Comparable with Pixel and Vector Graphics
The easiest way to describe the difference between polygon meshes and NURBS models is to compare them to 2D computer graphics:
Graphics on the computer exist either as pixel graphics or as vector graphics. In a pixel graphic, the image consists of many pixels. Each pixel has a specific color. If you enlarge the graphic on the computer and then print it on a large sheet of paper, the image becomes blurred. This is because the individual square pixels have been enlarged, but not the total number of pixels.
There are no pixels in a vector graphic; there are only a few points connected by curves. These curves are recalculated each time the graphic is resized. A vector graphic can thus be enlarged as desired, and a printout will always be razor-sharp.
Meshes Are Like Pixel Graphics and NURBS models Are Like Vector Graphics
In a polygon mesh, the surface is represented by many triangles. If a small polygon mesh is enlarged and printed in 3D, all previously round surfaces of the object will come out of the 3D printer angular.
The polygon mesh does not have enough triangles to create a cleanly curved surface.
With NURBS models, enlarging the image is not a problem. Curves define the object’s surface. The curves maintain the object’s perfect shape, no matter how much the 3D model is magnified. The curves are defined by a few control points, and an algorithm recalculates the curves each time the 3D model is resized.
Download the example files of a Polygon Mesh and a NURBs model
You can take a look at the difference between a Polygon Mesh and a NURBs model. We have prepared both for you to download. You will need a 3D viewer like Meshlab to look at the STL-file and a CAD Software like FreeCAD to look at the STEP-file.
- Polygon Mesh Example (STL)
- 3D Viewer Meshlab (free software)
- NURBs model Example (STEP, IGES, X_T)
- FreeCAD (free CAD software)
Conclusion
NURBS 3D models are infinitely scalable without loss of surface quality. Whenever possible, NURBS models are preferred over polygon meshes. However, NURBS models are much more complicated to create and more difficult to edit. Therefore, polygon meshes are used more often.
Do you have any further questions about polygon meshes and NURBS models?
Holocreators offers professional 3D-scanning and reverse engineering services. We are happy to advise you on the topic of polygon meshes and NURBS models. Please call us at +49 40 481133 or send an email info@holocreators.com
