Thursday, 10 November 2005

November Dome Update

...its been a while

I haven't posted for a while. I have to keep this blog a commercially-sensitive-information-free zone. At least until the tendering process for our dome is finished.

Quartz Composer vs Panoramas

It looks panoramic images will be important to the dome - I've been looking at various ways of creating them. iPix and QuickTimeVR seem to be the main methods for playback. The problem is that they produce an equiretangular view - really we need the underlying panorama - or a method to render out a cubic QuickTimeVR to a dome master. Given the original spherical equiretangular panorama, Quartz can produce stunning results. I've done some tests with the output from a LadyBug2 - both moving images and stills - these work well too. iPix gave us a link to one of their files - its big. When wrapped to a sphere in Quartz Composer - the results can be panned vertically and horizontally, with no visible seems.


I've been given an SGI O2 by the neuroscience department. Its a bit long in the tooth, but it should serve its purpose in getting me up to speed with IRIX. I use FreeBSD a lot, and have used NetBSD, OpenBSD, Solaris, Debian, Gentoo, Red I feel I have a pretty good overview of what Unix looks like. IRIX is hard. The installation is cryptic, there's no package management - but then the system wasn't designed for pragmatic sys admin...

The main reason for playing with a 5 year old O2 is to check out the 'famous' SGI libraries. Many of which have been replaced by open source equivalents, or have been given to the open source community. Its easy to see why SGI dominated the visualisation arena for so many years - Performer is a powerful library.

Mac/PC specs

Getting off-the-shelf Macs and PCs that will run and create dome content is quite a challenge. The weak links are the hard-drives and the graphics cards. The latest generation of cards from nVidia are capable. The Quadro range (FX 3400, 3450, 4400 and 4500) and the GeForce 7800 GT/GTX will do the trick - but they are expensive cards. In terms of disk speed, RAID is the way to go. I have just setup a FreeBSD 6.0 machine with RAIDed drives. Very practical under FreeBSD.

I have some concerns over speccing Windows machines for the project. Apart from some users having a requirement for 3D Studio Max - there is little requirement for it. In terms of real-time modelling, I would hate to write something in OpenGL then have Microsoft pull OpenGL from Vista. Mac OS X looks like a safer bet, but the threading and IO issues worry me.

I need to keep an open mind on this. Just as Quartz Composer on a Mac would enable a lot of dome content - easily, there might be environments in Windows that would enable the same. I haven't found them yet, but they might be there. There is also the fact the most of the Planetarium equipment suppliers use Windows machines for the playback devices.

The compromise I've come to, is to find a spec that will allow Linux/FreeBSD and Windows. That way the box won't end up being used just for 3D Studio Max. The trick here in my experience, is to buy a machine based on an nVidia graphics chip. Linux/FreeBSD can be made to work with ATI graphics cards through DRI (part of X11) but it never seems to get the full speed of the card. nVidia, on the other hand have produced native binaries for Linux and FreeBSD for years. Some complain that they're not open source - but there is a lot of IPR in the GFX business...

An ideal solution would be to find an nVidia based laptop that would run FreeBSD. These are quite rare. I've found a discontinued model on Ebuyer - a sempron based Acer with a GeForce FX 5200 - having owned an AMD based laptop before, I worry about heat/noise/battery with this. The other option I've found is a Dell - a precision M70.