Scans alignment

Marker space can be used to align multiple scans from PhoXi 3D Scanners. Please refer to Appendix 1 - Marker Space in PhoXi Control 1.2 - User Manual for complete information on what marker space is and how to use it correctly.

Marker patterns

Marker patterns for different scanning distances

Different models of PhoXi 3D Scanners have different scanning distances and use different sizes of marker patterns:

• A5 for distances 160 mm - 520 mm
• A4 for distances 380 mm - 1900 mm
• A3 for distances 380 mm - 1900 mm
• A2 for distances 1680 mm - 3780 mm

Recommended marker patterns for different models of PhoXi 3D Scanners

	XS	S	M	L	XL - scanning distance
					< 1900 mm	> 1900 mm
A5	yes	no	no	no	no	no
A4	no	yes	yes	no	no	no
A3	no	no	yes	yes	yes	no
A2	no	no	no	no	yes	yes

The marker patterns are able to comfortably cover the whole scanning range of the PhoXi 3D Scanners. For cases where the size of the pattern has to be scaled, the scale of the printed pattern has to be reflected as a corresponding setting in PhoXi Control.

To setup the scale of marker pattern use:

• Marker Scale X & Marker Scale Y parameter in PhoXi Control (available from PhoXi Control 1.2.9 beta)
• Use the following utility for Marker Scale setup (for PhoXi Control below 1.2.9)

Download marker patterns

• Marker pattern A5
• Marker pattern A4
• Marker pattern A3
• Marker pattern A2

To verify the scale of printed patterns, we provide patterns with coordinates of the centers of the circles:

• Marker pattern A5 with coordinates
• Marker pattern A4 with coordinates
• Marker pattern A3 with coordinates
• Marker pattern A2 with coordinates

How to set coordinate space to Marker space

1. Open PhoXi Control App and connect to the scanner
2. In the options pane on the left, check following options in group Coordinates:
   • CoordinateSpace = MarkerSpace
   • RecognizeMarkers = TRUE
3. Put marker plate in the view of camera. Make sure camera sees at least four marker circles, then trigger the scan. Point cloud will be returned in coordinate system of marker plate.

Please note that the parameter Inverted Markers present in scanners with FW versions 1.1.x has to be TRUE for the marker pattern to be recognized.

How to create the model of the object

1. Set up Marker space in PhoXi Control.
2. For scanners with FW version 1.2.x set up 3D ROI in the Processing settings/Data cutting group so that as much of the background as possible is removed from the scan. This will make creating the model much easier. The recommended parameter to set up ROI in Marker space is Point Cloud Space.
3. Put the object above the marker plate. You can now move the scanner to different locations, it always returns the point cloud in the same coordinate system defined by marker plate. The easiest approach is to setup the marker plate with the object on top of rotating platform and instead of moving the scanner, you can just rotate the platform.
4. Make several scans from different angles to capture the object from all sides. Save each scan to PLY file.
5. Open all PLY files in 3D point cloud viewer, e.g. Meshlab or Cloud Compare, crop the desired object, use some fine alignment algorithm (ICP), merge the point clouds and polygonize it to create a surface model.

Issues

Image corrupted

If the application does not return the scan and there is a message in the status bar "Image corrupted", check if:

• the visible portion of marker pattern is big enough,
• the circles visible in the scan are collinear,
• the angle between the scanner and the marker pattern is too big
• the point cloud is in half resolution (can be problematic mainly when the scanning distance is large)

Refer to Appendix 1 in PhoXi Control 1.2 - User Manual for more information about these issues.