2.5D Navigation Graph and Improved A-star Algorithm for Path Planning in Ship Inside Virtual Environment

A new method entitled 2.5D navigation graph for walkable domain modelling, and an improved A-star algorithm for path planning in large ship inside 3D virtual environment (VE) are developed. Firstly, the authors partitioned the XOZ plane with squared cells and then converted the 3D virtual scene model composed of triangular facets into cuboidal obstacles in each grid via projection and intersection algorithm. The top face of each cuboid obstacle is a candidate walkable area for the character in 3D VE. Top facets of all obstacles in the 2.5D navigation graph form the walkable domain of the 3D VE. Furthermore, the obstacle for the next stay position is found by the improved A-star algorithm among the obstacles which reposes on the surrounding eight cells. Experimental results indicate that the provided 2.5D navigation graph and the improved A-star method can deal with the problem of path planning for ship inside 3D VE. Especially, the proposed scheme has adequately taken the horizontal and vertical characteristics of the ship inside environment, the body size of the character, and the physiological specialty and walking customs of humankind into account.