Open topic with navigation

# Description of the Unreal import settings

Overview

- Import in Unreal

- Basic settings for importing

- Redshift light sources
- Redshift cameras

- Advanced import settings
- Selective import settings
- Import settings for animated assets
- Import settings for textures
- Settings for geometry caches
- Imported assets in Unreal

Note

The explanations on this page refer to the import of Cinema 4D files (.c4d) in the Unreal Engine. Other options are also available, e.g. via a Direct Link connection or the .udatasmith format, which are described on this page.

# Import of Cinema 4D assets into Unreal

If the plug-in components described here are installed and active in Unreal, a Datasmith>File Import... function will be available via a separate icon in the main menu of the Unreal Editor, which also directly supports the Cinema 4D data format .c4d, among others. Contrary to the way previous versions worked, the scene in Cinema 4D no longer needs to be saved via File>Save project for Cineware.... Normal saving, e.g. via File>Save project as... is sufficient. The Cineware settings under Edit>Project Preferences.../Cineware can also be ignored when working with Unreal. Generators and Node Materials will automatically be converted by Unreal during import, and the desired texture size can also be selected directly in Unreal during import.

Trigger a file import and select the target folder for the import.

## Basic import settings

Selecting Datasmith>File Import... will open the standard file dialog, which can be used to load a .c4d file directly. During this import, you will be asked for the desired directory within your Unreal project into which the data should be loaded. By default, this is the content folder, as can be seen in the right half of the above image. The imported data will then be stored there as native Unreal .uasset files.
The next step will open the actual import settings, which you can use to select the properties of the Cinema 4D file to be imported, among other things. The following options and settings are available there:

Geometry | Objects and their geometry will be imported as static meshes. Note that only the front side of the polygons is visible in Unreal by default. To make both polygon sides visible, the option for Material Property Overrides>Two Sided must be activated in Unreal for the material of the geometry. In addition, no objects or geometries created with scene Nodes are currently supported during import.
Materials & Textures | Materials and the textures used in them will be loaded. The resolution used for baking the material properties in bitmap textures can be selected separately in the Node Material Textures group. Please note that not all native Cinema 4D shaders and Nodes can be baked and imported as textures. You should therefore create all parametric material information as textures yourself before saving in Cinema 4D, if possible. Redshift Node Materials are also supported (no XPresso materials), although no displacement settings will currently be adopted. Materials will usually be implemented in Unreal with the default LIT shading model. Redshift materials that have active subsurface scattering (SSS) with a weight setting above 0 are an exception to this. The Subsurface Scattering Shading Model in Unreal is also used for these materials.
Lights | The light sources of the Cinema 4D scene will be imported as Light Actors. Please note that not all configuration options are also available in Unreal. For example, Area lights can only be rectangular, disc-shaped, cylindrical or spherical and are then generally imported into Unreal as rectangular Area lights. The use of several Infinite light sources can also be problematic with regard to shading in Unreal. Redshift light sources are also supported. Additional information can be found here.
Cameras | Imports the Camera objects of the Cinema 4D scene as Cine Camera Actors. Redshift cameras are also supported. You can find further information here.
Animation | Animated properties will be imported. This includes, for example, the classic Position, Angle and Size keyframe sequences, but also the render visibility of objects to animate their visibility. Animations implemented using scripts or XPresso circuits, for example, must be baked as keyframes before being saved in Cinema 4D. Animations in which the number, sequence or position of surface points change can be imported as a Geometry Cache. This also applies to simulations that have been saved as a cache. The principle corresponds to the use of the Allembic storage format, in which animations are saved image by image. You will find a separate option for this in the Geometry Caches group, which can also be used to import PLA keys, for example. By using the Custom Frame Range option in the Animation section, only a part of the Cinema 4D animation can be loaded.

### Redshift light sources

By activating the Lights option mentioned above, light sources from CInema 4D projects can also be transferred to Unreal. This also applies to Redshift light sources, although only these types are supported:

- RS Point Light (point light source)
- RS Spot Light (spot light source)
- RS Area Light (Area light source): Only rectangular light shapes are supported directly in Unreal (Light Type Rect). Special shapes, such as a Redshift Dome Light or a geometry that is used in conjunction with a Redshift Area Light for illumination, must be converted manually in Unreal.
- RS Infinite Light (Infinite light source)

Since lumens and lux are used in Unreal as units for determining light output and these are dependent on the size of a light source or a light cone, light brightnesses and intensities must be converted.

The following applies to Point lights (RS Point Light):

Redshift unit | Conversion to Unreal
--- | ---
Image | Intensity (lm) = Intensity / pi
Luminous Power | Intensity (lm) = Intensity
Luminance | Intensity (lm) = Intensity / (pi * 1000)
Radiant Power | Intensity (lm) = Intensity * LuminousEfficacy
Radiance | Intensity (lm) = Intensity * LuminousEfficacy / (pi * 1000)

The same applies to Spot lights (RS Spot Light) as to Point lights, except that the light intensity is also influenced by the aperture angle of the Spot light:
Intensity (lm) = Intensity * (1 - cos (angle of the light cone) * 0.5)

The following applies to Area lights (RS Area Light):

