High quality reflections in Unreal Engine 4

Michał Franczak 2017-05-19 11:45 tutorial  > Unreal Engine  > rendering

Make mirror-like planar reflections in Unreal Engine 4.

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One of the first things that we should do if we want to increase reflections quality is opening Project settings and changing Reflection Capture Resolution value. 1024 is a nice start. Of course - increasing this value is binded with performance cost quite noticeably.


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If you do not use Screen Capture Spheres, boxes or planar reflection, you will get artifacts, especially on a flat surface. Here you can see that the plane is reflecting black color on the edges, because Unreal is unable to capture the scene correctly. You can also see blurry Screen Space reflections - far from desired quality. 


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Just bringing Reflection Capture Sphere got rid of the black area problem. We also added Post Process Volume and turned "Screen Space Reflections" to 0, so they do not interfere with our captured reflections. Still - reflection of our trumpet appears jagged and blurry.


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Another setting that increases reflections quality is GBuffer Format. You will have better results if you change it to "High Precision Normals" setting. This way reflections will be smooth even on curved surfaces, like car hood.


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You need to open LOD0 settings of each object that needs high quality reflections and check "Use High Precision Tangent Base" setting. After that press "Apply settings" on the bottom of the list.


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We want to achieve nice mirror-like flat surface that reflects our trumpet. So we add Planar Reflection component from "Visual Effects" panel. At the default it has "Show preview plane" on - it helps to see reflections more clearly. You can turn it off after you are done with tweaking. You can see that reflections are really bad quality. I made it on purpose to show you the main quality setting of this component. It is "Screen Percentage" - here it is set to real low value (25%).


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If you drag the slider "Screen Percentage" to "100" you will see much smoother result. We can see some artifacts under buttons of the trumpet - bottom faces are not reflected correclty. We can fix that...


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I enabled "render scene two-sided" so we can now see buttons reflection correctly. I also disabled preview plane.


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I want to see if my reflections are good, so I change roughness of the floor to 0.


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I get rid of my reflection spheres. To have correct reflections from PlanarReflection I need to add some environment lighting. So I place BP_skysphere, Atmospheric fog and Skylight into scene. I also need to increase PlanarReflection size to cover all the floor. If I wouldn't do that, I would get again "black area" artifact, that we have seen before.


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Our reflection now seems very good, crisp and without artifacts.


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There is small problem though - when I place my camera further from models, their reflections appear black / shadowed. It is unrealistic. We will need at least one Reflection Capture Sphere after all.


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With the sphere, our reflections are bright even if we are navigating far from our models. You can tweak Sphere influence radius and brightness.


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The final screenshot.


Author: Michał Franczak Editor: Michał Franczak
Tags: unreal reflections planar
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daniel_raziel23:28:19  |  03-01-2018
thanks a lot for these useful information. i've been seeking and finding a good way to do this and got the whole in one package! btw i started ue4 recently and haven't done any projects for mobile (for architectural presentation) . can mobiles handle these reflections in small places like a hall and a mirror or etc?


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