Let’s start with the concept of this FX Scene. This FX was made in Houdini and is going to be used in the Unreal Engine for VR. So basically as our project brings together Virtual Reality as well as the real world, we decided to insert/import the FXs which are created in the virtual world. After hearing the concept the first things that hit my mind were Unique and different. Combining the FX of Houdini in the virtual world was something I never thought of for my project.
The instructions for this project were that The geometries would be floating in the air which will, later on, come together and form the model of this Kid (geometry). These geometries would be Cells, Viruses, Fungi, etc. Except for the geometry of Girl all other geometries are for the project of Cell Animation while the girls are for both the projects i.e. Cell Animation as well as Disintegration. The following are the geometries that I received especially for the FX purpose:
After taking a look at all the geometries, I started with doing the FX. To begin with, I tried the technique of creating a volumetric geometry of the Girl with the help of ‘VDB Polygon node’, and later boolean the new vdb geo in such a way that it deletes all the unnecessary objects and also fills the geometry inside. But unfortunately, as the geometry had a lot of errors while doing the FX the geometry used to split up in a weird way which resulted in giving me various artifacts. Hence, I was not able to create a suitable smooth FX that could be done along with it.
Hence, to overcome this problem, I went along with the ‘Color Transfer’ technique. In this technique, I gave the girl a “0” value i.e. a black color, and made a roughened sphere geometry and colored its red value to be “1”. Following this step, I gave animation to this sphere so that over time it changes the girl’s color, i.e. black to red. This color change happened due to the node of “Attribute Transfer” which transfers any attribute that we select from one geometry to another. So for this instance, I transferred the attribute ‘color’ to the girl so that she will have the color red. Later on, I deleted this red color to carry on three further processes. The processes were:-
- Delete the geometry which was affected by the color “Red”. (combined for both the project)
- Emit Particles from the color “Red”. (for particle disintegration)
- Attracting the particles to this “Red” color. (cell animation)
For Cell animation:
First I emitted particles from a Sphere with the help of a pop network. But, the default settings make the FX for these particles too dull. Hence to make it interesting, I added a bit of turbulence as well as swirl, so that it has a natural movement similar to the dust which floats in the air.
Following this, for making the particles attract to the geometry (red color), I added the node called “Pop attract” by which I could bring the particles closer to the object or attribute that I specify. Simultaneously, I also gave it a bit of Drag so that I could manipulate the speed by which this attraction is done.
Furthermore, after the step of Particle generation, it was time for particle instancing. A particle system can be used to create multiple object copies (so-called instancing). This technique simplifies scene authoring and also reduces loading time and memory consumption as compared to the use of single objects. The benefit of the particle instancing is that we can instance more than one geometry and that too in random order.
For Particle instancing, we have to give an attribute called as “Class” to each and every geometry that needs to be instanced. We can give this attribute to the geo with the help of the node ‘connectivity’. Hence, these attributes are further carried forward to the attribute from pieces as well as the node “copy to point”. And hence we get these variation in the particle instancing.
For the Disintegration Effect, I had to take Two things into consideration.
- Particle emission
- Geometry (surface affected by the color red) gradually disappears following that of particle emission.
The Red color attribute helped me in giving a smooth particle emission. To make it more interesting I gave it a bit of turbulence as well as swirl. Along with this, to make this thing more interesting and natural, I made the particles affected by wind (generated with the help of pop wind node).