Alien Drone Attack

In The Making

February 20, 2025

Week 03: Destruction Week 02

The first layer of Ground RBD was there, but there were so many problems with the simulation I needed to go back and troubleshoot. Secondly, the helicopter geometry was set up, ready for simulation in the following week.

GroundRBD Troubleshooting

Here are problems with the ground rbd simulation last week:

Many pieces got stuck on the ground
The ground fractured before the simulation begin
Collision guides turn on -> slow down the performance significantly
Collision objects was too dense -> slow down the performance significantly

Troubleshooting and optimization is definitely not everyone favorite part, but it’s 80% of the process in making VFX as I learned along the way as a junior.

Fracturing Pattern

The Voronoi pattern in RBD Material Fracture node was too clean and sharp, which did not create an organic look for concrete fracturing. Another valuable trick I have learn last week was save the position of all points in origin attribute, jitter the points of the surface right after remesh, then put those point back to origin P. Below is the result of the trick. With just low poly fracturing, I was able to achieve a more realistic, organic looking fracture pattern.

Reactive Velocity Fix

My initial intention was to create a fracture pattern that emphasized the impact of the drone with the helicopter; thus, the fracture pattern is denser around the contact area, and ease out gradually to other parts. I also separating all parts of the geometry and naming groups to build the constraint network in the next part.

Helicopter Geo Preperation

1| Fracturing

The velocity field I created last week created a non-realistic force field, which caused the simulation in the DOP Network looking not physically correct. As I go back to analyze the velocity field:

The impact of the drone to the ground should create a strong opposite velocity when it hit (plus the factor that the drone is spinning its bladed when travelling). Thus, the velocity needs to be pushed backward more than forward.
The velocity needs to be formed by the blend of the drone’s opposite velocity and the normal of the ground.

The constraint network aims to build a fundamental connection between particular parts of the helicopter. Depend on the surface and how it will react in the destruction, each part receives different constraint properties.