Redshift unit | Conversion to Unreal
--- | ---
Image | Intensity (lm) = Intensity * Area / 2pi
Luminous Power | Intensity (lm) = Intensity * Area
Luminance | Intensity (lm) = Intensity / (pi * 1000)
Radiant Power | Intensity (lm) = Intensity * LuminousEfficacy * Area
Radiance | Intensity (lm) = Intensity * LuminousEfficacy / (pi * 1000)

The following applies to infinite lights (RS infinite Light):

Redshift unit | Conversion to Unreal
--- | ---
Image | Intensity (lux) = Intensity * 500
Luminous Power | Intensity (lux) = Intensity * 200
Luminance | Intensity (lux) = Intensity / 10
Radiant Power | Intensity (lux) = Intensity * LuminousEfficacy / 17
Radiance | Intensity (lux) = Intensity * LuminousEfficacy / 17

### Redshift cameras

Redshift cameras contained in Cinema 4D projects can also be transferred. The following settings will be applied:

- The value for Focal Length (mm) as found in the camera's Object settings.
- The width of the sensor size as set via the X component of the Size (mm) value in the Object settings of the camera. The height of the sensor is determined by the Aspect Ratio value from the Output section of the Render Settings in Cinema 4D.
- The Focus Distance from the Optical section of the Redshift camera.
- The Shutter Speed (s) as found in the Optical section of the Redshift camera.
- Exposure (EV) or sensitivity (ISO), depending on the selected Exposure mode in the Optical section of the camera.
- The Aperture (f/#) from the Optical section of the Redshift camera.
- An assigned tTrget object within an Alignment Expression for automatically aligning the camera to an actor. The corresponding target object will be used as an Actor to Track within the Lookat Tracking Settings in Unreal.
  In order to be able to use the tracking of a Focus (assigned object in the Depth of Field settings of the Redshift camera) in Unreal as well, you must manually switch to Focus Method Tracking in the Focus settings of the imported Redshift camera and then manually assign the corresponding object for Actor to Track.

## Advanced import settings

Min Lightmap Resolution | Unreal can use existing or self-calculated UV maps on the objects to bake lighting information (so-called light maps). As a result, the display of static objects under static lighting can be accelerated and implemented with higher quality. This setting defines the smallest possible resolution for one of the resulting UV islands. In general, square UV-Map tiles will always be created.
Max Lightmap Resolution | This is where you can define the maximum resolution for the creation of light maps. Please note that you can also adjust this value individually for each Geometry Actor at a later date. You should therefore use an average value for the import.
Generate Lightmap UVs | Activate this option so that Unreal itself creates UV mappings of the geometry during import, which can be used to bake light maps. If the imported objects already have the appropriate UV processing that is also to be used for baking the light maps, this option can remain disabled. This not only shortens the time required for importing, but also saves memory, which would otherwise be required for the additional UV coordinates. Existing UV coordinates, which are used for assigning materials, for example, will be retained in any case.

## Selective import settings

If your Cinema 4D project contains several assets, you can already control which of them should be transferred to the Unreal Editor by creating a selection in Cinema 4D. If only the objects selected in a Cinema 4D scene and their subordinate hierarchies should be loaded, activate this option for Selection Only. Otherwise, all objects in the Cinema 4D scene will always be loaded as assets.

## Import settings for animated assets

If animations have been created within the Cinema 4D scene, you can selectively load only a single time segment of these animations. To do this, activate the Custom Frame Range option for the import and then enter the frame numbers of the first and last animation frame to be loaded for Start Frame and End Frame. If Custom Frame Range is disabled, the complete animation of the assets will always be loaded.

## Import settings for texture sizes

In the Node Material Textures settings group, you will find the square resolution used (Texture Resolution), which can be used for the automatic adjustment of the imported textures. All textures used in the Cinema 4D scene can therefore be scaled up or down to this resolution during import.
This scaling can be influenced via the setting in the Texture Resize menu:

- Don't Enlarge: Only textures that are larger than defined in Texture Resize will be resized accordingly. Textures whose original resolution is smaller than specified in Texture Resize will remain unchanged.
- Always: The resolution of all imported textures will be adjusted in order to achieve the default resolution of Texture Resize. Smaller textures will therefore be enlarged and larger textures will be reduced in size.
- Off: All textures retain their original resolutions, just as they are used in Cinema 4D.

Incidentally, the settings in the Node Material Textures group also apply to non-Node Materials, such as the old standard material from Cinema 4D. However, as Redshift is now the standard renderer for Cinema 4D, you should also use its Node Materials.

## Settings for geometry caches

Selection of the properties to be imported and activation of the import of parametric animations as geometry caches.

Import GeometryCaches | Geometry caches are required, for example, for importing animated point positions (e.g. PLA keyframes in Cinema 4D). This can be used to import object deformations or the results of a baked Cloth simulation, for example. Activating this option alone will not result in the import of this information, but will open an additional dialog when the import button is clicked, in which the creation of the geometry cache for the objects present in the imported scene can then be activated (see right-hand side of the image above).
Individual LevelSequences | Activates the imported objects for use in the Unreal Sequencer. The Import GeometryCaches option must be active for this.
Add to main LevelSequences | Adds the imported objects to the main level sequence. The Import GeometryCaches option must be active for this.

## Imported assets in Unreal

After importing, the objects will automatically appear in the outliner (see following image). In addition, all loaded components (animations, geometry, materials, textures) will be available in the Content Browser.

The loaded objects appear directly in the outliner.

All components can be viewed separately in the Content Browser.