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Ray Tracing with POV-Ray: 25 scenes in 25 days (2013)

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Re: Ray Tracing with POV-Ray: 25 scenes in 25 days (2013)

#21

Post by zodiac »

selfsimilar wrote: post #5
erjiang wrote: post #3

Wow, the state of the art in 3D rendering has changed dramatically. The state of the art in open source 3D rendering has changed even more dramatically. Compare these screenshots from 2013 (although I think POV-Ray was looking pretty dated by then) to renders that come out of Blender's Cycle renderer now. The big change is that everyone has moved to "physically based rendering" that do path-tracing for propagating li…

I agree the quality of the render engine is much better with physical rendering, but I still love constructive solid geometry and the ideal of pure curves to define the scene geometry. All these meshes with their triangles! Whatever happened to using NURBS or metaballs or other non-polygonal modeling?

You can have physically based rendering with those non-triangle primitives too!

Re: Ray Tracing with POV-Ray: 25 scenes in 25 days (2013)

#22

Post by Aardwolf »

BubRoss wrote: post #7
selfsimilar wrote: post #5

Earlier quoted context omitted.

I agree the quality of the render engine is much better with physical rendering, but I still love constructive solid geometry and the ideal of pure curves to define the scene geometry. All these meshes with their triangles! Whatever happened to using NURBS or metaballs or other non-polygonal modeling?

Polygons can be smoother and subdivided efficiently at render time without artifacts, which is how they are used now. Nurbs and other curved surface representations end up with huge problems pragmatically when it comes to tools, workflow, visualization, texture coordinates, keeping the surfaces together etc. The list is long. Polygons are very simple in all these areas and can be made smooth at render time so you get…

Every time I see a pipe, bucket, goblet or round thing in a game with otherwise very realistic rendering, I'm reminded I'm just playing a rendered game, due to seeing polygonal shapes rather than a true round bucket/goblet/pipe, and wonder if a quadratic surface would not look better and be more efficient.

Well, that and banding in the gradient of a sky. Those two things break the otherwise so realistic rendering quite commonly.

Re: Ray Tracing with POV-Ray: 25 scenes in 25 days (2013)

#23

Post by s800 »

trevortheblack wrote: post #15

If anyone is interested in getting started on Ray Tracing _today_. I recommend Peter Shirley's _Ray Tracing In One Weekend_ Series. https://raytracing.github.io/ (I edited the later editions)

Another recommendation: DKBtrace, which is a predecessor to Povray, has easier to grok code. IMHO.

Re: Ray Tracing with POV-Ray: 25 scenes in 25 days (2013)

#24

Post by anthk »

erjiang wrote: post #3

Wow, the state of the art in 3D rendering has changed dramatically. The state of the art in open source 3D rendering has changed even more dramatically. Compare these screenshots from 2013 (although I think POV-Ray was looking pretty dated by then) to renders that come out of Blender's Cycle renderer now. The big change is that everyone has moved to "physically based rendering" that do path-tracing for propagating li…

http://hof.povray.org/mouille.html

Year 2000. You don't know a lot, and I guess you didn't have a look on the PovRay's hall of fame.

Re: Ray Tracing with POV-Ray: 25 scenes in 25 days (2013)

#25

Post by anthk »

TylerE wrote: post #16
beering wrote: post #10

Earlier quoted context omitted.

Using this very nice POV-Ray render from Wikipedia: https://upload.wikimedia.org/wikipedia/commons/thumb/e/ec/Gl... It features a lot of effects (radiosity, HDR maps, etc.) which are added on top of its basic functionality. There's been a big shift in how rendering is approached, from the old way of adding a pile of special effects onto your original non-realistic renderer, to a newer way of simulating light as it ph…

> It features a lot of effects (radiosity, HDR maps, etc.) which are added on top of its basic functionality Huh? POV-Ray has supported radiosity for literally decades, since sometime around 1995.

Yep, I'm tired of these kids saying PovRay coudn't do shit as if PovRay had in 1997 the same capabilities of an Irix machine from 1987. They couldn't even be more wrong with that.

I remember seeing photoreallistic images made with PovRay in 1997 you coudn't even do with a GPU today in real time.

Kids today have a lot of ignorance on the 90's technologies, guess why they confuse the 80's and the 90's a lot thanks to that shitty vaporwave culture, having fake nostalgia on something they never truly experienced.

Man, I was playing 720p video under a Divx code in early 00's with a Pentium3 and multimedia was on its heayday, thus, people showing up a CGA pallete has no sense, it already was retro back in the day, you had those in the old MSDOS games you were running under W98 or DOSEmu under Linux, among the rest of the emulators for the ZX Spectrum and MSX for example.

Sorry for my rant, but I had to say it. The late 90's had nothing to do with early 90's, the technology shift we've seen it was outstanding. From DOS under a 286 in my early Elementary school, to W98 emulating Pokémon in my pre-HS days among recording TV streams in a computer, all of that in 5-6 years.

From 30Mhz and 5 1/4 floppies to ~450/600 MHZ a bunch of GB in 1999. For sure PovRay could do a lot more than these kids think.

Re: Ray Tracing with POV-Ray: 25 scenes in 25 days (2013)

#26

Post by BubRoss »

selfsimilar wrote: post #11
BubRoss wrote: post #7

Earlier quoted context omitted.

