Feature Request: How Do I Use VT's?

Post #41by **Toti** » 18.02.2004, 11:38

Ah, forgot to say that you are right in your asumptions:

I thought that tx_0_0.jpg and tx_1_0.jpg were supposed to represent the level0 textures. No?

That's correct. (But if you use the script with a 8k texture as 1st parameter you will not get a level0, but a level3. If you use a downscaled version of it to 1k you will get a level0)

If not, then what textures *do* go into level 0?

The tiles that you get when you run the script with a 1k downscaled version of your 8k mars texture as 1st parameter.

If I have to re-size the original texture in order to use this utility, then what's the point?

You only re-size it to construct the lower levels (ie. 0,1,2 the ones that Celestia will use when you look at mars from a greater distance, and thus can be of lower detail in order to save computer resources)

I think that the main confusion here is that you assume that the first level that the script produces must be level0 (ie.: the lowest one)
But it really depends on which texture you use as 1st parameter. If you want to build level0 first, then use the 1k texture as first parameter. It will create the two tiles tx_0_0.jpg and tx_1_0.jpg that you want.
But order doesn't matter really.

Follow the posts above and you will do fine. You are almost there!

Post #42by **Toti** » 18.02.2004, 12:16

Am I explaining it very well, does it make sense, if not I'll be back later to try again

You got it! I missed the source of that particular misunderstanding. You explained it very well, Malcolm, thank you.

Bob:
To go a bit further, the naming convention that you mention is:

tx_I_J.jpg

the first number (I) is the horizontal position of the tile. The second number (J) the vertical position (not in pixels, but in tile row/column units).

In level0:

Code: Select all

_____________________
|         |          |
| tx_0_0  |  tx_1_0  |
|_________|__________|

In level1:

Code: Select all

___________________________________________
|         |          |          |          |
| tx_0_0  |  tx_1_0  |  tx_2_0  |  tx_3_0  |
|_________|__________|__________|__________|
|         |          |          |          |
| tx_0_1  |  tx_1_1  |  tx_2_1  |  tx_3_1  |
|_________|__________|__________|__________|

And so on...

As Malcolm already noted, in level 1 there are tx_0_0 and tx_1_0 tiles too. It is not an error, but a logical consistence, derived from the way that tiles are placed (ie. like a matrix). In fact, again as Malcolm says, in level2 there will be a block the same size (8 tiles) and look as the level1 block I drawed above, and there will be a lot of other tiles (24) filling the rest. So there will be 8 tiles named the same that in level1 and so on...

So what tells Celestia that tx_0_0 is a more detailed tile than another tile with the same name and the same size?
The folder name where each one is located. But this is nothing to be worried about. Only more info on VT

But the important thing is that you are getting no contradiction to the naming conventions.

Bye

Bob Hegwood · Post #43by **Bob Hegwood** » 18.02.2004, 19:26

Toti, Malcom, Andrea, Jestr...

Thank you ALL for your patience and understanding. I just don't
have the brains that I used to. :oops:

My understanding of this topic has just been clarified again. Sheesh!

I'll try it one more time.

Look at the bright side though... If I get this thing working and - if I do finally understand it, I'll have a single document - called "Virtual Textures for the Brain-Dead" on my web page so that you all don't have to go through this again. You'll be able to point someone to a website that will explain the process so that anyone can understand it.

Thanks again... Gotta go now. Gotta Hangover! :wink:

Take care, Bob

Bob Hegwood · Post #44by **Bob Hegwood** » 18.02.2004, 22:16

Once again, thanks to ALL...

All I can say now is... WOW! :lol:

Was worth the effort. Sorry, I just didn't understand the relationship between Fridger's script, and the outputs. Got it now, and am viewing Mars up to level3.

This kinda screws my graphics - In terms of the color of stars and the background view - but I can certainly see some detail on my poor, limited machine now. All I can say is - again - Wow!

Thank you Toti, Malcom, Andrea, Jestr...

Toti and Malcom? I owe each of you at least one drink.

Again, thank you! This is way cool.

As promised, I'll be placing a document on my website so that the Brain-Dead can figure out how to use these tiles too. Might take me a while, but I think it's worth some effort.

Let's see now... Where was that 32k Mars image again? Hmmm...

Just kidding. Thanks VERY much for all of your help.

Take care, Brain-Dead Bob

Post #45by **Toti** » 19.02.2004, 00:29

That's very good!

