When two projectors are set up in front of each other, the image is shifted slightly. This is referred to as image distortion. This effect can also be called image blur. It can be caused by a variety of reasons, including a change in the control points of the two projectors.
Image distortion
When two projectors are placed on either side of the screen, there’s a risk that one will produce an image that’s more distorted than the other. This is called image warping, and can be corrected using an image processing technique known as geometry correction. It compensates for off-axis placement and non-flat surfaces by applying pre-compensating inverse distortion to the image. However, this method can cause a faint duplicate image and a phenomenon called multipath, or a delayed duplicate signal bounced off of an object.
In this embodiment, the panel 14 of the liquid-crystal projector is used to produce the image. The light beam propagates from panel 14 to lens 26 in a vertical direction. The upper and lower image portions will be reduced, while the remaining portions will be normal sized and will be projected onto screen S.
Image Blur
Image blur occurs when a projected image is not properly focused. This is caused by a process known as aberration. In an ideal system, every point of the object is focused to a volume that is equal to zero, but in practical systems, each point in the image is focused to a different size, resulting in an image that is blurred. Ideally, images produced by two projectors that are placed at the same distance would be perfectly focused.
Changes in Control Points
When two projectors cross, the changes in control points do not affect each other. Instead, each control point corresponds to a corner of the surface patch, and they do not control the entire surface. For example, suppose you have a 1920×1080 surface that is split into A1 and B1 patches. The first projector ends 10 pixels to the right of the split, and it controls the 10-pixel-wide strip to the right of the split. Likewise, if you have two projectors on the same surface, any warping adjustments made to one will not affect the other.
In addition, you can also edge blend multiple projectors onto a single screen, and each projector has its own set of control points. When you are blending two images, you can use the single-grid view to adjust the control points. Otherwise, you can use all of the grids to ensure that the control points are overlapping each other.
Orientation Control
Orientation control when two projectors are crossed is a problem encountered in the projection of two images. The problem is solved by utilizing a device that discriminates parts that are not oriented correctly. This device has a dual purpose: it can prevent images from crossing each other and can also help to maintain the luminous energy of the source image.
Lens shift
Lens shift occurs when the front of a projection lens crosses the front surface of another lens. This happens due to differences in the distance between the projection lens and the surface it is projected onto. A projector with two lenses may exhibit a slight shift in the image, which will create a blurred image.
This shift can affect both the horizontal and vertical position of the image. It depends on the positioning of the projectors.
