SL Texture Question

In retrospect this discussion/argument has been very valuable. There is nothing like having to defend your position against an erroneous attack to clarify the significant points in your mind.

I am now crystal clear.

Jpeg2000 allows a form of LOD to operate on the download link, by allowing the client to obtain a suitably sized low-res version of a texture if that is all it needs. And even to efficiently increase the resolution subsequently if it moves closer, without having to reload what it has, since jpeg2000 moves up the resolutions by sending compressed difference data.

Elegant and efficient. Yay !

I knew I had seen Philip imply something like this in a Town Hall or in a post somewhere, and now I understand it.

Now if Chosen had ever said that, instead of castigating me as foolish, the tone of this discussion would never have deteriorated. Remember, at the beginning I admitted to "speculation" ? How adamant is that ?

Technically you are right. I do not have a categorical Linden source which I can quote, to prove that they are using this capability of jpeg2000.

But I think you may agree the evidence is stacked pretty damn high.

And if they aren't, they could clearly cut the downloads to a fraction by doing so. It stretches credulity too far to imagine they chose jpeg2000 by accident, and are ignoring the potential and easy huge performance boost it offers.

Anyway, I'm sure I read somewhere that Jpeg2000 is being used in this way in SL. I'll look around the sources when I have time.

But don't we all SEE it happening all the time ? A texture appears first at low res, then clicks to higher in steps. And this happens again if we move closer to a previously low-res object ? We see the downloading restart, after having stopped ? And then the resolution goes up another step or two ?

Would these things happen if they are not doing what I claim ?

I found these two forum quotes, though not Linden sourced, should they not be almost enough to settle the matter ?

Kex Godel (july 2004) here

"JPEG2000 is neat in that the server can break down a larger texture into smaller resolutions and send higher resolutions progressively if your video card can handle it and if your camera is close enough to the textured surface that the extra level of detail is needed........I've not heard this officially, but I've heard it from more than one person.....you won't even be downloading the full texture when you view it, just one of the progressive stages, so it will appear blurrier than the original."

Strife Onizuka (mar 2004) here

"SL uses the very modern JPEG2000 compression format (which is run in lossless mode for TGA & BMP but lossy mode for JPEG), the specific library they use is Kakadu. JPEG2K is a progressive format so to get a lower quality version of the image, it only needs to be partialy decompressed; for which SL takes full advantage of when downloading textures (that is why textures change in LOD as they load)."

Haha! Actually, I do have a sun allergy, so I don't get much sunlight. Your insight servers you well, young Skywalker.

About 6 years ago, I suffered a heat stroke while bicycling in 105 degree weather in NYC (I used to bike 20 miles a day). Ever since then, whenever I go in direct sunlight, I instantly get a very painful headache. It's a rather unique type of pain, like nothing I else I've ever felt. If I ignore the pain, and stay in the sun for more than a minute or two, I feel sick and lethargic the rest of the day.

Whatever happened that day in New York, it permanently altered my body chemistry. I've asked doctors about it, and all they ever say is "stay out of the sun". Frustrating as that is, I can't help but laugh every time since it's the oldest one in the book. You know, "it hurts when I go like that... don't go like that".

I'd probably make an excellent vampire now.

In any case, we only get a few months of sunshine a year here in Buffalo, so even if I weren't allergic, you'd still be right. No one gets much sun here. We have two seasons, really, snow and not-snow.



Thanks, Eloise. I agree with you about the "eye of the reader" thing. I'm often astonished at what some people perceive as insulting. I try to be as informative as I can, as free with knowledge as I can, and every once in a while someone freaks out over it.

I've never been able to understand why, so I pretty much just chalk it up to statistics now. For every X amount of people who reply to a post, there will be a certain percentage who say thank you, a certain percentage who add further to the discussion, a certain percentage who troll, and a certain percentage who claim to feel insulted no matter what was said to them.

As for your comments about Cottonteil, I'll agree that in the past, she has come off as quite abrasive, but she and I do seem to be getting along much better as of late. I hope that trend will continue.


For someone who's bored and moving on, you sure do seem to be still involved in the conversation. Which is it? Are you done or are you not?

