Digital Universe

[John Van Vliet]

hi has aneyone geven this program a try
from an artical at linux.com
http://community.linux.com/community/06 ... d=1&tid=13
and
http://haydenplanetarium.org/universe/
to me the screenshots don't look all that impressive

[selden]

John,

Quite a few planetarium educational programs use both Partiview and Celestia for their presentations. Their features tend to be complementary: where one is strong, the other is weak, and vice-versa.

The Addons to Partiview provided by Hayden's Digital Universe are not quite as oriented toward "eye candy" as Celestia's Addons are.

Partiview is a more general purpose 3D visualization tool than Celestia is. It is not optimized for astronomical usage and does not have the various orbital and orientation controls, for example.

Some of its features that Celesita does not have (yet?) include control of the amplitude of the HDRI effect, selection and deselection of the various Addon objects and their components, direct access to OpenGL functions and a text command input console. There are quite a few others.

Partiview's user community tends to be more scientific and is not as vocal as Celestia's. Nonetheless, there are several web sites in addition to the Hayden which provide Addons for Partiview. One of the more active contributors is Dinoj Surendran at http://people.cs.uchicago.edu/~dinoj/index.html

[John Van Vliet]

just wondering -- something to do on this long weekend

[Cham]

I WANT THIS IN CELESTIA ! I WANT THIS IN CELESTIA ! I WANT THIS IN CELESTIA ! HURRY ! DO SOMETHING !!


http://astro.uchicago.edu/cosmus/projec ... icago.mpeg

From this web page :

http://astro.uchicago.edu/cosmus/projects/aires/

AAAAaarrrrgggghhhh !

[selden]

Yup. Partiview is very good at showing cosmic ray airshower development.

Right now that can be done in Celestia with "pageflipping" i.e. with many pages of SSCs containing Beginning and Ending directives plus a separate CMOD model of the appropriate portion of each particle's trajectory.

It should be possible using Lua OpenGL line drawing when that gets implemented. Lua already should be capable of doing the monte-carlo calculations to simulate a shower's development, although it might be a little slow.

[Cham]

I may try to built a CMOD model of a static shower, but I need tons of data and I really don't know how to manage that into a proper CMOD file. And we need some animated lines. This video is just awesome. I've installed the Digital Universe software on my Mac, and the galactic distribution is simply AWESOME ! Celestia feels so lame, in comparison !

[selden]

You don't have to generate the data. Write to Dinoj. I'm sure he'll be glad to send you a dataset.

[Cham]

What about showing letters from a CMOD file, in Celestia ? Currently, I don't think it's possible to show any font as 3D "markers". I think this should be a usefull (even a necessity) feature in Celestia.

We need those features :

1- show any letters-words-sentences at some user defined location in space, from a CMOD file.
2- show any letters-words-sentences as markers.

I already asked for some circles as markers (now in 1.5.0), but I think we need much more : full letters and words sets, as markers in 3D space, and the same from CMOD files.

[selden]

What about showing letters from a CMOD file, in Celestia ? Currently, I don't think it's possible to show any font as 3D "markers". I think this should be a usefull (even a necessity) feature in Celestia.

We need those features :

1- show any letters-words-sentences at some user defined location in space, from a CMOD file.

This can be done by generating the shapes of the letters as a model using a 3D modelling program. I doubt very much that any CMOD letter objects will ever be predefined: that's a lot of work to duplicate already-available functionality.

2- show any letters-words-sentences as markers.

This already can be done. It's called a "Location". A Location can be placed anywhere with respect to any SSC object by using a LongLat specification. Or you can define an object (with an appropriate name and position) and turn on its class of label in the Render/View Options menu. (Object labels are positioned with higher precision than Location labels.)

[Cham]

Selden,

this is very limited.

What I'm describing are letters (and words) floating in free space, as special data. We also need more classes (after the usual stars, planets, moons, spacecraft, comets, asteroids). We need custom classes, with a keyboard switch. Currently, there are many things I can't do in Celestia because of the very limited set of classes available.

Personally, I think much more important features should be added to 1.5.0 before adding SPICE support, etc. Grids are also needed desperately, with a keyboard key shortcut (CMOD objects associated to some custom classes...).

[selden]

Those are things that the Lua Edu package should be able to do. I haven't tried to use it yet, so I don't know if they've already been implemented. If they haven't, they will be soon.

[Cham]

To me, the Lua feature is just a contorsion to the basic things. Custom classes ARE basic, and more important (to me) than the Spice support, Lua support, and other stuff like this.

[selden]

Lua provides the ability to program extensions to Celestia immediately, without waiting for someone else who may have priorities that are different from yours.

