Polygonal and NURBS Modeling: What’s The Difference?
Polygonal and NURBS Modeling: What'southward The Difference?
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The main difference between polygonal and NURBS modeling is the fashion the mesh is calculated by the estimator.
For polygon modeling it calculates polygons, which are flat planes that incorporate a 3D shape (the way that a cube is made out of six squares for example).
NURBS calculates the mesh equally splines between points, which tin brand curves out of a single section of geometry.
NURBS (which is shorthand for Non-Uniform Rational B-splines) uses circuitous mathematics to calculate the surface of a model. This ways that it is far ameliorate suited for models where a high caste of accuracy is needed.
A good example where this is important is in engineering. When an engineer is trying to work out the aerodynamics of a plane or motorcar, and they want to run tests in a digital air current tunnel.
The downside of this highly mathematical manner of calculating a model'south size is that it becomes more than difficult for the computer to calculate, which means that it is unsuited for applications where return times need to be fast.
You would never observe NURBS surfaces in video games, for example (at least at the time of writing).
In polygonal modeling information technology is incommunicable to make a perfectly smooth curve, due to the fact they are ever calculated as a straight line between points.
However, using smoothing groups and a high number of polygons, you can make sections that are perceived every bit a smooth curve on the screen.
NURBS have the boosted do good of being a smaller file size, as all the data contained are mathematical points. This also ways the information is easy to read and understand between dissimilar programs and then you never end up with corrupted meshes, like can happen when transferring polygonal models.
When Are NURBS Used?
I'm sure you lot're thinking this all sounds bang-up! Why don't we use NURBS more often?
That's because I have withal to get into the limitations behind NURBS, which there are many.
NURBS objects are merely always iv sided. This is a limitation to the fact that a Polygon is normally an Due north-gon consisting of whatever number of sides upward from 3.
This makes the process of modeling with polygons a much simpler process. Expanding on this polygon modeling is a lot easier to manipulate and change, which again makes for far easier structure of meshes.
NURBS objects are always dissever from each other likewise, making them hard to attach together for ane model.
Due to their perfect calculations of curvature and position, this ways you lot will never see the seams between them. Simply it is yet a limitation in their workflow. If y'all wish to breathing a NURBS object, you lot would first need to convert it into a polygonal mesh so that you can weld joints together so they volition not come up apart.
It is also not possible to UV unwrap a NURBS object.
For this reason, if it's a model yous need to texture, information technology is amend to use a polygon mesh. That mode yous have the ability to arrange how information technology'south projected onto the mesh.
To summarize: the divergence between NURBS and polys can exist compared roughly to the differences between vector and rasterized images in second.
Vector images too employ mathematical data points to make incredibly accurate images that are oftentimes used for logos and marketing, but can be limited in what y'all can do with them.
In comparison, raster images apply pixels that make them easier to work with, and have more tools at their disposal for editing & manipulation.
Due to the benefits that NURBS bring to the table, most mod 3D packages utilise NURBS in some manner.
They are usually converted to polygons later in the production process, just NURBS are very skilful at making the initial base of operations mesh.
Author: Thomas Denham
Thomas is a 3D artistic working with both high and low poly modelling for withal renders or real time engines. He is currently working freelance afterward spending four years at a multi-national VR company. To run into Thomas' work and learn more than, experience free to look at his personal site.
Source: https://conceptartempire.com/polygonal-vs-nurbs/
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