Maxwell Render

This panel provides a fully-featured render manager. A single frame render requires only a few steps:

If you want to change some of the render's properties you can do that from the window, shown below, as well:

  • Image quality is controlled with “Sampling Level” under "Scene" (A).

  • Motion blur can be activated under “Globals" (E).

  • Compositing channels are located under "Channels" (D).

  • Once the image has been finished it will be saved to path specified under “Output” (C).


The window's layout is subdivided into several categories. When you right-click on the rendered image it will be be fit into the canvas:


Jump to

Scene Settings (A)

Time limit

Here you can adjust the maximum render time in seconds. When this limit is reached the render will be finished – no matter if the adjusted “Sampling level” has been reached or not.

Sampling level

The higher the sampling level, the less noisy the final image will be:

  • Plain surfaces are rendered very fast and you can work wither lower levels, e.g. 8.

  • With dielectric materials and SSS, a higher level should be used, e.g. 12 or even 14.

  • Higher levels also increase render time. The information bar keeps you updated about the render progress.


Specify, how many CPU threads you want to reserve for the render. A value of 0 means that all threads will be used.


Maxwell Render comes in two flavours:

  • “Draft” is suited for previews with small “Sampling Level” settings.

  • “Production” should be used for final renders.


The denoiser included in RealFlow is based on Innobright's Altus technology. The denoiser calculation is a biased process applied over unbiased Maxwell renders. The higher the sampling level of the render, the more accurate the denoiser solution will be and the less bias it will introduce.



If on, the denoised image will be calculated using the GPU (much faster usually), if not it will use the CPU. Please, note the scene has to fit into the graphics card memory for it to work.


The Multilight™ feature removes the need to re-render images when light changes are required. Multilight™ allows the user to change intensities of individual lights and multiple scene emitters during and after the rendering process (including Physical Sky and HDR Environment Lighting), eliminating the need to run various renders to tweak the lighting set up.

RealFlow enables Multilight™ support and the associated MXI file can be opened in the Maxwell Render standalone application for fine-tuning. If you save the rendered image as PSD or EXR you will be able to use the separated light layers for composition.

For more information please check out the → Maxwell Render manual. There you will also find a page about the available → intensity and colour modes.


If you the scene contains a preloaded MXS file you can use its lighting environment. Otherwise, the settings from RealFlow's → "Maxwell Settings" will be used.


Displays the current frame. Enter a new value to jump to another frame.


When enabled it is possible to specify an animation range using "First frame" and "Last frame".

First frame

Define the first frame of the animation range.

Last frame

Define the last frame of the animation range.

Camera (B)


The scene's cameras are shown here. Select the camera you want to use for the render.

Width | Height

This is the size of the rendered image in pixels. By default, these values are take from the → camera's own “Width” and “Height” parameters, but they can be overwritten here. If the scene does not contain a camera the sizes are taken from → File | RealFlow > Preferences > Preview.


This is the camera's light sensitivity. The lower the ISO, the more light is required to get a well-lit image. In contrast to real films/sensors, RealFlow's ISO does not add noise to the image. By default, is value is taken from the → camera's own “ISO” parameter, but it can be overwritten here. It is also possible to change a still image's brightness after the render has finished.


This parameter determines for how long the camera's "sensor" will be exposed to light and it is also responsible for motion blur effects. Smaller values create brighter images and longer motion blur streaks. By default, is value is taken from the → camera's own “Shutter” parameter, but it can be overwritten here. The unit is, as in real world photography, 1 / shutter value seconds. It is also possible to change a still image's brightness after the render has finished.

Output (C)

Color Depth

Choose from 8, 16, or 32 bit. If the used file format does not support the chosen depth (e.g. JPG does not support 16 or 32 bit) RealFlow will downgrade to an appropriate value.

Save image | MXI | MXS

If you want to save the different output file enable their checkboxes:

  • PNG is a standard graphic format and the default option.

  • MXI is the Maxwell Render engine's own format and provides important information for the render process.

  • MXS is a scene description format that can be read by RealFlow and Maxwell Studio.

Image | MXI | MXS path

An image's appropriate file path can be seen and changed here.

Channels (D)

Embed channel

When active the channels will be embedded to the rendered image and all existing format selections are ignored. Otherwise they are saved as individual file using the associated file format.

Channel types

There is a total of 12 channels. Activate them by enabling their checkboxes.

Channel format

The default format is an 8-bit PNG. For some channels, e.g. “Motion Vector”, a 16 or 32-bit format is required to get useable results.

Globals (E)

Motion Blur

Activate the motion blur feature here.

Motion Blur factor

The value acts like a multiplier to stretch the motion blur streaks of RealFlow scene nodes. With very small “Shutter (1/s)” values you might require very high factors. Objects from → embedded MXS scenes are not affected.


Maxwell material files (MXM) with displacement information can be evaluated and rendered with this option.


This feature is also know as the prism or rainbow effect, where light is split into its colours.

Search paths

Here it is possible to define additional paths where RealFlow/Maxwell Render should look for missing materials and textures.

Information Bar and Buttons (F)

The “Render” button triggers the render process. During the scene's voxelization you can see a progress bar inside the button. Some renders can be resumed. To do this, export the current MXI file and increase “Sampling Level” or “Time Limit”. In this case, the button changes from “Render” to “...Render”. You will also be asked whether you want to restart or resume the render. The following information is also displayed:

  • “SL” determines the current sampling level.

  • “Next SL” counts the time until the next sampling will be reached.

  • “Time passed” is the elapsed render time.

  • “Time left” tells you how long it will take to finish the render.

  • “Benchmark” is an internal rating system for comparing computer speeds.

The buttons at the window's bottom are self-explaining.