Default Options

Preset

You can choose from a wide variety of predefined resolutions for the preview. The list offers a wide range of often-used standard resolutions. Simply choose the desired preset and RealFlow automatically adjusts the related “Width” and “Height” values. With “Custom Resolution” it is possible to define the size of the preview window.

Width / Height

These parameters represent width and height of the final video measured in pixel. The default value is 640 x 480.

Keep Aspect Ratio

If you want to keep a certain aspect ratio based on the current setting under “Width” and “Height”, please activate this checkbox. Now you can either enter a custom “Width” or “Height” value and RealFlow automatically completes the second value.

Maxwell Options

The Maxwell Render engine uses physical data such as time of day and location to create a physically accurate sky system. This sky model is used to illuminate the scene. The result is a naturally lit image with realistic shadows and surfaces. A click on this button opens a new window where all the relevant settings are made:

Illumination

Intensity

This value is used to adjust the “brightness” of the sky and works like a multiplier. A higher value adds more light to the scene, lower settings result in a darker impression.

Physical Sky

RealFlow's Maxwell integration provides two global illumination models: with “Physical Sky”, Maxwell creates a physically accurate model of a sky depending on the adjusted location and time. With this sky model it is possible to simulate conditions like sunrise, dawn or sunny summer days. When this option is inactive, a conventional sky dome model will be used instead.

Light

In the real world, the sky's colour and brightness depends on the current time. In the morning and evening hours, the colours have a high ratio of red and yellow. Around noon, the colour tends to be blue or white. The exact simulation of these colours is one of Maxwell's key features and produces absolutely realistic lighting scenarios. With the “Light” slider you can easily determine the current sky colour by dragging it to the desired time of day – from dawn to dusk.

Hour

This read-only field is a directly connected link to the “Light” slider and shows the corresponding time to the slider position.

IBL Channels (Background, Illumination, Reflection, Refraction)

These four tabs provide exactly the same parameters, settings, and buttons. “Background” specifies the image you will see in a render's background. With “Illumination” you are able to load an HDR image that acts like a global light source. An image under “Reflection” will be reflected on objects. This channel assumes that the object's material has some reflective properties. “Refraction” works similar to the previous channel, but here the node's material must not be completely opaque and have at least a small amount of transparency.

At the moment, RealFlow only accepts images with the extension HDR. Other formats, e.g. EXR, are currently not supported.

Same as Background

This option is not available for the “Background” slot for obvious reasons. If you check this box, the background HDR will be used to create a consistent lighting situation and environment. When this feature is active you do not have to load the background image again to the appropriate “HDR File” slot(s).

HDR File

The empty field contains the path to the HDR image you want to use. You can either add a path manually or choose an image with the equal-named button and a file browser.

Intensity

If you want to brighten the HDR's lighting, simply increase this value. It works very similar to the “Global Intensity” field above. Sometimes, values of 10, 20, or more have to be used to get enough light.

Tile

With these parameters it is possible to create repetitions of the HDR in horizontal and vertical directions separately.

Offset

To rotate the HDR image around the horizontal and/or vertical axes, please enter appropriate values to the two fields.

Globals

Quality

This value determines the quality level of the render engine. Higher settings yield better images, but also need more time. The range for this parameter is between 20 and 100%. Please note that “Quality” also influences the default pixel size of the render. When the value is too low, the render process might fail and you receive a warning message. The “Quality” parameter determines the true preview size in pixels: for example 60 x 45 pixels with a value of 25. The reason why the preview is blurred is that the render will be upscaled to match the current size of the “Maxwell Interactive” window:

Original render size: 60 x 45
Window size “Maxwell Interactive”: 640 x 480
Upscaling factor = 10.7

To get a really crisp image, simply choose a higher “Quality” level, like 75 or 80. The image will be automatically updated in realtime.

