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Hi all,
Any Ideas what's causing these artefacts?
I'm going for ersatz fluffy clouds, they'll print quite small
so the level of detail isn't an issue.
It's a blob + media.
There's nothing special about the media:
#ifndef (CloudScale)
#declare CloudScale = 1;
#end
#local MCloudColour = rgb 0.95;
#local MCloudFinish = finish {
ambient 0.2
diffuse 0.6
}
#local MCloudTexture = texture {
pigment {
#if (1)
colour rgbt 1
#else
colour rgb 1
#end
}
finish { MCloudFinish }
}
#local MCloudInterior = interior {
media {
density { MCloudColour * 0.06 / CloudScale }
#if (1)
absorption rgb (1 - MCloudColour) * 8.0
#end
#if (1)
scattering { 3, MCloudColour * 0.1 }
// scattering { 4, MCloudColour * 1.0 }
#end
#if (1)
emission rgb MCloudColour * 0.07
#end
}
}
#declare CloudMaterial = material {
texture { MCloudTexture }
interior { MCloudInterior }
}
When I render the cloud in a scene by itself it looks fine,
but when I put it alongside other objects in a (not too) complex
scene these white flecks appear.
--
Bill Hails
http://billhails.net/
Post a reply to this message
Attachments:
Download 'mp-025-crop.jpg' (11 KB)
Preview of image 'mp-025-crop.jpg'
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Bill Hails nous apporta ses lumieres en ce 14/06/2006 17:48:
> Hi all,
>
> Any Ideas what's causing these artefacts?
>
> I'm going for ersatz fluffy clouds, they'll print quite small
> so the level of detail isn't an issue.
>
> It's a blob + media.
>
> There's nothing special about the media:
>
>
> #ifndef (CloudScale)
> #declare CloudScale = 1;
> #end
>
> #local MCloudColour = rgb 0.95;
>
> #local MCloudFinish = finish {
> ambient 0.2
> diffuse 0.6
> }
>
> #local MCloudTexture = texture {
> pigment {
> #if (1)
> colour rgbt 1
> #else
> colour rgb 1
> #end
> }
> finish { MCloudFinish }
> }
>
> #local MCloudInterior = interior {
> media {
> density { MCloudColour * 0.06 / CloudScale }
> #if (1)
> absorption rgb (1 - MCloudColour) * 8.0
> #end
> #if (1)
> scattering { 3, MCloudColour * 0.1 }
> // scattering { 4, MCloudColour * 1.0 }
> #end
> #if (1)
> emission rgb MCloudColour * 0.07
> #end
> }
> }
>
> #declare CloudMaterial = material {
> texture { MCloudTexture }
> interior { MCloudInterior }
> }
>
> When I render the cloud in a scene by itself it looks fine,
> but when I put it alongside other objects in a (not too) complex
> scene these white flecks appear.
>
>
>
> ------------------------------------------------------------------------
>
It don't look like a problem with your media, but with the blob that contains it. Do a
test by
removing the media, are the artefacts still there? If you use interior{fade_color rgb
0.5
fade_distance 1}, do you still see the artefacts?(adjust fade_distance to the
dimentions of the blob)
Check if you have any reflection, look if you have a user deffined default
texture/finish. Check any
personal include, or any that comes from somebody else (not from the distribution). It
came biting
back someone else some times ago...
A few shoots in the dark:
Try adding strum in the blob deffinition it you don't use it already.
Try changing the shape of the cloud, probably just changing the random seed.
Try altering the scale of the scene.
Try moving the other elements of your scene.
Try changing the thresshold value of the blob, change the components' radius
acordingly.
It looks like your media could benefit from more samples. Increasing the samples value
don't affect
render time that much. Don't increase the intervals value, it will realy impair your
rendering time.
--
Alain
-------------------------------------------------
Catholicism: If shit happens, you deserve it.
Post a reply to this message
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Bill Hails <me### [at] billhails net> wrote:
> Hi all,
>
> Any Ideas what's causing these artefacts?
>
> I'm going for ersatz fluffy clouds, they'll print quite small
> so the level of detail isn't an issue.
>
> It's a blob + media.
>
> There's nothing special about the media:
>
>
> #ifndef (CloudScale)
> #declare CloudScale = 1;
> #end
>
> #local MCloudColour = rgb 0.95;
>
> #local MCloudFinish = finish {
> ambient 0.2
> diffuse 0.6
> }
>
> #local MCloudTexture = texture {
> pigment {
> #if (1)
> colour rgbt 1
> #else
> colour rgb 1
> #end
> }
> finish { MCloudFinish }
> }
>
> #local MCloudInterior = interior {
> media {
> density { MCloudColour * 0.06 / CloudScale }
> #if (1)
> absorption rgb (1 - MCloudColour) * 8.0
> #end
> #if (1)
> scattering { 3, MCloudColour * 0.1 }
> // scattering { 4, MCloudColour * 1.0 }
> #end
> #if (1)
> emission rgb MCloudColour * 0.07
> #end
> }
> }
>
> #declare CloudMaterial = material {
> texture { MCloudTexture }
> interior { MCloudInterior }
> }
>
> When I render the cloud in a scene by itself it looks fine,
> but when I put it alongside other objects in a (not too) complex
> scene these white flecks appear.
