values here range from [0, 200+].
This image shows the spec_direct_power setting increasing from 0 to 100.
# set it to some value set spec_direct_power, float # for example turn it up set spec_direct_power, 200