Celestia Forums

Hey there...

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

Before you go hollering at me, the Name was Mr. Ball's idea...

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.

Howdy Bob,

NICE work!

Maybe now even *I* will be able to create VTs -- maybe -- we'll see.

Seriously, thank you for creating this guide Bob. I'm sure many folks will find it quite useful.

Cheers,

-Don G.

Very good!

2 small points:
In the pdf file, you put the link to this forum as http://www.celestiaproject.net/celestia/forum - it should just be http://www.celestiaproject.net/forum .

The downloads on your site don't have file sizes listed. It'd improve it a tiny bit more just to know what size the files are, for us poor unfortunates who still have dialup!

JackHiggins wrote:2 small points:

Jack,

Your suggestions have been implemented and thanks for the tips.

BTW, a cable modem is free with the service, and mine only costs about $40 per month. Hell, you'd spend that on an extra phone line.

I absolutely *love* downloading files at 350k per second.

Take care, Bob

Hi, friends!
I have read the pdf file and I have a couple of questions for you :
1) Suppose I find a beautiful photograph of (say) Rome, with Vatican City, Colosseum and so on . Perhaps indirectly, suppose I am able to compute the geographical coordinates of the 4 corners of the picture. Now, what would be the "name" of the corresponding file(s) to use in Celestia and at which level should I put them? Is there a formula to compute those values?
2) I like Windows very much (I use it since version "1.0" or whatever was its name ) but I do hate linux, unix and all the other "x" OSs (the reasons for this are hidden somewhere in my brain... perhaps due to bad jobs I had to do in my older than twenty years old experience in computer world ). So my question is: why do I have to install a lot of programs I'll never use for other purposes? Is there anywhere a pure Windows program (90% of computers in the world use this OS) to handle dds files in order to cut them into parts?
2 bis) Could someone convince me that linux is a good OS ? But why should we return to batch files or command lines, like the ancient DOS required ?
The fact is that I DO like Celestia and I would like to create something myself !!!
Thank a lot
Pierluigi

piellepi wrote:Perhaps indirectly, suppose I am able to compute the geographical coordinates of the 4 corners of the picture. Now, what would be the "name" of the corresponding file(s) to use in Celestia and at which level should I put them? Is there a formula to compute those values?

Pierluigi,

I'm in the same boat as you are at this point. I don't have any idea how the textures get arranged on a surface yet. That's next in my exploration of this topic.

However, I can tell you that the lower levels of the virtual texture must exist whether they contain any images or not. If your image exists on level9, for example, then the folders for levels 0 through 8 must also exist in the directory structure.

Shouldn't be too difficult to figure out where/what name a particular tile should use.

Selden? Are the tiles laid out in a standard grid across the planet's surface? Do they go from left to right, and top to bottom? Others have done this already, so maybe someone else here can enlighten us?

why do I have to install a lot of programs I'll never use for other purposes?

I haven't managed to find anything else which does the job that Dr. Schrempp's script does, and believe me - I have looked. If you'd rather cut up each image by hand? Also, if it's any consolation, Cygwin is *very* stable on my Windows XP system, and ImageMagick and NetPBM also offer you a wide range of other graphics-manipulation utilities.

Hope that helps a little bit.

Take care, Bob

Bob, et alii,

I've never actually created any high resolution VT images myself, although I have managed to place a small map at an arbitrary location. Doing it "my" way has problems (e.g. it covers up Location labels), but see http://www.lns.cornell.edu/~seb/celestia/map-plane.html

However, "Jim" Jens wrote a spreadsheet that's supposed to be able to calculate the latitude and longitude of particular tiles. It's available at http://ennui.shatters.net/~jim/files/VT-tile-calculator.zip

Level 0 - 2x 180 degree squares (ie halfway across and all the way up/down the earth)
Level 1 - 8x 90 degree squares
Level 2 - 32x 45 degree squares
Level 3 - 128x 22.5 degree squares
Level 4 - 512x 11.25 degree squares
Level 5 - 2048x 5.625 degree squares

and so on...

So if you've got an image, just crop it so that it matches, for example 5.625 degrees X number of tiles down & across, then put it in as a level 5 tile.

