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Wednesday, August 2, 2006

Windows Screen Savers: Terranova, Millennium, and Home Planet Updated

Concluding the twenty oh-six simmering summer super screen saver swoop, the Terranova, Millennium, and Home Planet screen savers have been updated to be compatible with dual screen configurations and store their settings individually for each user in the Windows registry (which also permits users without administrator privilege to save their settings).

Retrocausality notwithstanding, there isn't much point in counting down to a date in the past, so the Millennium screen saver now, by default, shows the days remaining until Black Tuesday, January 19th, 2038, when 32-bit signed Unix time() values go negative.

The Home Planet screen saver now uses the NASA Visible Earth imagery introduced in the Home Planet 3.2 Update package instead of the topographic map used previously; the new image has higher spatial resolution (still modest, as befits a screen saver) as well as natural colour rendering of a cloudless Earth.

Update: After further reflection I made a few additional tweaks to the Home Planet screen saver. This is the only Fourmilab screen saver which generates images whose ratio of width to height (aspect ratio) of two to one exceeds that of most computer displays. (The Slide Show screen saver shows images of any shape, but it does not generate images.) The other screen savers size their images based on the smaller of the screen's dimensions (usually the height, but portrait format displays work as well), but to better adapt to screen size, the Home Planet screen saver takes both the width and height of the display into account when computing the size of the image. On a dual screen configuration, this resulted in images which were so large they almost always spanned the two screens and, in addition, showed magnification artefacts due to being scaled up from the 768×384 pixel Earth image database. First of all, I've replaced the Earth image with a 2048×1024 pixel database; this avoids scaling problems on almost all displays of the present and near future. While a two megabyte screen saver would have been scandalous when Home Planet was first released in 1995, today it's par for the course. Secondly, I added code which detects dual screen configurations and other “ultra-wide” displays (defined as a screen which is more than twice as wide as it is high), and sets the image scale based on a screen of half that width; this causes the map display to be the same size on a machine with two monitors of the same resolution as on a system with a single such monitor. Finally, the image is now positioned so as to never span the two monitors (assuming they are arranged horizontally and share the same resolution). (2006-08-03 19:37 UTC).

Posted at August 2, 2006 23:34