Things You Might Not Know About the Align Mode

May 28, 2021

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Those who have been acquainted with EinScan-Serie scanners know that under turntable scanning mode, except for Einscan-SE, every device has 3-4 kinds of align modes to choose from.  But what is the basis of our choice?

Today we will introduce the differences between these align modes under the turntable scanning mode in detail.

Note: the choice of align mode is not limited to one, there is an overlap between different align modes, which means that there are certain objects that can be compatible with different align modes. Therefore the categorization of the align modes is not dependent on objects.

This article will try to explain the best align mode for specific scanning situations.

For some basic knowledge about the align modes under turntable mode, it refers to the alignment of the scan data after the turntable rotates around itself for 360 degrees. When continuing to scan, the align method between the data acquired by the current scan and from the previous scan is based mainly on features. If enough markers have applied to the object, and marker alignment has been chosen for both scans, the data from both scans will be aligned based on the applied marker points.

Feature Alignment:

Generally speaking, Feature is the geometric shape of an object. Feature Alignment is the alignment of data from multiple scans according to the object’s collective shape. Therefore, in this align mode, objects need to have distinguished features in order to be aligned correctly. This align mode is mainly for objects with richer features.

Object with rich features                               Object with fewer features

      Note:

  1. If the object is too small, it is possible that the features can’t be recognized by the software.
  2. Lots of repeated patterns are not regarded as rich features. As in the picture below, the object has a lot of repeated structures, therefore it doesn’t have rich features.

Turntable Coded Alignment:

The turntable coding points refer to the white points on the turntable. This align mode, as the name suggests, is to place the object on the turntable, the alignment of the data depends on recognizing the common coding points as the turntable rotates. Therefore, to ensure that enough coding points are recognized in the scan, the angle of the scanning head needs to be adjusted, so that coding points can be scanned. The object to be scanned also must not be so large as to block too many coding points.

Marker Alignment:

Marker alignment requires a certain density of marker points to be pasted on the surface of the object in advance, and in the scan, the data will be aligned according to these markers. This align mode is mainly used for the object whose features are not obvious. Without markers, the alignment of these object scans might poise errors.

Note: Selecting this mode requires covering the coding points on the turntable.

Turntable Alignment:

Turntable alignment is to use the positional relationship between the turntable axis and the scanning head determined during the calibration of the device. In this align mode, no relative position movement between the scanning head and the turntable is allowed after the calibration is completed; and if a relative position movement occurs, it is necessary to recalibrate.

The following explanation is based on examples of objects.

If the object has rich features and does not obscure too many coding points, you can choose whether turntable alignment, turntable coded alignment, or feature alignment to obtain complete object data with 2-3 scans.

Objects with insufficient features, for a single scan you can choose either turntable alignment or turntable coded alignment. But in order to complete the scan of this box, at least two scans are needed. Therefore a marker alignment for it may be more adequate.

In this case, the object obscures most of the turntable coding points, but it has sufficient features, so you can choose turntable alignment or feature alignment to complete the scanning of data.

In order to cope with the scanning of various shapes and objects, EinScan provides a wide range of align modes that may cause confusion for new users, but we wish this article helps you to determine the best align mode for your scan object.