Anyway, I had just prepared a lengthy explanation of how JPEG2000 progression works, as well as how prims are streamed over the internet as parametric objects, not as polygons as you had earlier suggested as part of your "streamed LOD" assumptions (something I had forgotten to respond to earlier). Unfortunately, as you may have seen on the news, we're in the midst of a snow storm here in Buffalo, and the power went out and I lost the whole thing. I had started to rewrite it, but about 1/4 of the way through, I said to myself, "You know what? He's not gonna believe me anyway, so what's the point?"

I'll listen to my inner voice on this one. I've already said what I needed to say several times over by now, so there's really no point in saying it all again. You can choose to believe it or not. It's up to you. My main concern was to try to help others reading this thread gain some better understanding, so not to be confused by your speculations, and I think more than enough has been said for that purpose.



Good point, Johan. I'll try to find some better words than "wrong".

Ok - Strife is the man !

His reference to SL using Kakadu is the key.

I Googled it and found it uses a streaming protocol called TPIP as an extension to the Jpeg2000 standard.

It's fantastic. A client-server protocol which allows the client to actually request the image at any power-of-two size up to that of the original. And then to request a resolution-update if it needs to. With fancy cacheing so you can up-res any time as long as you have the lower-res version still in your client.

Exactly and precisely what SL needs, and provided by the very software Strife says they use.

That does it. SL does NOT download every texture in full, it does exactly what I have been resoundingly derided for saying it does.

No more argument please. Lets just all be glad that we have learned more about how our game works.

Google Kakadu, and follow links to the TPIP documentation. It's wonderful.

A person who said "thank you" when you wrongly tell them they are wrong would be pretty strange, no ?Ok, so I'm weak on resisting - my only excuse was I kept discovering stronger and stronger evidence on the matter in dispute.I am almost sure I never said anything so specific. Straw man ?

So please say, Chosen. Do you still insist the the client must always download the whole texture ? The insistence which caused the disagreement ? Has your opinion changed at all ?

Or do you find the evidence unconvincing ? Have you looked at Kakadu and TPIP ?

Why? You have raised an interesting point about jpeg2000 (although note that you didn't mention it until well after you already made several long posts in which you stubbornly insisted things were a certain way) but things are still far from proven. You have raised an interesting hypothesis; now we need proof. And I'm talking real evidence, not your anecdote about Burning Life.


You started using bold and colors before Chosen's first post (btw, stop that. In an interesting parallel to the discussion about texture uploads, I think the admins on this board should disallow colored text because some people abuse it.) Although you did start with a reasonable tone in your first couple posts, you quickly degenerated into shouting. And I do think Chosen could have been more politic. I think you both need to simmer down.


In case it isn't obvious from all our posts disagreeing with you, no I do not agree that the evidence is stacked high. I've seen one provocative tidbit (that I had to find myself; you're just lucky I was bored and decided to follow up on your slim lead) but that's it.

Note that it wasn't until you mentioned googling jpeg2000 that I had any real reason to believe you. Please stop throwing a tantrum and look for references. I have great respect for facts; I have little respect for childish boors.


I have no idea why that happens. I do not make conclusions based on assumptions. In 3D graphics, the obvious conclusion is just as often incorrect as it is correct.

In this case, I defer to LL since they are the only ones who would know. It's fine to question things, but stop calling them imbeciles.

ADDITION: I should point out, this post is just a response to your first post after mine. I didn't read your other posts until this next part.

Oh, and if they aren't doing this then it is probably for sound technical reasons, not because they're stupid. Again, please stop implying or outright stating that others are idiots.

Seriously dude, even when you are saying something of substance, you say it in such a way that I feel compelled to disagree with you. Stop being absolutist, black-and-white, because you aren't on that solid of ground.


Finally, a good post. Why didn't you just say this from the beginning?

Just to nitpick, you ended with another pointless rhetorical question.


He won't believe you, but I might. Please explain.


God you're annoying. Please please stop being a jerk.

I've been trying this entire time to keep an open mind about you, but this post just tipped me over the edge. Chosen has been a bit condescending, but nothing compared to you. You're like a cartoonish supervillain, narcissistically gloating about your victory before the battle is actually over.

More straw man ? I think I said the LL developers would be imbeciles IF....

If I say a man is an imbecile if he eats his own head, as a way of emphasizing how silly that would be, am I saying he is actually an imbecile ? It's just a bit of hyperbole. Of course no-one is an imbecile. I wouldn't, and didn't say that.

