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When you perform a simulation, RealFlow writes out a wide variety of different files to store
particle data, motion paths, meshes, object geometry, and image maps. Many of these nodes
support multiple formats to improve the exchange between external 3D programs where the simulation
is finally rendered. The various files are stored inside appropriate folders for each
node type. All these resources have to be managed and this is exactly what "Export Central"
does: it is a clearly arranged control centre where you can choose from a node's available
file formats, change folders, and activate the export of maps.
The "Export Central" dialogue is located under RealFlow's "Export" menu. Another, more convenient,
way to launch this tool is using the "F12" key.
Let's take a look at the layout: The most striking element is the simulation tree.
This tree is subdivided into columns and contains a list with all of RealFlow's node types like
particle emitters or meshes. As long as a project is empty, there is nothing to export,
but once you have added a few different nodes you can see that the main areas become expandable.
one exception: daemons. The only daemon that provides export resources is the "Color Plane"
daemon. The other daemons add forces or remove particles, and these attributes cannot be
the node's available export resources. When you take another look at the different nodes
you will also recognize that some file formats are already active. These formats are a node's
default resources and they have been enabled automatically. This way
you can start simulating without checking whether the necessary files are written or
not.
Some export formats even provide another level, for example an emitters PRT format. PRT is
Krakatoa's native format and supports channels. These channels are used by Krakatoa to control
the shading of volumetric elements. You are free to decide which of these channels you
want to export, but please be careful with "vorticity", because this property is not
active by default and you have to enable it manually in the emitter's "Node Params" panel.
"Texture" is another channel that is often required by 3D programs in order to create
vertex maps.
It is totally up to you how many resources you want to activate, but please bear in mind
that it always takes a certain amount of time to write a file. With very large amounts of
data, a simulation can slow down and you should always ask yourself which export resources
are really necessary? You can also deactivate all export resources and in this case, the
data will only be present during simulation time. If a node does not have any active resources,
but export is enabled, you get a warning in "Export Central" and the "Messages" window.
Next to the export tree there is the "Name/Prefix" column and in most cases these entries equal
the nodes' names. Let's say your simulation lasts 50 frames and contains a circle emitter.
When you open the project's "particles" folder you can see 51 files starting with "Circle01",
followed by a five-digit pattern, ranging from 0 to 50, and a BIN extension. The prefix
is the name from the "Export Central's" "Name/Prefix" column and the numbers represent the frames.
The extension corresponds with the resource you have chosen under the export tree.
If you want to change the "Circle01" prefix into something different, for example "Water"
or "Honey" then there are two methods to do this. The first method is to change the name
in RealFlow's "Nodes" panel or the "Relationship Editor". This is the failsafe method, because
the associated prefix will be changed under "Export Central" as well.
In the second case, the name is changed directly under "Export Central".
There, double-click on the prefix and enter a new label. This way, the emitter's name
is kept under "Nodes", but it will be saved with the name you have defined here. If you
decide to use the second method you should be careful, because after a while it might
save different versions of a simulation, for example when you create a honey simulation
with different "Viscosity" values. Then, a prefix could look like this:
A similar workflow can be achieved with the entries under "Path". This column contains
the standard paths to a project's directories. The "scenedir" variable is substituted by
RealFlow with the name of the currently opened project file.
When you double-click on a path it is made editable and can be changed.
to a file browser. Therefore, please double-check that the entered path is valid.
Finally, there is the "Option" column where you can choose compression levels and image
formats. To open an option's drop-down menu, just double-click on the appropriate entry.
Another part of the panel is the button bar on the right. These buttons provide fast resource
management and you can choose whether you want to disable export completely, or write
out selected nodes like Hybrido emitters.
The "Update Time Line Cache" function is used when you want to restore the already simulated
data after a reset. When a simulation has been cached you see a yellow bar in the timeline.
After a reset, this bar disappears and the simulation data appears to be lost, but in
fact the cached files are still available. If the reset has happened accidentally, the
simulation cache can be restored again with this button. This function can also be executed
from the button next to the timeline and the "Alt U" shortcut. Please bear mind that "Update
Time Line Cache" is not a backup function. Once your simulation has been deleted or overwritten,
the previously recorded data will be lost. It only reads and displays what is currently
stored in the project's data folders.
Finally, all settings are confirmed with the "Done" button.
Accessing RealFlow's Export Resources
RealFlow's "Export Central" dialogue is just one way to access a node's resources. Another
method can be found when you right-click on a node either in the "Nodes" panel or the
"Relationship Editor". Under "Export" you find switches for disabling or enabling the
you can change or add export resources and the settings show up in the "Export Central"
dialogue as well.
Another way of accessing some of RealFlow's export features is the "Export" menu.
Initial States
When we talk about export resources and file types, we also have to talk about initial
states, because they can be seen as a special case. Initial states are required when you
want to restart a simulation from a certain state or frame. The workflow is pretty straightforward
and initial states can be created for each node individually. Let's take a look at the
following scene where we have filled a glass.
The idea is to use this state as a starting point for a new simulation. Switch "Use Initial
State" to "Yes" and click on "Make Initial State". Now, RealFlow writes out a single
file to the project's "initial state" folder. Then, activate the "Reset to Initial State"
option and reset the scene. RealFlow jumps back to frame 0 and reads the initial state
file. When the simulation is restarted, all of the previously saved data files will be
overwritten, but not the initial state file. So, you can reset again and again. It is also
possible to create initial states for multiple objects: just shift-click on the nodes and
proceed as shown before.
With rigid and soft body simulations, the process is slightly different, because here,
RealFlow does not write any files to the "initial state" folder, but the information is stored
in the BDC and SD cache files. They are stored in the "objects" folder.
So, if you want to create initial states from Caronte simulations, please check if the nodes'
export resources are active.
Another thing you can observe with an object's export settings is the existence of two different
SD files. The first one, in capital letters, is a global container for all of the scene's
objects, regardless of whether they are rigid or soft bodies, or just obstacles without
dynamics.
The object-based SDs, on the other hand, contain only the geometry and motion data of the selected
object. They are of particular importance if you want to work with an object's "Cache"
In the last chapter of this lesson you will learn how to activate and export different
image maps. When we say image maps we have to differentiate between a wide variety of
types. RealFlow supports the creation of displacement maps, velocity and vorticity maps, foam maps,
and wet maps. Before a map can be created, it is normally necessary to activate this
feature.
Displacement maps can be written from RealWave nodes and Hybrido domains. The latter type
also provides velocity and vorticity maps. In Hybrido, the displacement feature is located
in the "Ocean Statistical Spectrum" panel. When you take a look at the "Export Central"
dialogue you can see that this map type is always written as a series of TIFF files.
The reason is that other formats do not support the map's 16 bit colour depth.
An object's wet map feature has to be enabled with the "Texture" panel's "WetDry texture"
option. The maps are always squared and their resolution is set with the associated "@ resolution"
parameter. If you want the wet marks to vanish after a certain time then set "@ ageing" to
If you want to see how the map is created during a simulation, please check the "Texture"
The simulation shows the creation process of RealFlow's wet maps with the help of three
cubes.
With an expanded UV grid, the marks are mapped correctly.
With overlapping UVs, the pattern is repeated on each side of the cube.
Objects without or wrong UV coordinates appear black or grey during simulation and the maps
remain empty