Meshes and bezier patches are boundary representations with no information of the volume they enclose. Imagine you'd like to cut an object out of smoke or clouds. SDFs enable you to cut out arbitrary volumes from any material. This is more realistic than skinning a mesh object with textures, especially with translucent objects.
> So why do we need neural nets to represent them?
You don't. I didn't notice render times, but "interactive frame rates" would be lacking.
Most SDF primitives and their compositions are not analytic (from use of abs, fract, etc). Differentiation by finite differences is most common. Few are using automatic differentiation. I don't quite follow how back prop would produce the surface gradient, but I doubt it would be faster than these methods.
Meshes and bezier patches are boundary representations with no information of the volume they enclose. Imagine you'd like to cut an object out of smoke or clouds. SDFs enable you to cut out arbitrary volumes from any material. This is more realistic than skinning a mesh object with textures, especially with translucent objects.
> So why do we need neural nets to represent them?
You don't. I didn't notice render times, but "interactive frame rates" would be lacking.
Most SDF primitives and their compositions are not analytic (from use of abs, fract, etc). Differentiation by finite differences is most common. Few are using automatic differentiation. I don't quite follow how back prop would produce the surface gradient, but I doubt it would be faster than these methods.