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I am reworking an old globe of the Earth and I see that I used a cloud
map image with 4 bit colour depth. So that I could manage the
transparency (only 16 pallet entries).
It was okay for a small image but now I want something with more
resolution.
Any suggestions?
--
Regards
Stephen
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On 26-11-2014 12:36, Stephen wrote:
> I am reworking an old globe of the Earth and I see that I used a cloud
> map image with 4 bit colour depth. So that I could manage the
> transparency (only 16 pallet entries).
> It was okay for a small image but now I want something with more
> resolution.
> Any suggestions?
>
Could you use this?
http://www.shadedrelief.com/natural3/pages/clouds.html
Thomas
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On 26/11/2014 12:45, Thomas de Groot wrote:
> On 26-11-2014 12:36, Stephen wrote:
>> I am reworking an old globe of the Earth and I see that I used a cloud
>> map image with 4 bit colour depth. So that I could manage the
>> transparency (only 16 pallet entries).
>> It was okay for a small image but now I want something with more
>> resolution.
>> Any suggestions?
>>
>
> Could you use this?
>
> http://www.shadedrelief.com/natural3/pages/clouds.html
>
> Thomas
I am or something like it.
My understanding is that PovRay uses either an alpha channel or a pallet
based transparency. With the pallet based method 256 channels are the
most you can use. I was hoping that someone had devised a way to use the
greyscale value.
I have an acceptable result by converting the original image to 8 bit
and blurring it a small bit. Then inputing the pallet entries by hand.
Or by Excel, actually. :-)
--
Regards
Stephen
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On 26-11-2014 14:12, Stephen wrote:
> On 26/11/2014 12:45, Thomas de Groot wrote:
>> On 26-11-2014 12:36, Stephen wrote:
>>> I am reworking an old globe of the Earth and I see that I used a cloud
>>> map image with 4 bit colour depth. So that I could manage the
>>> transparency (only 16 pallet entries).
>>> It was okay for a small image but now I want something with more
>>> resolution.
>>> Any suggestions?
>>>
>>
>> Could you use this?
>>
>> http://www.shadedrelief.com/natural3/pages/clouds.html
>>
>> Thomas
>
> I am or something like it.
> My understanding is that PovRay uses either an alpha channel or a pallet
> based transparency. With the pallet based method 256 channels are the
> most you can use. I was hoping that someone had devised a way to use the
> greyscale value.
>
> I have an acceptable result by converting the original image to 8 bit
> and blurring it a small bit. Then inputing the pallet entries by hand.
> Or by Excel, actually. :-)
>
What is a pallet-based transparency? The term is unfamiliar to me.
Thomas
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On 26/11/2014 15:02, Thomas de Groot wrote:
> What is a pallet-based transparency? The term is unfamiliar to me.
Not surprised. I made it up.
From the top of my head:
It is an index of colours used in the image. In Pov we can set the
transparency and filter values in the image_map definition. Each entry
in the index can be set to a transparency, individually. I think that
pallet based images are limited to 8 bit images.
So in a cloud map each grey could have a different level of transparency.
rgb -> rgbft
--
Regards
Stephen
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Stephen <mca### [at] aol com> wrote:
> I am or something like it.
> My understanding is that PovRay uses either an alpha channel or a pallet
> based transparency. With the pallet based method 256 channels are the
> most you can use.
Are you using image_pattern and/or use_alpha?
> I was hoping that someone had devised a way to use the
> greyscale value.
I sort of see what you want to do...
Maybe you could "scan" the image with eval_pigment and then calculate a
transparency variable using the grayscale value?
I dunno - I'm still only on coffee #2, and the foot of snow we're supposed to be
getting is just starting to come down, so I'm not 100% focused...
> I have an acceptable result by converting the original image to 8 bit
> and blurring it a small bit. Then inputing the pallet entries by hand.
> Or by Excel, actually. :-)
That sounds somewhat labor intensive, though interesting.
Maybe some example code and a small illustrative image would help puzzle out a
solution.
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On 26/11/2014 16:10, Bald Eagle wrote:
> Stephen <mca### [at] aolcom> wrote:
>
>> I am or something like it.
>> My understanding is that PovRay uses either an alpha channel or a pallet
>> based transparency. With the pallet based method 256 channels are the
>> most you can use.
