These photos are of the same porcupine but two different days, both days having variable weather conditions & strong gusty winds. Hence the "quill blown" look on the porcupine.
When there are opportunities to view a porcupine's face close up, you can see the character & expressions in its face, regardless of the dark fur.
That stare is probably the result of poor eyesight but the porcupine's hearing & sense of smell are strong. Like the beaver, they probably detect movement. And trust me, when you are trying to be completely silent when moving around an area, porcupines can detect the slightest sound of crunching leaves.