About VT performance:
Is it too slow?
How about the delays?
Can you navigate comfortably?

This kinda screws my graphics - In terms of the color of stars and the background view

Can you post some images?

tip: now that you know how, you can try a bigger/smaller tilesize for your next texture (earth?) Perhaps you can get a performance inprovement.

Bob Hegwood · Post #46by **Bob Hegwood** » 19.02.2004, 03:58

Toti wrote:About VT performance:
Is it too slow?
How about the delays?
Can you navigate comfortably?
Can you post some images?

Toti,

The performance is not too bad at all. I have some noticeable delays, but the better resolution offered far outweighs a minor pause while the textures are loaded. Can navigate fine, again with some very minor delay.

The images aren't necessary... This is simply a problem that my non-graphics enhanced machine encounters every once in a while. I can actually watch the stars changing color as they cycle through different shades of Red, Green, Blue etc. If you look at my signature, you'll see that I'm using a simple Intel 82815 graphics controller. I can easily cure these problems by buying a graphics card, but I'm not quite up to that yet. :wink:

Intel doesn't really support OpenGL very well either, so this is part of the problem too. That's okay though. I'm *very* happy with the VT process now that I can understand it.

Thanks again for your help. You have been very kind to me, and I appreciate it.

Take care, Bob

Ptarmigan · Post #47by **Ptarmigan** » 20.02.2004, 02:40

Hi Bob,
I'm well pleased to see that you have got it sorted/implimented !
gud init !?!
(jest) I was beginning to feel sorry for that brick wall you woz banging your head against ! (/jest)

73,
Malcolm.

Bob Hegwood · Post #48by **Bob Hegwood** » 20.02.2004, 05:22

Ptarmigan wrote:I was beginning to feel sorry for that brick wall you woz banging your head against !

You oughtta see my head! :lol:

My understanding of the topic was just screwed up by old age and a basic lack of ability to understand what I read. Of course, it would have helped if what I read was written in plain English, but that's my problem.

Look at the bright side though... Now we've gotten a thread where almost all of the dumb questions about Virtual Textures have been asked, and answered in terms that almost anyone can understand.

Again, thanks for your help. It's going to take me a while, but I'm going to add documentation to my web page too. :wink:

Take care, Bob

John Van Vliet · Post #49by **John Van Vliet** » 23.02.2004, 06:59

glad to see that you got them working

Bob Hegwood · Post #50by **Bob Hegwood** » 23.02.2004, 07:24

Thanks, John...

Not only did I get them working, I now fully understand the things, and I've written an 8-page document entitled "Virtual Textures For Dummy's."

I really didn't like that title, but Selden suggested it, and it's starting to grow on me.

Within the next two days, I'll have the Guide AND a minimal Virtual Texture setup on my website so that *anyone* can understand them. I'm only going to place the first four levels on my website though. I think this will put me close to the point where I have to start paying MORE for the site. We'll see.

At any rate, I'm glad that I finally understand VT's.

Sure wish I had a Jack Daniels right now. It's 3 in the morning, and I'm all alone with Celestia. :lol:

Take care, Bob

John Van Vliet · Post #51by **John Van Vliet** » 23.02.2004, 08:04

hi bob it is 3am hear in mich. ( i just answard my ? you are in ohio ) i am a night owl
15 years of working 2d and 3d shift

Bob Hegwood · Post #52by **Bob Hegwood** » 23.02.2004, 21:09

Hey there...

I have placed a "Virtual Textures For Dummies" package on my website now. :wink:

I was going to place the link here, but I'd rather that you go have a look at the web-page in order to get the package. This package is 1.5 MB in diameter, so think about whether you really want it or not.

The package is large because it contains the first three levels of a Mars Virtual Texture, as well as instructions in both the Adobe PDF format, and a plain-old Notepad text file. The SSC and CTX files have also been included so that *anyone* oughtta be able to use this package.

Any problems, give me a holler.

Take care, Bob

BTW My website is HERE.

Post #53by **selden** » 23.02.2004, 22:56

Bob,

Why not add the text of the document as a Web page on your site?

The text seems to be short enough to be easily translated into HTML.
That page could include a link to the full kit. I suspect some of the people
who would need to read it might be hesitant to download such a large
file without really knowing what's in it.

