Lighting Tips Appreciated

[hereagain]

I've been working on this for a few days now (I know, hard to belive once you see it), and I still have many issues with it:

1. The building material is white stucco and red painted wood trim. If I increase the intensity of the sun to liven the scene up, the walls get overexposed. Anything I can do about this?

2. I am trying to get the effect of sunrise lighting (building is facing east). I'm currently using an HDRI and Vraysun (multiplier down to .003). How do I get a nice orange/pink light casting across the pavement? I've tried messing with the reflectance and glossy values, but it doesn't seem to do anything (currently a vraymat with diffuse and bump maps)

3. I would like to use the HDRI as the background to give the lighting some context, but, as you can see, it looks terrible (scale is off, pixelated, etc.). What is the best setup for using an HDRI as a background? This one is currently just dropped in as the Environment background. Do I need to map it to a background object?

Sorry about the length, just want to be more specific about the issues i'm most concerned about. Thanks for any help.

[Brian Smith]

Wyatt,
As a matter of preference, I always use the same background setup with almost every project...cylinder with a background image (visible to camera but not reflections), hemisphere with usually a slightly different spherical image (visible to reflections but not camera) and cast shadows and generate GI options turned off of both. When I use HDRIs, I may or may not use the same image on the cylinder for the background...it's more important to use a nice image and one that corresponds to the type of skylight you want. In other words, if the sun is low on the horizon in your HDRI, make sure the light representing the sun in your scene is low on the horizon as well. The background image you are showing is either not a good image or not mapped correctly...it looks blurry and not positioned correctly. For more information on setting up backgrounds, check out the latest Insider article.

To get that sunrise look, you need to play with the a couple of variables in particular...color mapping, turbity (if using vraysun), and of course intensity regardless of light type. Play around with small changes in the gamma also. I recommend not using the vray camera until you have a good fundamental level understanding of the critical settings...using a vray camera will throw too many extra variables in you really don't need to deal with right now. Here's a quick scene you can play around with (using a vray camera if you really want it).

[hereagain]

Brian,

Thank you for taking the time to address some of my issues. Since that posting I have switched to using a Vraysun and Vraysky system, which seems to be giving me lighting closer to what I originally wanted. The vraysky, though somewhat bland, does offer a better visual connection to the rest of the scene lighting. As you mentioned, I already got sucked into the Vray camera, though I have found it useful for this particular scene - being able to up the F stop helps with the overexposure on the white stucco.

Attached is an updated version of that scene. I’m having an odd issue with the vehicle in the foreground. The paint shader, which normally looks great, is getting this odd banding where it receives the direct Vraysun casts. Also, the glass shader used on the side windows usually works great too, but again the reflections just don’t appear correct – there should be some transparency (i.e., should be able to see the interior). I’ll attach those materials for reference as well.

Once again, thank you; the help is greatly appreciated. By the way, great tips on the Insider article about Site Plan generation – learned more from that than all four of these books on my desk.

[afterglow]

render an alpha and drop in your image background in photoshop. can manipulate it til your heart's content. not sure why you guys use a scene cyliner for a background in stills.

[kippu]

actually i have the same problems with glass and sky/sun/cam
very weird

[Brian Smith]

Just a suggestion for any situation where you get results that seem strange or unexplainable. Start with a brand new drawing, merge one object in that's causing problems, restore your normal settings, and bring remaining objects in after you've gotten one to illuminate correctly. There's so many ways to 'jack up' a scene accidentally, it's sometimes better to take a few steps back than it is to keep pushing forward. If only one object is still causing problems after merging, then it could be a material problem for that object.

[Brian Smith]

Originally Posted by afterglow

render an alpha and drop in your image background in photoshop. can manipulate it til your heart's content. not sure why you guys use a scene cyliner for a background in stills.

Steve,
Why do 2 steps when you can do it in one? I don't want to add extra photoshop work when it's not needed. I can manipulate the background when it's on an object all i want using material properties and using a light that effects only the background. I also have better control of the reflections when i use a separate object for that. When i get to the point in a scene when i need a background, it takes just a few seconds to merge in a rig from my library and all the work is done. I also use objects for backgrounds because the majority of my work is animated but even if i didnt do animations, i would still greatly prefer object backgrounds. I also would prefer to see my scene in the context of it's environment and not have to wait until the rendering is done to see the scene objects in their true environment. You also have alpha channel issues when you do it the method you say...you have to be much more careful about the antialiasing that takes place and the pixels that get recolored incorrectly because of the different background. There's probably more reasons but it's early and i'm not completely awake yet.

[jophus14]

Great posts Brian, thanks for the tips.