>
> --
> Bill Hails
> http://billhails.net/
I've seen this before.... and I suspect they are intersections of several
objects. You mentioned an object called "blob". If they intersect at many
places, you'll get these lines. With renderings I have done, the only thing
I could think of was to change the size or position of the objects by +/-
0.001 or 0.005 or some tiny random number, to minimize the number of
intersections.
However in your case, it might be better for you to put them into "Union" or
"Merge". Merge is slower but may be better in your case... because with
merge, the objects then actually merge into a single object, which means
there will be no intersections at all.
Now come to think of it... I think I'll try that on my renders... trying to
merge water with the surface of the planet....
Post a reply to this message
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Bill Hails <me### [at] billhailsnet> wrote:
> Hi all,
>
> Any Ideas what's causing these artefacts?
>
> I'm going for ersatz fluffy clouds, they'll print quite small
> so the level of detail isn't an issue.
>
> It's a blob + media.
>
Where are you adding the texture & interior? In the blob components, or to
the whole blob? It looks like the media is thicker where the components
overlap which would make me think it's the individual components, but I
haven't worked much with blobs and media so I don't know how they normally
look.
The media doesn't look like the problem, but since you're combining the
texture and media, the ambient value in the texture might be. If you're
already applying them to the whole blob try playing with the ambient and
see what happens.
RG
Post a reply to this message
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EagleSun nous apporta ses lumieres en ce 15/06/2006 09:02:
> Bill Hails <me### [at] billhailsnet> wrote:
>> Hi all,
>> Any Ideas what's causing these artefacts?
>> I'm going for ersatz fluffy clouds, they'll print quite small
>> so the level of detail isn't an issue.
>> It's a blob + media.
>> There's nothing special about the media:
>> #ifndef (CloudScale)
>> #declare CloudScale = 1;
>> #end
>> #local MCloudColour = rgb 0.95;
>> #local MCloudFinish = finish {
>> ambient 0.2
>> diffuse 0.6
>> }
>> #local MCloudTexture = texture {
>> pigment {
>> #if (1)
>> colour rgbt 1
>> #else
>> colour rgb 1
>> #end
>> }
>> finish { MCloudFinish }
>> }
>> #local MCloudInterior = interior {
>> media {
>> density { MCloudColour * 0.06 / CloudScale }
>> #if (1)
>> absorption rgb (1 - MCloudColour) * 8.0
>> #end
>> #if (1)
>> scattering { 3, MCloudColour * 0.1 }
>> // scattering { 4, MCloudColour * 1.0 }
>> #end
>> #if (1)
>> emission rgb MCloudColour * 0.07
>> #end
>> }
>> }
>> #declare CloudMaterial = material {
>> texture { MCloudTexture }
>> interior { MCloudInterior }
>> }
>> When I render the cloud in a scene by itself it looks fine,
>> but when I put it alongside other objects in a (not too) complex
>> scene these white flecks appear.
>> --
>> Bill Hails
>> http://billhails.net/
> I've seen this before.... and I suspect they are intersections of several
> objects. You mentioned an object called "blob". If they intersect at many
> places, you'll get these lines. With renderings I have done, the only thing
> I could think of was to change the size or position of the objects by +/-
> 0.001 or 0.005 or some tiny random number, to minimize the number of
> intersections.
> However in your case, it might be better for you to put them into "Union" or
> "Merge". Merge is slower but may be better in your case... because with
> merge, the objects then actually merge into a single object, which means
> there will be no intersections at all.
> Now come to think of it... I think I'll try that on my renders... trying to
> merge water with the surface of the planet....
A blob is a single, multi components object. It's a kind of special case isosurface
composed of
various spheres and cylinders. Search fot it in the documentations. It don't contain
any internal
surfaces and don't intersect itself.
--
Alain
-------------------------------------------------
Idolism: Let's bronze this shit.
Post a reply to this message
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Alain wrote:
> [...]
> It don't look like a problem with your media, but with the blob that
> contains it. Do a test by removing the media, are the artefacts still
> there? If you use interior{fade_color rgb 0.5 fade_distance 1}, do you
> still see the artefacts?(adjust fade_distance to the dimentions of the
> blob) Check if you have any reflection, look if you have a user deffined
> default texture/finish. Check any personal include, or any that comes from
> somebody else (not from the distribution). It came biting back someone
> else some times ago...