Bob Hegwood · Post #54by **Bob Hegwood** » 23.02.2004, 23:57

Mr. Ball,

Thanks for the effort, but I really don't want to put up another set of web-pages if you don't mind. I have taken your suggestion to heart, however, and I've made an Adobe PDF document available on my website. If you have the free Adobe Reader, then all you have to do is click on the button to display the pages of the document (with all links intact).

Shouldn't you READ the thing before you go making it into a web-page though? :wink:

It may contain errors... Especially since it was written by someone who is technically "Brain-Dead!" :lol:

Take care, Bob

Post #55by **selden** » 24.02.2004, 00:47

Really, Bob, false modesty won't get you very far. Your document is quite readable!

Guest · Post #56by **Guest** » 24.02.2004, 01:01

Selden,

It may be readable... :wink:

What I was concerned about is whether or not it's accurate? :roll:

Take care, Bob

Post #57by **selden** » 24.02.2004, 01:43

Bob,

It does indeed seem to be accurate.

Just a couple of suggestions:

I think it would be appropriate to mention on your Web page that your VT document is primarily intended for people who use Windows. Celestia runs under MacOS X and Linux, too, and people who use those operating systems might be a little disapointed. I suspect that mentally translating your instructions into what's appropriate for them is relatively easy, though.

On page 7 of the document, you might want to mention that either NetPBM or ImageMagick utilities can be used to rescale the images. That's easy to overlook in your phrase "or any other suitable graphics program."

Here's an ImageMagick command that can be used to create a 1K image from an 8K image:

Code: Select all

convert -geometry 1024x512! Mars8k.jpg Mars1k.jpg

(The exclamation-point forces "convert" to generate an image of exactly that size. Without the exclamation-point, sometimes it'll decide to create an image that's off by 1 pixel in one of its dimensions. As you know, Celestia doesn't like that at all! )

I hope this helps.

Post #58by **Toti** » 24.02.2004, 02:43

Bob:

I found the instructions very easy to understand. Thank to your job, now there is another useful source of info on VT.

Bob Hegwood wrote:What I was concerned about is whether or not it's accurate?

Yes, I found some small innacuracies on it. Most of them can corrected adding a "Keep in mind that this instructions are set for a TileSize 512 and a BaseSplit 0" line at the beggining.

level0 contains the images needed to display 1K texture

That's only true if the tile size that you use is 512. If you use a 256 tile size then the resulting texture is 512. If you use a 1K tile size then the resulting texture is 2K, etc.

The level (0) contains two pictures

That's true for a basesplit 0 texture. As you state at the document's end, Chris fixed a bug in basesplit 1 code (a new kind of VT), so there will be some level0 folders that will contain more than two pictures.

VirtualTexture
{
ImageDirectory "EarthHires"
BaseSplit 0
TileSize 256
TileType "jpg"
}

It is TileSize 512 (because you create 2 512*512 textures)

The real difficulty here lies in getting Cygwin, NetPbm...

As Selden already said, NetPbm is not really needed in order to run Virtualtex.

This is a tiny one:

I prefer JPGs because of my limited RAM

I think that JPGs are decompressed at load time. This means that once loaded, JPGs uses nearly as many RAM as other formats. Using JPGs is time-saving, because being smaller in disk, it takes a shorter time to load them.

Great job again!

Bye

Post #59by **chris** » 24.02.2004, 03:34

Toti wrote:
I prefer JPGs because of my limited RAM

I think that JPGs are decompressed at load time. This means that once loaded, JPGs uses nearly as many RAM as other formats. Using JPGs is time-saving, because being smaller in disk, it takes a shorter time to load them.

JPGs are indeed decompressed at load time, so once they've been loaded, you realize no benefits from the decompression. DDS textures are in a compressed format that's decoded by graphics hardware. This has two advantages: the texture are never decompressed so they require less memory than other formats, and they load more quickly than other types of textures since they're in a format that requires no translation before sending off to your graphics hardware.

--Chris

Bob Hegwood · Post #60by **Bob Hegwood** » 24.02.2004, 04:00

Toti wrote:
VirtualTexture
{
ImageDirectory "EarthHires"
BaseSplit 0
TileSize 256
TileType "jpg"
}

It is TileSize 512 (because you create 2 512*512 textures)

Toti,

The TileSize 256 was set to 256 after I read Mr. Ball's advice on how to make the display work more smoothly. I don't remember where I read it, but I know that Selden said to do that.

I know the Tiles are 512 pixels wide.

Thanks for all the helpful advice. :wink:

Take care, Bob