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This parameter field is only accessible when “Force type” is set to “Image”. To load an image (sequence), right-click on the small chess board, and choose “Load image”. Then, a new dialogue appears. For a detailed description of the features and parameters of this panel, please take a look at the “Mapped Parameters” chapter below.
Time
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Factor
If you have already worked with RealFlow's Graphs system or one of the demo scenes, e.g. “apply_stat_spectrum” then you have most probably already seen the “Time factor” setting. This parameter allows you to control the wave surface's speed. Values greater than 1.0 will accelerate the waves, while values smaller than 1.0 can be used to decelerate them. The advantage is that the waves' speed can be adjusted without changing any other parameter. Another plus is that the “Ocean Statistical Spectrum” settings from RealFlow Graphs, Hybrido, and RealWave have been unified as far as possible. This way, you will be able to get exactly the same results with identical settings in all three environments. "Time factor" is a dimensionless value and accepts floats – it works as a multiplier.
Resolution
You can choose from seven different levels of quality. Of course, higher quality settings require longer simulation times, but also create more details. This parameter is dimensionless and only accepts the predefined values from the select list.
Depth
This parameter affects the dispersion of the waves and is only noticed if the length of the wave is close to the value of the depth. In these cases this parameter has a decelerating effect on the wave's dispersion. In most cases you will not see any effects or changes, because depth is normally rather high compared to the length of the waves. The parameter's unit is metres [m].
Dimension
With this parameter it is possible to change the appearance of the fluid surface. This value can be seen like a scaling factor and is given in [m]. When you, for example, enter a value of 500, the distribution and scale of the waves will look as if the domain covers an area of 500 m x 500 m, although the physical dimensions of the domain did not change at all. Please note that you can enter only one value, because the shape of the displacement is always considered as squared. When you change “Dimension” you will most probably have to modify “@ preview height scale”. “Dimension” and “Resolution” are directly connected:
Level of detail [m] = Dimension [m] : Quality
An example: Let’s assume you have created a surface with a “Quality” of 1024 and a “Resolution” of 400 m. The smallest structures you can observe on this ocean have a size of 0.39 m according to the formula above:
400 m (Dimension) : 1024 (Resolution) = 0.39 m
As shown above, the parameter is given in metres [m] and accepts floats.
Wind speed
You can enter any positive or negative value, including 0. “Wind speed” can strongly influence and affect the look of the surface. The parameter's unit is metres per second [m/s].
Wind direction
This is the wind direction in degrees [deg]. Please note that in the case of using the linked daemons, the velocity vector is projected on the XZ plane and then converted to degrees. If you use another axis setup, where Y does not serve as a height axis, the orientation of the wind direction will change. By default (with YXZ orientation), RealFlow uses this notation:
- 0°: wind comes from the positive X axis (1,0) - positive wind directions are counter clockwise.
- 90°: wind comes from the positive Z axis (0,1)
Wind alignment
With small values only waves which are totally perpendicular to the waves' direction are removed. When “Wind alignment” is increased, RealFlow will remove more and more waves; waves which are less perpendicular. If the value is very high, only those waves which are absolutely parallel to the wind direction will remain.
Min Wave Length
With “Min Wave Length” the amount of details on the surface can be controlled. Higher values flatten the surface and create fewer ripples. Please keep in mind that the parameter is connected to “Dimension”. When entering lower values, this parameter should be decreased, too, to guarantee that the RealWave object still shows enough structures.
Weight Against Wind
This is a weighting parameter for waves which are moving to some extent in the opposite direction to the wind. If “Weight Against Wind” is 0.0 then all waves against the wind are eliminated. If it is set to 1.0 then its normal strength is used. Values between determine the amount of waves being eliminated.
Seed
A seed value is used to generate different initial conditions. This helps you to create different looks of the waves with a single click. You might already know this feature from RealWave's “Fractal” modifier. There you can also influence the waves with a new seed. This value is dimensionless and accepts integers.
Repeat U/V
Since the displacement is calculated from a texture map it is also possible to define the number of repetitions both in U and V direction of the mesh grid. U and V coordinates are related to the UV grid that is created with the mesh. Displacement maps are seamless, though very high values are very likely to create regular patterns on the surface. This value is dimensionless and accepts integers.
