softness is necessary

I finally got a more complex scene to look good with soft shadows. The problem was that area lights don’t seem to play nicely with my planes when they are reflective. I’ll show a comparison here.

This one doesn’t have any softness, but it has speed.

no soft shadow

This next one has softness, at the expense of a little speed πŸ™‚

soft shadows

18 seconds vs ~60 minutes. Just a tad slower.

The lack of anti-aliasing is exaggerated by squashing the image. I really should do something about that…

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6 Responses to “softness is necessary”

  1. Meh, it’s only a 59:42 minute difference, doesn’t sound too bad! πŸ˜‰

    … heh, I really like the “soft” look to it. What are you doing, shooting many rays to a jittered light position and averaging the comparisons?

    Just a little nitpick, but some more ambient light would be nice :). 99% black shadows suggest little (read: none) light bouncing, yet the spheres seem to be very reflective.

  2. bbarrett Says:

    Thanks for the comment!

    I think you have the technique in a nutshell, but I’ll elaborate anyway.

    Instead of a point light, I used to have what might be thought of as a 3d grid of smaller, dimmer lights. In fact, I could have actually removed the area light code and just deal with many, many small point lights. Such an implementation, unfortunately, produces banding for low sample counts. The difference between that and what I have is that each light isn’t in an exact grid, the lights are distributed slightly randomly. Nothing new, it has all been done before. Just not by me!

    You are probably right about the ambient term. I have kept the it relatively low from the start. TBH I barely examine the scene as a whole any more, I focus on the things I am changing and tweaking. I’ll increase it though. I tend to change things like reflection and refraction often though, I doubt I’ll keep changing the ambient to match it.

    Also, I got anti-aliasing working. Although at the moment it works on the whole screen, not on edges. But that kind of thing is for another post πŸ˜‰

  3. AA, interesting. By the “whole” screen, I take it you’re referring to FSAA? Sounds cool, can’t wait for a post on ray traced images with anti aliasing πŸ™‚

  4. bbarrett Says:

    Yes, you are right, FSAA. I hope to add something else worthwhile before posting again…

  5. Do you have future plans for adding any global illumination techniques, such as radiosity? I’ve been really interested in the topic, but the implementation of such things looks really time consuming.

  6. I have to say, those techniques look really interesting (if I am remembering them correctly). I would consider it, perhaps during the summer when I have more time (see my earlier entry, “busy, busy, busy”, for reasons why I might not have any of that time stuff for a little while).

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