In this tutorial, we will cover how to use the standard_surface shader to create realistic materials such as glass and metal. We will also replace the existing scene's lighting with the skydome light in combination with an HDR image to give us more control and a more realistic look. Lastly, we will add some jet thrust to the exhausts using a combination of spot lights and atmosphere_volume.
The original Maya scene files for this series of tutorials can be downloaded from Autodesk's Hyperspace Madness production.
This tutorial will cover the following topics:
Import the spaceship model into the scene. It contains various Blinn and Phong shaders. We want to convert these shaders to more physically accurate shaders within MtoA. Fortunately, we can use the shader Type menu in the Attribute Editor window to convert them. We will largely be using the multi-purpose standard_surface shader.
The incandescent file map (ship_wings_emissive.tga) should be connected to the emission_color of the Ai Standard Surface shader. Increase the emission_scale to 1.
We will assign a glass material to the cockpit glass. In this scene, the glass has been modeled without thickness. This will render incorrectly because glass has a thickness in the real world and Arnold is a physically accurate renderer. Select the glass objects and extrude them slightly.
Left: Thin surface: Glass refracts improperly as a solid object. Right: Extruded glass: Cockpit refracts properly through the glass. Rollover images.
Ensure that the normals are facing in the right direction. This is essential when rendering realistic glass.
Normals pointing in the correct direction (outwards)
Assign a Standard Surface shader to the cockpit glass and rename it to 'glass'. Reduce the Base Weight to 0 reduce the Specular Roughness to 0.
More information about Specular Fresnel can be found here.
Increase the Transmission Weight to 1 so that the glass is fully transparent. Change the IOR (Index of Refraction) to that of glass (1.5). If you want to add a tint color to the glass, change the Transmission Color to a light color.
More information about rendering glass surfaces can be found here.
We will use a Maya spot light to represent the jet's thrust emitting from the exhaust.
Spotlight positioned inside exhaust
To visualize the thrust effect, we must first enable Atmosphere Volume.
The exhaust thrust appears too long. We can limit the distance of the light from the spot light by using an Ai Light Decay filter.
Left: Ai Light Decay filter added to spot light. Right: Use Far Attenuation enabled
You can see the effect that adding a Light Decay filter has on the attenuation of the spot light in the images below:
Open up Sampling in the Render Settings Window. For test rendering Camera (AA) samples at 3 is fine. However, for final frame rendering, you will want to increase it to at least 5.
A simple guide to sampling can be found here.
When rendering scenes with MtoA, it is a good idea to get familiar with the Arnold Log in the Diagnostics tab of the Render Settings window. This log file will show you any warnings and statistics which will help you diagnose your scene file.
A guide on how to read a render log can be found here.
That's it. Congratulations, you have completed this tutorial. Now go out there and explore new worlds of rendering!