3D scanning is a technology where you create a digital copy of something that is in the real world. On the surface this sounds like like magical process where you take a photo of something and you immediately have a perfect digital copy of that object. This is not the case. You can scan an object but that digital copy will not be perfect. There is a lot of post processing needed before it is a good digital copy, and still then its not 100% perfect. So why 3D scan? It is a good way to reverse engineer old parts for manufacture, or creating bespoke products for a person to fit them perfectly. There are 3 main forms of 3D scanning. The first is Photogrammetry. The second is Structured light 3D Scanning, and the last is Contact Scanning.
In this blog we are going to focus on the most basic form of 3D scanning, Photogrammetry. This is the most simple way of 3D scanning as you don’t need any special equipment to do this. You just need the phone in you pocket. Photogrammetry is done by taking a series of photos around a subject ether done photo by photo, or in a scanning rig. These photo are then imported into a software which projects the images and build a point cloud using the light and dark shades in the image. This is converted into a 3D file that we can import into SOLIDWORKS.
We brought our scan subject in and build these stylish glasses to fit perfectly on to our subject
The problem with Scans from Photogrammetry is it isn’t very in accurate. You can see the scan is very rough on the surface. It also means the file is huge and we cannot import it as a Solid body STL or a Surface STL. We can only insert it as a graphic STL. This means we can’t edit it or move move the scan in SOLIDWORKS. It’s a background 3D image in SOLIDWORKS which we can then design around. To get a higher quality scan and cleaner scans you need a more accurate technology but these other types need specialised equipment.
The lowest cost form of 3D scanning that requires equipment is Structured light 3D scanners. This uses a projector to project either Lasers or light patterns on the surface of the model. A camera then takes this light and measures the shapes projected on the surface to determine the shape of the object. This is done a number if times around the model until the whole object is scanned and a 3D model is created. This can give a good overall accurate sized object but it won’t capture the small details or the geometry perfectly. So shapes like circles won’t be perfectly round.
To get a much more accurate scan you need to use contact scanning. This uses a probe sensor to lightly touch the surface of the object and accurately maps those points in the 3D environment. You can use a Structured light scanner or SOLIDWORKS to fill the gaps between the probe points.
Some companies use Contact scanning for accuracy checking and quality control on production lines as the entire process can be automated.
3D scanning is a long way from being a technology that can be run by the touch of a button. There is still some post processing needed and some reconstruction in SOLIDWORKS before you have a perfect copy. Using scanning to scan the human anatomy to create custom fitted wearables is a great use for scanning, even for those getting custom prosthesis fitted. Having a scan before the form is made can speed up the process and make it easier to machine the parts. It can also be used to reverse engineer parts that are not being manufactured any more. This is seen a lot in vintage car collecting. A lot of old car manufactures don’t make spare parts for certain cars so scanning existing ones to reproduce them is the easiest way to do this.
We hope one day 3D scanning can be a simple automated process that can work seamlessly with most forms of manufacture. it is inevitable for it to move in that direction. hopefully we still be around to see it.