Hi,

I wonder what povray lacks compared to vray. when I look at the renders produced
by vray I get the feeling they are very much up to date and modern looking.

In comparison povray has some awesome images produced so far but at times they
look somehow outdated. I hope you understand what I mean. Is it me or the vray
images are the same as povray quality but just uses better setups(environments,
etc, god knows what else)

I am a raging povray fanboy(45 yrs old though), I wanna see it rule the
raytracing scene, oh gosh.

This question has been bugging me for  a year or two, I had to ask it, sorry if
I offended anyone by any remark, my intentions are clear by the fanboy comment.
I really want to know what people's take on this is, since most of them (you
know who you are) are far more knowledgeable than me.

So the question is how do you compare povray to vray in/on any scale you choose?

I will appreciate any answer. Thank you.

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Am 13.12.2010 21:42, schrieb optima:

> So the question is how do you compare povray to vray in/on any scale you choose?

I don't compare it at all. One is a freeware open source renderer with 
built-in modelling language, the other is a commercial proprietary 
render engine available as a "plug-in" to commercial modelling tools.

Post a reply to this message

> Hi,
>
> I wonder what povray lacks compared to vray. when I look at the renders produced
> by vray I get the feeling they are very much up to date and modern looking.
>
> In comparison povray has some awesome images produced so far but at times they
> look somehow outdated. I hope you understand what I mean. Is it me or the vray
> images are the same as povray quality but just uses better setups(environments,
> etc, god knows what else)
>
> I am a raging povray fanboy(45 yrs old though), I wanna see it rule the
> raytracing scene, oh gosh.
>
> This question has been bugging me for  a year or two, I had to ask it, sorry if
> I offended anyone by any remark, my intentions are clear by the fanboy comment.
> I really want to know what people's take on this is, since most of them (you
> know who you are) are far more knowledgeable than me.
>
> So the question is how do you compare povray to vray in/on any scale you choose?
>
> I will appreciate any answer. Thank you.
>
>

You want to compare the offering of two totaly different groups of artists.
POV-Ray users are mostly hobyists using a great free tool.

vray seems to be a comercial addon for other comercial renderers, and 
thus, mostly used by professional artists using it for a living.

It is thus unrealistic to compare the end products.


Alain

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On 2010-12-13 15:47, Alain wrote:
> You want to compare the offering of two totaly different groups of artists.
> POV-Ray users are mostly hobyists using a great free tool.
>
> vray seems to be a comercial addon for other comercial renderers, and
> thus, mostly used by professional artists using it for a living.
>
> It is thus unrealistic to compare the end products.

I, for one, disagree that it's unrealistic to compare the end products. 
  Yes, there are differences, but they are measurable.  Optima is 
asking, it seems to me, if given an identical scene and light setup, 
what are the differences between POV-Ray and vray?  What features are 
present in typically-seen vray renders that are perhaps absent in 
POV-Ray renders?

The exact same question is valid to ask one's self as a hobbyist artist 
using traditional media vs the works of professional illustrator who 
also uses traditional media:  'what do they do that the I don't, so that 
I can improve my own skills?'

-- 
Tim Cook
http://empyrean.freesitespace.net

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On 2010-12-13 15:42, optima wrote:
> So the question is how do you compare povray to vray in/on any scale you choose?

Well, after looking at the feature list for vray and sample renders, a 
few obvious things stand out:

1) vray has a bigger library of good looking textures, where the stock 
povray textures are, well, lacking. It seems that most good artists here 
create their own or use what others post on the newsgroups or websites. 
This leads to more ability to make custom looks in povray, but at the 
expense of a considerable amount of time and requires that you have some 
expertise yourself.

2) vray has GPU acceleration. I know the official stance here is that 
povray needs to work with double instead of float, but nowadays CUDA 
allows for that (at reduced speed) and really, there probably are places 
in the scene where floats would work fine.

3) I'd assume vray has more efficient "SDL parsing" or their version of 
it, because they mention reusable things for animations and the like. 
POV-Ray speed can be increased considerably by unrolling loops, that 
should tell you something (besides that it's an interpreted language). 
The whole bit with opening an included file every time you call 
something inside it also is a negative for pov in the speed department, 
but allows for more powerful macros.

4) vray advertises motion blur, bokeh on DoF, ... All things that _can_ 
be done with povray but require someone to write macros.

Overall, I'd say that their main strength is the stock selection of 
materials and textures and the like, with a boost from (advertised) 
real-time rendering by using GPUs.
POV-Ray's strength in comparison is the lack of "hacks" to speed things 
up such as ambient occlusion, instead focusing on providing an 
"accurate" image for what you want. It may be slower, but it's more 
physically realistic if you get your parameters correct.

