The first lighting scenario I approached for the bathroom environment was moonlight. The characteristics I wanted to emulate were sharp specular highlights, glows, heavy shadowing, and an overall low key. In other words, I was looking for high contrast in order to carve out the profiles of objects in my scene.
My first attempt was to use an Environment Light (i.e. HDRI) with RmF to set the key lighting of the scene; I knew that this method is intended for use with exterior scenes, but I wanted to give this a try just as a test. The result was a horribly dark and essentially useless base on which to add my own custom light rigs:
I talked to Eric and he confirmed that HDRI was in fact only good for exteriors and was virtually ineffective for interior spaces. I decided to go the "old-fashioned" route, using a custom light rig composed of spot lights and point light arrays. Only one of the spots had a shadow turned on; I used Ray Trace shadows with a light radius of only 0 and a single shadow ray. I have typically used values of about .1 and 8, respectively, but upon doing a test render of this sole light (it was the first light I placed in my scene), I realized that the results were surprisingly satisfactory, and that I should not waste time tweaking the values or rendering out more tests.
At this point I was still subdividing my polygons at render time, which was working out perfectly with my direct lighting approach. RenderMan was able to give me very good results in relatively low render times. Because there is no IPR rendering supported by RmF, I would simply render within my Render View, but set my output resolution to 400x225 instead of the 1920x1080 which was going to be my final output. In this way, I was able to get a decent idea of how my lighting was coming along, while waiting typically no more than 25 seconds even when my rig neared completion.
Here is the beauty pass exported from RmF:
It was a 32-bit OpenEXR file that contained the passes Beauty (called "Ci" in the RmF settings), DiffuseDirect, SpecularColor, and SpecularDirect. It had actually originally contained the passes DiffuseColor, DiffuseDirect, OcclusionDirect, OcclusionIndirect, SpecularColor, SpecularDirect, SpecularDirectShadow, SpecularEnvironment, because I was unsure which passes would be useful to be in the compositing stage with Nuke. The render with fewer passes took about 5 minutes to be calculated, and the render with more passes took about 8 minutes, so I was glad that I didn't have to rely on a huge number of passes.
Ironically, I only ended up tweaking the beauty pass and did not find any use in any of the other passes. However, I am sure that at some point, I will be able to use these passes and take advantage of the fact that an OpenEXR file is a series of multipass renders cleanly bundled into one file. Additionally, at 32 bit, the color correction (especially the Exposure and Histogram nodes) was extremely robust and flexible, and gave very smoothly gradated coloration even when I tested out extreme crushing.
I was fairly satisfied with this beauty pass for its general varied lighting and specular highlights. However, I felt that the shadowing was very shallow and was revealing the simplicity of the model. For example, where the sink pipe intersects the wall, there is a sharp delineation around the pipe. I knew that I needed an ambient occlusion pass to help fix this problem, so I tried to pull one out of the EXR. Without any luck, I looked for a way to render one out with RmF, but was disappointed to not figure out that one either. I decided to use Mental Ray to create this pass. I first had to convert all of my geometry to SubD's before rendering. When I actually exported an image, the RmF and MR passes surprisingly matched up seamlessly. I figured that if the ambient occlusion pass was synching up perfectly, then I could get away with creating any other necessary passes with Mental Ray as well.
Ambient Occlusion from Mental Ray
I exported this as an OpenEXR because I knew that I would probably have to tweak the Histogram (i.e. Levels) to tighten up or widen the occlusion. I should note that in Mental Ray, there are no settings for the OpenEXR file's passes (at least that I could find in the Render Globals.)
I created a Depth pass by simply projecting a black to white Ramp on a Surface Shader and applying it to all of the geometry in the scene:
I rendered out a 32-bit EXR with RmF with nothing but a beauty pass included. I knew that the resulting image would be completely grayscale, so I would not be breaking the bank with file size, yet with this massive bit depth I would have total control over the contrast in Nuke. The flexibility of this pass is great; Eric taught us that it goes beyond simply driving depth of field, but also can be used to create environmental fog and to drive the effects of color correction nodes. In this scene, I used it very subtly for these purposes since the environment would probably be no more than 15 feet deep in the real world.
One of the things I had missing from my original beauty pass was a background for the window; I ended up just using a jpg of some clouds that I found online and then color corrected. I simply rendered out a seperate pass of the background alone and overlaid a color-corrected version in Nuke. Here is the result of using this background pass alongside the beauty, ambient occlusion and depth passes within Nuke:
I wanted to add some more realism by adding a vignette, camera warp and film grain:
(Please note that I lit, rendered, composited and color-corrected these images on a flat panel monitor, so they may appear dark on CRTs.)
In my next post, I'll be getting further into detail about the specific passes and how I manipulated them within Nuke.
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