Converting an Interior Scene to MtoA

Rollover image for wireframe

 

This tutorial is a breakdown of the workflow required to convert an interior scene that has been setup for

another renderer for rendering with MtoA. Scene setup and rendering should take no longer than an hour.

The scene used in this example is part of of architectural interiors.this collection

The workflow covers the following topics:

Lighting

Shading

Render Settings

 

The scene has been exported from 3ds Max as an .fbx file and imported into Maya using the FBX plugin.

Another tutorial that demonstrates different ways to approach lighting a room can be found .here

When you import the scene, you will see that the Outliner and Hypershade windows are quite messy. Before you start, Go to File> Optimize Scene to delete any empty group nodes and add the geometry to a group node.

Lighting 

The scene is lit very simply with a light and positioned outside of the Skydome Light Portalswindows of the room. You may need to increase the number of for final Skydome light samplesrendering ( or ).3 4Increase the   of the Skydome light to around .Exposure 4

Use a   to simulate sunlight coming through the far window. Increase the Directional light Angle slightly to around . This will give the sunlight a softer edge to the shadow on the floor. You may 0.2need to increase the Directional light's if you do ( should suffice). Enable Samples 3  Color

and choose a slightly warmer temperature like .Temperature 5000

Scene lit with light portals (with Skydome light) outside of the windows and a representing sunlightDirectional light

To preview how the lighting will affect the scene, you can apply a default shader Standard Surface

override to the scene. This effectively creates a 'chalk preview' of your render and allows you to

focus purely on lighting without being concerned about shading. Alternatively, there is a 'Lighting'

mode in the Debug Shading in the window.Arnold RenderView

 

Shading

The scene comes with default Phong shaders in Maya, visible in the Hypershade window. These need to

be converted to   shaders. Standard Surface

Default Maya scene with Maya Phong shaders visible in the Hypershade window

Reducing the to will disable indirect lighting. This is useful when you Diffuse samples 0  effectively

want to test render direct lighting in the scene and will also be quicker to render.

Diffuse Samples: 0 (disables indirect lighting)

 

Select a Phong shader and open the Attribute Editor. Select Phong from the 'Type' scroll down

menu and choose Standard Surface. Any diffuse color information will carry over to the Standard

Surface shader. 

 

If the Phong shader has textures assigned to the Color, these will automatically be connected to the Base

 of the Standard Surface shader, requiring no extra effort. Color

 

Floor Shader

A is supplied with MtoA to facilitate the conversion of multiple shaders to shader conversion script

Ai Standard.

Connect the diffuse color map to the of a Standard Surface shader. Base ColorConnect the bump map to the attribute. Reduce the to a small amount like Bump Bump Depth 0.03.Increase the   to and reduce the to to give the floor a Specular Weight 0.3 Specular Roughness  0.1 glossy appearance.

Mirror

Assign a Standard Surface shader to the mirror and rename it 'Mirror'.Increase the to . Base Weight 1Increase  to .Metalness 1

Curtain

Here, we will add some translucency to give the effect that the curtain is being lit from behind.

Assign a Standard Surface shader to the curtain and rename it 'Curtain'.Increase the to around and enable .SSS 0.5 Thin Wall

Rollover image to see the effect Thin Wall and SSS has on the curtain

Glass Door

Any glass surfaces will need to have ' ' disabled. Otherwise, any shadows cast by the object will Opaque

always be solid and not pick up the refraction color or density of the shader.

Select the window geometry and disable 'Opaque' in the Arnold tab of the Attribute Editor.

Opaque switch disabled for non-opaque surfaces such as glass

Assign a Standard Surface to the glass door and rename it 'Glass'.Reduce the to .Base Weight 0Increase the to .Specular Weight 1Increase   to (this makes the glass transparent).Transmission Weight 1Increase the  (IOR) to (glass).Index of Refraction 1.5You can also add a tint to the glass very easily by adding a subtle hue to the   color. Transmission

Ensure that the polygon face normals are all facing in the right direction (especially important when

rendering glass surfaces with Arnold). 

 

Render Settings

Sampling

For the final render, the   settings were increased to 6. Camera (AA)The   were also increased to 6 to reduce noise in indirectly lit areas of the room. The diffuse_samples  images below show the difference between rendering 2 (default) and 6.diffuse_samples

Rollover image to see difference between 2 and 6 diffuse_samples

Ray Depth

Diffuse Ray Depth

The images below were rendered using a  of 1 4 You can diffuse_ray_depth (default) and   (rollover image).  

notice a clear difference of bounced light around the curtain for example.

Care should be taken when increasing this value as your render times will increase dramatically.

More information and tutorials about removing noise can be found .here

Rollover image to see difference between 1 (default) and 4diffuse_ray_depth

Transmission Ray Depth

You can 'clearly' see the difference in the glass vases when increasing the in the transmission_ray_depth

images below.

2 4

Note that render times will linearly increase with regards to the number of ray diffuse bounces and

therefore care should be taken when increasing this value.

 

That concludes this tutorial on converting an interior scene for rendering with Arnold. 

 

 

More information about rendering glass surfaces can be found .here