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Arnold for Maya – Image Based Lighting

The following article explains how to use image based lighting using Arnold within Maya.

 

Image Based Lighting simulates light from a hemisphere or dome above the scene representing the sky. It can also be used with high dynamic range (HDR) images to perform image-based environment lighting. This is the node which is typically used for lighting exterior scenes.

 

Go to Arnold top and click “Lights” and then create a “SkydomeLight”. If you change the scale or position of the skydomLight it would not do anything. It would only make a difference  if we were to rotate with HDR image applied onto it. Make sure there are no lights in your Maya scene.

dome

When you render as it is you get a Gi_based render.

dome_face

Most of the Skydomelight property controls is within the SkydomelightShape in the attributer editor. For example color, intensity, use color temperature etc.

  • HDR images have a greater capacity to describe light accurately (by way of floating point numbers) because they store the amount of light (rather than just color) represented in a pixel. This prevents ‘blown out’ or extremely dark areas in an image that your eyes compensate for in the natural world.

How add an HDR image into the scene.

 

color_plog

 

  • Sample: Controls 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. The exact number of shadow rays sent to the light is the square of this value multiplied by the AA samples.

rendersetting1

 

In my case, this AA increase allows me to decrease the other sampling rates (GI/glossy/light) to compensate. To sum up, I get almost the same render time with AA=1 and GI=9 than with AA=9 and GI=1, but at AA=9  I get a better motion blur and  higher quality of depth of field.

noise_setting

 

sampling

 

  • Resolution: In order to keep noise and fireflies to a minimum when using the Skydome light it’s very important to set the “resolution”. By default this is set to 1000 which means if you’re using environment maps larger than 1000 pixels you should adjust the “resolution” accordingly. For example, if your environment map is 7000*4500 pixels, the resolution in the skydome shader should be set to 7000 and so on.