This week will be all about volumes and smoke, fire or explosions. In volumes we will learn to create and control combustion style simulations in a sparse thermal solver and then take it a step further by running a bunch of wedge SIM cards with PDG so we can work more efficiently. Custom simulation and post-simulation techniques, along with custom shader and lighting strategies, will allow us to create production quality work in a way that out-of-the-box tools cannot. After some compositing, we’ll end up with a big bang – but more importantly, the knowledge and confidence to hack solvers and shaders to create all sorts of effects.

Smoke is the display state of fog. For example, the fog volume in an ISO offset is directly a visual vector field;
ISO is a number of small squares that always face the camera, e.g. the SDF volume in ISO offset;
Pauli is the normal model display, e.g. ISO surface and quad mesh in ISO offset;
Volume is a vector field. By default it is displayed in smoke mode, but by default this node has no value and therefore cannot be seen’
In ISO displays it is also stored as a voxel from which distances, directions and other data can be retrieved;
VDB is an open VDB, which is an updated general volume data type. It is possible to export the VDB format as a generic material containing various density and other volume data;
Convert VDB converts the relationship between VDB and VDB;
Volume visualisation can be used to visualise the display colours of the fog;

node – Atmosphere_volume > shader to out_environment > atmosphere

Adding Volume Rasterize Attributes and Selecting Density Attributes.

Group – A group of points in the input for coarsening.
Attributes – The mode specifies which attributes are used to create the corresponding VDB.
Note – only floating and vector attributes can be razed.

The basic building blocks of a smoke simulation are the object, solver and procurement. The smoke object (sparse) node creates a dynamic object containing the required fields, and then the solver evolves the object as the simulation progresses. The simplest smoke simulation requires the following data.

density the area containing the smoke;
temperature the scale field used for buoyancy calculations;
vel the vector field that captures the instantaneous motion of the smoke.
The solver is responsible for ensuring that these fields change in a way that is consistent with the smoke, but sourcing is responsible for injecting these quantities during the simulation. For example, you may need to continuously add or cause hot areas to rise in the smoke source.

Fire

Pyrosolver_sparse – this node is an extension of the smoke dissolver (sparse). It takes into account an additional simulation field (capturing the presence of flames) and adds some additional shaping parameters to allow more control over the emergency appearance.

Add disturbance, add gas swirl and confinement scale 0.5, gas swirl limiting – gas swirl limiting DOP applies swirl limiting to the velocity field. This is a force that amplifies existing vortices with the aim of eliminating diffusion that occurs during the diffusion phase of a fluid solvent, confinement scale – the strength of vortex confinement.

Standard_volume

standard_volume is a physically based volume shader. It provides independent control over volume density, scattering colours and transparent colours. Blackbody emission is used to render fires and explosions directly from the physics simulation. Each component can be controlled by a volume channel from the volume object, and other parameters can act as multipliers on the volume object. Optionally the channels can be left blank and custom shaders (such as volume examples or procedural textures) can be attached to manipulate each component using more control.