From: Danielz Shackle
hey, im not suer if their is a better forumn for this question, but ill try here. ive read that using a 128,256,512 format image before uplaoding makes it run quicker or onvert better for sll because of way you do your texture files, so ive ben doing that.
Just so you know, power-of-two measurements for images are not just an SL thing, but a requiement of OpenGL, which is the language that many 3D applications are based on. You'll find that the power of two rule is common to nearly all video games, 3D modeling platforms, and similar programs.
Dimensions that SL allows are 32, 64, 128, 256, 512, 1024, and 2048. Any other measurements will be resized at the time of upload to the nearest of those numbers. Whether or not your images are that size prior to upload won't affect how they impact speed in SL, but it will affect their appearance. The resizing done by the uploader utility is not always pretty. For best visual results, always pre-size your textures to appropriate power-of-two dimensions before upload to SL.
From: Danielz Shackle
ive noticed some load different sppeds then others for diferent files bmp, tga, jpg, etc. but dont you convert to your own fle type? or does it stay in those formats in sl? im curious how i should uupload my miages to get a good sharpness but to help peopl ein my club be as lagfree as possible.
All images are converted to JPEG2000 at the time of upload. The format of the source file will not impact the file size on the server in any way, and therefore cannot affect what you're calling "load speed".
The amount of time it takes your client to download and display any texture from the server is highly variable, as it is dependant on many fluctuating factors (your connection speed, internet congestion, your available video memory, your other available system resources, the other textures you're downloading at the same time, the other textures you're viewing at the same time, etc, etc, etc). There is absolutely zero correlation between the source format that any given image might have been before it was uploaded, and its "load speed" in SL. (Well, technically, I shouldn't say ABSOLUTELY zero correlation. Since JPEG's are lossy, the artifacts they contain can affect the simplicity with which they convert to JPEG2000. This can result in a slightly larger or slightly smaller JPEG2000 from case to case, but the difference will be EXTREMELY negigible, certainly not enough to notice. A better way to say it would have been VIRTUALLY zero corellation.) I would suggest that any realtionship between source file format and in-game speed that you think you might have witnessed was entirely coincidental.
What will be affected by source format though is the image's appearance. Textures sourced from JPEG's will always be lower quality than those sourced from TGA. TGA is a simple, high-fidelity format, and is the industry standard for texture sources. JPEG on the other hand is a highly compressed, relatively low quality format, best suited for web applications where transmission speed and small file size are much more important than good appearance quality.
Every time a JPEG is opened or closed, it loses some quality. When you upload a JPEG to SL, it ends up losing quite a bit, as it gets compressed not just once, but twice. First, the SL client has to open the image, which has already lost some quality to the JPEG compression, then it has to re-compress it to JPEG2000. The end result is the "copy of a copy" effect. You get an image that's not as sharp as the original.
Since speed appears to be your concern here, the way to make sure textures load as fast as possible is not to worry about what format they used to be, but simply to make them as small as possible. I seem to be a bit of a broken record on this lately, as the question has been quite popular over the past week or so for some reason, but just to say it one more time, the biggest reason SL runs so slowly is because of poor texture size management. Professional game artists always optimize textures for maximum performance, but SL users rarely do. People end up doing really silly things like putting a 1024x1024 texture on a 2-foot sign, where a 128x28 would have worked just fine.
Every 1024x1024 uses 3 or 4 megabytes of texture memory, compared with a more reasonable size like 256x256, which uses only 1/16 that much, 192 or 256 kilobytes. (The reason for the "or"s is because textures with transparency are always 33% larger than textures without.) Multiply that by the hundreds of textures onscreen at any given time, and it's easy to see why video cards simply choke. The average scene in SL has gigabytes worth of texture data on display while the average video card can only process a few hundred megabytes at a time.
From: Danielz Shackle
also, this is maybe for other forum but on topic, uploading textures causes lag so ive heard to do several images on one texture and offset them tso not to have to make people download multiple textures, what is worse delay, the offsetting or the loading of new textures?
To use a simple example, what you're talking about here is the possible advantage of putting four 256x256's on one 1024x1024 sheet instead of having four seperate images. You won't save on texture memory either way, since a pixel is a pixel is a pixel, and four 256's is the same amount of pixels as one 1024. However, you will make things easier on the network if you use a single sheet since when you view the texture, you're only making one call to download an asset instead of four. Provided the images you're talking about will be in close enough proximity to eachother that you will have them all cached at the same time, it's always better to put them on a single sheet than not.
