DIP projector alignment - GlascherLab/LabWiki GitHub Wiki

Projector Alignment Overview

Achieving optimal projector alignment is crucial for ensuring that the projected images not only display clearly but also match the physical touch surface for accurate user interaction. The alignment process is divided into two main parts:

  • Hardware (Mechanical) Alignment: Involves physically adjusting the projector’s position and orientation.
  • Software (Digital) Alignment: Utilizes the projector’s firmware capabilities to fine-tune the image via point correction.

Hardware (Mechanical) Alignment

Key Components and Degrees of Freedom

  • Adjustment Parameters: The projector mount provides adjustments in pitch, yaw, and roll, as well as vertical height, horizontal offset, and the distance from the screen. Focus adjustments are also critical.
  • Procedure:
  1. Begin by manually setting the projector close to the desired position.
  2. Use the mounting screws to adjust the three angles (pitch, yaw, and roll).
  3. Adjust the projector’s height and horizontal offset to match the screen’s boundaries.
  4. Use a level to ensure the bottom line and the side edges of the image are straight. Considerations
  • Interdependency: Note that these adjustments are correlated; changing one parameter (like pitch) may affect the overall image placement.
  • Settling Time: After mechanical adjustments, allow about one day for the system to settle. Recheck alignment the next day and fine-tune if necessary.
  • Limitations: Although manual adjustments are sometimes required, over-reliance on mechanical alignment can be time-consuming and less precise. In many cases, the subsequent digital alignment compensates for minor mechanical misalignments.

Software (Digital) Alignment

Point Correction Using Projector Firmware

  • Alignment Target: Begin by projecting an alignment target onto the screen. This target will be used as a reference for the point correction.
  • Point Correction Grid: Use the built-in “Point Correction” feature available in the projector’s firmware. A 9×9 grid is recommended to cover the entire projection area.
  • Process:
  1. First, reset any previous corrections on both projectors.
  2. Align one projector’s output as the master reference.
  3. Adjust the correction grid until the projected points align perfectly with the physical screen edges and any reference marks on the touch panel.
  4. Once one projector is aligned, adjust the second projector so that its image overlaps seamlessly with the first.

Troubleshooting Tips

Remote Control Use: Access the projector’s menu using the remote to navigate to the geometry or point correction settings. Cable Checks: If the projected image is off, verify that all HDMI and USB cable connections are secure. Image Consistency: Ensure that the full image is visible; sometimes an image may appear only on one side if there are connection issues. Digital alignment via point correction not only refines the mechanical adjustments but also ensures that the interactive elements (e.g., touch inputs) correspond accurately with the displayed image.

Conclusion

Proper projector alignment in the DIP system requires a blend of careful mechanical adjustments and precise digital point correction. While the hardware alignment sets the stage by roughly positioning the projector, the software alignment refines the image for exact overlap and interaction accuracy. Following these procedures ensures a stable, high-quality presentation that is essential for interactive experiments. Periodic recalibration may be necessary to maintain optimal performance, especially if the system experiences accidental disturbances.