You can use the spreadsheet mentioned further up to make your calculations a bit easier.

Bob Hegwood wrote:Pierluigi,
I'm in the same boat as you are at this point. I don't have any idea how the textures get arranged on a surface yet. That's next in my exploration of this topic.

Bob, to add to what Jack has said,, and forgive me if I am misunderstanding your puzzlement, but Toti posted these pictures (I try to repeat them below) a short time ago showing how the tiles are arranged,
In his picture of level0 the top black line is North latitude 90, ie. the north pole and the bottom line is the South pole lat. -90, the left square is the western hemisphere, west of the central longitude 0, and the right square is err well the other hemisphere !
The vertical line on the left is longitude 180 and the vertical on the right represents the same longitude 180. ie 360deg following the turtles all the way round !
Does that make sense ?

To continue the saga, in the second, level1, picture the top line is the north pole as before, the center line represents the equator and the bottom line is still the south pole. In other words, each of the two tiles in the the top pic(level0) have been quatered to produce the 8 tiles at level1. So we now have 4 tiles in the wester hemi and 4 others in the eastern half.
In the level1 pic the vertical lines are, from left to right, longitude180, 270, 0-Greenwich meridian, +90, and on to 180
In level0:


In level1:

And so on...
[/quote]

Drat! The above Guest was me, Malcolm(akaPtarmigan),
I was loged in when I started the post !
but now i cant go back to edit it and add the Toti said : correct attribution to the to the code bit of the post

Where Toti has said "and so on" he means that at level2 there will be 24 more tiles making 32 in total.
They will be arranged as 4 rows with 8 columns, and the upper left tile will be another _0_0 tile. (( _0_0 is always the first (top-left) tile in all the levels.)) in other words 4 quadrants _each_ containing a grid pattern like that shown in the (previous)level1 pic.

Malcolm

Thanks Jack, thanks Malcolm...

I'm getting there.

I downloaded the spreadsheet as suggested, and it does make life a lot easier. When I fully understand what I'm doing here, I'll add some more to the Dummies document.

Thanks again for all of the help.

Take care, Bob

Bob Hegwood wrote:thanks Malcom...

A minor point for everyone - I see that someone else has recently registered as Malcom, but I am Malcolm (a Scottish name of some ancestry with which I'll not bother y'all ! But ) ,, the missing "L" is important!

Bob Hegwood wrote:I'm getting there.

I'm beginning to get vibes from that brick wall (again)! I suggest a mud hut ? !

I downloaded the spreadsheet as suggested, and it does make life a lot easier.

I wouldnt know, I cant run xls on my little freewares !
get down to basics first, forget the dongles, they come later. Study what Toti said previously.

Malcolm.

Ptarmigan wrote:A minor point for everyone - I see that someone else has recently registered as Malcom, but I am Malcolm (a Scottish name of some ancestry with which I'll not bother y'all ! But ) ,, the missing "L" is important!

Oops... Sorry Mr. Ptarmigan. Note that the previous message has been repaired.

Just remember to call me "Brain-Dead," and we'll be even.

Bob Hegwood wrote:I downloaded the spreadsheet as suggested, and it does make life a lot easier.

I wouldnt know, I cant run xls on my little freewares!

Ah, but you can son... Just search for the "OpenOffice.org" website, and download yourself a whole passel of freeware for the office. Includes spreadsheets, Word-Processors, etc. From Sun Microsystems, I believe.

Take care, Bob

Bob Hegwood wrote:

Ptarmigan wrote:the missing "L" is important!

Oops... Sorry Mr. Ptarmigan. Note that the previous message has been repaired.

hehee thanks, just didnt want owt that malcom said to be attributed to me, Malcolm By the pricking of my thumbs something (interesting) this way way comes, apol Bill/Macbeth

Just remember to call me "Brain-Dead," and we'll be even.

can I be brain-deadalus ? pse

But seriously folks :-

Bob Hegwood wrote:OpenOffice

Yeah, I know, tried that time to time over the years (it is _huge_) and things like AbiWord and so on, but like Cygwin, do we really really nead these mega sophisticated thingies to cure a little local difficulty ?
Know what I mean ??

have fun, that's the commandment

btw, how you getting on with the little pictures from Toti ? Hint : think of them a bit like Mercator ( dont take the analogy too far) atlas projections ,,
Malcolm

Ptarmigan wrote:do we really really nead these mega sophisticated thingies to cure a little local difficulty ?
Know what I mean ??

