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Comment by blauditore | Hacker News Reader

The image of that camera under "PBR Shader": Is that a photo or a rendering? Caption and context imply it's a rendering, but it looks too realistic for me to believe, with all those wear marks and fine textures.

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PBR (Physically-based render) Shaders are extremely realistic. The Suzanne monkey example is pretty neat, but you can find mindblowing examples from other artists. [1]

1. https://www.marmoset.co/posts/physically-based-rendering-and...

Those wear marks and fine textures probably are photos, kind of. It turns out one of the ways photorealism is achieved is by mapping textures onto 3d objects, and those textures usually originate from photos.

From heavily edited photos where the original surface has to be decomposed into rough estimates of base color, metallicity, roughness, anisotropy, subsurface scattering, transparency, normal maps, etc etc.

Metallicity?

Light reflects/diffuses of metals if different way then from non-metallic objects (insulators). This gives metals characteristic shine you can't replicate without metalic particles in real world (metalic paints). PBR Shaders take this into account and this creates so called "metalness workflow" instead of "specular workflow".

With specular workflow you would specify color of diffused light and color of reflected light (specular map, usually white for insulators and in color of the metal for metals).

In metalness workflow you specify albedo map and metalness map. The metalness map is usually 1 or 0 as materials in real world are either metals or not.

See https://www.marmoset.co/posts/physically-based-rendering-and...

Interesting—I've read the original PBR book but didn't realize that such robust support and culture had grown up around it.

Even the dents on the lens? Texture wouldn't be able to generate actual geometric deformities can it?

Textures can create the illusion that certain small deformities exist. This is often used for scratches and things that are not always modeled. https://www.marmoset.co/wp-content/uploads/2014/01/lenstextu...

Scratches like these could sometimes be painted directly onto the texture - or maybe sculpted onto a higher-resolution model and then "baked" down to the lower-resolution model. In this step lots of data from how light bounces off the high-resolution model can be imprinted to a texture and re-used in a lower-resolution model.

If you want to learn more the terms to be googling are "normal mapping" and "bump mapping"

In this article - If i was to guess; all the pictured spheres are perfectly spherical, and just textured differently. https://www.marmoset.co/posts/physically-based-rendering-and...

Also - heres an interactive model of the lens: https://www.artstation.com/artwork/kl0A6 The "Layers View" button in top right gives you a neat view of the model with/without certain texture layers

not talking about bump mapping.

Talking about the dents on the lens' filter silver filter ring. I doubt it was modeled.

https://www.blender.org/wp-content/uploads/2017/08/camera_pb...

That can be done pretty easily with adaptive subdivision and displacement mapping. You could also just create a super high-poly mesh manually and paint in the dents.

Sure. That's called displacement mapping. Fairly ubiquitous in high-end renderers.

Interactive PBR of the metallic monkey: https://sketchfab.com/models/39128f2ba3db4d30be7238a569fa234...

Man, the interactive stuff is getting so good. Never thought I'd see a reasonably photorealistic steampunk suzanne rendered realtime in my browser. (on a three year old low-end chromebook!)

Wow, I didn't realize how good sketchfab's model viewer is. Thanks for sharing this.

Render. The specularity of the surfaces is not quite right yet... with some more tweaking this could sure pass as a photo, though. Some wear marks are odd, too, but that can happen in real-life, too.

Definitely a rendering. But I was taken aback, I have a couple of similar Olympus and they are uncannily similar to that image.

Definitely a render.

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