TheBeals

Fire Test

I’ve never really dealt with particles, but I have to say once you get on the right road, it’s pretty fun. The black outlines at the base of the flames are an outline of the logo that will go in it. I am getting some weird build up right above the letter though. hrmm…

Fire_Anim

My Procedure for matching the lighting and materials of a photograph

I was asked what my approach is to matching the lighting and materials in a photograph. If you have had to deal with this, you know it is fairly tricky. However, I believe if you follow these steps it will make things much easier and much quicker to do correctly.

1A.) In this write-up I am going to assume you don’t have any specific data from the shoot. e.g: light data, camera data, hdr probe etc…

1B.) Research. This can happen after the modeling bit or before-it doesn’t matter  too much. Recently, I have had to match a photograph of a wine bottle. For my wine setup, I had to no idea how photographers setup their lights to light glass. It’s such a tricky thing to light. In fact you don’t even light glass-crazy right? You create reflections. I did not know this when I started and learned about it through my research. If you do a bit of research before, it will shave off hours of experimenting. You will learn little tricks and hints and see how they setup up their lights. That way when you see a reflection or highlight you understand how and about where that is coming from. Another good bit of knowledge is “family of angles.” This topic tells you based on the object from the camera, where a reflection will show up. Google is your friend with this area. Also know what you are ligthing. For example, you light glass and metal in completely different ways. Metal depends on reflections toward the camera, and glass depends on reflections on the sides. :)

1C.) Modeling. No matter the subject that you are trying to emulate, you have to try and model it as close to the photograph as possible, especially if it is highly reflective or refractive. Why? Well say you have the model pretty close to the photograph, but not exactly. The reason this will throw you off is because every surface point on your model that is different than from the photograph you will get a different light play than what is on the photograph, even if your lights are in the exact place in your scene as they are in the photograph. So you will not get the same highlights/reflections/refractions that the photograph is getting which will lead you to have to do hacks to make it “look” about the same. Which, in the end, will only cost you time and energy.

2.) Initial setup. As well with modeling, this part is key. First create a camera, never ever, ever, ever use the perspective camera to do these renderings. My favorite, and probably the easiest and quickest, method is to load the image as a background image and move the camera so your object is in the same place as the object in the photograph. Don’t forget to mess with the camera’s focal length to match the camera that was used. A more exact way is to measure out the vanishing points of the photograph, find those angles and recreate them in your 3D app. Key your camera or add a bookmark so you don’t lose your place.

3.)The real step one. Once you get your camera setup, setup your initial materials and a couple of lights just you can work w/ your mats. The mats don’t need to be exact. For this all I am saying to do is if your object is highly reflective, create a highly reflective material, if it has blurred reflections create something w/ blurred reflections, if it is glass create a quick glass with the appropriate colors of course. This way we can dial in where the lights are based on reflections and highlights.

Because we are trying to match real world materials, use physically correct materials, I believe every renderer has something like this in it now. DO NOT use a blinn or a phong unless you absolutely have to. If you do, make sure you get your falloffs correct. For mental ray stick with the Mia_Material (Arch&Design for you Max users). It even has nifty presets for metal and glass which is perfect for this step.

4.)Camera. Since we are dealing with the real world that means that everything has to be “physically correct” this includes the camera. This one I always go back and forth messing with. Sometimes I setup my lights first and then do this and other times I setup the camera first. I think it just depends on what you are doing and your taste. In this case I applied a photographic lens shader with just a basic light setup first.

5.) Lighting. I have found that messing with highlights and reflections first and doing the fill last is the best way to work. The highlights and reflections are the most obvious and so the easiest to nail first and then the fill will fall into place.

Make note of where the light sources are in the photograph. Generally real world photography deals with a minimum of 3 lights, sometimes 2. This is the point where you need to decide if you are going to try and match the lighting exactly as they did or if you are going to do some tricks that will give the same look, with less render time. An example of this is often in lighting, the photographer will shine a light at a bounce card which will bounce the light back at the object which creates really diffuse lighting and often a nice highlight. If you do this in 3D your render times are gonna skyrocket really quickly. An easier way is to use an area light w/ soft shadows and have it visible with maybe a reflect card BEHIND it. Gives about the same result w/ 1/4 the rendering time.

Also, I notice a lot of people have all their render settings turned up to max when testing. Don’t do this, it is unneeded. Turn down your aliasing to -2 and 0 instead of 0 and 2 and turn down the amount of reflections and refractions you have. If you are doing glass make sure they are high enough so you won’t get black in your refractions/reflections. These settings will lower your render time by half at least. Also if you are using fg or gi, lower these settings even if you get a little bit of blotchiness. Stop making life harder for yourself!

IF ipr will work for you in this part I would highly suggest using it. Create the light shape you need. If you are just getting a reflection then you can leave the intensity at 1 w/ no falloff, and ipr your scene  and now move that light and manip it so you can get that same shape and size on your object. Once you get this in place hide the light and do the same for every reflection. Once this is done then unhide them all and go to the next step.

6.) Lighting Cont. Along with your mats and your camera, your lights need to be physically accurate as well. You have a couple choices in this area. You can apply a physical light to the light/photon emitter of a POINT LIGHT and then an .ies profile to that to emulate a specific light. WARNING: Maya has issues with this. Max is muuch much better if you want to go down this road. These profiles only seem to play nicely with point lights.

Another option, and my favorite, is to load a blackbody or a cie_d into the color attribute of your light. This way you can control the kelvin temperature and intensity realistically. Don’t forget to have a quadratic falloff and shadows enabled.

NOTE: The white point of your camera will affect the look of the color of your temp on your light.

Once you get the reflection properties down, hide these lights, and work on the highlights. You only want to work with one light at a time to make sure you know what is doing what. Once you get these dialed in, then unhide the lights and see how they work with each other and adjust accordingly. Once you get the highlights and reflections down then go ahead and apply the fill. You can hide the other lights and dial this in or you can do so with the other lights in the scene, since you are just adjusting the fill and if fg in on the fill will need the other lights.

7.) Finally finesse the materials, add textures, crank the samples. During this mode, cranking the anti-aliasing and refl/refr properties will be a good idea.