Feature Request: How Do I Use VT's?

[Bob Hegwood]

I've read all of the texture forum links to see if I can understand what we can do with virtual textures, but I still don't have a clue as to how to create/use them.

Wondered if maybe some *knowledgable* person could create a rudimentary guide to virtual textures so that us brain-dead types can understand the thing.

For instance, I have been told that I can get around my poor limited 1024 x 1024 Intel graphics problems by using virtual textures to get better resolution images of a planet.

Is this true?

Thanks, Bob

[Toti]

Bob:
No, I meant that perhaps you can get around your card limitation using VTs.
It was my case. Some time ago I downloaded a 8k texture of earth. I tried to use it, but my old 32Mb video card couldn?t handle it. It was so incredible slow that it turned to be completely unusable.
So I returned to my 4k earth texture, which worked OK.
When 1.3.1 became available, I downloaded a 32k VT of earth up to level 4 included. It works very well, with the only drawback of the usual delays when a new tile is loaded from disk.
If your case is similar to mine, then you can try it and see if it solves the problem.

A VERY simplistic explanation of VT:

Imagine you want to use a very large texture (16-32k) in Celestia. Probably your system could not handle it, so -as a solution- you can split it in pieces, in order to use only those that you really can see in the screen. The ones that are hidden (for example, on the opposite side of the planet) are not used.
It saves a lot of resources, so you will be able to use that big texture.
VT uses a more efficient approach: when you see earth from, let?s say 100.000 km, you really do not need to use a giant texture because earth will be very small in your screen and thus you will waste a lot of detail. So you can use a smaller texture.
When you get closer, the size of earth in screen will get bigger and more detail will be needed. If you continue to use that small texture, you will see a blocky view. So you need a bigger texture.
And so on...

When I say that I use a 32k earth map up to level 4, I mean that I have 5 earth textures (0,1,2,3,4) each one bigger than the previous (not only bigger, but more detailed, of course). They are stored in different folders (level0, level1, level2, level3, level4).
But as I said, these textures are not in one piece, but splitted into tiles, to improve render efficiency. This whole set, plus a text .ctx file, is called a VT.

You may find a problem with VT: they are huge (about 100 mb and more for a 16-32k one). They are slow to download.
So, before attepting to download one, let?s do your own short version (that you can expand later):

1 ) in your celestia\hires folder create a new folder called earth
2 ) inside of it, create a folder called level0 (without spaces)
3 ) with the GIMP, create 2 images 1024x1024 in rgb: one red, the other blue, and save them as tx_0_0.jpg and tx_1_0.jpg inside the level0 folder.
4 ) with Notepad, create a new text file and write this in it:

Code: Select all

VirtualTexture
{
        ImageDirectory "earth"
        BaseSplit 0
        TileSize 1024
        TileType "jpg"
}

5 ) save it as earth.ctx in your celestia\hires folder
6 ) go to your celestia\data and in solarsys.ssc copy it as solarsys.bck (a backup copy) and change the line (in solarsys.ssc)

Texture "earth.*"

with

Texture "earth.ctx"

7 ) run celestia. Go to earth, orbit it, etc. If you can see the planet painted with the blue and red colors, then VT will be a solution for you.

And that?s all. I hope I am not forgetting something.

Hope this works. If not, try resampling the blue and red textures to 512*512 or 256*256 and change the 1024 in earth.ctx with 512 or 256 as it should

[selden]

Bob,

If you haven't already, you might take a look at the Web page http://www.lns.cornell.edu/~seb/celestia/textures.html#2.5. This link points to its section about virtual textures.

Is it too cryptic?
Does it need a better summary?
Is something left out?

Please make suggestions for improvements.

[Bob Hegwood]

Bob,

If you haven't already, you might take a look at the Web page http://www.lns.cornell.edu/~seb/celestia/textures.html#2.5. This link points to its section about virtual textures.

Selden,

To be honest with you, I didn't even know that the above resource was even available! I searched your excellent main resource page at http://www.lns.cornell.edu/~seb/celestia/ and searched for "virtual" and "vt" - but found nothing that led me to the page you've referenced above. Sorry about that, but I simply didn't know it was THERE!

