View source for Scans alignment

To align multiple scans in PhoXi Control Application, it is useful to use marker patterns.

==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'''

{| class="wikitable"
|+ Recommended marker patterns for different models of PhoXi 3D Scanners
|-
! rowspan="2" style="width:100px;" | 
! rowspan="2" style="width:100px;" | XS
! rowspan="2" style="width:100px;" | S
! rowspan="2" style="width:100px;" | M
! rowspan="2" style="width:100px;" | L
! colspan="2" style="width:200px;" | XL - scanning distance
|-
| style="width:100px; text-align:center;" | < 1900 mm
| style="width:100px; text-align:center;" | > 1900 mm
|-
| '''A5'''
| style="text-align:center;" | yes
| style="text-align:center;" | no
| style="text-align:center;" | no
| style="text-align:center;" | no
| style="text-align:center;" | no
| style="text-align:center;" | no
|-
| '''A4'''
| style="text-align:center;" | no
| style="text-align:center;" | yes
| style="text-align:center;" | yes
| style="text-align:center;" | no
| style="text-align:center;" | no
| style="text-align:center;" | no
|-
| '''A3'''
| style="text-align:center;" | no
| style="text-align:center;" | no
| style="text-align:center;" | yes
| style="text-align:center;" | yes
| style="text-align:center;" | yes
| style="text-align:center;" | no
|-
| '''A2'''
| style="text-align:center;" | no
| style="text-align:center;" | no
| style="text-align:center;" | no
| style="text-align:center;" | no
| style="text-align:center;" | yes
| style="text-align:center;" | yes
|}

===Download marker patterns===
* [http://photoneo.com/files/markerPattern/A5-160-520-mm.pdf Marker pattern A5]
* [http://photoneo.com/files/markerPattern/A4-380-1900-mm.pdf Marker pattern A4]
* [http://photoneo.com/files/markerPattern/A3-380-1900-mm.pdf Marker pattern A3]
* [http://photoneo.com/files/markerPattern/A2-1680-3780-mm.pdf Marker pattern A2]


* [http://photoneo.com/files/markerPattern/Marker_Grid_Classic_Inverted_A4.pdf Marker pattern A4]
* [http://photoneo.com/files/markerPattern/Marker_Grid_Classic_Inverted_A3.pdf Marker pattern A3]
* [http://photoneo.com/files/markerPattern/Marker_Grid_A2.pdf Marker pattern A2]


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

* [http://photoneo.com/files/markerPattern/A5-160-520-mm_debug.pdf Marker pattern A5 with coordinates]
* [http://photoneo.com/files/markerPattern/A4-380-1900-mm_debug.pdf Marker pattern A4 with coordinates]
* [http://photoneo.com/files/markerPattern/A3-380-1900-mm_debug.pdf Marker pattern A3 with coordinates]
* [http://photoneo.com/files/markerPattern/A2-1680-3780-mm_debug.pdf Marker pattern A2 with coordinates]

For PhoXi 3D scanners model XS, it is recommended to print the A4 marker pattern scaled at 50% and use the following utility to change the detection of marker pattern: [http://photoneo.com/files/utils/SetMarkerSettings.rar utility]. 

For PhoXi 3D scanners model M and S usually the A4 size marker pattern is sufficient.

For PhoXi 3D scanner L A3 size is mostly used. 

For PhoXi 3D scanner XL at distances below approximately 1900mm A2 size is sufficient.

For distances between approximately 1900mm and 2400mm, it is recommended to print the A2 marker pattern scaled at 125% and use the following utility to change the detection of marker pattern: [http://photoneo.com/files/utils/SetMarkerSettings.rar utility]. 

At distances of more than 2400mm it is recommended to scale the marker pattern at 150%.

==How to set coordinate space to Marker space==
# Open PhoXi Control App and connect to the scanner
# In the options pane on the left, check following options in group Coordinates:
#* MarkersSettings > InvertedMarkers
#* RecognizeMarkers
#* CoordinateSpace = MarkerSpace
# 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.

==How to create the model of the object==
# Put the object above the marker plate and switch the coordinate space to Marker space. You can now move the scanner to different locations, it always returns the point cloud in the same coordinate system defined by marker plate.
# Make several scans from different angles to capture the object from all sides. Save each scan to PLY file.
# 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", make sure the angle between the scanner and marker plate is not too small and that the camera can see at least 4 marker circles.