I realised a lot of the lighting talked of in the
Interior lighting in Arnold. (Youtube.com, 2016).
The first light in this scene was a skydome- they way in which it is used it different than I would have in my own compositing scene, as it lights the external of the interior, working in though the lights, but I thought that is would be useful to know, due to the idea of using the sun.
The first thing that had to be set was the X resolution (across the HDRI) to allow for multi sampling to occur. Arnold shoots more rays of light at the brightest points allowing for soft and hard shadows.
This tutorial really helped me with understanding using the light intensities and exposure settings, advising locking the light intensity and only working in the exposures. It explained that exposure is taken to 2 to the power, so if I was to input a value of 2, it is infact 2 to the power of 2, giving an intensity of 4.
The noise in this was really high, therefore the sampling must also be bumped up to compensate. The correct linear colour workspace must also be used, in the render settings, under Gamma correction. The driver gamma must be set to 1- this gives Arnold less control. It allows textures to have more control, directly from the Maya scene. The colour manager menu must also be fixed- the image prof colour set to linear sRGB and the display colour profile set to sRGB.
Using the sun values in this HDRI is no good- the values being 8 or 10 when they should be around 10,000! This can be fixed in photoshop or through the use of a directional light.
The colour of the light can be dropped from the HDRI used, turning on ray trace in the settings. In the Arnold tab turn the exposure to 2. The angle can be altered to compensate for the sharpness of the sun- in this case set to 2, as there is a haze in the HDRI, giving more of a blur in the shadows
Youtube.com. (2016). Cite a Website – Cite This For Me. [online] Available at: https://www.youtube.com/watch?v=8xd5C_4FlsY [Accessed 25 Nov. 2016].