Refusing to use it for emotional reasons may not be appropriate in the long run.

[Cham]

Lua provides the ability to program extensions to Celestia

That's exactly the problem. We'll have to "program" codes in the Lua language just to add some custom classes. This feels very unatural, and is in opposition of Celestia's current way. And after that, this will prevent (most probably) the developpers to add the natural features, just "because it's already there, with Lua". I just don't like the idea. In the long run, I think this will be an obstacle to Celestia evolution.

[Chuft-Captain]

Lua provides the ability to program extensions to Celestia

That's exactly the problem. We'll have to "program" codes in the Lua language just to add some custom classes. This feels very unatural, and is in opposition of Celestia's current way. And after that, this will prevent (most probably) the developpers to add the natural features, just "because it's already there, with Lua". I just don't like the idea. In the long run, I think this will be an obstacle to Celestia evolution.

Cham,
I think you are worrying about a problem that does not exist. Being able to program extensions is a GOOD thing. It enhances, but does not impact directly on the separate development of the C++ code. Celestia's "current way" can (and will, I'm sure) continue as before.

LUA will however make Celestia even more open-source than before, as any sufficiently skilled user will be able to extend the capabilities of their version of Celestia, and then share it immediately with others, in the same fashion as addons are currently shared.
This IMO is definitely not in opposition to Celestia's current way; to the contrary, it's exactly in line with the open-source principles which have contributed to Celestia's success thus far.
IMO, this will actually accelerate the development of Celestia, as it will be able to benefit from a much wider pool of programming talent outside the development team, people who may be willing to write a LUA extension to add a piece of functionality on their, yours, or Daniel's wishlist.
These will become available immediately they are published, and you won't even have to wait for the next release.
For example, as Selden mentions above, we are already benefiting from the LUA-EDU tools from Vincent/Hank etc.

I'm not a LUA expert, but from the little I do know, I believe that LUA is sufficiently similar to C++, that it would not be too difficult for the developers to convert and optimise the best, or most useful, of any future LUA extensions into C++ and incorporate the functionality into the standard distribution. The possible lifecycle of a LUA extension might be:

1. LUA extension created and published (anyone can use)
2. The development team establishes an official LUA library. The best of the published extensions (in 1.) may be periodically reviewed by the development team to evaluate quality, performance, and compatibility with core code and other already approved LUA library functions.
If passed, then they may be included in this LUA library of approved extensions.
3. The best of these, may be converted into C++, so they become part of the next official build.

Note that steps 2 and 3 are entirely at the discretion of the development team, so normal Celestia C++ development can continue independently.

In the long run, I believe this will be good for Celestia development, as it is revitalized by a wider pool of inspiration and talent.

Regards
CC

[DonAVP]

I WANT THIS IN CELESTIA ! I WANT THIS IN CELESTIA ! I WANT THIS IN CELESTIA ! HURRY ! DO SOMETHING !!


http://astro.uchicago.edu/cosmus/projec ... icago.mpeg

From this web page :

http://astro.uchicago.edu/cosmus/projects/aires/

AAAAaarrrrgggghhhh !

I know this is not directly related but I would like to see this type of Add-on
http://www.shatters.net/forum/viewtopic.php?t=10402
Thats right a meteor shower. I would be willing to create any of the 3D elements w/32 bit images of a shooting star effect. I am not a programer type but do have animation, 3D modeling and texturing skills. How about it Cham or anyone want to figure out how to do this?

Don

[chris]

Selden,

this is very limited.

What I'm describing are letters (and words) floating in free space, as special data. We also need more classes (after the usual stars, planets, moons, spacecraft, comets, asteroids). We need custom classes, with a keyboard switch. Currently, there are many things I can't do in Celestia because of the very limited set of classes available.

You'd like to be able to define custom groups of objects that could all be toggled on and off at once? Describe what you want in more detail.

Personally, I think much more important features should be added to 1.5.0 before adding SPICE support, etc. Grids are also needed desperately, with a keyboard key shortcut (CMOD objects associated to some custom classes...).

I think that SPICE support is extremely important. I'm interested in seeing Celestia adopted within the national and international space agencies, and SPICE support, reference frames, and flexible trajectory and rotation models are all essential features. I've had many requests for these things, and I happen to think that they fit better into Celestia than the particle cascade visualization. As neat as that animation is, why would it be integrated into Celestia than as a standalone application? Does it really gain anything by being part of a universe model?

There are features in Partiview that I would like to have in Celestia, but I only want to add features just because they're in Partiview. They need fit with the overall purpose of Celestia as a space visualization tool. Grids would be useful; better markers would be useful; and animated models would also be a worthwhile addition, but I guess I don't feel that it's quite as urgent as you do . . . I'd nevertheless be interested in seeing what the data file for that cosmic ray cascade looks like.