It is an excellent description of the VT layout, but it's a bit over my head at this point. After I try Toti's advice (as seen in his prior message) I'm sure that your resource will make more sense. Toti gave me exactly was I was looking for... A description of how to use VT's for the brain-dead.

Thank you sir.

Take care, Bob

[Bob Hegwood]

Bob:
No, I meant that perhaps you can get around your card limitation using VTs. Hope this works.

That's *exactly* what I was looking for Toti. I'll experiment with it over the weekend.

Thanks *very* much for the description. Your explanation of the process is the first one I've seen that I could understand.

Take care, Bob

[SloJoe]

I’ve got VTs running pretty well on my system--except for an approx. one second pause for each new texture to load. They’re really great! As well as Walton Comer’s incredible 32K BlueMarble Earth Texture, I’ve downloaded every VT I could find: Jim’s close-ups of Florida and islands, and his MercuryVT, dbrady’s Mars, Mike’s Moon. Thanks everyone, these are Spectacular!

I’d like to create VT tiles for the area around where I live (California central coast). I’ve got a high-res JPEG photo of the area. I’ve downloaded GIMP. But I don’t know how to proceed from there. Are there any resources out there that can get me going?

Thanks a bunch!

SloJoe
Windows XP
Celestia 1.3.1-1
2.5GHz Pentium 4
GeForce4 MX 440 with AGP8x Graphics Card
1024x768 Resolution
512MB DDR SDRAM
80 GB 7200RPM HD

[don]

If you haven't already, you might take a look at the Web page http://www.lns.cornell.edu/~seb/celestia/textures.html#2.5. This link points to its section about virtual textures.

Hi Selden,

I haven't looked yet, but does the User's FAQ contain Bob's question? If not, maybe it should, since a few folks have wondered exactly what Virtual Textures are, as well as how to create / use them.

-Don G.

[selden]

Ah, but Don, creating VTs is not a usage question!

I'll try to come up with a concise Q/A for the FAQ.

[don]

Selden,

The subject of this topic is "How do I use VTs". In Bob's specific case, it is "How do I use VTs on a 'limited' graphics card?"

I'm sure you will come up with something very useful <smile>.

Thanks,

-Don G.

[Bob Hegwood]

In Bob's specific case, it is "How do I use VTs on a 'limited' graphics card?"

Actually, in my case it's "Do you suppose this bozo can figure out how to use VT's when he doesn't even *have* a graphics card?"

I'll let you know after the weekend.

Thanks, Bob

[Ptarmigan]

Actually, in my case it's "Do you suppose this bozo can figure out how to use VT's

Hehe ! Bob, if I had found this thread a bit earlier I would have suggested that you go look at Selden's excellent guide on the subject, it got this bozo kick-started fine-biz !!
However, I see that I am now redundant

A stiff shot of Scotch helps as well,,,,

Malcolm.

[Bob Hegwood]

Actually, Malcom...

I prefer "Jack Daniels."

I'll give this a shot though. It's just that I didn't KNOW about Selden's page prior to this thread.

Thanks for the encouragement. (Hick-Up!)

Take care, Bob

[Ptarmigan]

Actually, Malcom...I prefer "Jack Daniels."

ach, yer heathen mon ! Laphroaig is the one true nectar
but enough of this else I'll be sent to purgatory

I'll give this a shot

Or even a wee dram?

It's just that I didn't KNOW about Selden's page prior to this thread.

and it took me a wee while to catch up with this bit of VT thoughts as well,,,

but this VT thing what got implimented recently is the beesknees, quite facinating, has gone down well with my (noncelestia -yet- friends when seeing their houses etc ) and well worth scratching those few remaining hairs/braincells over !!!
fingers xxed that you can sort out a graphics card or whatever to support it, gud luk,
Malcolm

[Bob Hegwood]

Bob:
No, I meant that perhaps you can get around your card limitation using VTs.

