3D Scanner:

General

These days everything about 3D printing is becoming more and more popular, including 3D scanning. 3D Scanning is the process of converting a physical object into a computerized 3D Model, which can then be used to print copies of the object. The potential final process would be an actual 3D copier.

Basic concept

Once you see the scanner in action you will realize that the whole concept is both complex and simple at once.
We acknowledging that 3D scanning cannot (yet) penetrate into a scanned object. The goal of 3D scanning is to record the details of the surface.
Knowing that the object must have a closed surface from each primary direction, this app measures each primary direction bottom to top. This is why we use a turntable. In order to capture all details of a specified angle, a vertically oriented line laser is used. And here comes the trick: If you observe the image from the side, you will note that the laser projects onto the object not as a straight line, but as a curved line. In areas where the object is wide, the captured laser light will appear at the border of the image. If the object is thin at a particular angle, the captured light will instead appear in the center of the image.

Illustrated guides can be looked up at SJ Bakers Wiki . This is where I maily derived my project from.

Walkthrough

Before you can scan an object you must have a device in place which assists in automatically rotating, lighting and recording a video of an object. One of many options is to build a turntable like the one at Thingiverse

These are the first basic steps toward getting your 3D scan. To start you must record the required video. If you cannot wait, or you do not have a turntable (yet), there is an option to install predefined Videos like Capture_owl.mp4 or Capture_duck.mp4 .
In order to use them, copy them onto your android device and put them as Scan3doid/Capture.mp4 in your movies folder.

  • Install the app from the Google Playstore and have it ready on your Android device.
  • Procure a turntable. The main components are: the skeleton, the laser, the motor and a surface to put your object on.
  • Optimize the line laser settings: First adjust the lens so the beam is as thin as possible. Then adjust for vertical orientation of the beam, and finally, point it precisely to the center of the turntable.
  • Once everything is in place, put your object on the turntable. :)
  • Turn on the motor and the laser, making sure to film in a dark environment for better end video quality.
  • Start the app and put your android device somewhere secure and still for filming. Make sure it cannot move or fall.
  • The filming and editing options of the app are divided into 4 sections which are labelled 1/4 through 4/4.
  • In the first section you will find the record options. Use ‘record’ to capture a nice video of the rotating object. Make sure to capture at least one full revolution. Do not worry about recording extra video, as there are options to edit this out in later steps. Once one full revolution is captured, stop recording and save the video.
  • Unless you want to repeat your recording, the turntable is no longer needed. At this point you can turn off the motor and the laser.

    The next steps are to edit the video into a useable file:

  • Start Time: Click into the video and you will see a time bar that allows you to set the starting time. Choose any start point at the beginning of the video.
  • End Time: This is the same procedure as Start time: Now you need to make sure to choose a point where the object has ended one EXACT revolution. Once finished, alternate pressing ‘Start Time’ and ‘End Time’ to check your success.
  • Bottom Line: Use the right hand slider to point to the exact horizon between the object and the turntable.
  • Top Line: Use the right hand slider to point to the very top of the object.
  • X Origin: Use the top slider to point to the center of the turntable. If you don't see it, you can estimate it.
  • Angular steps: Amount of calculated points around one revolution.
  • Vertical steps: Amount of calculated points from Bottom to Top.
  • Object height: Is specified in mm. The resulting object will have this exact height.
  • Maximum Object radius: Maximum distance from turntable center to outside object.
  • Masks: If the camera captures light in addition to the laser and not intended to be filmed it can disrupt the 3d scanning algorithm. Adjust masks with the sliders to avoid these effects.
  • These are the main settings. If they have been set properly, you can select ‘Process Video’.
  • Once finished, press "Save STL". This will store an stl file called "scan3doid.stl" on the external storage of your android device.
  • Before transferring the STL File off of your device, its advisable to use an STL viewer to first view the result.
  • If the end result is not yet perfect, fine-tune your chosen parameters and try again.
  • Once you are satisfied, you can press "Export STL" to export the file from your device for further reuse.

    Limitations

    This system is not yet perfect. Known problems are:
  • The laser’s line is not infinitely thin. It has a real thickness, which is about 3mm depending on laser quality. This results in an uncertainty, so the digital model could deviate by that amount.
  • Only details which are lit by the laser and captured by the camera can be translated. Hidden artifacts will not appear in the digital model. This means record only the object’s surface and no inner structures. Points on the surface which are obviously missing will be interpolated from the existing points.