Thursday, 18 April 2013

Lighting: Skyboxes

So for my lighting project I need a background or a skymap for the sky. For the corresponding scene in Unity we're using a cubemap, so Ruth sent me the texture files as then the cinematic would match up more with the gameplay environment. However cubemaps can only be viewed correctly from fixed camera angles, and this presented a problem as each scene contained multiple camera angles.

As seen in the picture above, I attempted to add the cubemap textures to an envcube material in Maya, but unless lined up correctly the illusion was ruined, and when rendered the cube's seams showed up.

I looked into a few workarounds for this, and found that a cubemap could be transformed into a spherical image in HDRshop and then applied in Maya using the image based lighting environment option. However this required a lot of manual work and the end result would not be worth it compared to simply using a suitable image to begin with. With this in mind I looked online for a an image I could use as a skydome, which is a half sphere that surrounds the scene. However using a skydome can create more problems, as if all of the settings are not calibrated correctly the skydome can end up casting unwanted shadows on the scene or interfering with final gather.

After considering these options I've decided to simply use a background plate attached to each camera, or to add the sky image after rendering in After Effects. This means that the cinematics won't match up with game environments as well as I'd hoped, but considering the differences in lighting and assets anyway this is the best option as it'll allow me more time to tweak the lights and render settings.

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