A phosphor plate is mounted atop the tube, and light is then dispersed by a large lens with a 160 degree field of view to cover the planetarium dome.
by Lincoln Optical Corp., L.A., CA for Evans and Sutherland Computer Corp., SLC, UT, Digital planetarium CRT projection lens, 43mm, f2.8, 160 degree field of view".
In this way, the stars projected by Digistar were substantially brighter than could be achieved using a raster display, which has to touch every point on the phosphor plate before repeating.
Likewise, the calligraphic technology allowed Digistar to have a darker black-level than full-dome projectors, since the portions of the phosphor plate representing dark sky were never hit by the electron beam.
Due to the use of vector graphics, as opposed to raster imaging, the Digistar does not have the resolution issues that many full-dome systems have.
Digistar was the brainchild of Stephen McAllister and Brent Watson, both of whom were long-time amateur astronomers and computer graphics engineers.
Likewise, planets and moons within the Solar System could be displayed accurately for any time in history, from any point of view.
[3][4] ILM projected the effort would take two weeks, but in fact it took from late November 1981 until mid-February 1982.
The last shot recorded was what became the first entirely computer generated feature film sequence.
It was the opening scene of the film, a rotating forward translation through a star field that lasted 3.5 minutes.
Even at this point the long-term success of the product was very much in doubt, but as of 2019 Digistar has an installed base of over 550 planetaria.
Digistar was driven by a VAX-11/780 minicomputer, with custom graphics hardware related to the E&S Picture System 2.
This control panel was approximately 3' x 4' and contained a keyboard, a 6 DOF joystick, and a large array of back-lit buttons.
[9] Later iterations of Digistar replaced the physical control panel with a common graphical user interface.
The model is a circle of parallel lines that, when defocused, appear as the continuous band of the Milky Way across the sky.
These are converted to their binary equivalents by a utility built into the Digistar system, which also checks for errors within the file.
Though it lacked the pin-point stars of opto-mechanical projectors, and the full-dome rendering abilities of the later Digistar 3, many planetarians consider it a good balance between the two, especially considering the novel capabilities of seeing heavenly bodies from any point in space and time.
[10] Terence Murtagh, past president of the International Planetarium Society, stated in 2000, anticipating Digistar 3's full-dome video, "I think the next ten years will see the most dramatic advances in all-dome presentations since the invention of the projection planetarium in the 1920s and the arrival of the electronic Digistar in the 1980s.