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yesbird <sya### [at] gmail com> wrote:
> On 16/03/2025 04:27, yesbird wrote:
> > This is what I got with theradius = 0.1 and no crash.
> > --
> > YB
>
> rendering complete animation and this is the first 11 seconds
> forward-backward loop:
> https://povlab.yesbird.online/pb/
>
> --YB
I also reverted to polygons, to get away from all the suggestions around discs,
media, interiors, etc. Seems to be OK in 3.7 and 3.8, although 3.8 is MUCH
faster, factor about 3 or 4.
#macro DoPoint(theposition,thecolour)
#local thenormal = vnormalize(VP-theposition);
#local thedistance = vlength(VP-theposition);
#local theright = vcross(thenormal,z);
#local theup = vcross(theright,thenormal);
#local theright = vcross(thenormal,theup);
#if (thedistance > 1.0) // Filter any points close to the camera
#if (thedistance < 30) // Filter any distant outliers
#local theradius = 0.01*(1+thedistance); // Diameter of closest points
#if (theradius > 0.3) // Diameter of most distant
#local theradius = 0.3;
#end
polygon {
5, theright, theup, -theright, -theup, theright
no_shadow
texture {
pigment {
onion
colour_map {
[0.00, rgb thecolour transmit 0.75]
[0.50, rgb thecolour transmit 0.95]
[0.95, rgb thecolour transmit 1]
[1.00, rgb <0,0,0> transmit 1]
}
}
finish { emission 0 ambient 0 diffuse 1 specular 0 }
}
scale theradius
translate theposition
}
#end
#end
#end
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"Bald Eagle" <cre### [at] netscapenet> wrote:
> William F Pokorny <ano### [at] anonymousorg> wrote:
>
> > Got up to go to the bathroom(*) and, wow, a lot of posts in this thread.
>
> > Lastly, you could play with higher adc_bailout values too as a solution
> > to the v3.7 rendering.
>
> I thought this was just straight rendering - no radiosity.
>
> Also, I replaced all of the ambient statements with emission.
>
> > On your particular question about artifacts. The discs at larger radius
> > values will start to cross each other. Where they do there will be a
> > seam of numerical instability somewhat like coincident surfaces. Some
> > likelihood this is the cause of the artefacts, but unsure how to be sure
> > at moment. Can you filter out some range of discs closer to the camera
> > location?
>
> I would think the lines would be curved in that instance?
>
> Just out of curiosity, I was wondering what the actual overall scene looked
> like, so once I wrapped my head around the coordinate system and
> camera-to-look_at orientation, I was able to pull the camera back and look down
> over the entire undistorted market.
> (see attached)
>
> There are places where there are significant holes / spaces.
> I'm wondering if perhaps part of the problem may be that the lines are places
> where the rays are making it through to the black background.
>
> Perhaps a non-zero (1/255) sky_sphere or background may help, or something like
> a fog effect where the foreground is crystal clear, but the far-away spaces get
> filled in with a lighter color. Maybe some sort of large box with a gradient
> that's the 4th root of the normalized total distance... that sort of thing.
>
> Due to the time difference, I'm _just_ getting up and having First Coffee - so,
> you're getting what you're paying for. ;)
>
> - BW
>
> A huge point set like this is a real treat to play with, since it is large,
> asymmetric, offers human-recognizable structure, and has color data built in.
> I've been wanting to do a 3D convex hull algorithm, and this would be a great
> final test for that.
> Wondering what would happen if instead of discs or cylinders or spheres, _cones_
> were used instead, oriented looking straight at the smaller face and the larger
> end being just large enough to protrude: maybe that might fix the dark artifact
> lines if it's a see-through effect.
"A huge point set" .... I need to tell you that the sample I put on line for
testing is about 1/100 of the points in the actual scan. :-)
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yesbird <sya### [at] gmailcom> wrote:
> On 16/03/2025 04:27, yesbird wrote:
> > This is what I got with theradius = 0.1 and no crash.
> > --
> > YB
>
> rendering complete animation and this is the first 11 seconds
> forward-backward loop:
> https://povlab.yesbird.online/pb/
>
> --YB
I think a I forgot to "post" after the "preview", sorry if it's a duplicate.
There were lots of comments around discs, their interior and so on. So I
reverted to polygons, problems seems to have disappeared.