Toti,

Tried to set up VT's on my machine, but got weird results. Here's what I did:


1. Created an alternate textures file "HiresEarth.ssc" in my extras directory which contains the following:

Code: Select all

AltSurface "HiresEarth" "Sol/Earth"

{
   Texture "earth.ctx"
}

2. Created "earth.ctx" file in my hires directory which contained:

Code: Select all

VirtualTexture

{
        ImageDirectory "earth"
        BaseSplit 0
        TileSize 512
        TileType "jpg"
}

3. Created earth directory in hires folder. In this directory, created level0 directory which contained two jpg images - one called "tx_0_0.jpg" and one called "tx_0_1.jpg"

4. Both of these images are 512 x 512 in resolution. The first one is a blue image, the second is a red image.

When I hit the number '3' and then 'g' to go to Earth, this is what I get:



Can you explain? If I right-click on the Earth, and select "HiresEarth" this is the image I get. If I right-click again, and select "normal" the normal view of Earth comes back.

I think I followed your directions accurately, and I downloaded and re-read Selden's reference page so I could look at it while I tried this experiment. Maybe my Intel graphics chip just can't handle the process?

Or, did I do something dumb again?

Thanks, Bob

[Ptarmigan]

3. Created earth directory in hires folder. In this directory, created level0 directory which contained two jpg images - one called "tx_0_0.jpg" and one called "tx_0_1.jpg"

4. Both of these images are 512 x 512 in resolution. The first one is a blue image, the second is a red image.

The second, red one, should be called tx_1_0.jpg, I think.

Malcolm.

[Bob Hegwood]

The second, red one, should be called tx_1_0.jpg, I think.

Okay, I'll give it a try...

Thanks Malcom.

Take care, Bob

[Bob Hegwood]

Malcom,

Yer a Genius, Son!

Now I have half a planet with Red, and half a planet in blue.

If I understand what Toti was trying to tell me, then I should be able to use the VT's. Obviously, I MISSED the location of the 1 in the texture name.

I'll play around with it some more but THANKS for the tip.

Take care, Bob

[Guest]

Hi Bob,
Glad to see that you're getting to grips with the vts, if not the dts, I've had a go creating the tiles, the main problem to me is the proliferation of files as the levels go up, ie 2000+ by level 5 in the blue marble. I've opened photos in my editing prog and laboriously cut them into tiles,just by selecting areas and copying them to new files, then created the directory structure like you've been doing; a close-up of Manhattan, worked well, it doesnt have to be a smooth transition through increasing resolutions, nor do the tiles need to be that small , you can have a jump in detail, so its like a postcard that pops up when you zoom into an area, its time consuming but satisfying to get a result at all.
Dr.Fridger wrote a script that automated the file slicing process, but I 'm apparently lacking in the skills or patience needed to get it to work, and gave up before I lost the rest of my hair....I'm hoping someone will come up with an even easier version. In the Orbiter program there is a facillity to organise tiles, ie positioning them and a converter to turn files into dds files (which load quicker), but it only seems to do one at a time, not batches...
So what would be nice, and has been requested before, is a simple fool proof utility or plug in, that you feed jpegs etc in at one end and get folders of tiles out of the other. Maybe it's there already? I'd love to have it.
Anyway, glad you're enjoying yourself,
regards
Ziggy

[Guest]

Bob-if you get a chance try a Dalwhinnie Single Malt, "the Gentle Spirit", I find that Jack Daniels is great on the night (well with Coke in it anyway) but gives a strangely depressed frame of mind the morning after. I live beside the River Spey, some say the home of the "water of life" so have tried a few.....
Ziggy *-)

[Ptarmigan]

Bob

Malcom, Yer a Genius, Son!

I try, I try

I'll play around with it some more

I think you are now fully qualified to move to level 1
In my case I can make tiles up to level 10, but I have failed miserably when it comes to displaying level 11. I think that means that genius ends at 10 and I have to become omnipotent to get to 11

Ziggy
The higher levels do not need to be fully populated with tiles. You can tile just the areas of special interest, so you can reduce the tile numbers that way, but I expect you knew that already, just checking.
PS. OT Dalwhinnie have a strange tendency to sometimes produce product with a slight nose of cabbages ! I kid you not !!
I am quite fond of Glenfiddich from Speyside, but I am sure their bottles are becoming less triangular.

Developers
All I need now is for someone to answer my BaseSplit 1 question in the Bugs department and then I'll be a happy bunny !

Malcolm.