The original discussion, where I introduced colors, was on a different issue, I believe before Chosen joined in half way through.

We fell out over something much simpler. Does SL have to download every texture in full ? I had (have) strong evidence that it does not, but carefully used the word "speculation" at first. I was repeatedly told in what seemed to me to be clear "lecturing the children" language that I was flat wrong. You want me to waste my time with quotes? Just look at it.

Can you wonder I got a bit exasperated ? I'm only flesh and blood.

Now here we are all committing the forum sin, posting on who said what and how, rather than on the technical issue. Wasting time on the irrelevant and the subjective, and each doing battle with the old ego, with varying degrees of success (as usual). But it's the facts that matter.

Do you still believe with Chosen that the client has to download every texture in full, Johan, maybe even for a prim 200m away ? Can you really support that view ? Could SL even function ?

Strife is more likely to give us an answer than LL. Shall we ask him ? Just that simple question ?

That's all the disagreement is about, we seem agreed on everything else. Does it really have to download it ALL ?

Come on, smile and be friendly - you know the answer is NO

I don't think I'm always right, I'm often wrong, but on this particular point I think it's pretty clear, whether by luck or judgement, I did get it right.

Read about Kakadu and TPIP, please ?

This would indicate that I have been successful at what I was intending to do. This feedback is useful to me. In the face of anger and irritation, some people choose to shut out and choose to form a generalisation of something they hate. They go like 'this is something I hate, and I will hate it forever'. While others constantly persist on reevaluating the cause of their irritation and do not form permanent opinions of people.



I was just guessing this actually, judging from personality alone. Anyway, if you look at vampire movies, the vampires tend to talk a lot more than the victims (See? I get my facts from reliable sources).

Ok, I said Chosen was correct on almost every one word. Most of what Chalky was spewing was way outlandish anyway.

But on the issue of progressive texture downloads, the server does seem to send you multiple versions of a texture. This is just an observation. Don't lambaste me on this.

This can be easily tested via the GLintercept tool, which actually churns out a set of the same texture beginning from low res and ending with the final product. Just inspect the texture dump folder and in there, you'd find multiple versions of a texture.

You can also test this by chucking a new big texture onto a prim and while selecting it, repeatedly hit the ctrl-shift-alt-T key while its loading to get the texture size. It will show it slowly climb to the maximum resolution.

While this doesn't prove anything, it does indicate a little of what really goes on between the SL client and the server. I don't think the information about the inner workings of this is of much practical use anyway, since we have no way of using it to benefit anybody.

Chalky wasn't totally wrong. I can confirm some of the points:

1.) There are many legitimate uses for large textures, even beyond 1024 pixels, like displays with lots of text that wouldn't be readable at 1024x1024, or a 10 x 10 meter wall with several windows cut out using an alpha channel (windows with different stained glass motives or too irregular positioned for tiling), or a large wall relief with fine details (a motive that can't be tiled).

2.) Now that the texture size is limited I'll more often have to split textures between four prims. No performance gain here, it even gets slower. One large prim with a large texture will both load faster and render faster than 4 prims with 4 (different) smaller textures. Why?

First the download speed, which is affected by the file size. Try it for yourself - save a large image as a complete file and then as 4 quarters, using the exact same JPEG compression. The single large file will be smaller than the four quarters added up. Only one file header plus larger areas with a similar pixel color, resulting in a more efficient compression.

Second, the load on the asset server. 2 database calls versus 8 (1 prim + 1 texture versus 4 prims + 4 textures). This would even happen when the 4 small prims share the same texture (that's at least how I understand the asset server works, correct me if I'm wrong please).

And third, the rendering. Your GPU will be glad that it has only one texture to scale and map instead of 4. It also has less polygons to handle. Lots of prims with the standard plywood texture will cause lag, even if the texture amount is neglectable.
A triangulated box prim consists of 12 polygons, 2 triangles per side. Since only 3 sides will likely be visible, only 6 polygons have to be rendered (the hidden polygons slightly slow the GPU too though, since it has to determine if they're visible or not). Using 4 smaller prims adds up 16 visible polygons (48 in total). Even when only the front side is textured, the GPU has to map 4 textures onto 8 polygons instead of mapping 1 texture onto 2 polygons.

