Alan, I experimented a little bit. At the moment, using your code and
also (now that I know what to look for) POV-Ray's example files, I am
ending up with this:

sphere
{
 < 0.0, 0.0, 0.0 > 10.0
 pigment { rgbt 1.0 } //makes it invisible
 hollow // enable it to contain your media
 interior // the "magic" starts here
 {
  media
  {
   emission 0.5
   intervals 1
   samples 5
   method 3
   density
   {
    spherical
	color_map
	{
	 [ 0.0 color rgb < 0.0,     0.0,     0.0 >        ]
	 [ 0.1 color rgb < 0.74902, 0.34118, 0.22353 > /4 ]
	 [ 1.0 color rgb < 0.74902, 0.34118, 0.22353 >    ]
	}
   } // starts at 1 at <0,0,0> and drops to zero at radius 1
  }
 }
 scale 10.0
 translate < 0.0, 0.0, 0.0 >
}

cylinder
{
 < 0.0, 0.0, -50.0 > < 0.0, 0.0,  50.0 > 2.50
 pigment { rgb < 1.0, 0.5, 0.0 > }
}

The media sphere, and for test purposes a cylinder.
I am quite happy, but would like still to have the same high density
within 1.0 units from the center, and then a fading out from 1.0 to 1.3.
The fading out I achieve, is not regular enough - it seems to end quite
fast.

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Le 15-12-17 21:09, Sven Littkowski a écrit :
> Alan, this is a great start-up help you have given, my appreciation! I
> started already to make experiments with it.
>
> Still, there is something I need to know:
> I want that the media covers up a sphere, let's say, of a radius of 1
> unit. Just outside that 1-unit-radius sphere, the density should fade
> down to 0.0 at a distance of 0.3 units to the outside of that sphere.
>
> That means, the density does not decrease constantly from center to 1.3
> units away. How can I implement it this way?
>

By judiciously using a color_map as follow:

sphere{
     0, 1
     pigment{rgbt 1} //make it totaly invisible
     hollow // enable it to contain your media
// the "magic" start here

     interior{
      media{ emission 1 // adjust as needed
      density{ spherical  color_map{[0 rgb 0][1-(1/1.3) rgb 1 ]}}
     }

     scale 1.3
// scale the sphere and the media as a single unit
     translate Location
}

This way, for all values of the pattern that are larger than about 0.23 
will have the maximum density. For those smaller, the density will 
decrease much faster doen to zero.

If you need to increase the quality of the media in case of missing 
details or banding, you increase the samples count. NEVER increase 
intervals to any value larger than 1.
The defaults are:
method 3
samples 10
intervals 1

In my tests, I found that "samples 100 intervals 1" is much faster than 
"samples 1, 5 intervals 5" and give a beter result.
Emissive media is the fastest to render, followed by absorbing and 
scattering is the slowest.


Alain

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Le 15-12-17 21:11, Sven Littkowski a écrit :
> Besides this all, it seems, when trying to look up MEDIA and DENSITY
> inside the help file, they were forgotten to be cross-linked to. I also
> tried successly to click these keywords inside the scene source code and
> then pressing "F1" - this just opens up the Help File's start page. Can
> that be? Do you all have the same experience? Please test.
>

The help page you get is absolutely huge!
It contains material for ALL aspects of the scene.
The part about media is about 85% down, before the lengthy description 
of the standard include files.

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This is strange - my Help File lacks functionality, it seems. Will check
out that problem later. The media works now the way I want it, and I am
very happy. Thanks a lot!

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On 18-12-2015 4:30, Sven Littkowski wrote:
> This is strange - my Help File lacks functionality, it seems. Will check
> out that problem later. The media works now the way I want it, and I am
> very happy. Thanks a lot!
>
The help file (F1) resident in POV-Ray has not been too good for some 
time now nor is it entirely up-to-date. Many links are broken, some do 
not exist. It would need a serious overhaul. However, The wiki page is 
entirely up-to-date and of easy access:

http://wiki.povray.org/content/Documentation:Contents

-- 
Thomas

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Alan, for you I have attached a first rendering of my spaceship, using
the media as you told me. I still have to make some adjustments, but it
looks really neat on my little ship.