Number of threads

On multi-core or multi-processor systems it is possible to exclusively reserve computation power for Maxwell. The mode of operation is actually the same as with “Threads” in the “Simulation” tab or the “Simulation Options”.

Global Scale

Because Maxwell Render uses real world units for lighting and camera settings, the size of your scene objects must also have a real world scale. For example if you wish to render a building, but that building was exported with a size of just 1 meter, it will be rendered it as if it were a miniature building, and the lighting will not match your intentions. These differences can be compensated with “Global Scale”.

Playback

Max Frame Time

If you want to limit the maximum render time per frame to a certain time, just enter the desired value here. The default value is 60 seconds. Please note that Maxwell will abort the render process after this time – even if the given “Sampling level” is not yet reached.

Max Sampling Level

Maxwell is an ‘unbiased render engine’ and uses this sampling level to reduce the amount of noise in an image. The higher the sampling level, the less noise the final image will have. The default value of 7 is suitable for most previews. Of course it is also possible to choose a higher value, but this will result in (much) longer simulation times.

Engine

Maxwell Render comes in two flavours: the preview engine and a high-quality production renderer for final images. Here you can choose which type you want to use for your images.

Motion Blur

Maxwell Render also support highly realistic motion blur. The value acts like a multiplier to stretch the blurs.

Channels

RealFlow's implementation of Maxwell Render lets you export several channels with your render. If you want to activate this feature just switch the appropriate channel from “off” to the desired image format. The channel data is only stored with a Maxwell preview (Playback > Maxwell preview) and the "Production" engine selected. When you do a single render with the “FIRE” engine, channels will not be calculated.

Alpha

This image contains an Alpha mask that can be used for compositing purposes.

Motion

When this channel is active, RealFlow will write out a file with colour-coded motion vectors. These images are used to create motion blur effect in a post process. Please bear in mind that motion vectors require at least a 16-bit format to work correctly. Therefore, we recommend using the “EXR” option.

Normals

If you want to visualize the normals please activate this channel.

Output Path

Ask Movie Path

By default, RealFlow uses a standard path to save the preview images and movies. When this option is checked you will have the opportunity to store the final video to a custom location instead of RealFlow’s standard directory.

Ask Frames Path Before Preview

The mode of operation is exactly the same as with “Ask Movie Path”, but helps you to find a location for storing the individual files from the image sequence that is used to generate the final preview video.

Post Action

Generate Video

With this option, RealFlow will automatically create a video file with the compression method, specified under “Code...”.

Codec...

This button lets you choose your favourite video compression method to save disk space and allows smooth playback. The list of available codecs strongly depends on your operating system and its installed components. Please note that Next Limit does not provide any codecs with RealFlow and only reverts to already installed compression methods, e.g. H.264, MPEG2 or other formats.

Open in a new Movie Player

With this option, RealFlow directly loads the freshly generated video to the “Movie player” window. If this window is not already part of your layout, it will be opened automatically

Shell Command

This feature can be used to define commands directly on an operating system level to specify certain aspects of the final video. The associated “Variables” button offers a drop down menu with available commands. It is possible to add more than one variable

Save Image Sequence

When a preview is created, RealFlow takes screenshots using the given “”Width” and Height” values and stores them temporarily. If you want to keep them permanently, you have to check this box.

Top Right Caption

A custom viewport label can be added by choosing one or more entries from the associated “Variables” button list. The caption can also be combined with your own text. Selected variables are listed in the empty field next to the input field. To show the label it is necessary to activate this feature under

Menu Bar > View > Show Preview Caption

An example:

$(SCENENAME) - Preview @ $(FPS) fps / Current frame = $(FRAME)

The first variable “$(SCENENAME)” prints the project's name to the viewport, followed by the adjusted frame rate, “$(FPS)”. Finally the current frame, “$(FRAME)” is attached. A complete output could look like this:

Hybrido_City_Flood_Ver_1.4_120814 – Preview @ 25 fps / Current frame = 428

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