Visual Alignment

This article will cover the Visual Alignment workflow in Collage Site.

The Visual Alignment workflow allows you to roughly position and orient a station in context to either imported references like floor plans or point clouds, or orient it relative to other stations in the project with scan data. This option is generally used to position a station close to its correct location prior to selecting points for localization or building links for cloud to cloud registration. You also must have a station selected in order for the Visual Alignment button to light up and be selectable.



Once you are in the Visual Alignment mode, you will see the points colorized by scan, like the picture below, and you are able to pick stations by selecting their points or their station markers.



As you select a station, you will see the movement gizmo update on the screen and jump to the selected station. You will also see there are right panel controls to adjust the orientation of the scan. The on-screen movement gizmo and right panel controls will vary slightly depending on the view mode you are using.

2D Alignment

The 2D “Floormap” view will allow you to adjust the scan’s relative position based on the view’s orientation to the scan data. As such, in plan orientation you can only move the scans in plan and rotate them around the Z axis (as shown in the image above). In an elevation orientation you will only be able to move them in the plane of that elevation and rotate them around whichever axis is perpendicular to the screen (as shown in the image below).



  • The Red Arrow will let you move the scan isolated to the X axis of the view (not visible in left/right)
  • The Green Arrow will let you move the scan isolated to the Y axis of the view (not visible in front/back)
  • The Blue Arrow will let you move the scan isolated to the Z axis of the view (not visible in top/bottom view)
  • Touching the square near the arrow intersection will let you move in both visible axes perpendicular to the screen freely
  • Touching the arc will let you rotate around the axis perpendicularly to the view

3D Alignment

The 3D view allows you additional control of the scans in a single view, and movements will be made relative to the project’s coordinate system rather than the view’s orientation. You will be able to adjust all three axes, in the plane of the X/Y axes, and rotate around the Z axis.



Otherwise, the controls match (arrows, squares, and arcs) but more will be visible at one time:

  • The Red Arrow will let you move the scan isolated to the X axis of the view (not visible in left/right)
  • The Green Arrow will let you move the scan isolated to the Y axis of the view (not visible in front/back)
  • The Blue Arrow will let you move the scan isolated to the Z axis of the view (not visible in top/bottom view)
  • Touching the square near the arrow intersection will let you move in both visible axes perpendicular to the screen freely
  • Touching the arc will let you rotate around the axis perpendicularly to the view

Workflow

Visual Alignment can be used to orient a single station to other localized stations as a pre-registration step making it easier to select points or link to scans close to its correct location. Alternatively, it can be used to align a large number of stations together all at once. This is useful when importing data as stations, importing an unregistered project, or if you completed a number of scans with the instrument without localizing them in the field.

When working with multiple scans, it is easy to quickly pull the scans apart into different locations as a baseline and orient one of them roughly to the screen as a starting point for your alignment.



Once separated, it is easy to select individual scans and orient them relative to each other using the movement gizmo.



We recommend doing this in Floorplan view first, and then setting elevations in one of the elevation views.



It is possible to do this all in the 3D view simultaneously, but it is usually harder and takes much longer. However, it can be very useful to review the results in 3D view once complete.



Once you are satisfied with the approximate alignment of stations, you can tap the Done button in the workflow menu to save the transformations you’ve applied to the stations, locations, and orientations in the project.

Additional Tools

There are several additional tools in the right panel in visual alignment mode to help with the alignment process.



  • Pick Transform/Rotation Point: By default, the movement gizmo and center of on-screen rotation is the instrument location. However, it can be helpful during alignment to define a different point to use as the center of rotation or as the point the movement gizmo is located, particularly when making small or precise alignments.

  • Undo Last Movement: This will undo the last movement of the selected station in case you make a mistake and want to roll back a single step.

  • Reset whole transformation: This will reset the scan back to the original transformation for that scan in this session of visually aligning scans.

  • Clip Scan Volume: This will turn on a clipping box for the scans so you can crop out floors, ceilings, or adjacent spaces captured in the scan that you don’t want to see while running visual alignment.