DATA CAPTURE

Data capture is the process in which we convert physical, real-world objects into electronic files. With these files, we are able to do things like inspect, design, modify, scale. Being able to capture this data is essential to building a better tomorrow.

When choosing how to capture the object in electronic format, we must first decide how we will use the data now and in the future. Below are the main avenues for 3D scanning real parts into the CAD world. Depending on the method, these can be hand held, arm based, rigid mounted, or a combination. Sometimes, depending on the fidelity you need, we will mix capture techniques to optimize the data file needed.

With these different methods comes strengths and weaknesses. Click on which option intrigues you to find out more.

Touch Probe

Data Capture

A touch probe is a tactile sensor used to gather position / surface information about a sample.

A touch probe is generally comprised of two parts; the body and a stylus with a tip that makes contact with the sample. There are a variety of touch probes capable of capturing single point data or continuous surface data on a sample. Touch information is defined by X, Y and Z co-ordinates and can be used to determine the size and position of sample features.

3D Laser Scanning

Data Capture

3D laser scanning, is used to rapidly capture shapes of objects, buildings and landscapes.

Most laser scanners use moveable mirrors to steer the laser beam. The steering of the beam can be one-dimensional, as inside a laser printer, or two-dimensional, as in a laser show system.

Additionally, the mirrors can lead to a periodic motion – like the rotating mirror polygons in a barcode scanner or so-called resonant galvanometer scanners – or to a freely addressable motion, as in servo-controlled galvanometer scanners. One also uses the terms raster scanning and vector scanning to distinguish the two situations.

White Light

Data Capture

White light scanners are usually tripod-mounted, where a fringe pattern is generated by scanner’s projector and is laid over an area at a time over the scan object. Within the scanning time, the fringe is modified in width and phase and the 3D scanner extracts the 3D coordinates from calculating the returned patterns. The term “white light” comes from the fact that the bulb is a white light generator. Recently, blue LED light is being used as a replacement so the term may need to accommodate blue light scanning. A more general description is called structured light scanning, which covers all colors.

Blue Light

Data Capture

Blue light scanners are usually tripod-mounted, where a fringe pattern is generated by scanner’s projector and is laid over an area at a time over the scan object. Within the scanning time, the fringe is modified in width and phase and the 3D scanner extracts the 3D coordinates from calculating the returned patterns. The term “blue light” comes from the fact that the bulb is a blue light generator. A more general description is called structured light scanning, which covers all colors.

CT Scanning

Data Capture

A CT scan stands for Computed Tomography scan. It is also known as a CAT (Computer Axial Tomography) scan. It is an imaging method that employs tomography. Tomography is the process of generating a two-dimensional image of a slice or section through a 3-dimensional object (a tomogram).

The CT scanner uses digital geometry processing to generate a 3-dimensional (3D) image of the inside of an object. The 3D image is made after many 2-dimensional (2D) X-ray images are taken around a single axis of rotation – in other words, many pictures of the same area are taken from many angles and then placed together to produce a 3D image.

Terrestrial Scanning

Data Capture

TLS technology is based on Light Detection and Ranging (LiDAR) and is also referred to as ground-based LiDAR or tripod LiDAR. It is an active imaging system whereby laser pulses are emitted by the scanner and observables include the range and intensity of pulse returns reflected by the surface or object being scanned. Some instruments are capable of measuring multiple returns or even the full waveform of the reflected pulse. LiDAR measurements, combined with the orientation and position of the scanner, produce a 3-dimensional “point cloud” dataset. The primary capability of TLS is the generation of high resolution 3D maps and images of surfaces and objects over scales of meters to kilometers with centimeter to sub-centimeter precision. This allows for high accuracy mapping as well as the determination of surface changes over time via repeat measurements.

Photogrammetry

Data Capture

Photogrammetry is the practice of determining the geometric properties of objects from photographic images. Photogrammetry is as old as modern photography and can be dated to the mid-nineteenth century.

In the simplest example, the distance between two points that lie on a plane parallel to the photographic image plane can be determined by measuring their distance on the image, if the scale (s) of the image is known. This is done by multiplying the measured distance by 1/s.

Algorithms for photogrammetry typically express the problem as that of minimizing the sum of the squares of a set of errors. This minimization is known as bundle adjustment and is often performed using the Levenberg–Marquardt algorithm.

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