--Chris

[Cham]

You'd like to be able to define custom groups of objects that could all be toggled on and off at once? Describe what you want in more detail.

Yes, that's it. As an example, lets define an ecliptic grid object in some TEXT file, the same way as for any other SSC or DSC object :

Code: Select all

"Ecliptic Grid" "Sol/Earth"
{
       Class "custom1"
       Mesh "ecliptic_grid.cmod"
       ....
}


Since we could be interested to use independently several grids, we should have at least three new custom classes ("custom1", "custom2", "custom3", ...), that could be completely turned ON and OFF using their associated keyboard shortcuts (or some menu items).

The point is, we don't have any easy way to help the user orient himself in space (except the celestial grid, which is always at infinity). Those grids could also be usefull to help the addon creators to place their models.

The only problem I can see with my suggestion is the ability to show the grid up to infinity, if the custom class object is defined in an SSC file (SSC objects are only visible under a LY range or so). Most probably, the new custom classes should be defined in a new file type (with a new file extension, designed for the custom classes).

[t00fri]

....
I think that SPICE support is extremely important. I'm interested in seeing Celestia adopted within the national and international space agencies, and SPICE support, reference frames, and flexible trajectory and rotation models are all essential features. I've had many requests for these things, and I happen to think that they fit better into Celestia than the particle cascade visualization. As neat as that animation is, why would it be integrated into Celestia than as a standalone application? Does it really gain anything by being part of a universe model?

...
--Chris

Chris,

one the one hand, I can very well see some of your driving motives that may justify this high amount of specialized activity towards "SPICE + frames" stuff, with particular emphasis on what space agencies are interested in...

As you may have noted, I have kept quiet since a while as to my personal opinions and preferences. But since you phrase things explicitly now, let me make some respective comments, nevertheless.

i) I think I was among the first in our community emphasizing again and again that my view about Celestia's purpose would be to make it a general visualization framework of scientific standards, rather than a specialized tool for e.g. education, world creators or gamers etc.

Hence a priori, an implementation of a SPICE interface had my full sympathies.

ii) However, as a theoretical physicist with much expertise in Astroparticle Physics, Cosmology and General Relativity (besides Astromechanics and all that, of course), I am increasingly sad to see where Celestia seems to be moving to, recently.

+++++++++++++++++++++++
From my perspective, there would be many other exciting areas related to a scientific visualization of the Universe, where Celestia could make a unique and conceptually pioneering contribution!
+++++++++++++++++++++++

As a physicist, I find this recent specialized work on custom spacecraft trajectories, rotating (spacecraft) frames etc largely "uninspiring", to say the least. From a physics point of view, these things are crystal clear to me and do not represent the slightest conceptual challenge (besides the considerable, respective coding efforts, of course!). On the other hand, I also can hardly see many people exploit these new degrees of freedom EXCEPT personel employed by space agencies...

I see much of these recent efforts as specialized yet FREE service work for space agencies, who always welcome oportunities to save money . We all have to get along professionally with limited budgets...

iii) Except for Selden as a loyal follower of your efforts, I can also see little enthusiasm & resonance in the rest of our community (including all other devs) for these new implementations, notably given the high price of a much complexified syntax etc.

Since you normally do things first before asking around, I thought I had to express my views at that advanced state of affairs at least once. I am also confident that you will not be upset by my honest attempts of expressing some respective criticism.

After all, Celestia is "your baby" and you are free to drive it wherever you please...

Cheers,
Fridger

[ElChristou]

...
+++++++++++++++++++++++
From my perspective, there would be many other exciting areas related to a scientific visualization of the Universe, where Celestia could make a unique and conceptually pioneering contribution!
+++++++++++++++++++++++
...

Have you already developed those ideas in the forum or have you new concepts in mind?

... iii) Except for Selden as a loyal follower of your efforts, I can also see little enthusiasm & resonance in the rest of our community (including all other devs) for these new implementations, notably given the high price of a much complexified syntax etc...

I tend to agree about free work for spacial agency, but those "tools" (Spice, refFrame) are quite interesting to present models to the public in much more appropriate attitude; as all this stuff is new and still in dev, I suppose people are waiting to see a finalized version and begin to work with this new syntax... In all case about this special point (complexity of syntax), if I recall Chris asked for your opinion and ideas on the topic... have you miss this post?
After all, once this part will be completed we will be able to go for new horizons or not?
Perso Wavelenghts are one of the feature I'm still waiting for...