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I made a shabby test to see how sun radius affected pool caustics. You can also see how it affects to shadow dispersion. Maybe somebody finds the results useful.

I let the images run 30mins and all reached around SL17-17.05

Water is displaced.

Sun radius = 1 (default)




Sun radius = 6




Sun radius = 12




Sun radius = 25




Sun radius = 50




Sun radius = 100

This is like life. Good things take longer and are harder.

so for this scene the sweet spot lies between 12 and 25.. try 18 or 19 maybe and leave it running longer and in highres?

normal map give good result ;why you use displacement ?
or use maxwell sea

sl:10; 10mn; maxwell sea

sl:9; 6mn

This is about the caustics seen through the surface

seghier wrote:why you use displacement?

I said it was a shabby test.

I first tried with a bump map with sun radius=100 and as I didn't get any defined caustics I thought it may not be working correctly so, as I had an mxm with displacement at hand, I just tried with it. Then I realized that sun caustics were there but blured because of the sun radius...

The problem is that when caustics are getting defined the render needs more render time.

Sun radius = 10

SL24

Water is a plane with bump.

lovely;)

i'd swim in that for sure....... smells good to me!

Nice result

@seghier what was your sunradius in your example images?

3dtrialpractice wrote:@seghier what was your sunradius in your example images?

i don't modify the radius ; default value

Not sure what the default Sun radius is now in Maxwell, but you can do a little experiment to find out if it is right.

The apparent diameter of the sun from the earth's perspective is 0.53 degrees. This means that if you create a 90mm diameter disc and put it exactly 10meters away from the camera, it should look the same size as the sun. If it doesn't, then adjust the sun radius until it does and that should be the correct default sun radius.

http://hudsonvalleygeologist.blogspot.c ... f-sun.html

Thomas, does it matter about the location and time of day?

I just did your test using the default sky, and the result for (istanbul at 9.30am) was; sun radius 1.9 = 0.53 degrees


Also I would consider 10 as the maximum sun radius, after that, to get even softer shadows, I would make an emitter. This is because such a wide sun/haze would have a broad soft edge, not a crisp circle. A broad crisp circle will give strange shadows esp noticable with the shadows of very thin objects,... well its only a subtle visual problem, but easy to miss, so worth talking about...