Realistic underwater lighting and caustics - added tutorial link

Artwork Focused Critiques
1

Edit again:

I now created an “Underwater volumetric lighting and caustic effect” tutorial , which is available here. Go to “Tuts and tricks”.

Edit:

I updated the animation: both the caustics and volumetric lighting effect, and I also included my previous whale shark into the scene for more realism.

I started playing around with particles to add zillions of small reflective particles in the water, but it just made the rendering too slow for my current purposes. Plus I would have had to motion blurred them to get the movement realistic… and you can imagine how slow that made the rendering!

Anyway, I am more looking for crit on the VOLUMETRIC LIGHTING and the CAUSTIC EFFECTS. I am in the process of writing up a tutorial for those who may be interested.


Original post:

I originally submitted a posting under Blender Tests re this experiment in creating realistic underwater lighting and caustics in Blender.

However, I am now at the point where I would like critique on its realism.

To recap: when I did my whale shark animation a while back, I was frustrated by the fact that one cannot use lights to display the light rays that one sees underwater. (The whale shark link shows the kinds of problems one runs into).

Enrico Valenza’s Bongo tutorial shows how one can emulate the light rays using tubes or cones with special material attributes.

I could not accept Blender’s lighting limitations, so I went about trying to figure out how to work around it. I think I found a way to do it.

I did the scenes below with three “straight forward” lights (and a few tricks) and no compositing or post-processing, nor material nodes. The light rays and caustics move around throughout the animation.

The caustics on the sea bed are combination of 5 procedural textures.

Below are 2 stills from my 4MB animation. (The object in the scene is not meant to be anything - especially not a fish! - but more to see what the light does on it. I’ll next tackle a realistic fish - maybe I’ll just add the whale shark again…)

C&C are welcome.

AnyMation

Ocean200019.jpg720×576 42.2 KB

Ocean200058.jpg720×576 41.1 KB

2

A good start and generally effective. Some observations:

  1. The blue of the water looks too saturated, though not by a lot. This might be remedied by fixing 2)

  2. The water’s too clean. For the light to form the visible rays shown there’d have to be considerable particulate matter in it, enough to be more apparent than shown in the animation. This will also produce more “aqueous perspective,” similar to aerial perspective in that it causes changes to hue, saturation and detail level with distance.

  3. The rates at which the sea-bed caustics and the rays change don’t match well (rays seem to be moving faster), and they should. They both have the same cause, light passing through the restless water surface, and thus should change at much the same rate.

  4. At the view angle shown, I don’t think the rays would converge as much as shown. The impression I get is that they originate from a point source fairly near the water surface. The sun’s rays being essentially parallel, they wouldn’t converge much unless looking more toward or away from the sun, and then perspective effects would cause convergence.

3

anymation,
it looks realistic!! gr8 work!!a tutorial explaining the setup and the workflow to reach the end result could help us a lot!
chela69

4

a tutorial could help noobs like me

5

Here’s two video clips of real underwater lighting:
http://www.fotosearch.com/ATB713/vsh121/
http://www.fotosearch.com/ATB717/vus108/

6

Thanks for the feedback, comments and links, guys.

chipmasque: I appreciate the detailed feedback, but what I should have said was that I was more looking feedback on the light rays and caustics specifically (as I have not seen anything similar [animation-wise] in Blender previously), which you did give me in your points 3 and 4. I appreciate the other two points, although that was not my aim for now. BTW, when you say “the blue of the water looks too saturated”, I am not 100% sure what you mean: is it the background, the “surface” of the water, the general colour of the scene … can you be more specific? Also, I did not give too much attention to the colour of the sea bed, but that can obviously vary from place to place.

I also found that, when I play the animation via VLC, the blue tends to be darker than through QuickTime.

The animation is now updated based on feedback. It is also smaller (1.8 MB) due to the XVid codec I used.

A frame from the animation:

Ocean24_NoPart0030.jpg720×576 45.7 KB

7

Yeah, the far BG blue is what looks too saturated to me. As far as the extent of my comments, the section is “Focused Critique” and you asked for comments about the realism of the scene. That includes more than the rays & caustics.

The new image/anim’n look somewhat better in terms of matching the rate of change. I think you may have misinterpreted my comment about the rays, though. I had no problem with them slanting, it’s the noticeable convergence that seemed artificial. The vertical rays in the new sequence aren’t nearly as interesting compositionally as parallel rays at an angle similar to that of the first images.

8

I updated the animation again with updated volumetric lights (see first post for link). This time it also includes the whale shark I modeled a while ago.

9

The lighting is very realistic! And the shark is great too.
Some crits that come to mind.
The spots and stripes of the whale shark should look a bit more random, not much just a little bit
And about the animation.
The shark’s animation looks great. The only thing I didn’t like is that it moves forward in the same speed at all times. The speed should change depending on the shark’s movement. ie When the shark’s tale is at maximum left or right then it should move a bit slower, while it should accelerate when it’s tale riches to the center since there is more thrust at that time.

Keep up the good work :slight_smile:

10

Good observation there, agtGreg.

I was wondering about the movement too, but I think - and looking at some videos - that the shark’s mass is so HUGE that its momentum keeps it at a relatively constant speed.

11

That is sweet, i like the whale shark, and cool lighting!

12

chela69: I created an “underwater volumetric light and caustic effect” tutorial, which you can find here. Go to “Tuts and tricks”.

13

Wow, that was a very good set of tutorials.

It’s funny, even with the computers today, I find people still using lighting techniques I have used in the theater for years. You made a very nice rotating gobo setup here.

I will be trying this with my underwater pipe organ!

Any chance you know how to get rid of the “banding” effect from halo lamps? I have run into this issue on my latest project:http://blenderartists.org/forum/showthread.php?t=121296

Thanks for the tutorial, time well spent :slight_smile:

–
Kevin

14

KevinW:

What I think you are talking about in your image is nearly not perceivable. But, I would guess it to be one of two things:

  • Try setting the halo step to a small value: 1 or 2
  • It may be due to image compression, which is determined by the image type (jpg) and quality (e.g. 90% - I don’t know what value you are using.) Try rendering it in a raw format or higher quality.I hope it helps.
15

AnyMation, Thanks.

Yeah, I got all my settings right so I guess I will just blur it out in post as this is only a still image.

Thanks for your help (and great tutorials). It’s cool when you can “see the beams!”

–
Kevin

16

Pleasure. I really struggled with the beams, but in the end, it was actually a simple solution.