Hallucination is a situation where the brain elaborates in a wrong way the "input" informations.So the output is a wrong vision of what we see. It is not a simple situation because other brain system affect this symptom. Normally it is produced in some particular types of situations: u mentioned schizophrenic hallucination. Vascular problems in brain may give the same effect(hypotension or variations in ions concentrations in blood. Even variations in hormonal concentration may give this effect) i don't know the way they are produced but I'll try to find it out!!!
Normally in the brain there exist some types of maps that help to understand the world around us in 3D or even 4D(considering the time: the circadian cycle,the day-night altering). This is the reason why we can still find the way in a place even when we close the eyes.or we can recognise an object just by touching it.These maps can change through the life according to the experience,usage etc...
i'll try to find out more information and write it here...
p.s sorry for my english but i haven't been practising it for 4 years.i have forgotten a lot of terms
