replace the sun with "light source" node question

[TheBadger]

Hello,

I want to build a galaxy similar to this in appearance http://www.malindalo.com/wp-content/uploads/2013/02/space-the-sky-the-galaxy-stars-Favim.com-481975.jpg or http://wallchips.com/wp-content/uploads/2013/06/Galaxy-Stars-Wallpaper-Widescreen.jpg and use the galaxy as the light source in a scene. The galaxy would illuminate a night/dusk shot from the surface of a planet02.

I am aware of just using an image in various ways as a means to put a galaxy in the back ground. But thats not what Im playing with on this one.

The first problem as I begin is that I cannot move the TG sun with the control that I have with a light source node. And I can't put clouds around the sun.
So what I was thinking is that I could delete the default planet and
1) place my light source at the plants center coordinates.
2) find some way of making the LS node work like a sun node in terms of how it looks in a render.
3) Put clouds around the LS node/new sun
4) make it all as big as I can.
5)move my camera as far back as I need and put my planet02 in.

I figure the scale of the galaxy will obviously be tiny relative to reality. But as long as it looks big (fills the background from my vista) than with the right details it would look fine.
I was thinking of using some of the methods Hannes provided from his nebula share. Also putting in a population of stars as he did in his nebula.

Ultimately I would like to animate the galaxy so its rotating around its center and be visible from my planet.

My questions are basically, does anyone know if any part of my work plan will fail outright? I don't want to get half way and hit a wall.

Thanks for any guidance on this.

[Matt]

I can't think of any reasons why it won't work.

Here are some starting points for you.

0) Start with the default project. Keep the planet.
1) Copy the coordinates of the sunlight in the 3D Preview via the context menu.
2) Paste coordinates into the position of a Light Source.
3) To get the light source to match the intensity of the sunlight in the default project, enter the following values:
Strength: 5e+016
Max distance: 1e+016
4) Enable "glow in atmosphere"

You could also drag the colour from the sunlight to the light source, as the sunlight in the default project is slightly blue.

Bear in mind that the Light Source node has an inverse square falloff, so if you put stuff close to the light it will get very bright.

I'll leave the rest up to you

Matt

[Oshyan]

Maybe it's a silly question, but I have to wonder why you want to do this. You seem to want to avoid the simple option of using an image map of a real galaxy, for some reason, though this would give you the quickest and most likely easily controlled option. So one might assume that "realism" is your goal. The thing is that in real life a galaxy will pretty much never provide meaningful illumination. We are, after all, *inside* a galaxy at present, and you can see what that looks like on a nice, dark night. Not much illumination at all. Even a very long exposure at night, when there is no moon, will give you minimal resulting light. So the end result will either be a dark landscape, or an unrealistically lit one, and in the latter case why not just fake it anyway then?

- Oshyan

[Upon Infinity]

Maybe it's a silly question, but I have to wonder why you want to do this. You seem to want to avoid the simple option of using an image map of a real galaxy, for some reason, though this would give you the quickest and most likely easily controlled option.

- Oshyan

Oshyan's right on this one.  You can see my post here: http://www.planetside.co.uk/forums/index.php?topic=15004.msg146188#msg146188 for how to use an image map as a light source (with the object you designed, none the less  ).  Again, that's the "easy" way.  Although, I can't remember if it's a true *reflection* of the light in the image.  And I think I had to change the light colour to an average of what the image was.

[TheBadger]

@Matt
Thank you for the conformation. Im glad that you don't think its necessary to delete the default planet, thats one part that I was really not sure about, among others.

@Oshyan
Yeah for a still, it would be exceedingly easier to use an image. But even for that, 1) I would have to use someone else's image or spend a long time in PS making my own that would look the same in every render... or spend even more time making more backgrounds. And 2) most of the images that came up in my preliminary google search for reference sucked, mostly in terms of size and quality, but also content.
But I want to animate it anyway. And this is one part that I think I will be able to animate and build faster than in Maya, at least at my user level of the two softs.

On the question of realism Vs fantasy. I want to do a fantasy that looks real. And I want to do a number of images from the same build. So having the galaxy in 3D will make that much easier when plotting out shots as opposed to repainting the galaxy for each new shot. Also, the galaxy will hopefully be rotating, so a still wont work on that level... But really this is just my starting place, if I only get a few really nice still renders I'll be happy too.

For context, imagine the vast empty space between galaxies, from there a planetary body may(?) be able to sit in view of a far away light source. IF there is  also other light sources properly positioned, then perhaps the light being used will appear justifiable, and thus plausible, in a science fiction fantasy way. I figure for the most part, if TG will render it and the image looks good, than the lights are real enough. I am saying this with the understanding that light in TG is built to work in a real world way(?).
These have a little less on planet light then Im aiming for http://www.desktopwallpapers4.me/nature/mount-rainer-and-the-milky-way-19093/
http://www.desktopwallpapers4.me/nature/milky-way-over-the-delicate-arch-19092/ but I could use human(oid) structures to justify the presence of more light sources on the terrain.

