The IPR window consists of a toolbar, the image area, and a status bar

The Arnold IPR window is designed to give real-time feedback on changes made in the scene, offering a significant workflow speed-up. The Interactive Preview Render window will automatically update the render every time it detects a change in the scene (such as moving the camera, objects or lights, or any kind of lighting or shading modification). This speeds up your workflow as it is not necessary to keep starting new renders because the IPR is constantly updating for you.

The interactive preview render uses a progressive refinement method to provide a fast response. The image is rendered several times by increasing the AA samples in each of the steps (previous steps are not reused). The render will complete when the target AA is achieved (it will output the same image as the final frame render). You can change the step settings of the progressive refinement in the Arnold render settings.

  • While the IPR is running, material previews are not rendered because only one render session can be active in Arnold at the moment. If you stop the IPR then the material previews will be updated. The last rendered preview is displayed with a small orange frame showing that the preview is delayed. The IPR will also stop if you start a render from the Picture Viewer due to the same reason.
  • The IPR requires the viewport (editor) window to be open. If the viewport window is closed, the IPR does not update any changes, resulting in an invalid state. This is a limitation in C4D as it stops calling the Arnold scene hook when the viewport window is closed.
  • C4D's built-in IRR (Interactive Render Region) feature also works with Arnold, however, it has a lot of limitations and it's not recommended. Use this IPR window instead.

Information about imagers can be found here.


The visibility of toolbar items can be specified via the View > Toolbar menu.


You can use the play  button on the toolbar to start and stop the interactive render. It's a two-state button, highlighted if the IPR session is active. Render starts automatically when the IPR window opens.


The pause  button stops updating (re-export and re-render) the scene until it is released and collects all changes in the background. It's useful to save time between multiple changes when the scene export takes too long.


Defines the resolution of the interactive render by scaling the final render resolution (Render settings/Output). A lower resolution gives faster interactive render times without affecting your scene settings.


Defines the resolution of the interactive render independently from the final render resolution. A lower resolution gives faster interactive render times without affecting your scene settings. You can enable this mode in View > Toolbar > Show resolution > Width x Height.

The widget has a popup menu where presets are listed (similar to the resolution in the Render Settings). The ratio can also be locked which means the width and height updates automatically when changing the other component.


The Zoom level of the image area.  Works the same way as zoom in the Picture Viewer. You can also use the mouse wheel to zoom in or out of the image. Zoom does not affect the render time or quality of the IPR.


This button  enables or disables imagers in the scene. Individual imagers can be enabled or disabled via the context menu of the button (right click). The context menu also allows you to add a new imager or select a LUT file for tonemapping. For further editing of the imager list (e.g. change order, remove imagers, etc.) open the Post side panel or click Edit... in the context menu.

Display Settings 

This button  enables or disables the display settings (e.g. color correction, LUT) in the IPR window. The display settings are applied to the color corrected (view color space) render output and affect only the IPR window (they are not applied to the PV or batch render).

Debug Shading

This button enables or disables debug shading mode. The active debug shading mode can be defined in the Render > Debug shading menu or from the context menu of the button (right mouse button).

Isolate Selected

This button  enables or disables the isolate selected mode which helps debugging scene by isolating the selected nodes in the render. The following nodes can be selected:

  • Geometry: renders the selected geometry only, all other geometry is rendered as a black matte.
  • Material: renders the selected material only, all other materials are rendered as a black matte.
  • Shader: renders the selected shader from a material (e.g. utility, texture, blend, etc.), showing its resulting output in the render.
  • Light: isolating a light means that all other lights are disabled, and the scene is lit exclusively with the selected light.

The selection can be locked from the context menu of the button (right mouse button) , which ignores selection changes.

Render Region

Use the render region tool  to marquee select an area within the IPR window that you wish to render. You can press Shift and left mouse button to define the region. You can also use the boxes on the corners and sides of the region to define the area that you want to update and the center box to move the region around the IPR window. The selected region in the IPR window will update as you adjust the scene. This speeds up workflow when fine-tuning areas of a scene, such as a particular shader or lighting effect.  

Marquee region updates only that part of the rendered image

Motion blur

This button  enables or disables the motion blur effect in the IPR when it's enabled in the scene. 

Motion blur requires a full copy of the scene by every change which affects performance. That's why motion blur is ignored by default.

Auto Tx 

This button  enables or disables auto tx generation in the IPR window. 


You can select an AOV to display in the IPR window. All available AOVs (active and inactive) are listed. Click Setup AOVs... in the menu to add AOVs to the scene. See AOVs.


You can select the render camera from the interactive preview. The box lists all Camera objects of the scene along with two special items:

  • <active camera>: always reflects the camera selected in the viewport.
  • <default camera>: the default C4D camera which is active when no Camera objects are activated.

Color Space

When enabled, the Color Space combo box is visible in the toolbar, listing the available color spaces based on the active color manager (e.g. OCIO). Select the option 'scene' to use the default view color space defined in the render settings.


You can select which color channel to display in the IPR window (e.g. R, G, B, etc.).

Reload Textures

This button  allows you to quickly flush the texture cache and restart the IPR when you edit a texture file.


Click on this button  to send the current IPR image to the Picture Viewer. Making snapshots this way allows you to compare the output of different scene settings and also enables you to save the image to the disk.

Custom information, such as render time, sampling settings, memory usage, etc. can be imprinted into the name and/or over the image via the Snapshot settings dialog (Render > Snapshot settings... or right mouse click on the button). For more details on the text overlay settings, please check the Text overlay page.

