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© 2011 3D3 Solutions
TEL (604) 568 9638 | FAX (604) 676 7218 | EMAIL [email protected]
3D Scanning Article
Selecting the Best Lens for Desired Field of View
Abstract
When scanning an object in 3D, it is important to determine if the hardware you
are using is best suited for the size of the object you are scanning. For optical
3D scanners including white light 3D scanners, the camera and projector lenses
determine a scanner’s field of view. This short article discusses how lenses with
different focal lengths (mm) and other factors can affect the field of view.
© 2011 3D3 Solutions
TEL (604) 568 9638 | FAX (604) 676 7218 | EMAIL [email protected]
Selecting the Best Lens for Desired Field of View
Which lens should I use for my 3D scanning application?
When scanning an object in 3D, it is important to determine if the hardware configuration is suited for the
size of the object. For optical 3D scanners including white light 3D scanners, the camera and projector
lenses determine a scanner’s field of view. Field of view (FOV) is the observable area that an optical
instrument is able to capture from a specific distance. The most common focal lengths for camera lenses
are 9mm, 12.5mm, 16mm, and 25mm lenses.
The field of view for 3D scanner configurations depends on the following factors:
camera lens(es) being used
lens on the projector
distance between the 3D scanner and the object.
At the same distance a lens with a small focal length (mm) allows you to see more of the scene whereas
one with a large focal length sees less of the scene but gives more detail.
To determine your camera lens’ field of view please use the calculator below:
http://www.machinevision.ca/fieldofviewcalculator
You will need to provide:
Focal length: The distance from the camera sensor to the lens, expressed in mm.
Distance to the object: How far the lens is from the object.
Image sensor: Equipment that converts an optical image to an electric signal. At 3D3 Solutions,
most of our 3D scanners use image sensors that are 1/2" or 1/3”.
To determine your projector’s field of view please use the calculator below:
http://www.projectorcentral.com/projection-calculator-pro.cfm
You want to make sure the FOV coverage from your camera lens matches the FOV coverage on your
projector from any particular distance. The projector lens generally doesn’t vary too much from model to
model.
Here are some general setups that we use in our 3D scanning lab:
9mm lens: Scans half a person from approximately 1.5 meters away from the scanner.
12.5mm lens: Scans human faces from approximately 75 cm away from the scanner.
16mm lens: Scans small objects such as a computer mouse
© 2011 3D3 Solutions
TEL (604) 568 9638 | FAX (604) 676 7218 | EMAIL [email protected]
It might appear that it would be better to use a lens with a smaller focal length. However, there is an
inverse relationship between focal length and lens distortion. For example, the smaller the focal length
(mm), the larger the distortion you tend to get when 3D scanning an object. All lenses have a certain
amount of distortion that is unavoidable. Even though 3D3 Solutions 3D scanner software, FlexScan3D,
compensates for lens distortion you do want to minimize the starting amount.
While zoom lenses provide more flexibility, they also have a tendency to create more distortion and are
more expensive than non-zoom lenses. We recommend using non-zoom lenses.
If you purchase your own lenses for your 3D scanner, another factor to consider is each lens has an
effective focal range. Focal range is the distance from a lens to its focus. Some are set to focus on
objects from 1 meter to 2 meters, while others are set to focus from 1cm to 10cm. Most scanning projects
require a focal range of 5cm to approximately 1.5 meters but experimenting with different settings is
critical to determine the desired field of view for your particular application.
About 3D3 Solutions
3D3 Solutions is a cutting edge developer of 3D scanning and visualization technologies. 3D scanning technologies have typically been available as high-end industrial systems that are expensive and limited to specific objects they can scan. The company's mission is to offer affordable 3D scanning systems that are versatile across many applications using their expertise in white light scanning technology and the latest digital measurement advancements.
For more information, please contact:
Telephone: (604) 568 9638 Email: [email protected] Website: www.3d3solutions.com
