I've modeled what should function as a kaleidoscope (modeled based on a real kaleidoscope I took apart.)

My first render showed no promise. Then I remembered the “reflect bounce” parameter under the “Render” tab and cranked that baby up to 10. My next render looked better… but not good enough. I took the value up to 100. No change…. so I figured I'd test the limits and cranked the value up to 10000. I thought for sure this would take my machine to the knees, but it didnt. My render also looked exactly the same… so my question is, is there a limit to the number of reflection bounces one can have in Houdini? I assume there is… and if I'm right, is there a way to bypass this limitation?

BTW the “reflect bounce” parameter in question is located at the object level in the parameters for the kaleidoscope model (not in mantra or a shader.)

The reason you are not seeing a change is most likely that all your rays are escaping, so the extra bounces are redeundant and don't add much to the render time (if anything). I'm not sure if there is a limit to it, if you are interested in finding out the limit, or just experimenting, you could place 2 reflective objects parellel to each other with your camera in the middle (pointing directly at one of the surfaces). Ensure that you can see the edges of the objects in the render, perhaps by placing them inside a large constant shaded sphere. Crank up the reflect bounce and get real comfortable, or go on vacation or something. When you get back from vacation (hope you had a great time!), if Houdini hasn't run out of memory, there may or may not be some rendered pixels.

If the render isn't long enough, throw in a bunch of depth of field with the anti-aliasing cranked way up

BTW: I just had to try the parellel object test, it works better if you put a border on the “mirror” objects so you can see the edge of it. Even with reflect bounc of 10 it took a really long time to render. It really makes you appreciate the speed of light. Light is fast… really fast. The good part is, it doesn't seem to eat up memory like I thought it would, since it is really only accumulating a single value. If there is a limit, you don't want to try to find it.

I also put together a quick Kaleidoscope and it seemed to work just fine with 4-6 bounces, depends on the framing. Make sure that the image/objects you are reflecting are close to the end of the tube or the results will not look right. A good distance is around 1/4 the width of one if the mirrors, that gives a nice tiny bit of parallax without getting too disjointed. If you go too far the parallax is so great that the kaleidoscope loses it's effect.

Excellent suggestions thanks! I was giving my model way too much credit, and wanting to blame the results on a limitation. With some tweaking I was able to achieve the effect I was looking for after reading your post. Very cool. Render times leave a bit to be desired though 8)

Another nice way of achieving a kaliedoscope is with a series of clips and copy's on the geometry you want to mirror. I wont get into specifics but basically you can create a fairly quick kaleidoscope using this method. Doing the reflections as actual geometry instead of actual rendered reflections.

My next project: A compound telescope.

Wish me luck… :wink:

hi
squid can you post some render please I am realy anxious to see how it looks