Snapshot specific tokens which can be used in the name and text overlay:

  • <aov>: name of the active AOV displayed in the IPR window.
  • <index>: snapshot index (e.g. 004).


The sidebar is located at the right of the IPR window and can be opened from the View menu or by clicking on one of the sidebar tabs.

Display Filter

The display filter panel allows you to adjust the displayed image by applying LUT files or color correction settings. See the Display Settings page for more details.

Pixel Information

The pixel information panel displayed detailed color information of the pixel under the mouse pointer. See the Pixel Information page for more details.

Menu bar

View menu

Show Pixel Information

Displays the coordinates and color of the pixel under the mouse pointer in the status bar. 32-bit RGB values in render color space and 8-bit RGB values in view color space are displayed.

You can sample a 5x5 pixel area under the mouse when pressing the Ctrl/Cmd key.


Defines visibility of the items on the toolbar (see above).


Defines the active side bar panel (see above).

Fit to Window

Updates the zoom to fit the image to the window.

Fit to Render Region

Moves the render region to the center and updates the zoom to fit the window.

Center Render Region

Updates the scrollbar and moves the render region to the center of the window.

Render menu 

Render All AOVs

When enabled all selected AOVs are rendered at once which means the IPR does not restart when you change the displayed AOV. Could be useful for debugging complex scenes where you have to change between AOVs frequently.

Rendering all AOVs affects performance so recommended to be disabled by default.

Debug Shading

Overrides the shading in the scene by the selected utility shader mode for debugging purposes. Debug shaders are presets in the Arnold material library. You can save custom debug shader presets to the Arnold user library (arnold user.lib4d) which can be selected from this menu as well. Click on User > Open Content Browser... to open the user library.

Copy to render settings

Copy debug shader settings to Render Settings > Diagnostics > Feature overrides > Shader override used in final render (Render to Picture Viewer).

Snapshot settings

Opens the Snapshot settings dialog where name and text overlay settings can be configured. See the Snapshot section above.

Copy Region to Render Settings

When you enable Render Region in the IPR and click on 'Copy region to render settings', then the region (left, right, top, bottom) is set as the render region in the Render Settings window. This enables you to transfer the same region render dimensions to the Picture Viewer window.

Region render dimension setting copied to Render Settings window

Anamorphic Workflow

When enabled the IPR window shows the de-squeezed image, allowing you to work on the original pixel aspect.

Render to Viewport

Display the render on top of the viewport instead on the IPR window.

Auto Start When Window Opens

If enabled the IPR starts automatically when the window opens (e.g. open from the Arnold plugin menu).

Clear Bitmap

Clears the bitmap (fills in with black).

Status Bar

The status bar provides information about the actual render and output. (Rendering...) label is displayed at the beginning of the status bar message while the interactive render is running. The following information about the render is presented in the following order:

  • Debug shading mode if enabled.
  • Render time.
  • Camera / Diffuse / Specular / Refraction / SSS / Volume indirect sampling rates. Check the Sampling page for more info.
  • Memory usage of the IPR process.
  • Resolution of the render.
  • Region dimensions if region render is enabled.
  • Pixel information when enabled.

Camera Controls

Camera controls are available in the IPR window, similar to the viewport:
  • Alt + LMB + move: Rotates the camera.
  • Alt + MMB + move: Moves the camera.

  • Alt + RMB + move: Moves the camera closer / farther (zoom in / out).

  • Alt + scroll: Moves the camera closer / farther with a unit (200 cm).

Alternatively, you can use 1,2,3 + LMB as well, similar to the viewport.

Controls are working only if the IPR is active.

In the viewport, zooming (scaling) moves the camera towards the object under the mouse cursor and speed depends on the distance from this object. In the IPR window, zooming (scaling) always moves the camera forward and with the same speed, independently from the mouse cursor.


Keyboard shortcuts that you can use are in the IPR window:

  • Alt + W and F: Updates the zoom to fit the image to the window.

  • Alt + W and G: Moves the render region to the center and updates the zoom to fit the window.

  • Alt + W and H: Updates the scrollbar and moves the render region to the center of the window.
  • Alt + W and P: Pause the IPR.
  • Alt + W and R: Start/stop the IPR. Opens the IPR window when it's not visible.
  • Alt + W and S: Take a snapshot to the Picture Viewer.
  • Alt + W and T: Enable / disable region render.
  • Alt + W and V: Redirect render to the viewport.
  • S: Frame the view to all selected elements.
  • O: Frame the currently selected object.
  • H: Frame all.

You can change these shortcuts in Window > Customization > Customize Commands...

Other shortcuts using the mouse:

  • Shift + LMB + drag: Select an area within the IPR window that you wish to render.
  • Ctrl + LMB: Select the object under the mouse.
  • Ctrl + Shift + LMB: Adds/removes the object under the mouse to/from the selection.
  • Ctrl + Alt + LMB: Pick focus distance in the IPR window. If you have a camera with depth of field enabled you can simply change the focus by clicking on an object in the image.

Context Menu

context menu is available in the IPR window when you right click on an object.  

  • Select object: Select the object under the mouse.
  • Append to selection / Remove from selection: Adds/removes the object under the mouse to/from the selection.
  • Pick focus: Pick focus distance in the IPR window. If you have a camera with depth of field enabled you can simply change the focus by clicking on an object in the image.
  • Create Arnold material: Create a new Arnold Shader Network material in the scene and assign it to the object under the mouse.

You can drag & drop a material onto an object rendered in the IPR window.

  • No labels
Privacy settings / Do not sell my personal information / Privacy/Cookies