No Bird's land FX Details

In this document, I will present the details of the special effects (FX) used in the short film No Bird’s Land. For this project, I had to create four main types of FX due to the specific assets of our short film and the stylization of our pigeon characters. Additionally, we had few stock shots available and suitable for our needs.

Rain

Creating the rain effects and raindrops required specific considerations for each element, as the challenges and principles differed. One of the main rain shots combines various techniques in Nuke to enhance the hostile and desolate atmosphere we aimed to achieve. However, the base was created in Houdini to work on the drips and rebounds on the ground.

We had to use Houdini because this shot is filled with various assets, and some objects had to be removed due to the type of materials (such as the fabric used as a door). For this, I primarily used fairly standard popnet systems combined with popcollision, replicate, and reactivity, which were then converted into polygons with copy to point and VDB. The main challenge for this shot was adjusting the intensity of the rain and managing the continuity of the drips between the different objects.

The ripple effects were also created in Houdini, then the geometry was exported as an abc file and rendered in Renderman to obtain the reflections of the deformed puddles. For the puddles, I used a ripple solver with three geometries to define the locations with the appropriate timing.

Rain

Ripple

Explosion

The explosions were the first FX in the film and also the first I created. This was a source of learning and difficulties, as World War I explosions are extremely specific. They are mud and dirt explosions, not fire. It was too specific to find high-quality stock shots, especially since some assets had to be projected during the explosion.

For creating this FX, we had to separate the effect into four layers: the dirt with a double pass of RDB for more detail and finesse, the mud with a mix of vellum and VDB, the dust generated in popnet from the first two passes, and finally the smoke with a smoke solver. The dirt and mud were exported as abc files for rendering in Renderman. We encountered problems with this step because the mud, due to the VDB, had very unstable UVs, making it impossible to use textures. Therefore, we had to work solely procedurally for this part. The smoke and dust were rendered with Karma in Houdini, and the flash was recreated in Nuke.

some details from differents layers

Mud

The mud was initially considered for the assault scenes where we see close-ups of the soldiers' feet. World War I is often seen as a war in the mud, with trenches, no man's lands, and the absence of military vehicles at the time.

To create this effect, I started with a system of projecting the shape of the foot into the ground to deform it according to the animation. After various projection tests, it was decided to refine the technique with a system of vellum and popnet, then convert it into polygons with VDB to create small mud splashes. This principle was later used to create more deformable muddy areas. Unfortunately, both techniques are very resource-intensive, so we had to work on limiting the deformation areas based on what was visible to the camera, with two additional difficulties related to our characters. To create the deformations, I had to wait until the CFX were fully done, and the rear claws of the bird legs always picked up a bit more mud splashes than necessary.

Smoke

For the smoke, I had to create two types: one for a specific shot and another that wasn’t necessarily required but was a bonus. I originally made them to learn and understand smoke creation with a smoke solver in Houdini. Ultimately, my tests were very useful in enhancing the desolate effect of the no man's lands. Their interest lay in the duration and size of the smoke, which were more significant than the stock shots we had.

For the specific shot of Jean's cigarette, the difficulty laid mainly in the hand movement extinguishing the match and the fact that we had three different smoke sources that didn't light up at the same moment. Ultimately, a smoke solver with multiple emitters whose attributes were timed was enough to achieve this effect.