What is the purpose of a Reflection Probe Box vs Sphere, and how do you choose size?

• A. Box reflection probes capture the environment in a cube-shaped influence, Sphere probes capture in a spherical influence.
• B. Box probes are better for reflective surfaces than Sphere probes in all cases.
• C. Box and Sphere reflection probes capture environment differently; size should cover the reflective area adequately without over-sampling.
• D. Sphere probes can only be used for the sky reflections.

Answer: (C)

Reflection probes determine what environment gets reflected on materials, and the shape of their influence defines which part of the scene is sampled. A box probe uses a cubic volume, while a sphere probe uses a spherical volume. Both end up capturing the environment to create reflections, but the area that contributes to those reflections is defined by the probe’s shape.

Choosing the size means matching the probe’s volume to the area you want reflected. The goal is to cover the reflective surfaces and the space around them enough so the reflections look accurate, without pulling in distant geometry that isn’t needed. If the volume is too big, you waste performance and you may blur reflections with stuff you don’t want; if it’s too small, reflections can clip or jump as objects move out of the probe’s range. In practice, size the probe to enclose the area that should reflect, and use multiple probes or appropriate shapes to get smooth, believable reflections.