If one wants to say the adage "you get what you pay for", well, I'm 
getting a heck of a better cost/results ratio from povray than I would 
get from vray! If I were doing professional work I'd probably be using 
one of the commercial packages for the reason that I'd be paying someone 
else to spend the time to make the materials and tracer so I would only 
have to spend time on the modeling itself, but I'm not.

That's really what it boils down to, what's the value of your time? I 
would posit that given enough experience and time a good artist could 
get an image from povray that would look as if not more realistic than 
one from vray, but it might take quite a while.

Post a reply to this message

Am 14.12.2010 00:08, schrieb CShake:

> 2) vray has GPU acceleration. I know the official stance here is that
> povray needs to work with double instead of float, but nowadays CUDA
> allows for that (at reduced speed) and really, there probably are places
> in the scene where floats would work fine.

That /used/ to be the official stance, when double precision floating 
point arithmetics wasn't available in GPUs.

While this is a non-issue nowadays, there are other remaining issues 
that make GPU use problematic (most notably the inavailability of 
recursions) as well as of low benefit (most notably the fact that GPUs 
are most efficient on bulk data that undergoes the same 
transformations). Avoiding those issues is possible, but in the case of 
POV-Ray would require a complete redesign of its internal architecture.


> 4) vray advertises motion blur, bokeh on DoF, ... All things that _can_
> be done with povray but require someone to write macros.

In the case of bokeh, macros are no longer needed (with version 3.7 that 
is) ;-)

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On 2010-12-13 19:31, clipka wrote:
> Am 14.12.2010 00:08, schrieb CShake:
>
>> 2) vray has GPU acceleration. I know the official stance here is that
>> povray needs to work with double instead of float, but nowadays CUDA
>> allows for that (at reduced speed) and really, there probably are places
>> in the scene where floats would work fine.
>
> That /used/ to be the official stance, when double precision floating
> point arithmetics wasn't available in GPUs.
>
> While this is a non-issue nowadays, there are other remaining issues
> that make GPU use problematic (most notably the inavailability of
> recursions) as well as of low benefit (most notably the fact that GPUs
> are most efficient on bulk data that undergoes the same
> transformations). Avoiding those issues is possible, but in the case of
> POV-Ray would require a complete redesign of its internal architecture.

Ah, didn't know for sure. Is that because of the function based 
primitives that POV uses compared to entirely triangle meshes in most 
other packages?

>
>> 4) vray advertises motion blur, bokeh on DoF, ... All things that _can_
>> be done with povray but require someone to write macros.
>
> In the case of bokeh, macros are no longer needed (with version 3.7 that
> is) ;-)

Neat, hadn't seen that. And now that I check the changelog, thanks to 
you for implementing it. :)

As for my comment above about the render being more realistic or 
accurate, I should qualify that by saying that POV seems to be the most 
physically accurate tracer that works on rgb internally instead of 
wavelength response.

Post a reply to this message

CShake <cshake+pov### [at] gmailcom> wrote:
>
> That's really what it boils down to, what's the value of your time? I
> would posit that given enough experience and time a good artist could
> get an image from povray that would look as if not more realistic than
> one from vray, but it might take quite a while.

Thanks for the answers. To make what I mean more clear by differences I include
the path to my gallery
http://www.optimadekor.com/galeri/mutfak_program_optima.htm

the first 4 pics are done with radiosity values like
#declare rad_quality= 1;
#declare rad_bounces=   2;
#declare rad_brightness= 0.8;
global_settings {adc_bailout 0.003922
assumed_gamma 1.0
irid_wavelength <0.247059,0.176471,0.137255>
max_trace_level 10
radiosity {
pretrace_start 0.05
pretrace_end 0.005
count rad_quality*rad_quality
nearest_count 10+rad_quality
error_bound 0.5/rad_quality
recursion_limit rad_bounces
brightness rad_brightness}}

and just one light
light_source{
0, rgb 3
area_light 20*x,20*z,4,4 jitter adaptive 1 orient circular
fade_distance 100
fade_power 2
translate <-198.2784,250,405.9303>}

the remaining pics after first 4 dont use radiosity. SDL files for all pics
produced automatically by C# code.

