Align N-Point Cloud to CAD
In many cases a simple one click alignment solution is not adaptive enough and a better starting condition is needed. For this purpose, we have the Align N Points to CAD command (also available through the right-click menu). This alignment tool provides the ability to choose starting points for the alignment which are used for a best fit prior to the final optimization. This N-point selection process is also available used in Cloud to Mesh and Cloud to Cloud alignments.
Both a properties dialog and a second graphical window will open to help you select corresponding points on both the moving feature and the feature to align to. The “Control Points” will be points on the CAD model. These can be selected by clicking on the CAD in the pop-up graphical window. The “Rough Align” points will be points in the cloud that correspond to the selected control points and can be selected in the popup window.
The Dialog Controls include the following options:
Stationary Alignment Control Points:
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Control Points. This button will initiate selection of reference points selected from the CAD surface. These points can also be imported using the Import from existing group button. At least 3 points are required for the alignment.
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Clear Points. This button clears the current control point selection.
Moving Cloud
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Rough Align Points. The idea is to select points within the measured cloud that directly correspond with the control points. These points are then best-fit to the control points and the alignment then refines from there. This means that 3 or more points very close to the control points should be selected.
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Clear Points. This button clears the current rough align point selection.
Move Corresponding Instrument Check box.This option ensures that aligning a cloud measured by an instrument also aligns the instrument as well as the could.
Move Additional Instruments & Objects. Selecting this option will initiate a prompt to select additional instruments and or objects to move as part of the alignment process.
To use the Align N Points to Objects command do the following:
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Right-click on the Point Cloud and select Align N Points to Objects > Cloud to CAD or use the menu option under Clout to CAD
. Both a properties dialog and a second graphical window will open to help you select corresponding points on both the moving feature and the feature to align to.
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Select the Control Points button and then click directly on the stationary feature within SA to identify location points (at least 3 Points).
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Select the Rough Align Points button and then click within the second graphics window on the moving feature to identify the corresponding points. You can delete the last selected point location with the delete key.
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When satisfied with the selected points press the Perform Alignment button and verify the alignment. You can do so both graphically and by checking the resulting RMS. At any time the applied alignment can be edited until you exit the dialog.