Align 2D Image Planes

The Alignment tab allows you to align the models with respect to the image planes. A multiple point alignment input scheme is used to adjust/scale the model size and orient it in the appropriate view, so that it looks as close to the input media as possible.
Important: A minimum of seven point pairs are necessary to define the point input scheme for scaling, orientation, and projection of the model with respect to the image/video.
  1. From the 2D Image Plane tab, click the Alignment sub-tab.
  2. Click the IN input collector to activate it.
  3. Select a point on the image in the image plane viewing area.
  4. Click the N1 input collector to activate it.
  5. Select a corresponding point on the model in the modeling window.
    The points on the image and the corresponding nodes on the model should be as close and accurate as possible, in order to optimize the alignment and scaling.
  6. Click Add to add the selected points to the list.
  7. Required: Continue adding point pairs until the minimum number of seven pairs is reached.
    An Error measurement is displayed above the Align button as soon as the seventh point/node pair is picked. This measurement will then be updated as additional pairs are added. An increase in the error measurement indicates that the last pair that was picked is not ideal and it is recommended that a different pair be selected instead.
    Note: Please note that the error unit is in pixels and therefore is relative to the resolution of the image/video. This means that for a given error value, the alignment would be better for a higher resolution image compared to that of a lower resolution image.
    Tip: It is recommended that you select two points which lie on different depth levels. More points at different depths will create better alignment. Also, points located at the center area of the image/video are generally preferred than points near boundaries. Incremental adjustments to orientation can be performed with the help of graphical manipulators.
    Point selection is only allowed on the active model. When overlaid models are involved, it is possible that selected points are from two different models. In this case, any point associated to active model will remain the same as before, however points associated to the inactive model will be displayed as red in the list.
    Restriction: As long as “red” points exist, the Add button will be disabled. Pressing the Align button will do nothing but show an error message.
    Deleting inactive models can clear all invalid points (“red” ones) or you can choose to specifically redefine each invalid point to a valid one.
    Note: The case of selecting points not belonging to the active model is usually caused by changing the active model, applying a style, or overlaying a model/window/page in the middle of a complete alignment operation.
  8. Optional: Click Delete to delete selected points from the list.
  9. Click Align to scale the image plane to the 2D options selected.
    Warning: If the currently selected points have an error value greater than 75, an error message will display and will ask if you would still like to proceed. If you answer Yes, the alignment is executed regardless to the error value. Otherwise, the view will remain the same as before.
    The plane is embedded in the modeling window. In addition, a new view is created in the Views entity folder in the Results Browser.
    Tip: The Views section of the Results Browser and the Entity Editor can also be used modify various image plane view settings.