Unreal Engine Reflection Captures Part 2: How to place them?

[@MemoryDealer]

Thanks for doing these videos. All the other reflection capture videos are not nearly as comprehensive, you've helped me a lot.

[@i_amthearteest4129]

Thanks for the 2 part reflection capture explanation

[@MrSmith01]

@Mai Ao your tutorials are really good! Will you continue making them from time to time? Many thanks! God bless you!

[@notverydarkmagic]

Thanks for the encouragement

[@emanatestudios2177]

very helpful for for understanding fine details of reflection probes. Thank you! Out of curiosity, what are the advantages/disadvantages of this approach vs using cube probes? I would have thought overlap would be easier to control with cubes.

[@notverydarkmagic]

Thank you! In general, sphere captures are more robust because the captured reflection is mapped to a dome instead of a box, so to speak. The cube capture has very sharp distortion when you move close to the edge of the box. So it only work better in rectangular environments.

[@emanatestudios2177]

@@notverydarkmagic Ah, makes sense. Much appreciated!

[@henryramsevik1655]

Hey! This was a very helpful video! I was wondering what difference does it make to put the reflection spheres in hierarchical order? And by hierarchical order, does that mean you put the biggest spheres first?

[@notverydarkmagic]

Henry Ramsevik Thanks! Hierarchical placement is a good "spatial" strategy as it tends to minimize capture influence overlap, which saves performance, while ensuring every corner is captured. It also helps to organize reflection accuracy according to the importance of the objects: a smaller, closer capture gives your hero assets less distortion and line-of-sight errors, but it's spatially inefficient to keep stacking small/medium spheres to fill the whole room. So we can use a big one to capture the less important corners. It's like a pyramid: the bigger the capture, the fewer you will generally need. The order does not refer to time of placement.

[@eraseme3089]

it is necesry to put a HDRI data on each sphere reflection? Or use just the global HDR?

[@notverydarkmagic]

Hey sorry for the late reply. Each sphere capture records what can be seen from that point: the diffuse version of everything it can see plus the skybox. Reflective surfaces read reflection data from spheres whose radiuses they are in. So if the captures don't include the skybox and the reflective surface is supposed to reflect the sky, the sky will be reflected as black. Besides, you don't have control over this, so it doesn't really matter. It is not multiplying the memory of the whole skybox with each additional sphere. Each sphere captures its own "360 photo" at its own resolution.