3.) When rendering a prim with 4 different textures, it's also more efficient to combine all 4 sides in one larger image file. The graphics card needs the texture data only once and the GPU just maps it differently for each side (again, correct me if I'm wrong). 4 small textures would increase the work for both server and client here too, even when we only have 1 prim in any case.

4.) The textures really seem to load at lower resolutions when the camera isn't close. When I stand in the middle of my shop with several giant displays around and wait until all textures have completely loaded (which happens pretty fast, despite some 2048 textures), I don't see the full resolution first. When I zoom onto a display it looks pretty pixelated for a moment (looks like a quarter of the original) before I get the full resolution, which shows that additional texture data is downloaded.


In my opinion, the whole point of reducing the max. image size to 1024x1024 was (aside from that Mac NVidia card bug) the inappropriate mass usage of large textures. Many people will upload their files in whatever resolution happens to look nice in Photoshop, not even noticing that they view an image at 25% only (most people who work with textures are far from being image editing professionals). The brickwalls on some buildings will likely be made of a single non-tiled texture. Of course this adds up, and many large 2048s will lag more than the same amount of smaller textures. But this doesn't change the fact that the appropriate use of one large texture to replace several small textures can greatly increase the performance.

Why do you have to apologize, Cottontail, for producing good evidence on the topic under consideration ? Do you feel you are letting friends down ? Have I stumbled unknowing into some sort of mutual admiration society ?

What is this all squabbling actually about, anyway ? Why does it matter ?

I started off asking questions arising from LL's new stricter cap on texture sizes. Why have they done it ? Is it really necessary ?

Apart from the obvious value of throwing spurious crap off the servers (which strangely LL did NOT give as the reason), the only other justification must surely be to protect the client from suffering deteriorated performance. This is the reason they implied, helped on by some real recent crashes on Macs, which turned out to have faulty graphics cards (so don't count).

I had reason to doubt the second justification, and believe that the true one is in fact to reduce the server database. Which I believe can be done another way (graded upload charges).

This matters because I, and some other content creators who have posted elsewhere, am/are suffering real loss and damage from this texture cap. Content creators of the future will similarly be crippled. If it needn't be, it shouldn't be.

To find out if it need be, there is no way but to probe into the details of how much of each these textures must be sent, which is what we have been doing. Such probing may seem "outlandish" but there is no way to avoid it if we seek the answer. Does an individual big texture by its nature genuinely stress the download or the client more or not ?

This is why discussion here ended up focussed on this one tiny point you saw us squabbling over. Everything seems to hang on it.

So, you see, the squabble is rational after all, and the questions I raised were germane, however outlandish they appeared to you.

As for my "spewing", there is a long tradition of gratuitously insulting others on the forums. I try hard to avoid it myself, but if it turns you on please go ahead. I'm sure you're lovely really . You might not believe it but outside the forums I'm a real pussycat myself.

Ishtara, I think I love you........

Crystal clear, and bang on.

I do appreciate the info, I really do!

http://alexanderhinkle.googlepages.com/textures3

I don't know who is right or wrong. But this is certainly not the first time I have seen Chosen 'talk down' to someone.

I wasn't apologizing. Neither did I have a history of any admiration of anyone. This is just more of your conjectures. And to clarify, what I said was not evidence. They are just observations.

Further, it is not proof of whether SL uses LOD or some sort of 'clipping
on user textures. Its just how SL loads textures in increments and has nothing to do with reducing processing load for anyone, since once a texture is loaded, it remains the same resolution regardless of whether you are zoomed in close or far away.



I see spewing when you say you successfully uploaded some gigantic texture followed by saying that SL flings bits of textures in and out of your screen depending on what you are looking at on screen, simply because your GPU and OpenGL is somehow intelligent nowadays and no longer needs to load textures as discrete blocks in memory.

In SL, just hit ctrl-shift-3. You can observe how textures occupying vram does not fluctuate at all.

What you saw was just an observation. And it is common to have observed wrongly and calling it 'evidence'. If you someday stumble on some real documentation of this texture flinging thing, then do let us know.



A box prim has 18 polygons on each side at highest LOD, followed by 8, and finally 2.

