Arnold is an advanced Monte Carlo ray tracing renderer built for the demands of feature-length animation and visual effects movies. This is a beginners tutorial that introduces MAXtoA, a plug-in which allows you to use the Arnold renderer directly in Autodesk 3ds Max. In this tutorial, we will cover how to build a simple photographic lighting studio setup that can be used for lighting and render all manner of objects. We will go through the steps of lighting, shading and render a toy robot model using the Arnold renderer. We will use Arnold's proprietary lights to achieve a physically accurate, photo-realistic lighting setup.
We will use the Standard Surface shader to shade the robot and give it a metallic finish. The Standard Surface shader is a multi-purpose shader capable of producing all types of materials, from simple plastic to car paint or skin. It is very powerful, and allows a large number of different sorts of materials to be created, but can be somewhat daunting at first. Due to a large number of controls, it is split up into several groups such as Base, Specular, Sub-Surface scattering, etc. We will need to adjust the Base and Specular parameters to get a believable brushed metal effect.
Lastly, we will look at how to optimize render settings and eliminate any noise that may appear in the render. Note that, although 3ds Max and MAXtoA have been used in this tutorial, much of the material is really about Arnold in general and so is also relevant to users of other Arnold implementations such as Maya for Arnold (MtoA) and Houdini for Arnold (HtoA), for example.
The estimated time it will take to complete this tutorial should be no more than 30 minutes.
|The final scene file can be downloaded here.|
- Start off by opening the robot scene. In the scene, you should see the robot model (positioned at 0,0,0 on the 3ds Max grid) and a simple studio backdrop model.
- Assign a Standard Surface shader to the Backdrop object. Change the Base Color to a medium gray and reduce the Specular Reflection weight to 0.
- Now we want to light our studio scene. Start off by creating three Arnold Quad lights. This can be done by clicking on the light icon in the Create Panel.
- Position one light on either side and another in the center, above the robot. Rotate them so that they are pointing inwards towards the robot as indicated in the screengrab below.
If you cannot see the quad light area shape of the Quad light in the viewport, you will need to enable Always Visible in Viewport in Shape Rendering for the light.
- The scene may appear dark when it is rendered. We, therefore, need to increase the exposure of the lights. Under the Arnold parameters, increase the Exposure to around 8 for each light.
- We can change the color of the lights by changing the color temperature of the light. Select the right light and Kelvin. Change the Kelvin temperature to 12000. This will give a cool blue feel to the light. Select the light on the left and do the same, except change the Kelvin to a warmer color, something like 4000.
- You may notice some noise in the shadows from the Quad lights. This is because the light's samples are set to 1 by default. To reduce the noise, try increasing the light samples to 3. This setting can be found in the Rendering parameters within each light. Light samples control the quality of the noise in the soft shadows and direct specular highlight. The higher the number of samples, the lower the noise, and the longer it takes to render.
- Now we need to create a brushed metal shader for the robot. Open the Slate Material Editor (M). Create a Standard Surface material and assign it to the robot.
- To turn it into a brushed metal material we will change the following settings. Lower the Base Color weight to 0.5. Increase the Metalness to around 0.8 and increase the Specular Roughness to around 0.4. The Specular Roughness controls the glossiness of the specular reflections. The lower the value, the sharper the reflection.
- Rendering the scene using the default Camera (AA) setting of 3 is good enough for test renderings. However, for a final render, you will need to increase this to at least 5 or more depending on the amount of depth of field you have set in the scene.
- There may be some noticeable glossy specular noise on the surface of the robot due to poor sampling of the indirect specular component of the robot's shader. Increasing the global 'Glossy' value to 3 helps resolve this noise and to create a cleaner looking render.
Sampling and noise
Noise nearly always comes from insufficient sampling, but increasing sampling for the wrong rays can make the render times increase without helping to remove the noise. The aim is to allocate rays as effectively as possible to minimize the noise in the most efficient manner. So if the Camera (AA) samples have to be increased to remove DOF noise, the other settings must be lowered to keep render times manageable. However, if DOF or motion blur is not a concern, then increasing Camera (AA) samples would fix all noise elsewhere but would also slow render times from the unnecessary rays.