[HN Gopher] Artistic Radiance Fields
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       Artistic Radiance Fields
        
       Author : Mizza
       Score  : 117 points
       Date   : 2022-06-21 15:38 UTC (7 hours ago)
        
 (HTM) web link (www.cs.cornell.edu)
 (TXT) w3m dump (www.cs.cornell.edu)
        
       | [deleted]
        
       | amelius wrote:
       | It looks cool, but like PhotoShop filters, the coolness factor
       | will wear off quickly.
        
       | raptortech wrote:
       | This is excellent! I can't wait for Pixar to pick this up and
       | release a gorgeous hand-painted film.
        
       | ipsin wrote:
       | @ak92501 posted this one last week. This isn't to say "it's old
       | news" (it isn't!) but that if you're on Twitter and like
       | summaries of ML papers, they're a great follow.
       | 
       | https://twitter.com/ak92501/status/1536518567688122368
        
       | hansword wrote:
       | Just yesterday someone asked me if "AI style transfer"* would
       | work for 3d models or video. I said "if the current speed of
       | progress holds, i think we will see this within the year".
       | 
       | And here it is.
       | 
       | "What a time to be alive!"
       | 
       | (*) this isn't style transfer on video, as far as i understand,
       | this is styling the neural radiance field before rendering it to
       | images.
        
         | dimatura wrote:
         | Adaptations of image style transfer specifically for video came
         | out pretty quick after the image ones, and there's been a few
         | iterations. For the most part they use the same ideas, but add
         | some extra steps to "stabilize" the result of the stylization
         | across time so that it doesn't jump all over the place from
         | frame to frame.
         | 
         | For 3D, it's more complicated as there isn't an obvious
         | translation of image-based stylization to the 3D realm - if we
         | are talking 3D mesh models, I've seen similar ideas applied to
         | generating textures as well as geometry.
         | 
         | In this case, the novelty is combining the stylization with the
         | NERF, which does result in a special type of 3D model (not a
         | mesh, but a volumetric representation that lends itself well to
         | rendering). There isn't really any video aspect to it, other
         | than that videos of the result from different viewpoints are a
         | good way of visualizing the result.
        
         | trhway wrote:
         | how Van Gough would paint an excavator? Now we know :)
        
       | pavlov wrote:
       | Note that the input here is not any arbitrary video, but a
       | radiance field, a type of data structure that's halfway between
       | photos and a 3D model:
       | 
       | "The radiance field representation can be seen as a 5D function
       | that maps any 3D location x and viewing direction d to volume
       | density s and RGB color c."
       | 
       | The radiance field is typically reconstructed from multiple
       | photos of a scene, which implies that either the subject must be
       | static or you need a fancy camera rig to capture the views
       | simultaneously.
       | 
       | We don't have any content pipelines for creating and editing
       | radiance fields, so movies produced with this approach are a ways
       | off. But one could imagine AR glasses in a couple of years that
       | capture the different views as you move around, then the radiance
       | field is built in the cloud and you can create artistic re-
       | renders of what you just saw.
        
         | robocat wrote:
         | > We don't have any content pipelines for creating and editing
         | radiance fields
         | 
         | I presume radiance fields can be generated from computer
         | graphic scenes? It would be awesome to choose your own style
         | while playing a video game! Real-time generation is unlikely,
         | but game replay videos in a surreal style would be tres cool.
        
       | Imnimo wrote:
       | Radiance fields really feel like they're taking off. Reminds me
       | of GANs a few year ago, where the number of papers seemed to
       | start growing exponentially one day.
        
       | fxtentacle wrote:
       | In my opinion, this looks like a 2D style transfer, not a true 3D
       | style transfer. In the horse statue example, a human artist would
       | add a separator line between the white box and the grey
       | background, to illustrate the depth disparity. But this approach
       | seems to somewhat ignore depth cues when styling.
        
       | rektide wrote:
       | I always pictured eventually Augmented Reality would have
       | artistic overlays, reinterpretations of the world, and this sure
       | does seem like a feasible implementation of that.
        
         | Wistar wrote:
         | Yes! Perhaps AAR: Artistically Augmented Reality.
        
       | timmg wrote:
       | Would love to have this in VR. Dumb question: is there a VR
       | "player" for NERFs?
        
         | andybak wrote:
         | I don't think consumer GPUs can render this in real-time yet.
         | I've seen around 5 to 10fps framerates on a 3080 just rendering
         | monoscopic output (from memory)
        
       | kleer001 wrote:
       | cool stuff, but isn't style-transfer pretty old hat? even on
       | moving images?
        
         | bckr wrote:
         | it seems like this is more stable. the style applies over a 3D
         | world without noticeable artifacts or distortions
        
           | wwalexander wrote:
           | This was my impression as well. It seems to have some sort of
           | object permanence when the camera is moved rather than just
           | convoluting a single frame; seems significantly more
           | difficult to me as a layman.
        
             | corysama wrote:
             | Yep. There has been some work to figure out frame-to-frame
             | coherence on a sequence of images in 2D. But, I think this
             | skips over that problem by working in 3D.
        
         | killerstorm wrote:
         | It's not a "moving image", it's a neural radiance field (NeRF),
         | a way to represent a 3D scene using a neural network.
         | 
         | Style transfer worked on pixels, this approach works on the
         | scene itself, before it's rasterized.
        
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