Explorations in Photogrammetry – Part 5

In the 5th and final part of my series on photogrammetry, I will discuss the process of 3D printing. For those unfamiliar with the process, 3D printing involves taking a digital object stored in a specific file format and creating a three-dimensional, solid object. Typically, the object is “printed” using some kind of plastic, although more expensive printers can utilise metal alloys.[1] The process involves creating a StereoLithography file (or STL for short) that contains a 3D model. This file can then be sent to a 3D printer and, after several hours or even days depending on the size and complexity of the object, a real world representation of the digital object can be seen.

Types of 3D Printing

There are a few different types of 3D printing:[2]

  • Selective Laser Sintering (SLS) – utilises a high powered laser to super heat and fuse together tiny particles of glass, plastic, or ceramic in order to create a 3D object.[3] Objects created with an SLS printer typically require little post processing, such as sanding or other alterations.  Also, because SLS doesn’t require the use of support structures for the object while it is being printed, it is typically faster than FDM and SLA.
  • Fusion Deposition Modeling (FDM) – creates objects by heating thermoplastics and constructing the object layer by layer.[4]  When the object is complex, the 3D printer will build scaffolding to support the structure while it is being printed (this scaffolding can then be broken off or dissolved in detergent later).  It typically supports more complex geometries and cavities than SLA or SLS.
  • Stereolithography (SLA) – like FDM, SLA builds a 3D object layer by layer.  However, the difference with SLA is that the layer is built in a liquid polymer that is then hardened by a laser (as opposed to using heated thermoplastics such as FDM).[5] Like FDM, SLA also utilises support structures while printing the object, which are then cut away once the process is complete.

3D Printing Services

A number of different 3D printing services are available.  One of the most common providers is Shapeways. While working on my models and googling for solutions with regards to questions I had about tools within the software packages, I found a number of references to Shapeways for 3D printing. Shapeways is a type of retail market that allows users to sign up as “sellers”.  They can then submit their 3D models, choose their material and have it printed. The cost varies based on the material selected.  Further, the size of the object that can be printed is also limited by material (some materials allow you to print larger items at an increased cost). You can then feature your items in the Shapeways marketplace for purchase.

Sculpteo is another 3D printing service and is quite similar to Shapeways.  With Sculpteo, however, you can opt to not sell your items in their marketplace and simply use them as a 3D printing service. Sculpteo offers a number of different materials (which influence the cost of the printing) and provide specifications for each type of material that include minimum sizes and specifications for a model should that material be selected.

iMaterialise is another common 3D printing service. Unlike Sculpteo and Shapeways, iMaterialise also offers student discounts which is certainly an incentive for cash-strapped students such as myself. They offer 17 different materials along with a number of finishes.  Additionally, they also offer a comparison tool where a user can compare the various types of materials on offer and see the differences between them.  Their process is very straightforward, and they provide a considerable amount of information in an easy-to-consume format.

My Selection

As for my selection, I chose to use the 3D printer on campus, which is housed at the library.  This choice was made strictly for sake of convenience.  I was able to provide my lecturer with the 3D object.  He then uploaded the file to the 3D printer and set the appropriate sizes.  The cost of this effort was covered by my department, so I had no out of pocket expense.

However, had the option of the Library printing been unavailable, I most likely would have chosen iMaterialise as my 3D printer.  While the student discount was certainly a mark in their favour, the overriding reason was the presentation of information.  As mentioned above, all of the information regarding the different materials was easily presented, and I really liked the comparison tool, which allowed me to fully understand the differences between the different types of materials.  The easy to find specification information for each material provided me with all of the information I needed for my model to ensure the process would happen smoothly.

Conclusion

3D printing is certainly an emerging technology and is being leveraged today more than ever.  It is useful in the rapid production of prototypes and also can provide for unique marketing and economic opportunities for small businesses (as evidenced by the marketplaces popularised on Shapeways and Sculpteo). For the purposes of my explorations in photogrammetry, 3D printing offers a way for me to reflect on my 3D model in a real, tangible way (as opposed to only viewing it on screen).  I can use the 3D printed version and compare it to the real version and see where I might make improvements in the future.

3D printed objects can also provide value within the sphere of Cultural Heritage.  By creating a 3D printed object of an ancient piece of pottery, we can allow for the general public to closely examine the object without risk of damaging something that is irreplaceable.  In this same regard, 3D objects can also enhance museum or cultural heritage exhibitions by creating more immersive experiences. These types of experiences should continue to be explored and leveraged whenever possible as they raise awareness of Cultural Heritage and the Humanities as a whole.

References

[1]Casting aluminum parts directly from 3D printed PLA parts“. 3ders.org. 25 Sept 2012. Web. 3 April 2015.

[2]What Is 3D Printing“. 3dprinting.com. Web. 3 April 2015.

[3] Palermo, Elizabeth. “What is Selective Laser Sintering“. Livescience.com. 13 August 2013. Web. 3 April 2015.

[4]FDM Technology: 3D print durable parts with real thermoplastic“. Stratasys.com. Web. 3 April 2015.

[5]Stereoligthography“. Materialise.com. Web. 3 April 2015.