Converting a Scene to C4DtoA

 

In this tutorial we will cover how to convert a scene that has been setup to use the Standard renderer in C4D to the C4DtoA plugin renderer. We will cover how to use the Standard Surface shader to create realistic materials such as glass, chrome and paint work. We will replace the existing scene's many lights with the Skydome light to give us more control and a more realistic look. We will also use volume scattering to create a realistic thruster effect for the spaceship. The scene that we will be using is part of the content library. If you do not currently have this, you can install it separately via the C4D installer. 

This scene will cover the following topics:

 

Scene Lighting

Shaders

Volume Scattering

Background

Render Settings

 

  • Open the scene Retrospace.c4d from the Content Browser. It can be found in the folder Presets> Prime> Example Scenes> Retrospace.

 

  • The scene should look like the image below. We will only require the body paintwork texture (retrospace_body_Color.psd). We will not require any HDRI environment maps because we will be using the physical sky shader to light the scene. The dial texture maps wont be needed as we will be focusing on rendering the exterior of the spaceship. Also, we will not need the reflection headlight textures because they are fake reflection effects which are not required for proper production raytracing (Arnold is a raytrace renderer and therefore traces rays in a physically accurate manner). 

Click on the 'Textures' folder to view the textures associated with the scene

 

  • Lets remove all C4D Materials first. We will create our own Arnold shaders.
  • IPR render the scene (Plugins > C4DtoA > IPR Window). You should see a completely black screen. This is because there is an environment spheres surrounding the scene, found within the Environment null group. Delete the complete Environment group as we will not need these objects to light the scene. We will use one skydome light to illuminate the scene instead of the many lights that this scene contains. This will give us a realistic lighting setup that requires minimal effort and will be far easier to control.

Scene Lighting

  • Create an Arnold Sky object (Plugins > C4DtoA > Arnold Sky). This will add a skydome light to the scene.

 

  • The skydome light is visible in the background by default. We don't need that now, so change the Camera flag to 0.
  • You should now see that the scene is evenly lit by the white color of the skydome light. Don't worry about the shadow noise at the moment. We can increase the number of light samples once we are ready to do a final render.

 

  • Change the Type of the Arnold Sky to physical_sky.
  • Increase the Exposure of the skydome light to around 2.
  • IPR render the scene. It should look something like the image below.


Shaders

We will now replace the existing C4D shaders with Arnold's proprietary, physically accurate shaders.

Chrome

  • Create a Standard Surface shader in the Material Manager - Create > Arnold > Surface > Standard Surface and rename the material to Chrome. Select the metal Material type to give it a shiny metallic appearance and lower the Specular Weight and Specular Roughness to 0. (The Specular channel is used as the edge tint of the metal which is not needed now.)

Note that the material preview does not update while the IPR is running, indicated by a small orange frame. It's a limitation in Arnold, only one render session can be active at the same time. If you stop the IPR the preview updates normally.

 

  • Apply the Chrome material to all of the objects in the scene that have chrome on them. This means the chrome polygon selection of the main / Null / newBody object, the bolts, backbolts, nosebolts, finChrome, antenna, exhaust pipes and chrome groups.

A video that demonstrates working with the Arnold Shader Network editor can be found here.

 

Paint

  • Create another Standard Surface shader and rename it to Paint.
  • We now want to apply the paintwork texture from the Textures Folder in the Content Browser. Open the texture retrospace_body_Color.psd and save it to disk. Drag & drop the file texture onto the shader network editor window. It should automatically generate an image shader for you. Connect the image output to the Base Color input of the standard surface shader.

retrospace_body_Color image connected to the Diffuse Color input of the Paint standard shader

It is recommended that you convert all texture maps to .tx format prior to rendering using the TX Manager to achieve the best performance.

 

  • Assign the Paint material to the newBody object.

 

  • IPR render the scene again. You should see something like the image below. 

Glass

Let's add a glass shader to the windscreen. 

  • Create a Standard Surface shader, rename it Glass and apply it to the windscreen geometry (newBody / Polygon Selection.3). You can replace the existing glass shader that is already assigned to the existing polygon selection set.

