Because I can. Bits of what I go over here can be seen in the Gaslit Labs scene, and to a lesser extent in the rather rushed composition I put together to display Metum in Unreal. Frankly after looking into it further I could have done better in general with my lighting composition, but some of what I learned shows through, and then rest are just point to work on. So without further to distract:
Fundamentals of Lighting (for 3D and in general)
Things I’ve done well
Bounce light is much as the name implies ambient lightning created by bouncing light off of reflective objects.
Modern rendering has seen the introduction of global illumination lighting, and with it manual bounce lighting has become less essential than it was previously, but it’s still important to consider if you want to get the best out of your scene space, given that what the renderer will interpret as being true bounce lighting may not actually be visible isn’t actually going to be that visible.
For this reason and particularly for the sake of adding coloured highlights via your bounce it can be beneficial to manually simulate a bounce light using a point light. To get bounce light tones to look natural use a low intensity/ high saturation colour to add illumination to corners that otherwise would remain dark. Doing so will add life to a scene that using global illumination alone might have missed.
Indirect light comes in many forms and spill light is the next on the list. Spill light in the secondary illumination that you get off of a directed that, that illuminates the area directly surrounding where it falls. To use an example from Gaslit scene, I applied a manual spill light by adding a second and third point light to the area surrounding the wall lanterns.
So yeah, at a fairly introductory level that functions, but I could have made it even more subtle in the end to achieve a better effect. The projecting object, in this case the lamp, could also benefit from a separate collision model for lighting purposes, as at present it’s difficult to allow for accurate shadow casting with the additional spills casting shadows.
Dividing up the space
This is a bit more of a abstract concept and relates to composition as much as maintaining accurate lighting conditions to reality. What dividing the space is referring to is that a larger scene can have very different lighting across the space to create more visual interest. On a more technical level, if you have a room which is lit from the windows that the areas in the corners or the center of the room are likely to be lit very differently. Using the lighting from Gaslit as an example again, the differences could be seen if you count the light spilling from the broken window as your key lighting, the room directly beyond it being one zone, then the corner with the writing desk being another zone, then around the tank where the primary source of light become the green glow, and finally the very dreary and obscured lighting conditions of the factory floor.
These sorts of subtle changes to the light can help make a space seem much bigger. Those 4 shots are all within 10 meters of each other.
Things I didn’t do so well
Your key light is the primary light source when considering scene composition. It should be as a rule the strongest light in the scene while also being the strongest light affecting your focus point. From the perspective of a dynamic game environment this can be bent a little, but if you have control over when the light can be pointed in a situation you should always be striving to follow these rules.
Most of the key lighting in the Gaslit scene was already done for me when I got a hold of it, and it does a pretty good job of doing what is intended. I added the key lighting around the workbench myself so I can say in earnest I did an alright job there. The instance I’m not terribly proud of is how I handled the light in Metum’s pose scene.
It would be fair to say I failed to light the character properly at all for a pose-shot. This was a perfect opportunity to have complete control over light-sources, given it was a shot with a central pivot. In truth despite the scene itself being fairly well lit overall if zoomed back there is no conditional lighting at all on this shot, which is something I must ensure never to repeat for a posed turnaround of all things.
Optimising my models
This again can be made apparent from the screenshot above. In this case optimising the model is referring to making sure the geometry is not so much efficient, but smooth enough in all places to properly interact with the light hitting it. Overall most of Metum’s model works fine in this sense, but the mechanical arm is mostly made of hard 90 degree + edges which shade as hard edges as well. Where the light over the rest of the model graduates across the geometry as it fades to shadow it’s an overly hard edge on the arm. As a general rule with geometry this is something I need to improve, by at least having an appropriate normal map baked to fake a curved edge for lighting purposes if nothing else.
Construct from reference
This is a bit of a good an bad again, as the lighting in the Gaslit scene does draw from the compendium of reference photos we compiled for the project, but still doesn’t truly capture what the lighting should be for that situation. Could always use tweaking etc.
This is pretty self explanatory in any sense, when you go to light a scene, much like anything else with visual artistry, it will only be better if you draw from reference to reality if it’s available.
When I go back to do the Wastes for Metum’s scene for example, I’ll spend a good deal of time getting the lighting to look something like…
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