Starting at the turn of the 21st century, planetariums across the world began to invest in new, digital projection to reproduce the solar systems, stars, galaxies and nebulae. Projected onto the inside walls of a dome, digital imagery allowed for a more immersive experience. But the biggest advantage was the sudden ability to make the content completely dynamic.
Black and white
A major concern for an accurate image in planetariums is the contrast level. The true black of deep space is a challenge for most current projection technologies. Huge strides in contrast ratios have overcome this challenge, however. For example, with liquid crystal on silicon (LCoS) technology, projectors can theoretically achieve contrast levels of over 4 million to 1.
Geometry master class
The three key Barco technologies useful for domed projection surfaces entail geometry correction (also called warping), innate brightness and color equalization from the start and over time, as well as a choice between electronic and/or optical edge blending. This results in a smooth composite image free of disturbances.
Detail and 3D
The increasing pixel count of the latest generations of projectors has been advantageous for planetariums in two ways. On the one hand, they can achieve the same image quality with less hardware and less calibration, or up the ante with even more detailed images of star clusters or planetary surfaces.
Because a modern planetarium is not unlike a cinema - and shares many principles with an IMAX theater - 3D makes sense. Certainly, both the movie theater and the dome have been familiar with projection for many years, but it is only now that sufficient content and reliable technologies are available to generate believable 3D imagery. For this purpose, planetariums usually rely on DLP projection, because of its proven reliability in cinema environments and, more in particular, 3D.