 

  • Select glass from the Material type menu of the standard surface shader.
  • Add some color to the Transmission to give the glass a colored tint effect.

Opaque

When rendering glass surfaces you should disable Opaque for the geometry and ensure that the geometry normals are pointing in the right direction. More information about rendering Refraction and Opacity can be found here.

  • Add an Arnold Tag (C4DtoA Tags> Arnold Parameters) to the windscreen geometry and disable Opaque.

The images below show the difference when rendering with and without Opaque enabled.

 

The final glass shader settings should look like this:

 

  • Assign the Glass material to the headlight Sphere object at the front of the spaceship as well (main / Null / Sphere) and position a point light there.

Interior

  • Create a standard surface shader, change the Base Color to red and assign it to the interior and rear view mirrors groups.
  • Create another standard surface shader for the seat leave it on default values and Assign it to the interior / seat / HyperNURBS / Symmetry / Null / Cube / Cube object.

Volume Scattering

JetFlame Lights

We can replicate the light thruster effect using Atmosphere Volume shader. If we create the volume scattering first, we will be able to view any changes to the lights in the IPR window.

  • In the Material Manager, create an Atmosphere Volume shader - Arnold > Volume > Atmosphere > atmosphere_volume.
  • Increase the Density to 1.
  • Drag the  material onto the Atmosphere field in the Arnold Render Settings window.

 

  • Select the Light under the JetFlame group in the Object Manager window. Under the General tab change the Type to Spot.
  • Add an Arnold tag to the light (C4DtoA > Arnold Parameters) and increase the Exposure to around 5.
  • IPR render the scene. You should get something that looks like this:

You can use the Aspect Ratio to affect the shape of the JetFlame spotlight shape.

 

  • To give the light a cool blue effect, enable Use color temperature under the Details tab in the Arnold tag and change the Temperature to around 15000.

 

  • You can control the way the thruster's light falls off using a light_decay filter. The light decay filter can be found in the Material Manager - Create > Arnold > Light Filter > light_decay. Enable Use far attenuation and increase the Far end to fade out the thruster effect (around 200 cm should suffice). Drag the light decay material onto Light filters in the Details  tab of the Arnold tag. 

 

  • Repeat the same process for Light.2, however, change the color temperature to around 2800 to give a warmer effect and extend the light decay (create a new one) Far End to around 4 to extend its effect slightly beyond the blue JetFlame light. Once you are happy with the effect, you can either duplicate what you have done for the other thruster or copy the Arnold tags to the other JetFlame lights. You should have an effect similar to the image below. If you are happy with what you have done, why not try replicating the effect using an Arnold Spot light.

JetFlames using volume scattering (remember to make a 'shhhoooooofffffff' sound when viewing this image)

Background

We will finish by creating a suitable background image of space for our spaceship scene.

  • Start off by creating a Background Object - Create > Environment > Background.
  • We will need to apply an image texture to the background. In the Material Manager go to Create > Arnold > Texture > Image and drag & drop it onto the Background in the Object Manager.
  • Open the shader network editor of the image shader and under Image name choose a suitable image. In this case we have used a photo of the milkway. This texture can be downloaded from the sIBl Archive. Alternatively, you can drag & drop the texture map from a file manager onto the Arnold Shader Network editor window and it will automatically create an image shader for you.
  • You could also try connecting a color correct node to the image shader. The settings below have been used to adjust the look of the milkyway texture.

Render Settings

Once you are happy with the scene it is time to do a finished render. 

  • Select the Arnold Sky and increase the number of Samples to 3. This should reduce the overall shadow noise in the scene at the cost of increased render time.

 

  • Open the Render Settings window  and go to the Main tab. Increase the Camera (AA) samples to around 5 or 6. That's it! You are ready to render.

 

That concludes this tutorial on converting an existing scene that has been setup for the standard renderer to render with C4DtoA.

 

The final scene (R18) can be downloaded here.

 

 


Thanks to Anders Kjellberg for the use of his Retrospace scene.


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