Let me preface this, since you folks don't know me well yet. I am in a network guy working on various discipines. One of which is CCNA. Another is my associates of science. I do graphic design and work on computers on both the hardware and software side. So after reading this, I will agree with Chosen.
Chalky, you fail to understand on little detail. Your client is doing most of the work.
Think of it your own sight. The stuff around you is actually colored what you see, that is the one wavelength of visible light that is be reflected. You see electrical impluses translated into images from the reflections of the wavelengths.
As for the downloading textures, the client and the server are in constant communication. The client displays what the server tells it to based on your physical address on the server in a server farm somewhere in north america. Every texture you see is fully downloaded and then parsed based on the current code that is being displayed. If I am underwater, then I will see land and water around. If I am in the sky, I see ground and cloud. You massive image was downsampled by your client and arrived at the capped size and displayed at the capped size. You simply assumed that because you sized it at that huge amount on your system, it arrived at.
On every MMORPG I have ever played that allowed uploads, you get two choices, downsampling for size or nope you can't upload that, its too big.
This slinging is you believing something that can't be generated. It is a rendering of perspective by your graphics card and the client. It isn't the server at all.
As for the JPG2000, this piece of text from the actual website is the actual reason LL decided this insteal of Png or another common 3d format.

As its name suggests, Part 1 defines the core of JPEG 2000. This includes the syntax of the JPEG 2000 codestream and the necessary steps involved in encoding and decoding JPEG 2000 images. The later parts of the standard are all concerned with extensions of various kinds, and none of them is essential to a basic JPEG 2000 implementation. A number of existing implementations use only Part 1. Part 1 also defines a basic file format called JP2. This allows metadata such as colour space information (which is essential for accurate rendering) to be included with a JPEG 2000 codestream in an interoperable way. JP2 uses an extensible architecture shared with the other file formats in the JPEG 2000 family defined in later parts of the standard. Part 1 also includes guidelines and examples, a bibliography of technical references, and a list of companies from whom patent statements have been received by ISO. JPEG 2000 was developed with the intention that Part 1 could be implemented without the payment of licence fees or royalties, and a number of patent holders have waived their rights toward this end. However, the JPEG committee cannot make a formal guarantee, and it remains the responsibility of the implementer to ensure that no patents are infringed.

LL is in the business to make money by providing a unique service for our entertainment. As anyone who is in the business of creating Intellectual Propertity knows, royalities is how you make money. Jpeg has royalities attached, as does other formats. This way you can own your creations as opposed to, for example Sims, Halo etc. Linden Labs is being very generous with this.
So my suggestion is do some research on how a 3d game client communicates with its server before you decide to go consuming your shoe. To save space, I am posting only the url I quoted from.
If you doubt my talents or abilities, email or message me. I will happy to send you the link on networking, client side 3d mapping, image rendering in 3d environment and so one.

On a lighter note, all I see is womens clothes around hand crafted. Is anyone interested in photo realistic clothes drawn from people who have signed release forms. What can't be made at all?
And can we upload meshes, or must all meshes be created in world using prims? (i saw the blender thread, so I am wondering)
So there you go. No sig yet. I will get one.
Thunderclap

I'm sorry Thunderclap, I find this, and the stuff around it, pretty incomprehensible. Color requires three wavelenghts, whether it is the three sets of receptors in our retina, or the three images sensed by a CCD, or the three channels in Photoshop. Not a good start. I realise that almost all of you here believe this. So let me ask you a very simple question which may disturb your confidence.

You all seem to agree that as we see images download, they start blurry, and get clearer in sudden steps. OK so far ?

So, if we just stopped downloading an image before it reached full resolution, then we would have downloaded a low resolution version wouldn't we ?

Don't you see that this proves the system is capable of downloading an image at less than full resolution ?

Don't you also see that for distant objects this is exactly what we need. To go on and unnecessarily download the lot when we have a way of not doing so would be hugely wasteful. Download a 1024x1024 texture for something occupying 10 pixels on our screen ?

You don't find this suggestion at all ridiculous ?

Given the known capability of Jpeg2000 to do exactly this, given Strife Onizukas knowledge that SL uses Kakadu, given Kakadu's ability to stream partial Jpeg2000's in exactly this interactive client-server situation, I really think we only need a confirmimg post from Cory as the icing on the cake. I genuinely believe this to be one of the enabling technologies which made SL possible, and I am astonished we are all so ignorant about it. If SL is not doing this, it is hugely vulnerable to a competitor which does, running much faster with only maybe a fifth the downloading.

