@Override
    public void read(JmeImporter im) throws IOException {
        super.read(im);
        InputCapsule ic = im.getCapsule(this);
        fogColor = (ColorRGBA) ic.readSavable("fogColor", ColorRGBA.White.clone());
        fogDensity = ic.readFloat("fogDensity", 0.7f);
        fogDistance = ic.readFloat("fogDistance", 1000);
    }
the distance of the fog. the higher the value the distant the fog looks

@param fogDistance the desired distance (in world units, default=1000)
jme3-effects/src/main/java/com/jme3/post/filters/FogFilter.java