This scanning method is more convenient than scanning without markers. In this mode the object or supporting surface is covered with special round marks (markers).
In addition to construction of the object surface, in this mode the scanner finds marks, determines size and calculates their coordinates. If each of the following scans has enough related marks from previous ones, new fragment automatically will be placed in the desired position. In this way, all the pieces will automatically form a three-dimensional object model, making it easier for further processing of the scan data, speeding up the process of obtaining a 3D model.
Found marks form a reference grid. You can create a reference grid of markers in advance, and then scan the object. Thus each scan will be connected to the reference grid, and not to the previous scan, without the need for overlap between them.
From this it should be noted that you can stick fewer markers to an object. Reference grid can be used repeatedly, if you're using auxiliary object for your scanning process (for example, plate with markers). Reference grid can be uploaded in different formats: basegrid, obс, txt, dxf from third-party sources, for example, from photogrammetric system, that allows you to scan large objects (for example, vehicles) without significant loss in accuracy.
The dxf format is designed to provide faster data transfer when interacting between Agisoft Metashape Pro and RV 3D Studio.
When sticking markers to an object it is desirable to choose flat areas. In this case, on obtained model you can cut the section with the mark, and cover the blank space without significant losses in a result. Using a dark surface, which is "invisible" for the scanner, simplifies removing extra fragments when processing the model. An example of auxiliary surface - plate with markers
<aside> <img src="https://s3-us-west-2.amazonaws.com/secure.notion-static.com/ad7d8b8d-b7df-47b6-8951-d0bbc608ccf3/blank.png" alt="https://s3-us-west-2.amazonaws.com/secure.notion-static.com/ad7d8b8d-b7df-47b6-8951-d0bbc608ccf3/blank.png" width="40px" /> Markers should be attached as chaotic as possible. Avoid expressed patterns or curves, as this may provoke incorrect detection of markers. When using auxiliary surface, object should not move in relation to the markers during the scan!
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Marker type and size can be chosen at project creation. It is possible to automatically detect visible marker type and size in Markers menu.
Scanning procedure:
1. Stick markers on the object or auxiliary surface.
To help control the definability of markers, a 2D marker focus preview algorithm has been implemented.
Marker focus preview works in projects with markers when the “Focus assessment” option in the “Software Settings/Advanced” dialog is enabled and the “Focus Display” option on the Scaning widget is enabled.
Scanning widget
2d markers that fell into the field of view of the cameras and are present in the views from two cameras are evaluated by the detection algorithm for focusing.
Detected 3d markers and not detected due to poor visibility and out of focus borders.
Detected 3d markers and not detected due to poor visibility and out of focus borders.
Marker focus threshold for scanning controls the filtering of markers by the degree of sharpness of the markers borders.
