some jutsu for you

Name: Demonic illusion: false surroundings technique

Classification: Genjutsu

Rank:C

Class: Supplementary

Range: all

Description: To use this jutsu you have to concentrate and send your chakra by surrounding an object. When opponent looks at the object, then he is caught in ,This Genjutsu, that allows the caster to change the visual appearance of a nearby object or the local area in order to disorient an opponent. This can be used to change one's appearance in a way that Henge can not, or to conce alone's identity even from those skilled enough or otherwise able to penetratea Hengeno Jutsu.Alternately, one can use False Surroundings Techniqueas a sort of 'Genjutsu Stealth', and make oneself or another appear to vanish into thin air, or be invisible even before the opponent sees the caster.

still needs a mode of activation. is this genjutsu activated through sight, smell, taste, touch, hearing?

I would say sight...

first of all you saying sight does nothing. Edit you post and add into the description of the jutsu how it is activated. Some one else could have this exact tech, but activates it though touch.

and sight has a couple of other things behind it. Does the target have to look at you or a certin location? Is it activated only through eye contact?

Done

I don't think your fully understanding genjutsu. To activate a genjutsu on a person you have to effect one of their senses. They would have to be the one who looked at you, or what ever. It not about what you do to affect them.

Is it good now?