Did some other things like filtering distant and really near points, fade
distance and power on the light.
The final render will be a stereoscopic pair as omni directional cylindrical
panoramas (created using a vertex shader style approach) at 12816 x 2048 pixels.
It's for a 8m diameter, 4m high LED cylindrical display.
#macro DoPoint(theposition,thecolour)
#local thenormal = vnormalize(VP-theposition);
#local thedistance = vlength(VP-theposition);
#local theright = vcross(thenormal,z);
#local theup = vcross(theright,thenormal);
#local theright = vcross(thenormal,theup);
#if (thedistance > 1.0) // Filter any points close to the camera
#if (thedistance < 30) // Filter any distant outliers
#local theradius = 0.01*(1+thedistance); // Diameter of closest points
#if (theradius > 0.3) // Diameter of most distant
#local theradius = 0.3;
#end
polygon {
5, theright, theup, -theright, -theup, theright
no_shadow
texture {
pigment {
onion
colour_map {
[0.00, rgb thecolour transmit 0.75]
[0.50, rgb thecolour transmit 0.95]
[0.95, rgb thecolour transmit 1]
[1.00, rgb <0,0,0> transmit 1]
}
}
finish { emission 0 ambient 0 diffuse 1 specular 0 }
}
scale theradius
translate theposition
}
#end
#end
#end
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[running Windows 10. Most of my notes are a recap of what has already been
said.]
According to the documentation, POV-ray's disc object is actually a transparent
plane with a colored circle on it(?). So there are a lot of overlapping
transparent planes in Paul's scene!
Using his original scene code as-is:
In v3.7.0:
The parsing of the include file takes a very long time, then the render fails
about 1/3rd of the way down during the first animation frame. That render area
seems to coincide with a very dense collection of discs in the far distance.
Interestingly, by removing the finish {'transmits'} from the discs, the entire
scene renders OK.
In v3.8 beta 1:
The render crashes (hangs) during the parsing of the first frame. However, by
adding 'emission 0' to the disc's finish{...} as William P. suggested-- to
eliminate all of the many text warnings that are generated concerning a
'too-high ambient value'-- the scene renders OK. Nice call, William!
Also, v3.8 parses the scene at least 10X faster than 3.7.
-----------
In several of the posted renders here, I noticed what look like
coincident-surface problems on some of the discs. I set up a simple 2-disc scene
to see if I could recreate that, where the disc-planes exactly overlap. I don't
see such a problem-- but if I reverse the 'normal' of one of the discs,
coincident surface artifacts do show up. It is probably due to numerical
precision under-the-hood.
-----------
#version 3.8;
global_settings{assumed_gamma 1.0 max_trace_level 5}
camera {
perspective
location <.1, .1, -1.5>
look_at <0, .3, 0>
right x*image_width/image_height // aspect
angle 50
}
background{rgb .1}
// left
disc {
<-.25,.5,.7>, <0,0,1>, .5
texture{
pigment{rgb <.5,1,1>} // LIGHT BLUE-GREEN
finish{ambient 1 emission 0 diffuse 0}
}
interior_texture{
pigment{rgb .5*<1,.2,.2>} // DARK RED
finish{ambient 1 emission 0 diffuse 0}
}
}
// right:
// Change the z-normal to -1 to see the coincident-surface effect.
disc {
<.25,.5,.7>, <0,0,1>, .5
texture{
pigment{rgb <.2,1,.2>} // GREEN
finish{ambient 1 emission 0 diffuse 0}
}
interior_texture{
pigment{rgb <0,.5,1>} // SKY BLUE
finish{ambient 1 emission 0 diffuse 0}
}
}
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On 17/03/2025 03:27, Paul Bourke wrote:
> Looks good. What was the magic sauce? 3.7 or 3.8?
> I'd be much happier if I could use 3.7.
>
> The look I currently have is with 3.8, sample frame attached. Final render will
> be 12816x2048, and a omni directional stereo pair. Should look good in a 360 LED
> stereo cylinder.
>
> This one has many more points, 1500K.
> I vary theradius depending on distance from the camera, with some bounds.
> Added light falloff and other stuff.
>
Thank you for appreciating my work. The alchemy recipe is following:
https://github.com/LeForgeron/povray
built from sources under Ubuntu 24.04.
