Aligning a 3D model using tie points

If your 3D model does not align with the point cloud, you can use the Refit Model tool to adjust its position.

To use the tool, click on "Adjust model with tie points" under the dataset options for the model you would like to adjust.

Alternatively, you can right click on the 3D model to open the context menu.

Creating tie points

Model alignment works by defining pairs of points (tie points) between the model and point cloud. A least squares fitting algorithm is then applied to minimize the distance between tie points.

To create a tie point, first click on a recognizable part of your 3D model (for example the corner of a roof or wall), then click on the corresponding point in the point cloud. Repeat this process until you have an even distribution of points around your model

Editing/removing tie points

If you right click on a tie point, you will find options for deleting or editing its position. You can also delete tie points in the list view of the tool panel.

Aligning your model

When you are happy with the tie points, press align. You may make further changes to the tie points and click "Align" again. By default the fitting algorithm will apply a scale factor to your model in order to further minimize the distance between tie points, if your model was designed with real world units this may be undesirable, uncheck the "Adjust scale" box to disable this behavior. 

Tips and Tricks

The model was imported far away from the point cloud

If the model was imported far away from its desired position, it can be cumbersome to move the camera back and forth while defining tie points. You can define a single pair of tie points and press align to get the model in an approximate position, then define the rest of the tie points.

Auto visibility

If your model already has decent alignment with the point cloud, it can be difficult to tell if you are defining a tie point on the model or the point cloud. Enabling the "Auto visibility" option will cause the scene to toggle between viewing just the point cloud or just the model.