Object Properties
Volume tab
Here you specify the path to the .vdb file to be loaded by the RS Volume object and prepared for volume rendering. Since fluid simulations usually involve sequences of many .vdb files, simply specify the first .vdb file in the directory here. The evaluation and automatic loading of the files in this sequence is controlled by the settings in the Animation tab.
Volume objects must be stored on a GPU's memory in their entirety, volume rendering is not handled by Redshift's out-of-core system. Therefore, if a scene uses too many volume objects (or if these volume objects are of a particularly high resolution) and do not fit on the GPU's memory, rendering will be aborted with an out-of-VRAM error message.
Animation tab
If you have specified a .vdb file in the Volume tab that is part of a .vdb sequence, you must specify in these animation settings at what frame rate and in what order these files are to be loaded. This step should always be done immediately after specifying the .vdb file so that the subsequent display options of the RS Volume object can work correctly.
Mode
Here you specify how the .vdb files should be loaded and in which order they should be played:
- Off: Only the one .vdb file entered at Path is loaded.
- Simple: The .vdb sequence is run only once.
- Loop: The .vdb sequence is run through and then repeated.
- Ping-Pong: The .vdb sequence is always run through alternately, first forwards and then backwards.
Timing
With this setting you determine in which rhythm the individual files of the .vdb sequence are to be loaded, i.e. whether they are to be loaded simply coincident with the frames of your animation in Cinema 4D or in accordance with a specified frame rate every second.
- Frame: For each image in the Cinema 4D animation, one image is loaded in the .vdb sequence. If the frame rate of the simulation does not match that in your Cinema 4D scene, it may cause the simulation to render slower or faster than in the original.
- Time: This setting guarantees that the simulation will play back at its original speed regardless of the frame rate you use in your Cinema 4D project. However, this then also requires that the value for the Frame Rate of the .vdb sequence be entered correctly.
- Range: In this mode, only a part of a more extensive .vdb sequence can be specified and played back at the exact time.
Range Start
Only relevant when the Timing mode is set to Range.
With this value you can specify at which frame of your animation the VDB sequence should start playing. All frames before Range Start will use the first VDB file of your sequence.
Range End
Only relevant when the Timing mode is set to Range.
With this value you can specify at which frame of your animation the VDB sequence should stop playing. All frames after Range End will use the last VDB file of your sequence. Leaving this value at 0 has the same result as entering the last frame of your animation.
Loops
Only relevant when the Timing mode is set to Range.
This sets the number of repetitions for the VDB sequence within the given range (between Range Start and Range End). Increasing the Loop value will always speed up playback of the VDB sequence and can result in more skipped VDB files.
Start Frame
Frequently this should be 0 to start the sequence with the first .vdb file found at the given Path (similar to the numbering of the first element of a array structure), but this can be used to trim unnecessary frames from the beginning of a .vdb sequence.
End Frame
This can be used to trim unnecessary frames from the end of a .vdb sequence by controlling at which .vdb file the sequence should stop at. To play the full .vdb sequence you can always use the button Detect Frames. This will fill out both Start Frame and End Frame values for you, based on the given Path to the .vdb file.
Frame Rate
Since a sequence of files doesn't have a fixed playback frame rate, you can enter your own here. Try a Frame Rate of 30 if you don't know which frame rate the simulation was calculated at and then adjust if you feel the sequence runs too fast or too slow during playback. For example, if you used the Pyro simulation system itself to save a .vdb cache sequence, then use the identical frame rate here that you used in the Pyro simulation scene to load the simulation at its original speed.
Start Offset
This value will offset the number of the .vdb file within a sequence. For example, using Start Offset 3 would use the third file of the sequence as the new start frame. In this case, the first two files in the sequence will be handled as if they are the last two files of the sequence, so in total the amount of files in the sequence will remain constant.
Detect Frames
This button will automatically detect the number of .vdb files in a matching sequence and fill out Start Frame and End Frame for you.
This option draws a wireframe cuboid around the loaded .vdb volume. This makes it easier to estimate the location and shape of the simulation, even if its shape is not visible even in the viewports.
A wireframe cube indicates the dimensions of the loaded simulation data.
In addition to the wireframe Bounding Box, other elements can be added to the viewports to help estimate the shape and size of the loaded simulation:
- Off: There is no additional representation.
- Bounding Box: Similar to Show Bounding Box, the volume of the simulation is indicated by a cuboid. This time, however, it is a shaded cuboid that can obscure other objects in the scene.
- Points: This mode allows the best preview of the loaded simulation by representing its volume by small points. Their number can be freely selected. In addition, a threshold value can be used to control how dense the volume must be for a point representation to occur at this location.
The image on the left demonstrates the Bounding Box Preview. The images on the right showcase Preview Points in various densities (controlled by the Maximum Points to Display value).
Maximum Points to Display[0..2147483647]
When using the Points Preview, this number controlls the overall density of points used in the loaded simulation volume. More points take longer to calculate, but allow a more precise preview of the volume.
When using the PointsPreview, this value controlls, how dense the loaded volume has to be to receive the Point Preview. Smaller values will always lead to a more complete coverage of the simulation. With higher values only the most dense areas are covered by the Points.
Decreasing Prune Threshold values lead to a more complete covering of the simulation volume with points.
Motion blur simulation is a bit different with volume files as they are stored frame by frame rather than, for example, an object animated via keyframes where the speed and motion curves can be accessed at any time. The solution for this is recording speed information to a velocity grid which can be included in a .vdb file. Either separate XYZ grids with float scalar values or a single velocity grid with float vector values is required.
When working with Pyro simulation data, the velocity channel of the .vdb files is already holding the complete x, y, z vector. In this case just enter the name velocity for Velocity Grid X.
Enter the names of the three appropriate velocity channels that include the x, y, and z components here.
If you only have a single 3D velocity channel with float vector data you can add it all by itself to the Velocity Grid X field and Redshift will handle the rest. For a loaded Pyro simulation this would be the name velocity.
Velocity scale is a multiplier for the velocity grids to increase or decrease the motion blur intensity of a volume.
Depending on the values in the velocity grid, velocity scale may have to be increased dramatically before Motion Blur becomes visible.
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| Velocity Scale: 1 | 1000 | 10000 | 50000 |
Displays all the available .vdb channel names found in the loaded file that can be used for driving volume shading and motion blur in a RS Volume material or RS Pyro Volume material.