3D Modelling Techniques

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Describe different modelling techniques used in digital art

 

3D artistry is an extensive topic and 3D modelling techniques are no exception. “There are countless numbers of new toolsets being introduced by multinational corporations such as Autodesk nearly every year as new versions of their software are being introduced”[1]. Modelling techniques, especially in Maya are used to develop technical comprehension of modelling pipelines as well as to solve issues. Elements of 3D modelling include:

–       Common toolsets

–       Common terminology

–       Modelling workflow options

–       Limitations of different surface types

–       Typology requirements for deformation

There are several different modelling techniques, each with their own advantages and disadvantages. These include:

–       Box/Subdivision Modelling

–       Edge/Contour Modelling

–       NURBS/Spline Modelling

Subdivision modelling, more commonly known as box modelling “is a polygonal modelling technique in which the artist starts with a geometric primitive”[2]. Primitive shapes include cubes, spheres and cylinders. “Polygons are the building blocks of 3D modelling”[3] It is a modelling technique worked in stages in which the modeller starts with a low-resolution mesh and adds greater detail later. It is a primitive modelling technique that “uses basic geometric shapes and combines them to contrast more complex structures”[4]. A heavy disadvantage of using this specific modelling technique is that it will never truly be a smooth model. However, there are several advantages to polygonal modelling including:

–       Modelling detail is easy

–       UV texture coordinates are editable

–       Hard edges and corners are easily accommodated

–       Simple toolsets are available

–       Models are transferable between different software

These advantages are excellent when using polygonal models, but it is important to remember that they do have some disadvantages as well, including:

–       Data size of a smooth polygon object is comparably large

–       Adding detail to smooth objects can be difficult at times

Contour modelling, also known, as edge modelling is another technique that is polygonal in nature despite being different from subdivision modelling. “The model is essentially built piece by piece by placing loops on polygonal face” [5]. It may sound like a tedious task but is completely necessary, as models require strict management of edge flow and topology. This can prove to be a heavy advantage as “certain meshes are difficult to complete through box modelling alone”[6]. This allows certain areas of the model to be redefined and for the rest of the model to automatically order itself neatly.

Spline modelling, more commonly referred to as NURBS modelling (Non-Uniform Rational B-Spline modelling) “uses curves defined through mathematical functions”[7]. It is commonly and heavily used for automotive and industrial modelling. Unlike polygons NURBS surfaces have no faces, edges or vertices. They are “Instead…comprised of smoothly interpreted surfaces, created by “lofting” a mesh between two or more Bezier curves”[8]. The curve of a NURBS surface is drawn in the 3D space. It is edited by moving a series of handles along the curve known as CV’s or control vertices. For a 3D artist to model a NURBS surface, curves are placed along prominent contours therefore allowing the software to automatically interpolate the spaces between. “A NURBS surface can be created by revolving a profile curve around a central axis. This is a common (and very fast) modeling technique for objects that are radial in nature—wine glasses, vases, plates, etc.”[9]. There are many advantages for a NURBS model. These include:

–       Few Control Points

–       Resolution Independence

–       Texture Coordinates

–       Conversion Ability

Despite all these advantages, NURBS still have several disadvantages including:

–       Seams

–       Breaching

–       Texture mapping across multiple surfaces

Despite these basic modeling techniques, there are several other techniques especially within Maya that allow modeling to become easier. There are also rules that need to be followed in order for a model to be formed correctly. “Avoid triangles and n-gons (face with more than 4 edges) in organic modeling with polygons. Polygons must be coplanar. N-gons and triangles cannot be planar on curved surfaces and won’t deform properly (strange results) when the model moves”[10].

Other tools that allow an artist to shape a model within 3D are important. Certain tools such as:

–       Extrude

–       Combine

–       Merge

–       Delete Edge/Vertex

–       Insert Edge Loop Tool

–       Delete History

Can be very useful when modeling within 3D space. These techniques emphasize the importance of 3D modeling.

“Most people learning to use 3D software still might not even get comfortable even after years and years of practice, and at the same time new toolsets are being introduced as time passes”[11]. It is important to understand the fundamentals of 3D modeling techniques in order to get a grasp of understanding 3D itself and how to control it. These techniques are the basics and therefore the foundations of 3D modeling.


[3] Tom Meade, Shinsaku Arima, 2007, accessed 19/9/12, The Complete Reference; Maya 8, page 58

[4] Sue Smith, eHow Contributor, 2012, 17/9/12, <http://www.ehow.com/list_7505857_3d-modeling-techniques.html>

[6] Ibid.

[7] Sue Smith, eHow Contributor, 2012, 17/9/12, <http://www.ehow.com/list_7505857_3d-modeling-techniques.html>

[9] Ibid.

[11] Ibid.

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