Preview Type
Here you can define how the force field should be displayed in the viewport. “None” disables the representation of the height field, but the domain's bounding box and icon are still visible. Their visibility is controlled under “Display”. “Surface” is the default option and shows the ocean statistical spectrum in a 3D viewport representation. “Magnitude texture”, on the other hand, visualizes the daemon's force field in the form of a coloured map: red indicates high forces, while blue colours stand for low forces.
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If you want to decrease the height field's height in the viewport use a value smaller than 1.0. With settings greater than 1.0 the spikes become higher.
Mapped Parameters
Take text/image from http://support.nextlimit.com/display/rf2014/Objects+-+Particle+Fluid+InteractionYou have already read that many parameters can be represented with image maps – here is some additional information. Image maps create areas of different influence, based on the colours of a bitmap or texture. The adjustments are made from a separate window, providing all relevant parameters and switches to make use of this feature. An additional function is that you are even able to load image sequences for animated parameters. Dark areas indicate zones with low values, while white represents the maximum.
Especially larger objects can strongly profit from this feature. You can, for example, create a river bed with low “Particle Friction”, while the outside areas have higher values. All this can now be painted to a map and then projected onto your object. This does not only work with RealFlow’s native items, but also with imported objects from SD files. It is important that imported objects carry (correct) UV coordinates.
It is even possible to make the used map or image sequence visible in RealFlow’s viewport. If you cannot see it, or work with multiple maps for different parameters, you can easily to show the desired map with:
Display > Texture > [ Map type ]
If you want to replace the fixed value with an image map, please do the following:
Right-click on one of the parameters with a chess board icon.
Choose “Load Texture” from the context menu.
RealFlow opens a new window called “Load Texture for Parameter”.
Fill out the dialogue and confirm your settings with “OK”.
File
Under “File” you can load one or more image files with TGA, BMP, JPG, PNG or TIF format. The path to the image is shown under File. With the “…” button it is possible to open your OS’s file picker. The images must be coloured – either 8 bit, or if supported, also 16 bit. Image sequences are recognized automatically and you do not have to select the first and the last frame. All files with an equal padding are loaded to the canvas.
Channel
Here you can choose one of the picture’s RGB channels. The currently active channel is shown in the canvas and updated according to your selection. “Min. value” and “Max. value” are, by default, the pixels’ intensities. They are spread over the available minimum and maximum range of a parameter but, in case of need, this range can be clipped by entering new values. The shades of the image channel are then spread over the given settings.
Min. value/Max. value
The grey shades of the loaded image will be transferred into values ranging from “Min. value” to “Max value”. So, the lowest grey tone will get the value from “Min. value”, and the highest grey tone receives the value from “Max. value”. All the other grey scales are calculated automatically between the given minimum and maximum.
Please bear in mind that the maximum value is 1.0 and “Min. value” cannot be greater than “Max. value”. This feature is also very interesting if you see problems like local instabilities or exploding particles. This can often be observed with very high “Particle friction” settings. In such a case, simply decrease “Max. value”, e.g. to values around 0.1.
Min. frame/Max. frame
These values are important for image sequences. You are able to specify a certain frame range that is used for parameter mapping. Simply enter the desired start and/or stop value and the frames outside of this range will be ignored.
FPS Ratio
With a value of 1 the image sequence is played at its original speed, e.g. 30 FPS. If you want to achieve faster or slower playback then you have to change "FPS Ratio" accordingly. Values above 1 will increase playback speed; smaller values are used to slow it down.
Offset
If you do not want to start with the first frame of your sequence, you can determine an “Offset” from which the series will start playing.
Loop
This option creates an infinite back and forth loop from the currently loaded image series.
Control buttons
They work exactly as in other video players. You can go to the first or last frame, to the previous or following frame, and start/stop playback. The slider allows you to scrub through the entire sequence and jump to a certain frame.
Skip
Finally, the “Skip” option is related to “FPS ratio”: while playing back an animated sequence, RealFlow cannot always achieve the given FPS rate. By checking “Skip”, RealFlow will play the image sequence with the adjusted FPS rate, but some images might be dropped. Without “Skip”, RealFlow shows all images, but there is no guarantee that the desired frame rate can be maintained.