New sprites based nebulae

[Fenerit]

Eta Carine is on the path?

[Cham]

Aaarrgh ! So close, and yet so far away !

etaCar.jpg

web.jpg

[Cham]

Some progress :

etacar2.jpg

Need more work on that model family.

[Cham]

This morning, I had an interesting idea and the effect is very good ! Two fluffy rings superposed, rotating with a small difference in their rotation period. One of the ring has the "blend add" option in its CMOD definition while the other doesn't. The net effect is a very convincing "hot" accretion disk (the picture below doesn't do justice to the live effect) :

rings.jpg

Same ring around a pulsar. Isn't she beautifull with her clothes ?

ringy.jpg

[MiR]

Yes, the models are highly mathematical in origin. While a user wihout any knowledge on maths could in principle use the Mathematica file, by just changing the 20 parameters in the code's header and test the models in Celestia, it wont be very practical without knowing what he's doing with the parameters !

These models cannot be done without maths knowledge, unfortunately.

That's what I thought as much. Although I am interested - and rudimentary educated - in mathematical formulas and concepts ... but that was long ago. And Mathematica - I've taken a look on it - is really very complex.
So, thank you Martin for your reply.

Few years ago I made an experiment to warm an exoplanet with sprites. It is always a prototype, but you can take a look.
http://shatters.net/forum/viewtopic.php?f=6&t=12921

Oh, thanks Massimo for the link (and the files). I didn't seen this site before... and I like it. A little too bad that it has stopped...

Michael

[Cham]

Woa ! Now, this is a shooting star !

pulsar.jpg

[Cham]

Still working on the lobes nebula. I'm really not satisfied with it yet.

lobes.jpg

lobes1.jpg

lobes2.jpg

[Fenerit]

They looks fine, tough.

[Cham]

Some pictures of real planetary nebulae which are an inspiration for my two-lobes models :

hub5hstl.jpg

ngc-6302.jpg

PIA09194.jpg

I may put a similar nebula around Betelgeuse, which apparently has a nebula forming around it :

http://www.sciencedaily.com/releases/20 ... 085844.htm

Some interesting pages on planetary nebulae, as references...

http://www.biochem.szote.u-szeged.hu/as ... ebula1.htm

http://www.noao.edu/image_gallery/plane ... bulae.html

[Cham]

I've found several nice sets of parameters :

lobes.jpg

More to come ...

[Cham]

Here are 12 variations on the lobes nebula. Please, tell me which you prefer. Any crittics, comments, opinion, etc ?
I need comments to improve the models.

Preview :

12lobes.jpg

Pack of 12 nebulae to test :
http://fsgregs.startlogic.com/Public_Fi ... ebulae.zip (905 KB)

[MiR]

I think your technique has the advantage that the colors can be changed in your add-ons.

Therefore it would be important to me to make the color adjustments adequately to a chemical composition of the different nebulae.
Because the representation (harmonizing with the performance of galaxies in Celestia) is almost perfect, in my view.

M.

[t00fri]

Here are some comments about rendering planetary nebulae (PN) from my point of view. For Celestia.Sci, I did already quite a bit of preparatory work about rendering issues of PN. There is also a rich literature about the subject.

Firstly, one needs to know about the morphology of PN that will allow a systematical classification, in analogy to the Hubble classes for galaxies. It actually turns out that all known PN can be satisfactorily represented by ONE 3d shape (with 2 lobes) that exhibits an axial symmetry! When looked at under different angles, the well-known and very different PN patterns appear in skyplane projection!

For a detailed discussion of these basic aspects, see e.g. this scientific paper
http://www.mpi-inf.mpg.de/~magnor/publi ... tvcg05.pdf

Here are some crucial quotes from that paper:

Most PN exhibit a symmetry axis. This axisymmetry
reduces the 3D volumetric reconstruction problem to a
2D emission density function in cylindrical coordinates

The universal 3d model for PN looks qualitatively like this

pn-model.jpg

++++++++++++++++++++++++
In this post, I just wanted to emphasize that for a transparent, systematic and economic approach to the rendering of PN, symmetry considerations and the generic morphology class is crucial. The latter is supported from physics considerations (see paper)
++++++++++++++++++++++++

I am coding all this in C++ to fit into Celestia's DSO class scheme. Moreover, I am using internal sprites and Perlin noise functions that are long employed to render the irregular galaxies in Celestia. Here is a colored example (DDO64) in Celestia.Sci in comparison to SDSS imaging (right)

DDO64.jpg

Fridger

[Cham]

Fridger, we don't see much in your example above. Can you make the pictures larger ?
And apparently, your example is just a galaxy, not a planetary nebula, according the the left corner info.

Also, what about more colorised examples (M57, Eta Car, etc) ? Can you give some examples of your rendering in these cases ?

[t00fri]

Fridger, we don't see much in your example above. Can you make the pictures larger ?
And apparently, your example is just a galaxy, not a planetary nebula, according the the left corner info.

Also, what about more colorised examples (M57, Eta Car, etc) ? Can you give some examples of your rendering in these cases ?

I included the DDO64 irregular galaxy example merely as a reminder that Perlin noise is a familiar tool in Celestia .

As I indicated above, only the logistics for implementing PN is completed, not the rendering code. However, the latter is no big deal, once the PN axis symmetry and the single model approach are accepted. A problem that I am still contemplating about is how to deduce the orientation angles of the universal 3D (2-lobe) model from scientific PN catalogs (that refer of course to the 2D skyplane)!?

If I have something to display, it will be over at CelestialMatters. As usual, I'll make a notice here.

Fridger

[Cham]

Well then Fridger. However, since your way is VERY far away from a completed state and available, my approach still has its value.

[t00fri]

Well then Fridger. However, since your way is VERY far away from a completed state and available, my approach still has its value.

Sure, your approach is certainly useful and the results look quite pleasing. Yet for my taste the approach so far lacks some systematics and also has no better clue about model orientation parameters in 3D space. As I noted, the rendering part is now largely routine within the mentioned framework and thanks to the existing scientific papers. Last not least, my OGL coding abilities have strongly improved after recoding a lot of OGL stuff for Celestia.Sci from scratch.

Unfortunately, Celestia development has come to an effective halt, despite ChrisL's recent assertions.

The existence of Cosmographia doesn't mean the end of Celestia, nor does it mean the end of my own participation in Celestia development.

Hence some of us, don't feel too much motivated to continue thinking and working in terms of Celestia...or to wait a long time without receiving substantial feedback from Chris.

Fridger

[t00fri]

Cham,

back to to Perlin noise for a moment:

here is a larger screenshot of the irregular SMC in Celestia.Sci.
Click

smc.jpg

A great feature of the Perlin noise function is that one may control the "granularity" and other features very easily by varying just a couple of parameters. That is certainly handy for rendering PN as well.

Fridger

[Cham]

A great feature of the Perlin noise function is that one may control the "granularity" and other features very easily by varying just a couple of parameters. That is certainly handy for rendering PN as well.

It's interesting. I'll check if the Perlin noise is included in Mathematica. However, I can control and adjust the granulity too with the Beta distributions in my models, by adjusting several parameters (actually, the parameter space of my model is very large, and the results are hard to expect since there are so many possibilities).

[t00fri]

There are many links to Perlin Noise in the net and as it seems Mathematica has it, too.
For Maple one gets it via Mathlab that works in conjunction with Maple.

If you switch to images in Google you'll get a great variety of 2d Perlin noise imaging

Fridger