>
> Are you using image_pattern and/or use_alpha?
>
I am using image_map
>> I was hoping that someone had devised a way to use the
>> greyscale value.
>
> I sort of see what you want to do...
> Maybe you could "scan" the image with eval_pigment and then calculate a
> transparency variable using the grayscale value?
>
LOL
You might be able to do that. I couldn't code my way out of a wet paper
bag. ;-)
I use a modeller for everything. I can modify and add code, though.
> I dunno - I'm still only on coffee #2, and the foot of snow we're supposed to be
> getting is just starting to come down, so I'm not 100% focused...
>
Excuses, excuses. I've been up for eleven hours, allready. ;-)
>> I have an acceptable result by converting the original image to 8 bit
>> and blurring it a small bit. Then inputing the pallet entries by hand.
>> Or by Excel, actually. :-)
>
> That sounds somewhat labor intensive, though interesting.
>
Yes it is. :-(
But I have automated a lot of it in Excel and I copy and paste into the
modeller.
> Maybe some example code and a small illustrative image would help puzzle out a
> solution.
>
I'll make up a little package including the transparency map, later. But
you could use one of the ones Thomas pointed to.
The basic material is:
#declare CloudedEarth =
texture {
#declare BISHOP3D_TEMPORARY_IDENTIFIER =
texture {
pigment {
image_map{
png "f:\Graphics\B3D Data\Maps\Planets\Earth\EarthMap2.png"
/*
This is the image map of Earth.
*/
interpolate 4
map_type 1
}
}
normal {
bump_map{
png "f:\Graphics\B3D Data\Maps\Planets\Earth\EarthBum_Neg.png"
/*
This is the bmp map of Earth.
*/
interpolate 2
use_color
map_type 1
}
0.100 }
}
texture {
pigment {
image_map{
png "F:\Graphics\B3D
Data\Maps\Planets\Earth\earthcloudmaptrans_Neg240.png"
/*
This is the cloud map that I want the dark parts transparent.
*/
interpolate 2
map_type 1
transmit 0, 1.000
transmit 1, 1.000
// Snip lots of entries
transmit 238, 0.007
transmit 239, 0.000
}
}
}
;// the semicolon is necessary or POV-Ray will not figure out that
the declarations has ended
BISHOP3D_TEMPORARY_IDENTIFIER
}
--
Regards
Stephen
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Am 26.11.2014 14:12, schrieb Stephen:
> ... I was hoping that someone had devised a way to use the
> greyscale value.
>
#declare PP_Claud = pigment{image_map{jpeg "my_cloud_map" map_type 1
interpolate 2}}
sphere{ 0, 1.005
texture {
pigment_pattern{PP_Claud}
texture_map {
[0.00 texture {pigment{rgb 1 transmit 1} finish{diffuse 1}}]
[1.00 texture {pigment{rgb 1 transmit 0} finish{diffuse 1}}]
}
}
}
...where "my_cloud_map" is a grayscale, not a color palette image!
and it might be a good idea to add the cloud texture to a slightly
larger scaled sphere (than the planet) and not as top layered texture as
you did.
And you didn't ask for it but anyway: adding a specular map in pretty
much the same way (giving highlights to the ocean covered area but not
to the land mass) makes it even more realistic.
You can obtain maps for this e.g. from NASA's Blue Marble page.
With some scattering media atmosphere it gives something like this:
http://news.povray.org/povray.binaries.images/thread/<4a056976@news.povray.org>
-Ive
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On 26/11/2014 18:54, Ive wrote:
>
> With some scattering media atmosphere it gives something like this:
> http://news.povray.org/povray.binaries.images/thread/<4a056976@news.povray.org>
>
Before I look at your suggestions. The above link only goes to the index.
And thanks for the reply
--
Regards
Stephen
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Am 26.11.2014 20:16, schrieb Stephen:
> On 26/11/2014 18:54, Ive wrote:
>>
>> With some scattering media atmosphere it gives something like this:
>> http://news.povray.org/povray.binaries.images/thread/<4a056976@news.povray.org>
>>
>>
> Before I look at your suggestions. The above link only goes to the index.
>
> And thanks for the reply
>
this should do
http://news.povray.org/povray.binaries.images/message/<4a056976@news.povray.org>/<4a056976@news.povray.org>
-Ive
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