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Also:
Since we have trace (), we can do a synthetic / virtual LIDAR to take any
geomtric scene and place similar points.
What we DON'T have, is a combination of trace () and eval_pigment () to return a
color.
I suppose there are a number of workarounds that we could do there...
3D to 2D reverse projection (screen location macro)
Scan all of the objects in the scene sequentially with trace, and assign color
based on which object gets hit. (ugh)
Render the geometric scene and use that as an image_map for eval_pigment, and
use trace () in a sort of orthographic scanning mode.
I think the last has the most merit.
- BE
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On 16/03/2025 21:44, Bald Eagle wrote:
> Super nice job, Sergey. :)
>
> This is pretty much what I envisioned Paul was shooting for when I saw that all
> of the points were a sort of firefly glow.
>
> I just did a quick render using "puffs" that I used in place of spheres.
>
> It adds a peaceful, ethereal, Christmassy feel.
>
> 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".
> Or it might look like a total nightmare of a mess ;)
>
> - BW
Thanks, Bill, it was not a "rocket science" task, having Three.js, a
powerful server and such rich data in hands.
I like your idea about snowflakes - winter in HK looks excellent !
Animated animation sounds intriguing, and looks like a lot of space for
experiments. If you will send me a scene, I'll do the rendering.
Now I am working on a stereo version with VR support, for those who have
a headset (static images at first). Btw, this is the reason why I am
prefer HGPovray - it has a stereo camera.
--
YB
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On 16/03/2025 21:51, Bald Eagle wrote:
> Also:
>
> Since we have trace (), we can do a synthetic / virtual LIDAR to take any
> geomtric scene and place similar points.
> ...
Really, and by applying different objects to points we can produce
fantastic effects ! I like this idea very much and can assist as I can.
Quick googling shows that colorization of point clouds is not a trivial
task, but there are different approaches and solutions to choose from.
Interesting, how did PB solve it in his scene ?
Let's try ?
--
YB
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"Bald Eagle" <cre### [at] netscape net> wrote:
> "Paul Bourke" <pau### [at] gmailcom> wrote:
>
> > Thanks for the suggestions. I am now rendering in 3.8, only takes about 20s and
> > that's with an even bigger inc file. But speed isn't an issue for me, at least
> > with 3.7 since I can distribute it.
>
> Well, I was juggling making the kid dinner + other stuff + Bourke-level POV-Ray
> creativity, so I wanted to get a finished render so that I could get a better
> overall idea of what was going on.
>
> > The 3.8 I downloaded has the gui (MacOS), is
> > there a pure command line for 3.8? Can't efficiently do a distributed render
> > with the gui.
>
> Yes Sir.
> I just ran [Path] pvengine64 /RENDER scene.pov, and that seemed to work fine
> under M$ Win 7
>
> > See previous message, tried cylinders and spheres (3.7), same problem.
> >
> > There are also nasty defects in the 3.8 render (discs), see attached example
> > frame. Strange they are mostly on the right half, it's those narrow dark
> > slivers. Perhaps they are a cue to what's happening.
>
> Dunno. If they're disks or something, maybe somehow they got oriented wrong,
> and they're dark colors in front of light?
>
> I just tried again with spheres that are scaled by 0.01 in x, so that they
> resemble your original disc. Can't tell if the lines are there.
> What resolution are you rendering at?
>
> - Bill
No problems with spheres.
There is only one light source, it's at the camera.
I can't imagine misorientated discs, the normal is the vector from camera to
point position.
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"Bald Eagle" <cre### [at] netscapenet> wrote:
> "Bald Eagle" <cre### [at] netscapenet> wrote:
>
> > I just tried again with spheres that are scaled by 0.01 in x, so that they
> > resemble your original disc. Can't tell if the lines are there.
> > What resolution are you rendering at?
>
> "Just download the render at look at the image size, Bill."
> <eyeroll>
>
> Take a look at this and see what you think.
Except that's not the look I want. The "ghostly" effect is the goal.
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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
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.
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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 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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