Polygons can be smoother and subdivided efficiently at render time without artifacts, which is how they are used now. Nurbs and other curved surface representations end up with huge problems pragmatically when it comes to tools, workflow, visualization, texture coordinates, keeping the surfaces together etc. The list is long. Polygons are very simple in all these areas and can be made smooth at render time so you get…

Pragmatically, I think the real issue is editor tooling. Polygons are much simpler to subdivide and edit and are perfect for real-time interaction, at least much better for high-complexity scenes. At render time, though, you need to use a bunch of extra tricks to get the right smoothing - bump/texture mapping, increased subdivision, etc. But some of these other models might actually decrease the scene complexity and…

It isn't just tooling.

> At render time, though, you need to use a bunch of extra tricks to get the right smoothing

Nurbs or any smooth geometry needs to be subdivided too. You can set levels, max size of polygons, smoothness constraints subdivide based on the pixel size from the camera projection or any combination. In practice this is not a problem for polygons or nurbs.

> - bump/texture mapping,

This is orthogonal to the geometry type, with the exception that UV coordinates are far easier to deal with with polygons.

> increased subdivision,

There isn't any increased subdivision, both geometry types need to subdivided. Blue Sky's renderer raytraced nurbs directly but this isn't generally as good as just tracing subdivided polygons.

Polygonal geometry, even subdivided, is typically not a big part of memory or time in rendering in all but the most pathological cases. 4k would still mean that one polygon per pixel would be 8 million polygons, which is going to pale in comparison to texture data typically.

Re: Ray Tracing with POV-Ray: 25 scenes in 25 days (2013)

#27

Post by BubRoss »

TylerE wrote: post #17
BubRoss wrote: post #12

Earlier quoted context omitted.

I'm not sure what you are trying to say here, constructive solid geometry does not solve any of the problems I mentioned and would have to be treated specially to be raytraced (while being likely being much slower). Converting it to polygons at a modeling or effects stage is workable but rendering it directly is unlikely to be widely valuable any more.

There is no need to "subdivide" because the exact volume of the object can be calculated exactly to any arbitrary detail.

And what do you subdivide it to? How do you trace rays against it? How do you map textures on to it? How do you visualize it in real time? How do you work with it in a different program?

Re: Ray Tracing with POV-Ray: 25 scenes in 25 days (2013)

#28

Post by TylerE »

BubRoss wrote: post #27
TylerE wrote: post #17

Earlier quoted context omitted.

There is no need to "subdivide" because the exact volume of the object can be calculated exactly to any arbitrary detail.

And what do you subdivide it to? How do you trace rays against it? How do you map textures on to it? How do you visualize it in real time? How do you work with it in a different program?

You don't subdivide. It's a mathematical intersection.

Re: Ray Tracing with POV-Ray: 25 scenes in 25 days (2013)

#29

Post by klodolph »

Aardwolf wrote: post #22
BubRoss wrote: post #7

Earlier quoted context omitted.

Polygons can be smoother and subdivided efficiently at render time without artifacts, which is how they are used now. Nurbs and other curved surface representations end up with huge problems pragmatically when it comes to tools, workflow, visualization, texture coordinates, keeping the surfaces together etc. The list is long. Polygons are very simple in all these areas and can be made smooth at render time so you get…

Every time I see a pipe, bucket, goblet or round thing in a game with otherwise very realistic rendering, I'm reminded I'm just playing a rendered game, due to seeing polygonal shapes rather than a true round bucket/goblet/pipe, and wonder if a quadratic surface would not look better and be more efficient. Well, that and banding in the gradient of a sky. Those two things break the otherwise so realistic rendering qui…

I think you may have missed what the parent comment was saying—that the polygons can be made smooth before render time. This is not a question of just faking it with normals. Instead, you can actually just work with a polygonal mesh and then post-process it to make it actually smooth. The classic technique for this is Catmull-Clark subdivision. If you think polygons on screen are offensive, you can just run the algorithm until the individual polygons are under the size of a pixel.

The fact that you see polygons on an otherwise circular object in a game just means that the game isn’t giving you a more detailed mesh when objects are close to the screen. There are a lot of reasons for this, and it’s important to consider that you often get the best overall quality in modern real-time graphics with retopologized meshes. It’s easy enough to make these with a given quality and make lower-LODs from them, but just as a matter of consequence you won’t see higher-LODs than the retopologized version. And why bother making super-high-LOD models anyway? If you look closely at an object there’s a finite amount of texture/model/etc. detail that the game can present. Might as well make the LOD for the model complement the amount of detail in the texture.

The whole process is rather complicated these days, with different workflows (even different programs) for organic objects (like people, animals, demons, whatever) and hard surfaces like goblets, stone tiles, architecture, etc. The two main things people want to do when modeling are sculpt and create a sensible topology, and surfaces like NURBs (or worse, Bézier curves) turned out to be a bit cumbersome for both sculpting and creating meshes.

Re: Ray Tracing with POV-Ray: 25 scenes in 25 days (2013)

#30

Post by tlb »

klodolph wrote: post #29
Aardwolf wrote: post #22

Earlier quoted context omitted.

Every time I see a pipe, bucket, goblet or round thing in a game with otherwise very realistic rendering, I'm reminded I'm just playing a rendered game, due to seeing polygonal shapes rather than a true round bucket/goblet/pipe, and wonder if a quadratic surface would not look better and be more efficient. Well, that and banding in the gradient of a sky. Those two things break the otherwise so realistic rendering qui…

I think you may have missed what the parent comment was saying—that the polygons can be made smooth before render time. This is not a question of just faking it with normals. Instead, you can actually just work with a polygonal mesh and then post-process it to make it actually smooth. The classic technique for this is Catmull-Clark subdivision. If you think polygons on screen are offensive, you can just run the algor…

Yes, but then any edges that should have been sharp get rounded too.
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