Recently I seem to have been saying this quite a lot to people, so I figure it's time to blog it, and possibly after that write it as a resources web-page.

Second Life is still a textual interaction medium as I write, but, as you would hope would be obvious, it's a video medium, not a print one. A lot of people don't understand what that means though, so let's spell it out a bit.

Your inkjet printer prints 300dpi minimum, more if it's a photo-printer. Laser printers typically start with even more dots per inch and rise. Professional quality printed material (your typical glossy brochure say) doesn't really have dpi, because it's a continuous ink-print process, but if we say it's all photo-quality at about 1,000 dpi it's a good guide. Your monitor screen, for most monitors displays 72 dpi. That's less than a quarter of the resolution from the standard print from your inkjet printer. This forms a large part of the reason why webpages have bigger writing on them than most printed pages - you need some width and height of dots to make the letters stand out clearly with all the curls, printed areas and spaces (black and green areas in this blog format). Fewer dots per inch means fewer charcters per inch to make it easy to read. Incidentally if, like me, you usually read PDFs at 125% or larger resolution when reading them on screen, this is exactly the same cause.

Preparing the display materials

What does this mean in practise? Well, if you plan to adapt existing materials:
  • DON'T adapt your PDF of your glossy brochure,
  • DO adapt your corporate powerpoint

Why adapt your corporate powerpoint? Well, powerpoint, keynote etc. are designed to be run on a computer, through a monitor - exactly how you see Second Life. The typical rules of good design powerpoint design slip over into good material design for Second Life. That doesn't have to be bullet points, which the presentation tools tend to force you to, but the principles of size, amount of content on each slide etc. remain, and the idea of a title on each page which is pure powerpoint is worth remembering too.

Summary 1 - design your materials with powerpoint in mind (you don't have to use powerpoint, I tend to write directly into Photoshop or Illustrator) but that sort of presentation is the right way to go.

Preparing the materials for uploading and uploading

Preparing your materials for uploading is also an important part of the design process. If you write your materials in powerpoint you have an option to save as jpg - use it. If you're fussier, or write directly into Photoshop/Illustrator or similar, find something that will export as targas - it's a loseless system that SL reads. To be honest, for good presentation materials it doesn't matter, because the loss of quality in the jpg export and upload process will not be noticeable.

If you are working directly in a graphics programme, set your canvas up first to the right sizes. Powerpoint export doesn't give you the choice, but if you can resize your exported jpgs sensibly too. Choosing the right size is an art form, but there are some rules.

OpenGL, which SL uses, insists that all textures have sides which are powers of 2 pixels long. Currently the available numbers seem to be 32, 64, 128, 256, 512 and 1024. Your image doesn't have to be square - a banner could easily be 1024 X 32, which is a totally legal upload. SL, perhaps nicely, doesn't insist the textures you upload meet this specification on your computer, but it will resize your images to one of these sizes (it seems to round down but this behaviour does change sometimes). The process that SL uses it totally outside your control - it is far better, if you can, to resize in a graphics programme that gives you the ability to do this and see the results rather than hit and hope. This will change the proportions of the written material, but see below for a tip about that.

NOTE: If you're inserting a photoshopped slide into an existing ppt set, it's worth setting the texture to the size of the original ppt (usually 740 X 520) and then resizing so you keep the font proportionality on the display.

You might expect to use 512 X 512 as your upload size, and that would always be my first stop, but having done that, have a look at 512 wide X 256 high, and even 256 X 256 pixels. Don't squint at the tiny print at 100% - remember in SL people will zoom in, so use your zoom tools to have the slide fill as much of the screen as possible. This is, more or less, what will happen in SL (although here SL's zoom engine is probably better than your graphics package's zoom engine). If the text remains legible at this sort of zoom it will be comfortably readable in SL, so use it. Smaller textures in SL tend to load faster, and are less of strain on your audience's graphics cards. Although streamed as a jpg2000 (which is a small texture format) your graphics card has to unpack this to draw it. A 512 X 512 pixel image with no transparency information takes up 3MB of your graphics card's memory. A 256 X 256 pixel image takes less than 1MB (786324 bytes to be precise), so your computer will be happier drawing a few of these as you change them, and so will everyone else's card.

Having done this, upload away. The simplest way is to put everything into a folder and use the bulk upload option in SL, and then go and get a cup of tea. Sometimes this doesn't work smoothly - particularly when the asset server is under heavy load, but it does work well most of the time.

Summary 2: Resize images to a power of 2's sides if possible, and as small as possible (256 X 256 pixels is often fine). If you don't resize the uploader will, and you lose control of the process.

Displaying the materials in world

Having uploaded your textures, you will want to display them somehow. If you build your display screen to the same proportions as the original image size, say 7.20m X 5.40m and apply your (resized) texture to it the graphics engine in SL will rescale your texture back to those proportions and suddenly the fonts will look good again. You can resize with the white corner stretch buttons to resize whilst retaining the proportions if you wish a larger or smaller display. If you wish much larger or smaller you can link 2 or 4 prims together built to these proportions and stretch them too - but remember that, unlike RL, people will be able to zoom in on your display and make it roughly fill their screen if they wish so it's rarely worth doing.

Summary 3: Make your display prims to the proportions of your original textures (before resizing) to re-establish the right proportions of the font. Consider how large it must be, remembering people will zoom in on it if needed.

Key points to remember:
  • Remember you're building a presentation for a monitor not a printed page - less text, bigger fonts
  • If possible resize in a graphics programme to the smallest size possible, with powers of 2 pixels per side: 256 X 256, 512 X 256 or, perhaps, 512 X 512 are good bets.
  • Build your display screen to the same proportions as your original slide images to re-establish the font's proportions.

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