How to use the Corona VFB?

Corona includes its own Virtual Frame Buffer (VFB), designed around the most common needs of artists. It offers advanced post-production capabilities, and various tools you can use to streamline your workflow. 

Some of the actions you can perform directly within the VFB include:

• Drawing render regions and fuzzy regions
• Selecting scene objects directly from the VFB
• Picking a point on the surface of an object to focus the Camera DOF ( 3ds Max | C4D ) directly from the VFB
• Sending the image to Chaos Cloud for AI Enhancement ( 3ds Max | C4D )
• Flipping the image horizontally
• Saving to the CXR format
• Resuming rendering from file or current scene
• Right-click menu in docked interactive render ( 3ds Max | C4D )
• Saving the image downsampled to half of its resolution
• Docking in the UI
• ...and more!

See also: 

Corona VFB 2.0 at the Chaos Documentation Portal:

• 3ds Max
• Cinema 4D

Drawing render regions and fuzzy regions

Enable the "Region" button and click-and-drag in the VFB to draw a region. You can draw multiple regions, and they can be combined. Hold Left Control and click-and-drag on a region border to make it fuzzy (gradually blend with the area outside of the region).

Selecting scene objects directly from the VFB

To pick an object from the rendered image and have it become selected in the scene, click the "Pick" button in the VFB toolbar:

With the "Pick" button active, you can click on any object in the rendered image and that object will be selected in the viewport.

Picking a point on the surface of an object to focus the Camera DOF

To set your Camera's focal point to a certain point in space (on the surface of an object), with the "Pick" button active, right click the point in the rendered image and select "Set focus to this point":

If your Corona Camera has Depth of Field turned on and set to override with "Value" selected as the override, Corona will calculate the distance of the picked point to the camera and set this distance as the value of the Corona Camera's override value:

If the Corona Camera you are using does not have Depth of Field activated or "Override focus" is not activated, selecting a point will change the camera's "Target distance".

Sending the image to Chaos Cloud Collaboration for AI Enhancement

Simply click the "AI Enhancer" button to start the upload and enhancement process:

To send your image to Chaos Cloud without the AI Enhancement data, use the "Collaboration" button:

Flipping the image horizontally

Use the "Flip" option to flip the VFB content horizontally so that you can see it from a different perspective:

To enable proportion guide lines, open the Proportion Guide Lines section in the VFB sidebar and tick the checkbox of any guide you want to display. 

The following guide types are available:

• Center Cross - displays a single vertical and horizontal line crossing at the center of the image.
• Diagonals - displays the two corner-to-corner diagonals of the image.
• Rule Of Thirds - divides the image into a 3×3 grid, useful for placing key subjects along the third lines or at their intersections.
• Golden Ratio - divides the image based on the golden ratio (1:1.618), a classic compositional aid.
• Custom Grid - displays a user-configurable grid (rows and columns can be adjusted).
   

Accessing VFB settings from a dedicated dialog

Starting from Corona 15, the most commonly used VFB settings can be accessed directly from the VFB itself, without having to open the Render Setup window. Click the Settings button in the VFB toolbar:

This opens the VFB Settings dialog, where you can configure multiple options: 

 

Saving to the CXR format

You can save a CXR file for further editing in the Corona Image Editor or to continue rendering from it:

Resuming rendering from file or current scene

You can use the "Resume Last" option to continue rendering the current scene or "Resume File" to continue rendering a previously saved CXR file: 

Right-click menu in docked interactive render

With interactive rendering docked in the viewport, right click to bring up a menu with various handy options:

• Set focus to this point
  Sets the Corona Camera focus point to the clicked point on the object.
• Copy to clipboard
  Copies the IR image to clipboard
• Copy to max
  Copies the IR image to the Max's native VFB
• Stop
  Stops the IR in the viewport
• Restart
  Restarts the IR in the viewport

Saving the image downsampled to half of its resolution

Click the vertical arrow next to the "Save" button and pick "Save 50%" to save your image in half of its original resolution. When combined with denoising, you can use this option as a way to greatly reduce your render times.

See: How to render 6x faster in Chaos Corona

Docking in the UI

You can dock the Corona VFB in 3ds Max UI by using the "Dockable" option. In Cinema 4D, the VFB can be docked natively. 

Using the color picker

Hold right mouse button over a pixel to read its color values:

Hiding button labels

Go to Render Setup > System > System Settings and enable the "Hide tool labels" option under "VFB Settings" to make the VFB's top toolbar more compact:

Hide the right-hand sidebar

You can use the "Hide or show tools sidebar" button to toggle the sidebar on and off:

Print useful information in the VFB title bar

Go to Render Setup > System > System Settings and enter custom text next to "Title" under "VFB Settings" to have it printed in the VFB title bar. In the example below, we are showing current RAM usage in the VFB title bar:

To find out what variables are available, click the small "?" button in System Settings. 

See also: 

Corona VFB 2.0 at the Chaos Documentation Portal:

• 3ds Max
• Cinema 4D