3D is a term that is overused to describe a variety of topics today. (Much as the term video is overused to describe the movie on video, the video tapes, and the video tape player it plays on). 3D is a contraction of 3rd Dimension. Referring to depth in a spatial relationship. A regular image has width and height but no depth.

3D is variously used to indicate:

• Stereo films
• Computer graphics
• Video games
• 3D Television (Stereo)
• 3D Printers
• 3D scanners
• 3D Sign-age (Non-Flat signs)

This page on Mahalo is a leaping off point to pages dedicated to focusing on these aspects of 3D.

3D Stereo films are having their third resurgence now. The first Hollywood movie released in 3D was in 1922 (The Power of Love)http://www.imdb.com/title/tt0013506/trivia. The 3D stereo film had its heydays in the early 50s (e.g. Creature from the Black Lagoon http://www.imdb.com/title/tt0046876/) and again in the early 60's and 70's. These mini-booms did not last. Even with technical changes to get the stereo images side by side on the same piece of film - the costs and technical difficulties in projection and shooting caused these efforts to die out. In the mid 80's (e.g. Jaws 3D)http://www.imdb.com/title/tt0085750/ 3D Stereo tried again but ended up only gaining a foothold in the special venue genre as theme park rides using Showscan (e.g. Devils Mine ride http://www.showscan.com/films/).

The current resurgence is due to James Cameron's Avatar and a concerted effort led by him to persuade the theaters to offer 3D as a hedge against declining patronage due to DVD and Internet delivery mechanisms. Many of these films are being entirely created in 3D using computer Graphics. E.g. UPhttp://www.imdb.com/title/tt1049413/(2009) by Disney-Pixar

Computer Graphics is used extensively in effects movies both Stereo and regular. It is also the driving force behind Computer Games. CG is used to create virtual models of objects in the computer - where they are rendered out to form images. (Or Printed in 3D)

These objects are described either as simple polygon representations (still actively used in video games) or more complex solid models defined mathematically by complex curve equations used in CAD systems.

Computer generated characters can be controlled by sophisticated skeletal systems to take the motion captured from an actor and map it onto flexibly skinned and clothed characters. Making for very believable images. For many years CG has been trying to cross the Uncanny Valley - the term used to describe the creepy feeling you get when the character almost looks real but seems somehow alien and wrong.

The state of the art has accelerated rapidly since the first movie (Tronhttp://www.imdb.com/title/tt0084827/) to use a lot of CG was made in 1982. The computing power available to enable this has also accelerated enormously and now CG is being democratized by the advent of fast cheap commonly available CPUs and GPUs.

Several software applications have risen to become the standards for professional work. These are generally expensive and have steep learning curves. The top four general purpose creation tools are:

• Mayahttp://usa.autodesk.com/adsk/servlet/pc/index?id=13577897&siteID=123112 by Autodesk
• Maxhttp://usa.autodesk.com/adsk/servlet/pc/index?id=13577897&siteID=123112 by Autodesk
• XSIhttp://usa.autodesk.com/adsk/servlet/pc/index?siteID=123112&id=13571168 by Autodesk
• Houdinihttp://www.sidefx.com/ by Side Effects

Autodesk has acquired these applications and now supplies all except Houdini.

In the last few years a growing number of free applications have arisen that enable people without a lot of money or highly trained skill-sets to enjoy creating 3D Computer Graphics. These include:

• Blender - a full production suite
• DazStudio - rendering and animation using purchased and free content

There are several other mid-level applications at reasonable prices:

• Carrara by Daz

3D Printing is the process of taking a virtual model and making it real. There are several technologies for this such as Fused Deposition Modeling (FDM), Selective Laser Sintering (SLS) , thermal printing, and powder matrix printing.

There are several home based technologies that allow a low cost approach to making your own 3D models. These include:

• Repraphttp://reprap.org/wiki/Main_Page
• Candyfabhttp://candyfab.org/
• CupCakehttp://store.makerbot.com/cupcake-cnc.html

Scanning an object in 3 Dimensions can be done using several technologies:

• touch - using a mechanical scanner to feel its way around an object
• stereo imaging - using two or more cameras to recover depth information
• laser stereoscopy - projecting a line onto an object to recover depth
• laser range finding or LIDAR - measuring time of flight

All of these will produce, as an end result, a model representing the surface of the scanned model.

There is a free version of a software package for doing laser stereoscopy called Davidhttp://www.david-laserscanner.com/. It uses a simple laser pointer for the light source. It is easy to make and do yourself.