Disadvantages of Polygon Modeling
The following are some disadvantages of polygonal modeling.
Data Size of a Smooth Polygon Object
Is Comparably Large To represent a smooth, curvy object, without noticing any faceting in the silhouette of the model, it could take many faces. This will result in slower interaction compared to that of NURBS models. The tail of a dinosaur may need several hundred or thousands of faces to define its shape and render smoothly. A similar structure in NURBS may only require a small fraction of that data.
Because of the number of vertices needed to create a smooth detailed object, the data size can be significantly larger than that of a similar NURBS model. Your computer may run into problems loading or rendering a scene if sufficient memory is not available. Also, sending large files over a computer network can clog a pipeline.
Adding Detail to Smooth Objects Can Be Difficult A common polygonal modeling workflow has the modeler work on a low-resolution version of the model and then smooth, or subdivide, that model to view the final result. When the model is smoothed, the position of the vertices is interpolated to result in a much smoother form. The problem is that whenever detail is added to the model, the smoothed version will appear flat in that area, so the modeler must shuffle the position of the vertices around to obtain the smooth shape they once had. This make it difficult to model high-precision, subtly curving surfaces such as those found on a car. Figure 3-6 shows two objects. The object on the left shows a polygonal sphere that is generated by smoothing a cube. The object on the right shows what happens to the resulting sphere when an edge is added around the initial cube. To re-obtain the spherical shape, the modeler must manually reorganize the vertices.
Post a comment