This is the best I got from Povray, Of course POV is capable of doing better.
So, as C Shake states, is it my lack of good textures, lack of better radiosity
or lighting settings? Or am I just trying to play catchup with vray hopelessly?
the quality of some POV images I've seen so far are second to none. So I know
there is hope.

thank you for everything :D
optima

To C Shake
> one from vray, but it might take quite a while.
Whay do you mean by quite a while?
to get the good textures
to gain the experience
to render the image

Post a reply to this message

> 1) vray has a bigger library of good looking textures, where the stock
> povray textures are, well, lacking. It seems that most good artists here
> create their own or use what others post on the newsgroups or websites.
> This leads to more ability to make custom looks in povray, but at the
> expense of a considerable amount of time and requires that you have some
> expertise yourself.

This is the main reason, plus realistic lighting/environment setups 
ready-made.  It's all too easy with POV to create unrealistic looking 
scenes purely because of bad textures and lighting.

Fundamentally I don't think there is anything POV is lacking to prevent 
you creating very realistic scenes similar to other commercial renderers.

Post a reply to this message

Am 14.12.2010 10:42, schrieb optima:

> Thanks for the answers. To make what I mean more clear by differences I include
> the path to my gallery
> http://www.optimadekor.com/galeri/mutfak_program_optima.htm

Image #1 appears overly bright to me; the ceiling appears to have an 
"ambient" term (or, in case it was rendered with an up-to-date 3.7 beta, 
an "emission" term); same with the fruit.

Geometry looks fairly sophisticated, with beveled edges and stuff 
(though the geometry of the lower shelf in the corner seems incomplete, 
see the shadow), and radiosty settings seem fairly good.

You might try improving on the diffuse reflections. Focal blur might be 
a good idea for that, because it can do a fairly good antialiasing.


#2 has the same problems with the ceiling as #1; wall tiles texture 
could be improved (not enough bump, maybe too much ambient), floor tiles 
look much better. Doors texture shows that you're already using 
sophisticated texturing features, but I think the scale is wrong, and 
the bump mapping maybe a bit too strong. Metal surfaces appear somewhat 
too bright, maybe too much diffuse.


#3 ceiling is much better, but shows that you need better radiosity 
settings. Wall tiles seem to use ambient once again. Glass doors might 
look more convincing with stronger reflection (try "reflection 0.0 1.0 
fresnel" and "ior 1.5"). The lower door of the fridge appear "decal-ish" 
somehow.


#4 appears to use ambient on the ceiling again, and maybe also on the 
walls. The doors look too flat for some reason I cannot identify; 
something about the reflection doesn't seem quite right. The glass doors 
look like they could use more reflection again (see above). The pot on 
the very top shelf on the right is the only convincing metal I've seen 
in your shots so far (and is very good at that), so have a closer look 
at that one.


I don't think we need to discuss #5 and following - you just can't get 
convincing results without radiosity (or, to use the more general term, 
"global illumination"; radiosity is just one out of various algorithms 
to compute that).


So all in all: Yes, there's still room for improvement in your images 
with POV-Ray.

In general, many of your textures appear to be using ambient; this is ok 
for preview renders without radiosity, but it is an absolute no-go for 
realistic radiosity renders; if you're using radiosity, make sure you 
also use "ambient_light 0" to disable the ambient in all textures (or, 
alternatively, use an up-to-date 3.7 beta and make sure you have a 
"#version 3.7" statement in your scene).

You also seem to have problems getting metal textures to look right; 
maybe this has to do with ambient as well, but there may be other 
reasons. Look at the pot I mentioned, because its metal texture looks 
really good. Unfortunately, POV-Ray is currently rather poor for 
modelling dull metal: You really need blurred reflection to make that 
look convincing, the "diffuse" term is an insufficient substitute. At 
present, that means you'll need to use some micro- or macronormals 
approach. (My personal favorite approach is to use a single-layer 
texture with a very small-scaled normals bump, and use high 
anti-aliasing using AA or focal blur. Other people prefer a 
multi-layered approach, which does not require anti-aliasing but gets 
very costly for rays reflected multiple times.)

Speaking of reflection: When you're working with mirrors, make sure to 
model a complete room so that the mirror doesn't just reflect a uniform 
background. You can mark the corresponding geometry as "no_image" if it 
would otherwise obstruct the camera.

Speaking of mirrors: The second-to-last image (non-radiosity) suffers 
from the reflected wall being brighter than the non-reflected wall, 
which is obviously physical nonsense. Photons may help in such cases.

And finally, you may also want to look at your glass textures; I'm not 
exactly sure how they will look best, but I'd recommend trying 
"reflection 0.0 1.0 fresnel" and an IOR fitting for window glass 
(something roughly around 1.5). Also make sure that the glass has no (or 
very little) diffuse.

Occasionally you may be struggling to achieve some particularly vivid 
colors. In such cases, dare to set some color components to /negative/ 
values. While counterintuitive at first, such values /can/ make sense 
physically.

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