@Upon Infinity
There are more than a few images in the sharing section that have galaxies that are, or are similar to the method you use. THey look great. I want to try and move it a bit further though, if I can.



Ill post my fails and see what you guys think are the issues. I have wanted to try something like this for a long time and have been collecting forum threads that relate. I want to try and pull it all together finally and see if it will work.
If I get the galaxies looking good then Ill worry about the terrain surface.

Found this in the forum search, worth a little repost.
http://vimeo.com/22439234

[Dune]

If you can live with just masses of tiny illuminated dots in 'space',  you could populate an illuminated sphere. It'll glow, but wont have atmo or shine upon atmo among them.

[TheBadger]

I will be sure to try that Ulco, thanks.

Here is another WP for inspiration. http://www.desktopwallpapers4.me/nature/northern-lights-19098/ These WP links I posted are not really what Iv set out to do, but if I get that kind of realism whatever the context, Im not going to be complaining about it. Anyway, the general idea of what I want is there.

some on topic forum image sharing links for any one else interested in this topic.
http://www.planetside.co.uk/forums/index.php/topic,7322.msg78054.html?PHPSESSID=fdcc073f924ae32981fa0b1f088ebecd#msg78054
http://www.planetside.co.uk/forums/index.php/topic,2026.msg19805.html#msg19805

Here is an example with a little of what U-I was talking about but in the contest of this tread http://www.planetside.co.uk/forums/index.php?topic=14290.0

[Oshyan]

Hmm. Well, it's clear you're going for fantasy at this point, and there's nothing wrong with that, so feel free to ignore the rest of my response...

That being said, for real-world imagery there is no better source than NASA (or another similar space agency). All NASA's data is completely free for use in any way you like.

Regarding animation, you would never, ever see that on any realistic human time scale, or any known living thing's time scale for that matter (e.g. trees that live 5000 years). It's fine if you want to make it spin or something, but it's not something anyone would ever see; it'd be a time lapse movie spanning millions of years, hehe.

As to the light, the further away you were, i.e. outside of the galaxies, in-between as you say, the *less* light from each galaxy's stars you would actually have shining on the planet. So you're actually getting less realistic with that idea vs. a situation more like here on planet Earth where at least we're within the galaxy relatively close to a lot of its stars. And as I say, even then the light reaching us is minimal, either for our eyes or our best modern photography equipment. Certainly there are pictures of the galaxy in the sky looking nice and clear, but that's quite a distance still from lighting the terrain up in any meaningful way.

Also interesting that all the examples you provided are indeed using the image map technique.

If animating really is important to you, you could still consider an image sequence approach.

- Oshyan

[TheBadger]

Also interesting that all the examples you provided are indeed using the image map technique

All? No. The last link yes, but the one that used clouds to form the spiral around the light source is clearly not a background image. But even that is not exactly what I am after.
But yes, not "real", Just looking real enough.

I couldn't find images to post of exactly what I am being motivated by. But there are many scenes in poular films that are similar in the look im going for; The new Star Trek films, a bit from the Riddick movies and a number of other films. And in terms of "real" there was a Discovery Channel or NatGeo program ("it'd be a time lapse movie spanning millions (billions) of years") narrated by alec baldwin (I think) about the entire universe. In that program the viewer saw the entire universe in about an hour or so. It looked real enough.

Also, in terms of reality, I believe in the existence of the soul/spirit. So space time it not the most important thing, always. Anyway, if I can make this look like I want too (with a little help probably) I think you will be glad to see it.

If animating really is important to you, you could still consider an image sequence approach

I will. I am considering everything so that if I do get stuck, I don't have to just give up on this one.
And Thank you for challenging me on it. It helps. And it makes doing the work a lot more fun too!

Edit*
Oh, and the Thor movies too. But I want the realism of the wallpaper links from above, as much as is possible.

[Oshyan]

To be clear I don't mean to discourage you *on principle*. Artistic vision isn't constrained by realism (though it can be a good guide for certain styles). Just trying to save you getting into another potentially really time-consuming project without maybe having thought it through completely yet. But I am definitely interested in seeing what you come up with.

- Oshyan

[TheBadger]

No worries. I get you.

[Upon Infinity]

I was having a bout of inspiration as I sit here at work...

You could use something similar to the post you made here: http://www.planetside.co.uk/forums/index.php/topic,2026.msg19805.html#msg19805

The real challenge after that comes from making the stars outside the galaxy glow (inside would be easy, as they have the cloud to glow around them).  Light source combined with localized atmosphere?

I might have to go and try something similar when I get the time.

[Goms]

Ah, now i see why you asked about my script for populating stars.

I dare say I'm getting there. My script now loads a bitmap and populates lightsources depending on the brightness of a pixel and colors the resulting stars in the color of the pixel.
you would probably have a hard time getting the combination of lightsource strength, distance, cloud density right in order to illuminate a terrain while not making the sky white, but it should be possible.
Though i've noticed that animating it is... tricky. if you want realistic movement, you will have to deal with a n-body problem (where n>2000) and therefore with some quite nasty differential equations....

[bigben]

Sounds like a hurricane model with the eye filled in...