nassredean

[nassredean]

Undulating Voronoi ball, procedurally in Houdini and rendered in mantra.

[nassredean]

ASCII Rose Blooming.

This ASCII art was built entirely using houdini. The effect is achieved by casting a 2D projection of a 3D object onto a plane using ray intersection in a fully procedural technique first detailed by Junichiro Horikawa here. The ASCII is selected from a dynamic user specified set of characters, from which a density is procedurally created for each character. I modified the vex to also keep the grid size fixed instead of shrinking and growing with the object model, and also to copy over the color onto the projection.

For the rose, I used an L system to model a rose. We can get a natural looking growth effect by incrementing the number of generations.

To render, I first tried a simple mantra node, but observed bad anti aliasing and severe jitter from frame to frame. I tried a few different things, including boosting the resolution of the camera, ticking "sample lock", increasing pixel samples, and disabling aa. While the result was better, the render time was enormous, which was not acceptable since the in scene view was perfectly adequate. I tried using a lens shader using the techniques detailed here. This significantly sped up the render and allowed me to reduce sample count. However I then learned about Houdini's flipbook functionality. In the bottom left of our viewport, the tiny little flipbook icon lets us create a flipbook of images from our scene! TIL! This turned out to be exactly what I wanted, and fast to.

The last thing I did was load up the flipbook frames into a cop network to just slightly decrease the contrast.

Lastly I used ffmpeg to use the final exr sequence to generate the video above. I think it was pretty neat to be able to get this entire effect done using just houdini.