A polygon mesh is a mathematical representation of a 3D object. It is composed of a set of vertices, edges, and faces that define the shape of the object. A vertex is a single point in 3D space, an edge is a line connecting two vertices, and a face is a closed loop of edges. The faces are usually triangles or quadrilaterals, and can be used to represent curved surfaces or other complex shapes.
Polygon Mesh method basically used to represent a broad class of surfaces or solids in computer graphics. It is possible to render a polygonal mesh by applying the hidden surface removal methods as per requirement. So, the polygon mesh can be represented by three ways which are:
Explicit representation: The mesh is represented by a list of vertex coordinates. Typically these vertices are grouped into threes. Each group representing a triangle. As discussed, the vertices are stored in counter clockwise order. This representation is not space efficient, because a shared vertex, will be stored many times. In a Cube for instance, each vertex is shared by 4 faces and 4 edges. Also it is unclear from this representation, which faces are connected to which, this make manipulation difficult.
Face Vertex representation: In the representation we have a vertex list, which contains the (x,y,z) coordinates of all the vertices in the mesh. Each vertex is only stored once. There is a also vertex index which lists the vertices for each face(each group of three represents on triangle). The vertex index does not contain the coordinates of each vertex, instead, it contains indices or pointers into the vertex list. This representation is much more space efficient because, even though the vertex indices are repeated, they take up much less storage space than the 3 coordinates of a vertex. This representation is the most common representation used for rendering in computer games and graphics. However, it is still difficult to answer question like which vertices are on an edge or which faces are touching.
Winged-Edge representation: Where dynamic changes to mesh topology are required for applications such as mesh editing, a more flexible representation is needed. The winged edge mesh explicitly represents vertices, faces and edges of a mesh. The core structure is the Edge List which lists the faces, vertices and the 4 closest neighboring edges for each edge. There is also a vertex list which stores the vertex coordinates and a list of edges for each vertex. Finally there is a Face list which stores the edges belonging to each face This representation is widely used in modeling programs to provide the greatest flexibility in dynamically changing the mesh geometry, because split and merge operations can be done quickly. Their primary drawback is large storage requirements and increased complexity due to maintaining many indices.
The following are the advantages of Polygon Mesh:
Polygon mesh has several advantages over other 3D modeling techniques. It is relatively easy to use and understand. It is also highly efficient, as it requires fewer polygons to create a 3D object than other techniques.
Polygon mesh is also versatile. It can be used to create a wide range of shapes, from simple cubes to complex characters. It can also be used to create 3D printing models, as well as realistic animations and simulations.
Polygon mesh is highly scalable. It can be used to create 3D models of any size, from tiny objects to large structures.