Yeah I think you're right. Checking over the log, I'm getting lots of
parse warnings about "degenerate blob element at .." - I'm not really
sure what that means - a sphere with zero radius? I don't think
I have any of those, but it's possible. I'm going to rework the
code for the blob anyway.
> A few shoots in the dark:
> Try adding strum in the blob deffinition it you don't use it already.
> Try changing the shape of the cloud, probably just changing the random
> seed. Try altering the scale of the scene.
> Try moving the other elements of your scene.
> Try changing the thresshold value of the blob, change the components'
> radius acordingly.
>
> It looks like your media could benefit from more samples. Increasing the
> samples value don't affect render time that much. Don't increase the
> intervals value, it will realy impair your rendering time.
I'll definately try more samples, Thanks!
>
--
Bill Hails
http://billhails.net/
Post a reply to this message
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gonzo wrote:
> [...]
>
> Where are you adding the texture & interior? In the blob components, or
> to
> the whole blob?
It's to the whole blob.
> It looks like the media is thicker where the components
> overlap which would make me think it's the individual components, but I
> haven't worked much with blobs and media so I don't know how they normally
> look.
>
> The media doesn't look like the problem, but since you're combining the
> texture and media, the ambient value in the texture might be. If you're
> already applying them to the whole blob try playing with the ambient and
> see what happens.
I'm not sure, but if the pigment is rgbt 1, then doesn't that effectively
disable the ambient and diffuse? I'm not sure, so I'll experiment.
(there's no radiosity here, btw.)
> RG
--
Bill Hails
http://billhails.net/
Post a reply to this message
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Alain wrote:
> EagleSun nous apporta ses lumieres en ce 15/06/2006 09:02:
> [..]
>> I've seen this before.... and I suspect they are intersections of several
>> objects. You mentioned an object called "blob". If they intersect at
>> many
>> places, you'll get these lines. With renderings I have done, the only
>> thing I could think of was to change the size or position of the objects
>> by +/- 0.001 or 0.005 or some tiny random number, to minimize the number
>> of intersections.
>
>> However in your case, it might be better for you to put them into "Union"
>> or
>> "Merge". Merge is slower but may be better in your case... because with
>> merge, the objects then actually merge into a single object, which means
>> there will be no intersections at all.
>
>> Now come to think of it... I think I'll try that on my renders... trying
>> to merge water with the surface of the planet....
>
>
>
> A blob is a single, multi components object. It's a kind of special case
> isosurface composed of various spheres and cylinders. Search fot it in the
> documentations. It don't contain any internal surfaces and don't intersect
> itself.
>
Yes. EagleSun, If you go into the scenes/ directory of the pov
distribution and look at advanced/gaussianblob.pov you can get
the general technique for doing cloud shapes that I'm using -
though I'm not using gaussian distributions particularily -
in fact it's my variations on this method that are probably
the cause of the problem.
--
Bill Hails
http://billhails.net/
Post a reply to this message
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Bill Hails nous apporta ses lumieres en ce 15/06/2006 18:08:
> Alain wrote:
>
>> [...]
>> It don't look like a problem with your media, but with the blob that
>> contains it. Do a test by removing the media, are the artefacts still
>> there? If you use interior{fade_color rgb 0.5 fade_distance 1}, do you
>> still see the artefacts?(adjust fade_distance to the dimentions of the
>> blob) Check if you have any reflection, look if you have a user deffined
>> default texture/finish. Check any personal include, or any that comes from
>> somebody else (not from the distribution). It came biting back someone
>> else some times ago...
>
> Yeah I think you're right. Checking over the log, I'm getting lots of
> parse warnings about "degenerate blob element at .." - I'm not really
> sure what that means - a sphere with zero radius? I don't think
> I have any of those, but it's possible. I'm going to rework the
> code for the blob anyway.
>
It can be a component with zero strenght as it can be one with zero radius. If you
have cylinder
components, they may have 2 identical end points.
If you use randomly selected radius or strenght, it can drop to zero. Try reducing the
random range
and add a minimum value like: rand(Seed)*0.9+0.1
--
Alain
-------------------------------------------------
If all the world is a stage, where is the audience sitting?
Post a reply to this message
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Bill Hails <me### [at] billhailsnet> wrote:
> Alain wrote:
>
> >
> > A blob is a single, multi components object. It's a kind of special case
> > isosurface composed of various spheres and cylinders. Search fot it in the
> > documentations. It don't contain any internal surfaces and don't intersect
> > itself.
> >
>
> Yes. EagleSun, If you go into the scenes/ directory of the pov
> distribution and look at advanced/gaussianblob.pov you can get
> the general technique for doing cloud shapes that I'm using -
> though I'm not using gaussian distributions particularily -
> in fact it's my variations on this method that are probably
> the cause of the problem.
>
Ah... ok thanks for explaining it to me..... I've seen the same phenomenon
with multiple spheres... and I've never seen "blob" before... so I had
mistakenly thought it was a sphere-like thing.
Post a reply to this message
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