3D Optical Scanning Process
Once we have set up all the equipment we calibrate the blue light optical scanner head with the calibration plate. This plate is coded and embedded into the system we use so; the system knows the volume and dimensions of the calibration plate to ensure complete accuracy. Calibration is to ensure that the scanner head matches up to the points on the plate which act as a reference to form the scanned data. This is because the scanner is made up of multiple elements and regular calibration is necessary to ensure high levels of accuracy are achieved when coordinates are generated.
We ensure the item being scanned is perfectly clean and clear from any additional particles or dust using equipment that doesn’t damage the item being scanned. The reason for this is because we want to ensure that the scanning system doesn’t pick up anything that could effect the quality of the data captured.
We then place reference point markers randomly on the item being scanned, this is because the markers ensure high accuracy is achieved within the measurement process. The markers come in a variety of sizes/volumes. Which size you use will depend upon the size of the item you are wanting to scan, and the type of light being used to scan. More information about volume sizes and measures of accuracy can be found here.
Where required Photogrammetry can be introduced into the scanning process, using the GOM TRITOP system. This is a technique of taking measurements from photographs, where we place coded markers around the item which act as a measurement device for when the data is being used in CAD. The output of photogrammetry is a 3D model of a real-world object.
In some cases, the next stage is covering the item with a powdered aerosol spray. The spray ensures that if the surface of the item is too shiny, it won’t distort the scanning results. Only an even, thin layer of spray is needed, as variations in powder density can impact the accuracy of the results.
Then we scan the item. This is when we capture the surface geometry of the component, part, etc. The 3D scanning system captures high density surface measurements from a projected blue light which is pointed onto the object being scanned.
The data acquired is in the form of point cloud, which is a set of data points in space which are generally produced by 3D scanners,. Scanners measure a large number of points on the external surfaces of objects around them. Once the point cloud data files are created, they are polygonised into a polygon mesh which consists of triangles to provide a facetted 3D stl file, processed with Siemens NX CAD software.
This CAD software allows our team to design, simulate and manufacture products faster by enabling design decisions to be made in an integrated product development environment. Stl is a file format which has a triangular representation of a 3D object. Stl files are flexible as they allow you to directly 3D print from. However, Stl files are not suitable for reverse engineering, as they are not high-quality CAD surfaces that can be manipulated in most CAD tools.
Finally, we have to carefully remove all of the reference point markers with a specialist tool to prevent any damage to the item being scanned. We then remove all the residue from the powdered spray in a safe and clean manner. The spray is temporary and can easily be removed, which leaves the part in the same condition as it was prior to the scanning process.