I prefer this fork, because it supports stereoscopic and many other
useful camera types. In my works it' important, as I am using stereo
VR180 and VR360 projections in XR mode.Please find more info about
Le Forgeron's cameras here:
https://wiki.povray.org/content/User:Le_Forgeron/cameras
If you will choose this way and have
difficulties while compiling sources, I can assist you.
Here are previous and new versions of static images rendered at
resolution 12816x2048 for comparison:
https://povlab.yesbird.online/pb/lidar_static.html
https://povlab.yesbird.online/pb/lidar_static_v2.html
I noticed that all "ghost magic" disappeared for unknown reasons, please
feel free to send me new code for experiments, as this project is very
close to my interests - data visualization in XR.
Also video have some improvements: start/stop button and additional set
of frames (587 total now):
https://povlab.yesbird.online/pb/
Unfortunately, I am limited in hardware resources, having only
Intel(R) Xeon(R) E-2236 CPU @ 3.40GHz 12 Cores
and
Oculus Go VR headset,
so rendering of 1200 stereo frames at 12816x2048 resolution will take a
lot of time - frame of the first version was rendered ~4 min,
the last ~20 min.
Now I am working on a VR stereo version, and hope tomorrow I will
publish it.
PS: Can't find the attachment you mentioned - don't you forget
to add in ?
--
YB
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> > So now I'm thinking that if there was a way to use a collection of actual
> > snowflake shapes and have them appear, fall a sort way, then fade out - in a
> > cycle centered on their locations, that might make a cool "animated animation".
And here's a short proof of concept.
Post a reply to this message
Attachments:
Download 'snowingmarket.mp4.dat' (1897 KB)
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> I prefer this fork, because it supports stereoscopic and many other
> VR180 and VR360 projections in XR mode.Please find more info about
> Le Forgeron's cameras here:
> https://wiki.povray.org/content/User:Le_Forgeron/cameras
Including a ODSP camera!
I've just implemented one using a vertex shader approach, that is transform
points to a longitude/latitude/distance and do final render with an ortho
camera. Works fine but I would love a ODSP with a cylindrical camera within
PovRay itself.
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On 18/03/2025 07:25, Paul Bourke wrote:
> I've just implemented one using a vertex shader approach, that is transform
> points to a longitude/latitude/distance and do final render with an ortho
> camera. Works fine but I would love a ODSP with a cylindrical camera within
> PovRay itself.
>
>
Vertex shader approach ? It's interesting - I would like to look at
(through) it.
I see you already have good set of cameras, that possibly can be
extended: https://paulbourke.net/stereographics/povcameras/
When I was looking for cameras to produce VR images I also
found these sources:
http://stereopov.ichthyostega.de/
http://www.triplespark.net/render/stereo/create.html
--
YB
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On 17/03/2025 03:27, Paul Bourke wrote:
> The look I currently have is with 3.8, sample frame attached. Final render will
> be 12816x2048, and a omni directional stereo pair. Should look good in a 360 LED
> stereo cylinder.
>
Not having a 360 LED stereo cylinders at home, I modeled them in VR:
https://povlab.yesbird.online/pb/lidar_video.html
https://povlab.yesbird.online/pb/lidar_static.html
Camera located inside two cylinders with the same location, but
different textures - one for left, order for right eye. Now it's only a
mono preview (both have the same texture, while I am looking for the
best way to render stereo pairs).
--
YB
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Dr. Bourke,
Let me just briefly segue from your project to say:
It is great to see you here, still using POV-Ray after all these many long
years.
We would love to see you, and many others with your creativity and skill set,
here on our forum more often, and would like to attract others so that we can
sustain and improve this beloved piece of open source software.
I'm not sure what level of exposure to POV-Ray your colleagues get, but it would
be wonderful if undergrads and graduate students, as well as physicists,
mathematicians, statisticians, astronomers, artists, and engineers could be
introduced to what it is currently capable of.
Hopefully by doing so, we can get computer scientists and their students
interested and perhaps attract new interest in further developing POV-Ray.
I was very excited to see a somewhat recent video by Dr. Oliver Knill:
https://people.math.harvard.edu/~knill/various/povray/index.html
Perhaps you can put in a kind word to your colleagues and professional
acquaintances about what we strive to do here in our little corner of the
internet, and help keep POV-Ray - not just alive - but thriving and growing.
Thank you,
Bill Walker
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