![]() ![]() N-Pole - A vertex with five or more edges coming out of it.Īsking what makes a good mesh is almost like asking what makes a good painting.Pole - A vertex with three edges coming out of it.N-Gon - A polygon with five or more vertices.Quad - A polygon with exactly four vertices.Triangle - A polygon with exactly three vertices.Mesh - A collection of polygons, a shape in 3d space.Polygon - A face of a 3d shape, connecting several vertices via edges.Edge - A connection between two vertices.Vertex - A point in space where edges meet, the corner of a shape.The reason that some of these things have names will also become apparent later. I've probably already thrown some new ones at you which I'll revise here, but once you get to grips with these, everything becomes a lot easier to explain. In computer graphics there are new terms for almost everything. But, with a good mesh, these artefacts can be minimized or even overcome, and this is where subdivision modelling comes in. These arise from issues with the approximation of vertex normals, and also with the interpolation calculations across triangles. In many cases it does not quite work as expected, and can lead to visual artefacts or sections of the lighting that look weird. This allows us to render smooth surfaces using angular geometry (and a fixed number of polygons), but it does come at a cost. To truly find the direction a vertex is pointing is impossible (it has no surface, so has no normal), but what we usually do is simply average out the face normals for all of the faces attached to this vertex - and use this as an approximation for the normal. This is what happens in all 3d computer graphics, from Lord of the Rings to Quake II.īut, before we can do this interpolation, we have to work out the actual vertex normals to use. In fact, for any triangle, graphics cards are specially designed so as to be able to do this interpolation the normals from the three vertices at each corner, very fast. If, instead of looking at face normals (the direction the face is pointing), the renderer looks at vertex normals (the direction the corner is pointing) then it can interpolate (a kind of averaging) this direction across the triangular face it is rendering, giving it something of a smooth look. This second option is often what we want, and this is where vertex normals are used. Either it can render each polygon (or face) of this shape as a flat surface and do lighting calculations based of that, or it can try to render some smoothed version of the same shape. When a computer renders a shape on the screen there are two options. They can be thought of as the corners of geometric shapes. The main two examples of this being the default method by which vertex normals are calculated and the way in which Catmull–Clark subdivision (after which the technique is named) works.Ī vertex is a point in space where various lines (or edges) meet. The technique and subsequent art of subdivision modelling arose more or less naturally due to several aspects or phenomena in how digital art is typically rendered. Other popular techniques are per-poly modelling, nurbs modelling and digital sculpting. Saying this, it is often at the discretion of the artist or the tool, as to what modelling technique they choose to use. It is used to some degree in almost all industries that employ digital artists. Subdivision modelling is a technique of digital 3d modelling used to create clean models with scalable detail that look good when rendered. Subdivision Modelling Created on March 31, 2011, 3:17 p.m. ![]()
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