Please, Guys, look at Kakadu and the link to TPIP. It made my mind up for me, and I think it might for you too.

Let me say - failing categorical confirmation from LL, it IS OF COURSE POSSIBLE THAT I AM WRONG. But I put the possibilty, examining all the evidence, including the two posts I quoted earlier, as almost vanishingly small.

I am afraid that after all my investigations, little short of a categorical high-level Linden post in the opposite direction will change my mind.

Everybody handles this thorny question about quoting/claiming RL qualifications and experience on an anonymous forum differently. Personally, I adamantly crush any temptation in myself to try to "pull rank" like this. I believe each persons viewpoint here should be judged purely on its logic, its clarity, and the evidence it brings forward. That is how I judge others, and how I expect to be judged myself.

In this thread, in the court of forum opinion, I am currently not doing too well, am I ? But the truth will eventually be uncovered, and I hope that whichever side is discovered to have backed the wrong horse will have the grace to admit it. If it's me, I promise I will.

Though if I am wrong, I may find myself suggesting to LL an easy way to drastically cut our downloads. Stop downloading each texture when its resolution on the screen reaches screen resolution, anything more being wasteful. We can see the system is capable of doing it. Do you think they would pay me for this gem of brilliance ?

You are incorrect. Real light comes to our eyes in a single wave. The three color channels of RGB images is an artificial construct, allowing us to artificially recreate colors at high quality. There are many color spaces we could use, not just RGB: CMYK, HSV, etc. As for the three sets of receptors in our retina, I don't recall if that is true (although I majored in biology, it's been a while) but even if it is, that is not a feature of light, that is something our body has done to help interpret the light.

Confusing the matter, it is possible to have multiple wavelengths of light appear to be a single other color due to mashups in how our brain processes color. This does not change the fact that a color (say, orange) is a single wavelength of light.

Irrelevant tangent, just fyi.


That's fine, but why do you keep whining about this?


Some gem of brilliance. You'll also note that the progressive versions look awful. The jpeg2000 compression generates progressive levels that are much worse than if the texture was designed at that size in the first place. In other words, the progressive 256 of a 512 texture is much worse than if you uploaded the texture at 256.

I think it's probably better to avoid conflict and disagreement, beyond what is unavoidable to uncover the real technical facts we are trying to resolve here. So let me just say that my understanding of color, and how the human visual system works, is rather different from that of Johan and Thunderclap. It doesn't matter that much, does it? It's not really what we are discussing.

It's SO easy to get ones puny ego sucked into a thread meant to be trying to resolve a contentious technical issue. And it SO not constructive. I'm gonna try harder than ever to always go after the issue only, and never get diverted to the personal.

A soft word turneth away wrath - other cheek and all that........ wish me luck - it's against my instinct lol.

Well if so that's still ok. You should never see it except on a more distant object. If you are interested you move your camera closer and it "pops" to higher resolution.

You can never closely inspect such an "intermediate" texture except in cases of severe lag, because it should "pop" the moment you try.

If the designer used an appropriate texture size, you view the top resolution when you are at the closest distance the designer designed for. If she used one too big, the effect you postulate will leave you stuck with something a little inferior unless you move unnaturally close. I can't say this is an effect I've noticed, but I'm willing to believe it, and if so it's another good reason for using an appropriate texture size. Something on which our texturers need much more education.

You are aware that a pixelated image is incomplete, correct. And I wasn't "Pulling rank" I was simply stated my knowledge base. If you want proof, you can ask. Its no big deal, I'm not a 14 yr punk using dad computer.

I see what you are getting at, but sometimes what makes sense to us, isn't what is applied. For example at the college library, the IT tech has save blocked on the computers but leaves open enabled. So while I can't download any exes (unless I run them onto a usb drive) I can run anything I want. When I called him on it he gave me a Bull**** excuse about premissions. JUst like when he was told to filter out myspace. He when to the router and changed the hosts file to block myspace.com and only that. Of course he didn't realize that myspace has about 20 other domains like www1.myspace.com that are still accessable.
LL runs there servers the way they see fit for them and it keeps them in the black. Can we do anything here about it? No.

Seriously, stop being a jerk.

Oh Johann, you misunderstand. I was clearly referring to MY puny ego.....no-one else's. At least, that's what I meant.