This week Ben & Ian discuss 3D scanning and photogrammetry. Used in a wide variety of fields
- Entertainment and Arts
- Cultural / Historic Heritage
General Discussion on Point Clouds
Mechanical Contact Probe Scanning
- Carriage Scanning
- Arm Scanning / Pen Scanning
Pros – Older technology, but highly accurate, has a higher resolution.
Cons – Scanning is very slow and tedious, and could damage the object being scanning, such as older and valuable historical objects.
Useful for smaller objects, such as toys or figurines.
Pros – Fairly accurate, with high resolution.
Cons – Scanning can be slow, depending on the desired resolution, and requires the subject to not move. Also multiple scans are required to construct and stitch together the whole model. Depending on the laser scanning method used, the shape is reconstructed, but without color information.
Useful for small to medium sized objects, such as toys, figurines, dolls, faces.
Structured Light Scanning
Using Projectors and a Camera
Pros – The advantage of structured-light 3D scanners is speed and precision, and you can often capture the color information along with the model. Can be more precise than laser scanning. Also moving / animating objects can be captured in realtime.
Cons – Multiple scans / viewpoints are needed to reconstruct the whole model, and each scan needs to be stitched together either manually, or automatically depending on the software used in reconstructing the point cloud data. Useful for medium to large sized objects, depending on the method used, such as faces, people, progressive scanners can capture environments.
Photogrammetry Stereo(Multi-Image) Photogrammetry – Stereo Cameras – Multi-Camera Rigs – Image-Based Modeling – Reference Modeling – 3Sweep
Pros – Very good accuracy, especially with capturing color detail with the model, no special equipment needed for scanning, easy workflow.
Cons – Process can be slow and require a large amount of images, using up disk space, multiple cameras gets expensive.
Useful for a variety of object sizes.
Photometric Stereo – Multiple Lighting Conditions – Shape From Shading – Form Recognition – Bump Mapping
Pros – High accuracy and detail and speed. Realtime capturing can also be possible from multiple angles.
Cons – Also results in a large amount of images which are captured, Multiple angles need to be captured and stitched together.
Useful for very small to medium sized objects, and also useful for capturing surface detail for bump mapping.
Light Fields (Capturing the angle of light) – Lytro
Volumetric 3D and 4D Scanning
- CT Scanning
- MRI Scanning
- Ultrasound 3D and 4D