BRDF and BSSRDF both offer unique perspectives on how light interacts with surfaces in computer graphics. BRDF focuses on surface reflection, providing a snapshot of light's behavior at the interface which makes it ideal for rendering opaque materials with precision and clarity. However, BSSRDF goes beyond the surface and dives into the complexities of subsurface scattering, particularly suited for translucent or semi-transparent materials like skin or wax. This evident as the photo of the face with BSSRDF is a lot less textured and appears as if it has a filter on it. It is extremely interesting how BSSRDF can add depth and realism to renderings which heavily enriches the visual experience with subtle nuances and lifelike textures.
ArjunPalkhade
Here's a video that gives a high-level view on BSSRDF: https://www.youtube.com/watch?v=QxBhZjG5CaI
maldenz
The BRDF applies to light that reflects off the surface of a material without penetrating it, and is used for modeling the reflectance properties for direct reflection, both diffuse and specular. It assumes that the light interacts at a single point on the surface. In contrast, the BSSRDF accounts for light that penetrates into a translucent material, scatters internally, and then exits at a different point. This model is necessary for materials like skin, marble, or wax, where subsurface scattering plays a significant role in their appearance, affecting both the color and the softness of the light as it emerges from the material. While BRDF is sufficient for opaque materials with surface scattering, BSSRDF is required for a realistic portrayal of translucent materials with complex light interactions within them.
andrewn3672
Seeing the difference between using BRDF and BSSRDF on skin makes it extremely clear to me the drawbacks of purely using BRDFs for everything. In the previous example with the marble, I could tell there was a difference, but it didn't look too bad to me. BRDF on skin however looks strange and is very obviously not correct. It makes sense why BRDF doesn't work very well on skin as skin itself isn't fully opaque and is much more complex.
anavmehta12
Intuitively I understand the BSSRDF a function that takes into account translucent material like the human skin where light penetrates the object and scatters within while the BRDF only accounts for light reflecting off a surface which is why it looks much worse using BRDF.
noah-ku
On the left, we have BRDF, which is used for materials where light just interacts at the surface. It's good for direct reflection, but it does not take into account subsurface scattering. BSSRDF gives a more lifelike and natural look because of the way it takes into account the light that travels through the surface before scattering out.
Zzz212zzZ
I interpret the difference between BRDF and BSSRDF as that the BRDF doesn't account for how material absorbs light it interacts. The result shows it is more coarse for the BRDF-rendered image. So for the smooth part in the right image, is that made so by the scattered absorbt light?
cvankeuren
From my understanding, the BRDF solely accounts for the surface reflection of light and is primarily used for opaque materials. On the other hand, BSSRDF accounts for the scattering of light that happens within a semi-transparent material, and is likely a much more complicated function. That being said, a question I have about this is whether there exists a material that utilizes both of these behaviors?
AbhiAlderman
This example helped me understand the usefulness of BSSRDF much more. I thought that maybe with a few tweaks BRDF could effectively used for any material, but this plus the previous examples show just how different these results are. The material looks completely different on the left, looking like a clay person, while the person on the right looks "realistic" to me. I never thought about how light works on materials that are somewhat transparent and let some light through, like skin or certain metals, but it's fascinating to see just how much this transparency affects the look of the material.
BRDF and BSSRDF both offer unique perspectives on how light interacts with surfaces in computer graphics. BRDF focuses on surface reflection, providing a snapshot of light's behavior at the interface which makes it ideal for rendering opaque materials with precision and clarity. However, BSSRDF goes beyond the surface and dives into the complexities of subsurface scattering, particularly suited for translucent or semi-transparent materials like skin or wax. This evident as the photo of the face with BSSRDF is a lot less textured and appears as if it has a filter on it. It is extremely interesting how BSSRDF can add depth and realism to renderings which heavily enriches the visual experience with subtle nuances and lifelike textures.
Here's a video that gives a high-level view on BSSRDF: https://www.youtube.com/watch?v=QxBhZjG5CaI
The BRDF applies to light that reflects off the surface of a material without penetrating it, and is used for modeling the reflectance properties for direct reflection, both diffuse and specular. It assumes that the light interacts at a single point on the surface. In contrast, the BSSRDF accounts for light that penetrates into a translucent material, scatters internally, and then exits at a different point. This model is necessary for materials like skin, marble, or wax, where subsurface scattering plays a significant role in their appearance, affecting both the color and the softness of the light as it emerges from the material. While BRDF is sufficient for opaque materials with surface scattering, BSSRDF is required for a realistic portrayal of translucent materials with complex light interactions within them.
Seeing the difference between using BRDF and BSSRDF on skin makes it extremely clear to me the drawbacks of purely using BRDFs for everything. In the previous example with the marble, I could tell there was a difference, but it didn't look too bad to me. BRDF on skin however looks strange and is very obviously not correct. It makes sense why BRDF doesn't work very well on skin as skin itself isn't fully opaque and is much more complex.
Intuitively I understand the BSSRDF a function that takes into account translucent material like the human skin where light penetrates the object and scatters within while the BRDF only accounts for light reflecting off a surface which is why it looks much worse using BRDF.
On the left, we have BRDF, which is used for materials where light just interacts at the surface. It's good for direct reflection, but it does not take into account subsurface scattering. BSSRDF gives a more lifelike and natural look because of the way it takes into account the light that travels through the surface before scattering out.
I interpret the difference between BRDF and BSSRDF as that the BRDF doesn't account for how material absorbs light it interacts. The result shows it is more coarse for the BRDF-rendered image. So for the smooth part in the right image, is that made so by the scattered absorbt light?
From my understanding, the BRDF solely accounts for the surface reflection of light and is primarily used for opaque materials. On the other hand, BSSRDF accounts for the scattering of light that happens within a semi-transparent material, and is likely a much more complicated function. That being said, a question I have about this is whether there exists a material that utilizes both of these behaviors?
This example helped me understand the usefulness of BSSRDF much more. I thought that maybe with a few tweaks BRDF could effectively used for any material, but this plus the previous examples show just how different these results are. The material looks completely different on the left, looking like a clay person, while the person on the right looks "realistic" to me. I never thought about how light works on materials that are somewhat transparent and let some light through, like skin or certain metals, but it's fascinating to see just how much this transparency affects the look of the material.