Full-body scans using standard Structure iOS apps


#1

Hi everyone
We’re very interested in using the Structure hardware and Scanner iOS app to obtain full-body surface scans. However we’re having a number of quality issues with Structure output. I’m wondering if I’m expecting too much from the standard iOS apps and whether I need to use the SDK in order to achieve desired results?

We have a Structure with 128GB iPad Air 2 iOS 9.1, viewing in Rhinoceros for Mac 5.1.

For example, and noting infra-red caveats for working with black and shiny surfaces:

  • Scanning indoors, following an indoor calibration, it’s very difficult to get the subject within the scan capture cube. The Scanner app seems to want to scan the room not the subject in front of it.
  • Scanning outdoors, following a regular calibration, the Scanner app seems very sensitive to light levels, works best with overcast lighting but again very difficult to find the optimum level.
  • Resolution accuracy seems poor, even after immediate calibration. Far too much detail is smoothed out. We’re interested in 8mm diameter markers attached to the body.
  • The integrity of the scan mesh is poor, with difficulty scanning closed volumes, and webbing between the legs and between the arms and the body.

I’ve considered normalising the lighting with the use of photography LED floodlamps such as the Ikan iLED312-v2 (and see forum thread below) however right now the overall poor quality of full-body scans is leading me to look elsewhere.

Welcome your advice on persisting with Structure and investing time in the SDK.

Thanks – Bill Johnson
School of Sport Science, Exercise and Health
The University of Western Australia


#2

The best we’ve been able to do is https://skfb.ly/DGpA of a seated nude figure. The mesh is very undetailed. We’ve tried duplicating that several times and have not been able to get even that poor level of detail again.
Unfortunately, I don’t know if this is a limitation of the hardware, the software (using the basic app linking to Skanect), or the fact that you have a living breathing subject, which is impossible to keep perfectly still.
If anyone knows of better software for scanning a human figure I, too, would be very interested to learn of it. In the meantime, our Structure sensor sits on a shelf gathering dust.

Regarding adding an LED to the iPad, it seems that would cause shifting shadows across the surface as you moved the sensor. Any change in lighting, it would seem, would make the scan worse rather than better. That’s just a guess. We used several studio lights with softboxes and aimed the lights away from the model, causing light to diffuse and evenly illuminate the subject. Even that’s not great because as you walk around the subject the person doing the scanning casts changing shadows.


#3

My best solutions for full body scanning are to either:

  • Use the Structure sensor with the itSeez3d app. It has options for bust or full body scanning. The one downside is needing to upload the data to their servers to crunch and build the model. But it’s pretty much your only option.
  • Use a Primesense Carmine scanner, connected to a laptop running Skanect. Skanect gives you the option to double the height of the bounding box, which is perfect for body scanning. I’ve used an iPad Air but the FPS on the real-time scanning is quite low and you can easily lose tracking. Not sure if anyone else could suggest a better laptop that is just as light and portable.

Either way the quality isn’t going to be amazing, but it can be ok. I have heard that there’s potential for some software tweaks that’ll help increase the quality of the Structure scanner. http://www.theverge.com/2015/11/18/9758078/occipital-structure-sensor-lynx-laboratories. Only time will tell :smile: