Stephen <mca### [at] aolcom> wrote:
> I remember it it made the news here, in the UK, big time. Did you have
> to evacuate?

No, I live on a different island, about 300 km to the northwest.  But we got
quite a bit of the ash.

Post a reply to this message

On 18-7-2013 20:01, MichaelJF wrote:
> I think as with all things in nature not all can be classified into the one or
> other category. I think the eruption with the following link is a mixture of a
> pyroclastic flow and a magma eruption (and the most magnificent eruption I ever
> found depicted):
> http://upload.wikimedia.org/wikipedia/commons/1/17/MountRedoubtEruption.jpg

True. The typical pyroclastic flow /sensu stricto/ runs along the 
topographic slope of the mountain. The lighter ash goes upwards. While 
the composition is identical, the pyroclastic flow is the coarser one 
and also to be found at the base of a typical tephra deposits, covered 
with an ash layer. They can show internal graded bedding but this is 
often obscured by the gas turbulence and the high density of the whole 
thing.

Thomas

Post a reply to this message

"Cousin Ricky" <rickysttATyahooDOTcom> wrote:
> Stephen <mca### [at] aolcom> wrote:
> > I remember it it made the news here, in the UK, big time. Did you have
> > to evacuate?
>
> No, I live on a different island, about 300 km to the northwest.  But we got
> quite a bit of the ash.

Still a bit close.
We were almost neighbours, just after that. I was working in Jamaica in 1998.
Where I discovered PovRay

Stephen

Post a reply to this message

Stephen <mca### [at] aolcom> wrote:
> That is the fun bit, experimenting. :-)
> If your media containers are the same size you can combine them into one
> interior. I have done this to get colour by using red, green and blue
> df3 files. Well three df3 files each with a different emission.
> This might speed up the render if it is suitable to your scene.
>
Hi Stephen, yes this is exactly what I'm doing. I placed invisible little
spheres at the corners of the bounding box of the whole object to assure that
the parts are adjusted.

>
> > Take a look at this:
> > http://www.maniacworld.com/erupting-volcano.htm
> >
>
> A sight indeed. To be enjoyed at a distance.
>

Yes indeed distance is needed. They speed up to 700 km/h and have temperatures
of 300 up 800 degrees Celsius. But still impressive.


> >> google have lots of white in them. But that is, I think, being very
> >> critical.
> >
> > I don't think it very critical. I plan to work a little bit on the colors and
> > the densities. May be I
> > change the grouping of the clouds.
> >
>
> We await with interest.
>
This will take the one or other day due to the rendering times. I have reviewed
the two lower levels now. Not completely satisfying but the best compromiss I
can yield so far. Sometimes a change of 0.01 for the scattering color changes
the image completely having this strange density maps. I'm not quite sure to
repair the density of the upper "cloud", may be I change the color to be more
white. But as Thomas said the lighter parts are blown up into the air and they
must be more easily be influenced by the wind, which is blowing here from right
to left, especially at greater altitudes.

Best regards,
Michael

Post a reply to this message

On 21/07/2013 9:37 PM, MichaelJF wrote:
> This will take the one or other day due to the rendering times. I have reviewed
> the two lower levels now. Not completely satisfying but the best compromiss I
> can yield so far. Sometimes a change of 0.01 for the scattering color changes
> the image completely having this strange density maps. I'm not quite sure to
> repair the density of the upper "cloud", may be I change the color to be more
> white. But as Thomas said the lighter parts are blown up into the air and they
> must be more easily be influenced by the wind, which is blowing here from right
> to left, especially at greater altitudes.


We have the patience. :-)

-- 
Regards
     Stephen

Post a reply to this message

Stephen <mca### [at] aolcom> wrote:
> On 21/07/2013 9:37 PM, MichaelJF wrote:
> > This will take the one or other day due to the rendering times. I have reviewed
> > the two lower levels now. Not completely satisfying but the best compromiss I
> > can yield so far. Sometimes a change of 0.01 for the scattering color changes
> > the image completely having this strange density maps. I'm not quite sure to
> > repair the density of the upper "cloud", may be I change the color to be more
> > white. But as Thomas said the lighter parts are blown up into the air and they
> > must be more easily be influenced by the wind, which is blowing here from right
> > to left, especially at greater altitudes.
>
>
> We have the patience. :-)
>
> --
> Regards
>      Stephen

Sometimes I'm not quite sure I will have the patience needed. But today I found
out the reason of my problems just by chance. I always had ribbon like
structures around my "cloud" which were annoying completelly. But they did not
come from the df3-file or the scattering or absorbing parameters or the the warp
turbulence, I would have expected them. They came from "interpolate 2" within
the density file definition. I ever thought that a cubic interpolation would be
better than a linear one only resulting in longer rendering time. But seems, I
was wrong with that.

Best regards,
Michael

Post a reply to this message

> Stephen <mca### [at] aolcom> wrote:
>> On 21/07/2013 9:37 PM, MichaelJF wrote:
>>> This will take the one or other day due to the rendering times. I have reviewed
>>> the two lower levels now. Not completely satisfying but the best compromiss I
>>> can yield so far. Sometimes a change of 0.01 for the scattering color changes
>>> the image completely having this strange density maps. I'm not quite sure to
>>> repair the density of the upper "cloud", may be I change the color to be more
>>> white. But as Thomas said the lighter parts are blown up into the air and they
>>> must be more easily be influenced by the wind, which is blowing here from right
>>> to left, especially at greater altitudes.
>>
>>
>> We have the patience. :-)
>>
>> --
>> Regards
>>       Stephen
>
> Sometimes I'm not quite sure I will have the patience needed. But today I found
> out the reason of my problems just by chance. I always had ribbon like
> structures around my "cloud" which were annoying completelly. But they did not
> come from the df3-file or the scattering or absorbing parameters or the the warp
> turbulence, I would have expected them. They came from "interpolate 2" within
> the density file definition. I ever thought that a cubic interpolation would be
> better than a linear one only resulting in longer rendering time. But seems, I
> was wrong with that.
>
> Best regards,
> Michael
>

It's a bug present in version 3.6.x. When you have areas with a value of 
zero, the interpolation cause some areas to evaluate to a negative value 
that warps around to give values that are close to 1. I think that it's 
corrected in version 3.7.

The workaround is to never have any zero in the DF3 file and to adjust 
the colour_map accordingly.

Yet another reason to upgrade to version 3.7 :)



Alain

Post a reply to this message

Alain <kua### [at] videotronca> wrote:

> > Stephen <mca### [at] aolcom> wrote:
> >> On 21/07/2013 9:37 PM, MichaelJF wrote:
> >>> This will take the one or other day due to the rendering times. I have reviewed
> >>> the two lower levels now. Not completely satisfying but the best compromiss I
> >>> can yield so far. Sometimes a change of 0.01 for the scattering color changes
> >>> the image completely having this strange density maps. I'm not quite sure to
> >>> repair the density of the upper "cloud", may be I change the color to be more
> >>> white. But as Thomas said the lighter parts are blown up into the air and they
> >>> must be more easily be influenced by the wind, which is blowing here from right
> >>> to left, especially at greater altitudes.
> >>
> >>
> >> We have the patience. :-)
> >>
> >> --
> >> Regards
> >>       Stephen
> >
> > Sometimes I'm not quite sure I will have the patience needed. But today I found
> > out the reason of my problems just by chance. I always had ribbon like
> > structures around my "cloud" which were annoying completelly. But they did not
> > come from the df3-file or the scattering or absorbing parameters or the the warp
> > turbulence, I would have expected them. They came from "interpolate 2" within
> > the density file definition. I ever thought that a cubic interpolation would be
> > better than a linear one only resulting in longer rendering time. But seems, I
> > was wrong with that.
> >
> > Best regards,
> > Michael
> >
>
> It's a bug present in version 3.6.x. When you have areas with a value of
> zero, the interpolation cause some areas to evaluate to a negative value
> that warps around to give values that are close to 1. I think that it's
> corrected in version 3.7.
>
> The workaround is to never have any zero in the DF3 file and to adjust
> the colour_map accordingly.
>
> Yet another reason to upgrade to version 3.7 :)
>
>
>
> Alain

Thanks, bur I have forgotten to mention my version. I'm using a machine which is
only some months old and I had never older versions of POV installed on this
one. The only POV installation I had ever at my actual machine is version 3.7 RC
7 (Windows version).

At my Suse laptop I have only 3.6 since I failed to compile the sources due to a
problem with the boost library. It is installed by default but the POV configure
cannot find it even after specifying the path given by yast.

Best regards,
Michael

Post a reply to this message

So, the eruption is still under work and running on another machine. Here is an
impression of the texturing I will use for the visible parts of the landscape.
Some 500.000 arbaro trees (only the foliage), a sea at the background (where
Canada should be originally, but even the 16.385x16.385 height_field of the
Puget Sound data has its limits). But most parts of the picture will be occupied
by the eruption itself, which will be more prominend as with the first wip. Not
due to changes to the df3-files but only due to changes with the media
parameters. I think I have revealed some of their mysteries by now but certainly
not all.

Best regards,
Michael

Post a reply to this message

Attachments:
Download 'pugetsound_b20130801texture.png' (1174 KB)

Preview of image 'pugetsound_b20130801texture.png'

On 1-8-2013 22:24, MichaelJF wrote:
> So, the eruption is still under work and running on another machine. Here is an
> impression of the texturing I will use for the visible parts of the landscape.
> Some 500.000 arbaro trees (only the foliage), a sea at the background (where
> Canada should be originally, but even the 16.385x16.385 height_field of the
> Puget Sound data has its limits). But most parts of the picture will be occupied
> by the eruption itself, which will be more prominend as with the first wip. Not
> due to changes to the df3-files but only due to changes with the media
> parameters. I think I have revealed some of their mysteries by now but certainly
> not all.

Looking good indeed. As far as the trees are concerned: the green ones 
to the left would need some random hue differences, like the other ones. 
There, the red trees are - imho - a bit too prominent in the whole. 
However, they all give a nice sense of scale to the whole scene.

Thomas

Post a reply to this message