The invention comprises a cannula assembly kit for a trocar suitable for use in minimally invasive surgery. The cannula assembly kit comprises a cannula and a pattern generating member. The cannula has a distal end and a proximal end and comprises a flange portion at its proximal end and an elongate cannula shaft portion extending from said flange portion to its distal end and an access port through the flange portion and the elongate cannula shaft portion, such that a surgical tool of a surgical instrument can be inserted through the access port. The pattern generating member comprises a pattern light source and a projector arranged such that the pattern light source is operatively connected to the projector for projecting a light pattern. At least the projector of the pattern generating member is configured for being at least temporarily fixed to the cannula shaft portion of the cannula.