When you are making a single Ray scan which you do not need to align with any other scans, generally, there is no need for targets.
When making multiple Ray scans and aligning these together, having targets in your scans may be very beneficial for both enhanced accuracy and shortened post-processing time.
The alignment of multiple scans can be done using either the best-fit or the align-by-geometry method, without any targets at all. But depending on the scanned object, the accuracy of an alignment done in this way may not be optimal, and geometrical alignment requires computing power and time.
Types of Targets
Different styles of targets will provide different levels of accuracy. Targets can be professionally laser-engraved checkerboards (most accurate), spheres(less accurate), and checkerboard targets printed on paper (least accurate).
Note: If 2D paper targets and 2D metal targets are used simultaneously the accuracy will be defined by the 2D paper targets, the less accurate of the two targets.
Spheres vs. Checkberboard Targets
|Checkerboard Targets Advantages
|Spheres can be detected almost from any angle.
|Scans made with checkerboard targets can be 2-3 times more accurate than those made with spheres.
|Spheres are faster to position and allow faster setups.
|Targets can be printed on large sheets of paper to be easily detected at large distances (over 15 meters).
|Spheres can be more easily recognized in the preview when the user plans to select the areas.
|Targets can be very compact to store, and they don't require large cases.
Can I define the size/diameter of the spheres?
- Sphere size can be defined in Artec Studio.
What are some best practices for scanning with spheres?
- We recommend placing spheres at different heights. For instance, you can use the magnet in the base of each sphere to attach it to a tripod or wall.
- The spheres should not be placed in a single line.
- For better detection and accuracy, Artec Ray should see the “north pole” of the sphere.
- The bigger the distance from Artec Ray to spheres, the bigger spheres are needed for guaranteed detection. At the distances larger than 10-15 meters we recommend working with checkerboard targets printed on large paper sheets (e.g. paper size 11x17, A1, A2).
- When placing spheres and targets on poles or tripods, make sure that there is no strong wind and the spheres do not wobble.
What are some best practices for scanning with checkerboard targets?
- If you scan at large distances, consider printing large targets on 11x17 or A1/A2 paper.
- Be sure not to scan targets at a sharp angle (40° or less), otherwise they may not be detected properly.
- When using the signs printed on paper, mount them such that they are less susceptible to gusts or wind.
- Unless the targets are expendable, we don’t recommend using duct tape to attach targets since it may damage the paper.
- Printing targets on metal sheets make the targets more accurate and reusable.
- Laser-cut metal targets are more accurate than paper targets due to the optical properties of paper.
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