RE: Jamie's Project!

Hi Jamie, [Deli team animation probably want to read this too]

Wow your concept art has real expression in it!   Great work! What are you going to do for the background?  a photo or a mattepainting?

I think image based lighting is a good idea, it is particularly useful for integrating CG into film/TV.  It is common practice to use an environment light as well as other lights.  I would normally use an env light as the fill light in my trio of initial lights but I would not use raytraced shadows, instead I would render out as a separate ambient occlusion pass and dial it in later in the comp [I'll give an example of this later].  From the what I know about image based lighting, it is quite hard to get an obvious light direction even when your map has one, as you said, you will probably end up with a evenly lit scene, this is why it is ideal as a base for your lighting, rather than being the only lighting.  You might want to photoshop your HDR image (once you have made it) as to remove the hot spots leaving a more 'fill' like map, and then on your env light turn off the specular component, as the fill light is generally a diffuse light source.  

Truthfully I am no expert in Final Gathering as I have only used it when matching to someone else's work (in lightwave, not in mental ray).   It gives 'nice' results, its a relatively quick way of working but it has its own issues, especially if you have any intension of using transparency and need continuity between frames :)  It works really well for showing off architecture, and from what I gather that is the main industry it is used in, as the only animation is normally a camera move, it is efficient to bake/save out the data and re-use it.   I have never used it in film (or had the option to), and only used it on one commercial and I have worked on quite a few.

Final Gathering (FG) is extremely computationally expensive, the more complex the model you have, the more detailed you want your render to be, the longer you have to wait for your test render. This leaves less time for actual lighting!  I believe this is partly why it is not used in film, the other factor being the lack of control the artist has.  Both ways you mentioned for using FG are valid, either using just an env sphere and changing the image or using coloured bounce boards or both.  Be careful adding extra lights though as it will quickly blow out, and depending on the number of bounces, adding a light will create more light overall (which gets bounced around) and you will loose your dark areas, ending up with a low contrast image.  Using it is an art form in itself, it involves tweaking a bunch of confusing settings, and I don't find it a particularly intuitive way to work, although that is probably because I am used to using lights.  My advice, only use FG if it gives you the artistic result you really want.

The top image uses Mental Ray and Final Gathering with a env light, (settings just enough to remove all artifacts) at HD 720 it took 2min 35secs.  Adding one raytrace shadow key spotlight took that to 4min 8secs.  Looks like you can bake this out so that you can re-use it, sounds like a good idea to me!  I am sure someone has a nice example on the internet.

If you light a scene and then use an ambient occlusion pass (your only bit of raytracing, unless using brickmaps, and if your doing a still image, you can reuse it), I promise that with a little effort and time you can get the same effect (or better), only its quicker to render.  Use coloured lights instead of bounce-boards!  Think about the way light reacts to different surfaces, and simulate it with bounce lights.  You have bags more control and it is a more creative process.   

This ambient occlusion pass took 1min 58secs and I will be reusing it in the comp as a multiplier of the beauty image (you could bake it in or project it through the camera)That way I have full control, I could decide to only use occlusion on the ground and not the objects, or I could increase the effect on one particular object (I will be rendering mattes to be able to do this).  I do this all the time.

It seems to me that your natural drawing style is very expressive, and I would like to see this reflected in your CG work.  You probably want to bump up your HDR image so that it looks like a dramatic summers day.  If your looking to add drama, sunrise and sunset are way more dramatic, or even a storm!  I think your concept art colour palette has that stormy summer sky look, maybe you could go that way?  This is your project and you have creative license.  When you start lighting, you can change your mind and try out a few different styles and methods.  You can start experimenting early, with your un-textured model.  See how you get on.

I am sure I will be posting more relevant posts so keep visiting.

Look forward to seeing updates.

Tessa