HA4 Task 4 - Mesh Construction

How are 3D models constructed? Describe and explain the different modelling techniques available to a 3D designer.

Remember that you are trying to comprehensively explain the theory and applications of 3D with elucidated examples and consistently using subject terminology correctly.

Box Modelling

This is a technique that is used in 3D modelling where the model is created by modifying primitive shapes to create a rough draft of the final model, in most cases. A primary function of box modeling involves extruding and scaling the faces, which are the flat planes that make up a model.

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This image is a good example of box modelling. It features a box, which then has the faces modified, and then modified even further to look like a foot. It is made by modifying the faces of the model to turn something as simple as a box into something more.

Extrusion Modelling

This is a common modelling method that is also sometimes referred to as inflation modeling. In this method of modeling, you could create a 2D shape which traces the outline of a photograph or a drawing. This would be done more commonly using the line tool, because of its simplicity and because it is so easy to work with and create things with it. You then use a second image of the subject from a different angle and extrudes the 2D shape into a 3D shape by following the shape’s outline again. This method is common for creating faces and heads in modeling, and artists will generally model half of the head and duplicate the vertices, invert their location relative to a plane and connect the two pieces to ensure that the model would then be symmetrical. This method is widely used by 3D artists because of it being so practical, quick and simple.

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Spline Modelling

A spline is generally a special function that involves polynomials in the mathematics realm. The term spline may also be more familiar to people as it links to computer science. It is adapted from the shipbuilding term that describes the tools used by draftsmen and the ship builders to easily draw accurate shapes. This makes sense, as splines are the shapes that you could create on 3d software. Constructing a spline is simple, which makes it a popular choice of modeling when it comes to designing digital models, and their curve design helps to easily manipulate it. They can be used in one dimensional or multi-dimensional applications and can be used in various functions.

Lofting

A loft is a sort of wireframe of a 3D object, and it is used as a technique in 3D modelling software. It is derivable from flat sections by doubling it along the path that is given. Lofting is a way of modelling an object based on splines. Usually you would model objects or start off modelling objects by modifying the primitives on the system, or create splines that are quickly converted to editable meshes, or whichever way you prefer. But when you loft a spline you’re creating a 3d object that won’t become an editable mesh. Lofting splines could inevitably produce more efficient collision models. In game design for example, you could be able to improve the performance of your models in-game, or get collision molded closer to your model without sacrificing any.

Lathing

A lathed object is a 3D model that has its vertex geometry produced by rotating the points of a spline or other point set around a fixed axis. A lathing can be partial and doesn’t neccessarily have to be a full 360 degrees, and the point that is set providing the source data could be thought of as a cross section through an object along a plane that would contain its axis of radial symmetry. It is similar to a real lathe because it would produce the same type of object; one that is symmetrical around an axis of rotation. Lathes on a 3D modelling program are also different to those in a real lathe by the fact that the model could have an axis of rotation through a hole. A good example of this is a torus.

This image is an example of what can be created using a lathe. It is a chesspiece, a pawn to be exact, that was created through a quick modelling procedure. I had imported an image of a pawn into 3ds max by going into views and viewport background to import an image, and then using the line in the shape panel and curving the lines that I created, I traced over half of the pawn image before turning it into a lathe and completing the shape.

Common Primitives

Common primitives are basically the most simple polygonal models that 3D software can create, and make it easier for a user of the program to create a model by using this as some sort of base for their modelling a lot of the time if they aren’t creating a piece of work from scratch.  The Standard Primitives in 3ds max, the program that we are using in our lessons, are the Box, Cone, Sphere, GeoSphere, Cylinder, Tube, Torus, Pyramid, Teapot and Plane. The Extended Pimitives that can be created are the Hedra, Torus Knot, ChamferBox, ChemferCyl, OilTank, Capsule, Spindle, L-Ext, Gengon, C-Ext, RingWave, Hose and Prism.

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Sketch modelling

Sketched modelling is a form of 3D modelling used for 3D computer graphics. Sketched based modelling uses a different modelling interface than most other 3D modelling software, this is what makes it different. Sketch based modeling is primarily designed for use by persons with artistic ability, but no experience with 3D modeling programs. Curvy3D and Teddy, below, have largely been designed for this purpose. However, sketch based modeling is also used for other applications. One popular application is rapid modeling of low-detail objects for use in prototypingand design work.

3D Scanning 



A 3D scanner is a device that analyzes a real-world object or environment to collect data on its shape and possibly its appearance (i.e. colour). The collected data can then be used to construct digital, three dimensional models.

Many different technologies can be used to build these 3D scanning devices; each technology comes with its own limitations, advantages and costs. Many limitations in the kind of objects that can be digitized are still present, for example, optical technologies encounter many difficulties with shiny, mirroring or transparent objects. For example, Industrial computed tomography scanning can be used to construct digital 3D models, applying Non-destructive testing.


Collected 3D data is useful for a wide variety of applications. These devices are used extensively by the entertainment industry in the production of movies and video games. Other common applications of this technology include industrial design, orthotics and prosthetics, reverse engineering and prototyping, quality control/inspection and documentation of cultural artifacts.