Windlight Contributor, Myra Wildmist is back with tips on Ambient Occlusion settings:
No one can know everything about Second Life photography and I certainly don’t.
I’m writing these articles to give back and help others, of course, but they’re also a learning device for me, too. If I’m writing about something that’s a gray area for me, I try to research it and understand it better.
As a result, there’s a possibility I might get things wrong, sometimes. I wanted to say that before we venture a little more into the Ambient Occlusion settings, because, frankly I might get some of this wrong.
I think I’ve done a good job in my research, though, and I’ve gotten the basic facts right. If anyone has corrections or more to add, please contact me or simply add it in the comments.
Warning: This next part gets very technical (Can you hear me scream?). I promise a far less technical article, next time. This one made my brain hurt.
Firestorm usually does a good job of clearly defining what a setting does. Unfortunately, the tool tips for the AO settings are confusing and in some cases misleading; so I’m going to try to explain them or at least clear up some of the ambiguity.
I’ve listed the 5 AO settings below, with explanations of what they do from three sources. First, I’ve given you the Phototools tool tip. Second, I’ve quoted from what I believe are the corresponding debug settings in the SL wiki. Lastly, I’ve given you my less-techie interpretation of what the setting means.
It’s my hope that between the three different explanations, these settings will make more sense. AO is important to your photography: the more you understand it the better.
Scale – Phototools: Controls sampling region; larger regions are more accurate. It can be helpful to set these values high and then add a bit of shadow blur to soften their effect.
SL wiki: Render’SSAOScale: Scaling factor for the area to sample for occluders.
Myra: AO Quality. This setting affects how quickly the shading effects fade with distance and how many occluders and ambient sources your scene accounts for.
The default value is 500.
Max Scale – Phototools: Controls the maximum screen radius from which to sample from, to avoid graphics card cache misses and associated large performance penalty. It can be helpful to set these values high and then add a bit of shadow blur to soften their effect.
SL wiki: Render’SSAOMaxScale: Maximum screen radius for sampling (pixels).
Myra: AO Distance. This determines the maximum distance at which ambient occlusion occurs.
Factor – Phototools: Scaling factor for the effect (larger is darker). It can be helpful to set these values high and then add a bit of shadow blur to soften their effect.
SL wiki:’Render’SSAOFactor: Occlusion sensitivity factor for ambient occlusion (larger is more).
Myra: AO Strength. The setting controls how strongly occluders affect the ambient light.
Effect – Phototools: Controls the overall darkening effect of Ambient Occlusion. The default value of 0.8 produces an almost imperceptible effect. Values of 0.0 and below provide a more realistic result. Please note that the Ambient Occlusion produces a noise like effect and this can be softened using the ‘AO Soften’ controls below. In addition, the standard mesh avatar can look less than appealing with high Effect values due to the low quality geometry of the avatar. Please Note: The lowest value you can set in the slider is 0, while in the spinner you can enter negative values of up to -10000.
SL wiki: ‘Render’SSAOEffect: Multiplier for (1) value and (2) saturation (HSV definition), for areas which are totally occluded. Blends with original color for partly-occluded areas.
Myra: AO Effect. This controls the AO contrast effect.
AO Soften – Phototools: Controls the softening of the Ambient Occlusion effect. One simple way to set this value for your specific needs is to first set the ‘Shd. Blur’ value above to around 4.0. Then the slider here to soften the AO to your liking. Please note, a value of 0.0 will effectively turn off Ambient Occlusion rendering.
SL wiki: ‘Render’ShadowGaussian: Gaussian coefficients for the two shadow/SSAO blurring passes.
Myra: AO Shading Blur. This controls the degree of softening/blurring of AO shading in your scene. A setting of zero mean no shading.
Tip: Sliders in Phototools are limited, but you can go beyond the slider min and max in most cases by typing in your numbers or using the up and down arrows.
Ambient Occlusion adds shading to your photos and used properly can add a high degree of realism to your scenes.The default values work well for most of what you’ll do. However, try playing with these settings, because they can change the look of your work in ways that can significantly improve your photos.
Try setting your Scale and Max Scale to 10000 and see if that improves your photo. Personally, I find their effects most noticeable in landscapes, though the high settings can improve your interiors, too.
The default Factor value of .3 is too low for most of what you do. Be sure to play with this value. Start at 3 and adjust from there, but keep in mind its effect is very dependent on Effect setting.
Effect’s default value of .8 is probably too high. Try .2 as a starting point and adjust from there.
In the images below, I’ve photographed the scene with the AO defaults and in the image below that I’ve used a Scale and Max Scale of 10000, Factor 3, and Effect .2. The differences in the landscape are most noticeable – the terrain appears more defined, especially on the hills in the distance.
Your results will vary depending on the scene, ambient light, and Windlight. Sadly, that means there’s not a default setting that will be ideal for every photo. You’ll have to adjust these parameters depending on your environment.
The AO defaults are “acceptable”, but for the best photos you’ll have to adjust these settings for every new environment. Yes, that’s a pain, but it’s worth it.