Wooden Mirrors
If you have never seen any of Daniel Rozin’s work you should go youtube it right now. It is some pretty awesome stuff. The works are pretty simple actually. Put a camera in the middle of the work to create the “mirror”, have motors move your medium to either reflect more light or turn your bands(applies only to the weave mirror) and have fun! The students in the Houdini class I sit in got an exercise to recreate this effect with the power of houdini. It’s a straightforward exercise: find a movie, turn it into an image sequence, use that sequence to create luminosity values over a series of points, and stamp that value up to the rotation of however you are changing values.
I wanted to take it a step further. While watching the lesson and what exactly they had to do I drifted off a bit and remembered a friend of mines work he had done a few quarters back. It was for the renderman class, the procedural shader in an environment. He ended up making pong on a tv, but instead of just drawing out the pixels he had groups of red, green and blue that when pulled far enough back mixed into their proper colors. If you look around 1:08 on his reel you can see exactly what he did. I wanted to apply what he did to what the assignment was. I was particularly moved by Rozin’s weave mirror piece and wanted to implement the rgb much in the same way.
The nice thing about this exercise is I had to forcibly remember how to do things in SHOP. When you haven’t touched Houdini’s SHOP much, take a year off and go back to it things can be mind boggling. I enjoy making shaders, and having Houdini’s interface to make the shaders is a joy, as long as you can even think of what you want to accomplish. It took me a half hour just to remember how to sync a uvCoord node with the current definition(yes I realize it is very simply in the right click menu, but I would much rather have a button in the param interface that says SYNC). So anyway, I made a simple ramp shader(dear god so simple) to put the change in color where I wanted.
After that issue came pretty smooth sailing from there. Though I do have to say the scene gets quite heavy once you up the “resolution” of the mirror. It is basically 3 cylinders per “pixel”, so upping resolution quickly makes a scene very very heavy. I digress… I actually made 3 versions of this. One very close to Rozin’s pieces(basically a shiny disk that rotates to catch more light and show brighter pixels), my version with the ” color pixels” and a melding of the two. The third is pretty much a polychromatic grayscale image using my tube implementation.
With this implementation one of the things I was worried about was the color mixing that had to happen. The problem is, as I increase the resolution to get a closer 1:1 ratio for the pixels my poly count and footprint shoot through the roof. I thought of a solution, well an optimization, as I was typing this but as I am already rendering it will have to wait to test. It is fun to see what happens at lower resolutions, as a Moiré pattern starts to happen. I will upload the videos I have rendered later and edit this post when they come up. I will say this, my “test” footage is RickRoll. Why? Because I enjoy the video and giggle thinking of all the silliness it causes! Anyhow, here is a sample from the video:
