public void setLightDensity(float lightDensity) {
        this.lightDensity = lightDensity;
    }
sets how much the effect is visible over the rendered scene default is 1.4

@param lightDensity the desired density (default=1.4)
jme3-effects/src/main/java/com/jme3/post/filters/LightScatteringFilter.java