Aside from many useful things (closed loops!), there are two things that stick out to me as exceedingly useful for creating dynamic digital signage:

• Data crunching: Quartz Composer can now load, and download XML files, which makes it much easier to move large chunks of data in and out of your composition.
• Multiple screens — or multiple projectors: There is now support for running Quartz compositions across multiple screens, and also a cluster.

Being able to use XML data rather than just an RSS feed could be extremely useful for specifying things beyond text and images. Color values, timing, or any number of things could be included here in XML. The way we generate most of our pages here at the walker, our output is XML, so piping something like the Walker Calendar into a Quartz Composition just got much easier.

The second thing on that list is the really exciting part. As part of the Developer Tools, apple added a new application called Quartz Composer Visualizer, aka QCV. It does a couple of things. It lets you play a single quartz composition across multiple screens, which you could not do with Quartz Composer in Tiger. I’m not sure yet how this works across multiple video cards. It also adds a network mode, where a host and clients share the same composition and synchronize via the network. Here’s a movie I made of a modified version of our Vineland Lobby Kiosk Screensaver:

This is running on two different computers, my laptop and my desktop (with two displays). For the most part, the displays are in perfect sync. There is a little blip, but I think that’s probably because my Desktop is struggling to keep up, due to an older video card. There is also the option to run a second composition as an “optional processing composition”. What this means is that you can create another composition that has the logic for processing the data and settings, which gets passed along to the display compositions. Basically, this allows you to use a MVC way of doing things. Here’s a screenshot of the app in use:

Finding clients is done via bonjour, so it is limited to the local network, but all you have to do is fire it up on each machine and they find each other. Depending on how well separate video cards are supported, it could be quite easy to run a multiple screen setup from one high-end Mac Pro, since most of QC processing happens on the video card(s). Mac minis could also work as well, though due to the underwhelming onboard video, might not have enough horsepower to do any fancy core image effects.

QCV isn’t an industrial level application; you couldn’t ship this off to a client as a complete solution for a digital signage project. But for use in house, or a situation where it could be monitored more closely, it could be extremely useful. The complete source code to QCV is also included in the developer tools, and it’s meant as a template and example for people. An enterprising objective-c developer (which I am not) could create such an industrial level application. But as a template application, it is surprisingly useful. QC and QCV are the things in leopard that excite me the most.

The screensaver on those kiosks is something that Eric had played with before. I also made a version of a screensaver that uses more of Walker Expanded, and posted about it a few months back. In depoloying it to the iMacs, though, I ran into some trouble. The machines we’re using have their graphics driven by a lowly GeForce FX 5200, the 64mb lame dog of the quartz extreme world. When I put the screensaver on them, it would create horrible drawing problems, similar to the artifacting you would see on a jpeg file at the highest compression, except worse.

This hung me up for a while, but at some point I decided to try again. Through a process of trial and error, I figured out the magic bit that was missing was the Clear object:

Paints the entire rendering destination with a constant color and clears the depth buffer. This is usually the first rendering operation a composition should perform, in order to reset the rendering destination to a known state and prevent visual artifacts. If the rendering destination is intended to be composited over some other visual content, make sure the alpha component of the color used to paint is smaller than 1.0.

Dropping a clear object in there did the trick and the saver was now running quite well. Sometimes it is the simple, obvious things that are missed the most easily. Here is a rendered preview of the kiosk screensaver.

The trick to getting the background pattern bars to swoop in the way that they do is to use two different interpolation objects, one for X position, and one for Y rotation, feeding into a sprite. Both objects should be set to the same duration. The X position simply moves the sprite from left to right (-4 to 4), and the Y-rotation (-30 to 30) changes the tilt as it moves right to left. Since they’re both running at the same duration, the animation appears very smooth. Put this all in a macro patch, copy and paste a bunch, changing the duration, pattern and color, and you have our flying identity patterns.

I would love to give away this screensaver so those of you on Mac’s could enjoy it, but it depends the fonts Walker Expanded and Avenir. It is possible that I could convert the identity patterns to images and change the typeface to Arial or Helvetica and get pretty close. Would anyone be interested?

Here’s a larger image of the Kiosks in the Bazinet Garden Lobby, with the new Vineland entrance being prepared in the background: