scanning methodologies

3D Scanning Technology review


3D scanning is a tool which is becoming more and more integrated within the world of additive manufacturing. It has now established itself as a significant link in the realignment of the supply chain and design process taking us further forward into the digital era of manufacturing.

But by no means is 3D scanning a 21st century breakthrough. It predates key events such as the lunar landing, the floppy disk and the first Star Trek series. However, white light and laser techniques were not introduced and adopted until 1985. Now, with some contemporary refinement 3D scanners are becoming an ever popular item on the 3D shopping list.

In 2015, the brainy people at MarketsandMarkets totalled the 3D scanning market at $5.9 billion and estimate it to reach $13.3 billion by 2020. Also, Pete Basiilier, research director at Gartner, backs them up by saying 3D scanning technologies are “maturing quickly” and “have the potential to make high quality 3DP more accessible and affordable.”

Enough small talk, let’s get to the root of 3D scanning….

The tree diagram below shows the main methods of capturing 3D data. Contact scanning can be very precise but is also heavily time consuming and carries the inherent risk of modifying artefacts. For these reasons, non-contact scanning techniques have been better adopted with the ongoing intention of improving scan accuracy, resolution, affordability and cycle time.

 

3D Scanning Methods Diagram

 

The next branches on the 3D scanning tree focus more specifically on how scan data is collected. Active methods involve directing radiation at an object and analysing its reflection and/or absorption. Whereas, passive techniques do not emit anything; instead they obtain 3D captures by processing reflected ambient radiation.

 

Current 3D scanning technologiesGartner's Hype Cycle for 3D Printing

As with all new disruptive technologies, making it accessible is the key to its success.

The scanning up rise has not gone unnoticed by you 3D enthusiasts. Increasing numbers of open-sourced systems, such as FabScan and FreeLSS, are hitting the web. This is encouraging to see and shows that more and more people are adopting this technology just as Gartner’s 3D hype cycle predicts.

The following information allows you to analyse and compare a few of the front runners in today’s 3d scanning market.

 

A Comparison of Current 3D Scanning Devices

 

So what’s the catch?Hidden Detail Illustration

With all this said, there are still some major drawbacks with current scanning techniques. First of all tomography methods and destructive slicing are the only techniques which can truly capture hidden internal geometries. The other techniques require direct line of sight which is not always applicable.

Secondly, detecting reflected radiation from shiny and non-opaque objects delivers scans ripe with inaccuracies. For transparent and translucent parts, the light tends to scatter within the volume of the object. Whereas for high sheen parts the light seems to reflect of multiple surfaces before falling into the sensors field of view and thus contaminating the scan with snippets of the external environment.

Problems further arise when scanning objects in continuously changing environments, like the outdoors. Once again, current sensor technology is not yet sophisticated enough to differentiate and identify the correct signals.

 

A few scanning top tips:

  • For photogrammetry scans, Autodesk recommends that your photos should include a 50% overlap of the previous image.
  • The addition of reference points and careful background selection will dramatically help out the stitching algorithm for photometric scans. It is best to use a colourful and busy background for monochrome featureless artefacts. In contrast, neutral backgrounds are best for complex characterful objects.
  • Using laser lines over point lasers drastically increases scan cycle times for triangulation methods.
  • Some of the best 3D technologies are founded by start-ups so check Kickstarter regularly for new campaigns that might be worth your back!

 

What does the future hold?                         

In the years to come I am really looking forward to seeing how the interaction between the physical and digital world develop.

HP has recently added the Sprout to its 3D fleet. The sprout is the combination of a normal desktop PC and structured light scanner, a reality computer some would say. It brings us that one step closer to bypassing the middle men in the product development cycle.

I also believe scanning will put an emphasis on one of 3D printings main drivers – personalisation. In the future, I predict a greater focus will be put into collecting and using anthropometric data to create ergonomically perfect items tailored to the user’s needs and wants.

And what do you know; maybe one day we will even be sharing 3d selfies through Snapscan or Instafile.

 

 

Kieran Nar, Summer Research Intern