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Attachments:
Download 'sl - seneca ii - close view 1 km - wormhole generator - 002.jpg' (543 KB)

Preview of image 'sl - seneca ii - close view 1 km - wormhole generator - 002.jpg'

Thanks, Thomas! Good hint!

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Thanks again for the assistance, Alain. See here the fine result. She's
not finished yet, but she's already a fine ship, and looks even finer
thanks to your help.

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Attachments:
Download 'sl - seneca ii - distance - 001 - compressed .jpg' (5603 KB)

Preview of image 'sl - seneca ii - distance - 001 - compressed .jpg'

Am 18.12.2015 um 21:24 schrieb Sven Littkowski:
> Thanks again for the assistance, Alain. See here the fine result. She's
> not finished yet, but she's already a fine ship, and looks even finer
> thanks to your help.

Sven, please don't post such huge pictures.
Not generally, and certainly not in newsgroups without "binaries" in
their name.

Are you even aware that your image is 5.5 MB large (despite apparently
being heavily compressed)?

Also, the image size in pixels is beyond what we can possibly view on
screen. Heck, even on a 4K display it doesn't fit even remotely!

A 16th of the file size (a 4th by a 4th in terms of resolution) would
have been more than enough for most of us.

If you do want to provide us with extremely high resolution images (e.g.
for poster printing), please feel free to make them available on your
website and post a link.

If you want to show off high-resolution details, please feel free to
post detail views (i.e. images showing only a subsection of the original
image) rather than the entire image in high-res, on
povray.binaries.images rather than povray.general.


(BTW, someone cut off a piece of your planet. Not good. Expect massive
earthquakes, the oceans draining into that region, and -- presuming that
the hot core is exposed -- the drained water promptly and violently
evaporating into the atmosphere, leading to disastrous climate
changes... or is that why the people have built the ark?)

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Hi Clipka, I think, I have to agree with you. The loading and display of
the image are not good. Point taken. Will host the image from now on one
of my websites and link here with a small thumbnail and URL. Even my own
newsgroup client (Mozilla Thunderbird) crashes sometimes while loading
the image. Not a good idea...

The planet:

I didn't even see that i missed a part of the planet when adding it to
this image. Did it after an entire night without sleep but working on
this scene. Yes, this is the target planet. It contains an ocean of a
liquid, and even better, that liquid is water, too! And even better,
this planet got an atmosphere, though it is not breathable for humans
without equipment or genetic/operative adaptions. I think, no Earth-like
planet we may discover in the entire future will already have an
atmosphere that can be breathed right away. I think, in all cases we
have to adapt - the atmosphere if the planet is uninhibited, or
ourselves if there is some sort of life there already. I believe,
mankind will develop, having then these special needs, scientific
knowledge how to change our own bodies through genetic engineering, or
to implant artificial organic or non-organic mechanisms into our bodies
that can do this extra job. No planet ever we will find, will be
"perfect to enter right away". There are too many factors in the
development of a planet, to create a perfect 2nd Earth. There will
always be differences. Even any animals there wouldn't be edible just
like that. And besides, who says, that on other inhabited planets there
are exactly the same divisions of life into bacteria, fungi, amoebas,
fauna and flora as here on this planet? our five "kingdomes" developed
based on the conditions of this planet. Expect different divisions on
other planets, though the extremities of life forms on other planets
will be of similar designs as gas, solid surfaces, and liquids fall
under the same physical rules applicable to movement. Wow, this is one
of my favorite subjects to discuss and exchange with others about, so I
better stop now. Otherwise I am writing here entire books...

Besides, I am actually writing a book. It is a scifi novel of a human,
stranded in a far far future 5 billion years from now, in a solar system
modified by its future inhabitants, encountering sentient life forms of
different development stages (culturally, technically, psychologically),
and also seeing the continued aging of the entire universe, and how
these different sentient life forms may have managed each in their own
way to live together or not. Lots of work still ahead, I am just on page
20... :-)

Sven



On 18.12.2015 22:16, clipka wrote:
> (BTW, someone cut off a piece of your planet. Not good. Expect massive
> earthquakes, the oceans draining into that region, and -- presuming that
> the hot core is exposed -- the drained water promptly and violently
> evaporating into the atmosphere, leading to disastrous climate
> changes... or is that why the people have built the ark?)
>

Post a reply to this message