OmniCal Alignment

Alignment is a user-guided process to align the calibrated data with the coordinate system in Designer. OmniCal also includes the ReShape feature to adjust 3D model vertices based on the user alignment.

OmniCal Stage Plan

In the Stage editor, under Projectors, click OmniCal Calibration to open the Calibrator widget. This widget controls the main OmniCal behaviour.

Once you have created a Capture Plan, you can click on it to open the OmniCalStagePlan widget.

In the OmniCalStagePlan we recommend working through the sections from top to bottom: Capture, Calibration, Alignment, and Mesh Deform (if required).

Alignment

Alignment is the process of registering or aligning the coordinate system of the captured point cloud with that of Designer.

Perform Alignment

1. In the plan editor, roughly edit the point cloud Alignment via Position, Rotation and Scale. This does not need to be exact at all, just close enough in terms of scale and rotation that further steps are made easier.

2. Once the point cloud is roughly aligned (i.e. somewhat close to your projected surfaces in the visualiser), click QuickAlign… to open the tool for detailed alignment. In QuickAlign you should see a reprojected wireframe of the first projection surface. The top two views relate to cameras which can be chosen from the view tab. The bottom two views relate to the cursor location in the camera view. This is essentially a zoomed in view, for better view finding.

3. There are some automatic options to automatically align the point cloud to the stage. Click QuickAlign, and choose Alignment Estimate which is automatic alignment estimation based on point cloud and all projection surfaces.

   Align to plan cameras which is the automatic alignment based on positions of plan cameras.

   Align to plan which aligns to plan cameras and projectors.

   Align to point cloud is useful for alignment using 2D camera reference points. Use this option when you want to apply the current alignment data to the stage.

4. If the Alignment assistance tools don’t provide a good enough alignment, create manual alignment points and line them up in multiple cameras. At least 3 alignment points need to be lined up in at least 2 cameras each. It’s best to edit the alignment points one by one in each camera view. Alignment points are best placed on mesh vertices that correspond to distinct features in the physical model (e.g. a corner of a building). Not every camera will see every alignment point, so additional points may be needed.

5. Create AlignmentPoints (AP). Click near a point on the wireframe to create an AP for this mesh vertex. Alternatively, AlignmentPoints can be imported from existing QuickCal projector ReferencePoints.

6. Drag it to the corresponding point in the image. Do the same for the corresponding point in the second camera view.

7. Repeat this process for a minimum of three points.

   1. A Red point means this point is not being used as part of the alignment, but has been added to the view.
   2. A Yellow point means it has been aligned in the current camera, but it is not being used in the calculations.
   3. A Orange point means it has been aligned in a different camera.
   4. A Green point means it has been aligned in both cameras and is being used in the calculation.
   5. If selected points flash, and you can use the arrow keys to move them around.
   6. When points are selected, use SHIFT + arrow keys to move the point around & hold CTRL & left-click for fine control.

Multi-screen Alignment

If there is more than one screen in the plan, it may be helpful to use Multi-screen alignment. This allows aligning surfaces in the stage based on the captured images and a common master screen. If the relative offset and rotation between all surfaces in the stage matches the relationships of the actual physical surfaces, then this may not be needed.

• The master screen should be aligned first.
• The master screen acts as a registration base for all other screens. Reshaping or scaling of the master screen will therefore affect all other screens.
• When aligning secondary screens, they will be moved to the correct position relative the Master screen.
• When stage automation is used to control physical screen positions, it is best to choose a non-moving surface as the master screen.

An example for how to align multiple surfaces can be seen in the demo video from the Overview page, at around 2:40 minutes.

Alignment Reshape

If the proportions of the model match the physical surface exactly, then the alignment should fit perfectly. But if the proportions are not correct, you may need to perform Alignment reshape. Reshape allows adjustments to mesh vertices based on lined-up alignment points. This can be useful for adjustments such as stretching or squeezing the projection surface, or even moving some internal mesh elements (such as a window) by a certain amount. Typical applications are in theatre where scene elements are built according to a CAD drawing, but the physical construct ends up with minor deviations due to the construction process or limitations imposed by the stage.

The reshape process does not use the captured point cloud, but simply adjusts existing mesh vertices and mesh proportions. This is done according to the calibrated cameras, captured alignment images and alignment point data provided by the user. UV coordinates for a vertex are not modified during Reshape.

Note

When reshape causes stretching between vertices, this will in effect reduce the spatial resolution of the content, since any texture is now covering a slightly larger physical area. If a mesh requires significant changes (such as moving a building’s window by a meter) then it may be a good idea to export the reshaped mesh, clean it up and adjust the affected UVs in a 3D modelling software, then export it again as an OBJ file into Designer. Note that such UV changes will also affect content for this screen, so this may then also need re-rendering.

Enable Reshape

1. To enable Reshape for an alignment point hold SHIFT and left-click it. This will turn it into a reshape point which is indicated by a diamond marker (45 degree rotated).
2. Left-click the point again (without holding SHIFT) to turn it back to a non-reshaped alignment point.

An example for how to use reshape points can be seen in the demo video from the Overview page, at around 4:24 minutes.