All I know is that I use the spreadsheets for all kinds of interesting problems. This is only one use for the thing. I also use it for creating SSC's from TLE's (Thanks to Mr. Hutchison!) and a whole bunch of other neat Celestia-related gizmos are also available if you look around a little bit.

Ptarmigan wrote:btw, how you getting on with the little pictures from Toti ? Hint : think of them a bit like Mercator ( dont take the analogy too far) atlas projections

Oh, hell... I'm way beyond that point now. All I really needed was Jack's explanation to get at what I was trying to understand.

I'll be adding to the Dummies package as soon as I get some time. Been trying to figure out Lua all day. Now you'll see some head-banging. Sheesh!

Take care, Bob

Bob Hegwood wrote:

Ptarmigan wrote:btw, how you getting on with the little pictures from Toti ? Hint : think of them a bit like Mercator ( dont take the analogy too far) atlas projections

Oh, hell... I'm way beyond that point now. All I really needed was Jack's explanation to get at what I was trying to understand.

You said :

I'm in the same boat as you are at this point. I don't have any idea how the textures get arranged on a surface yet. That's next in my exploration of this topic.

Sorry, we tried, we cant all be up to the second or even minute in our attempts to help, with or without changes of server !
I'll try to keep my bugle better polished in the future so that we can muster the cavalry a bit quicker next time

Malcolm.

Bob Hegwood wrote:I haven't managed to find anything else which does the job that Dr. Schrempp's script does, and believe me - I have looked.

Doesn't my GIMP script work in your computer? If so, please give some feedback. I used it very intensively with excellent results.

Bye

Malcolm and Toti,

You guys are referencing a message I wrote while I was in the process of trying to understand the tile layouts.

After Jack posted his message, I was all set. That's all I really wanted to know.

Toti... What I was referring to (in terms of Dr. Schrempp's script) was a Windows-based program that could split images into tiles. I came close, but I still haven't found anything which is as easy to use in order to create the level tiles.

I haven't gotten your script to work yet, but that's only because I don't know BEANS about Gimp scripts either. I'll be getting to it, just as soon as I get finished with about 400 other things I'm trying to do too.

Malcolm...

I'm in the same boat as you are at this point. I don't have any idea how the textures get arranged on a surface yet. That's next in my exploration of this topic.

Again, I just wanted to know what the layout was. Jack's description made sense to me. I wasn't trying to be a smart-ass. I wrote the above BEFORE Jack posted his message. AFTER I read his message, it all made sense. Do you know what I mean? Again, I wasn't trying to be a smart-ass.

You guys have bent over backwards to help me understand these things and I *do* appreciate it. Please forgive me if it sounded like I wasn't grateful for the advice. I certainly didn't mean for it to sound that way.

At any rate, I'm worn out now. I think I need a break.

Take care, and thanks again. -Bob

Toti wrote:Doesn't my GIMP script work in your computer? If so, please give some feedback. I used it very intensively with excellent results.

Toti,

Installed the Gimp script and got it to work just fine after I figured out what you wanted in the output directory field.
Was getting errors, but that was because I really didn't understand how to define the output directory. Once I re-read your instructions, it worked perfectly.
Would you mind if I put the instructions and the script into a package that can be downloaded from my website? That way, others will have access to it.

Take care, Bob

Bob Hegwood wrote:Installed the Gimp script and got it to work just fine after I figured out what you wanted in the output directory field.

I am happy that it worked

Yes, there is no internal support for directory fields in the GIMP script module, so I had to fake it. The counterpart is that the user must know how to enter the values on this field. I will try to add some -very basic- error handling.
And please, go ahead with your "script with instructions into a package" idea. It will be a good complement to the available tools and info.

Bye