My brain has gone dead.
How do you set up a scene so that a box with an image map is visible 
when it is only lit from behind. It is visible when the background is 
not black.


-- 

Regards
     Stephen

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On 3-4-2016 13:14, Stephen wrote:
> My brain has gone dead.
> How do you set up a scene so that a box with an image map is visible
> when it is only lit from behind. It is visible when the background is
> not black.
>
>

You mean: the box should be /invisible/ with a background other than black?

-- 
Thomas

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On 4/3/2016 12:23 PM, Thomas de Groot wrote:
> On 3-4-2016 13:14, Stephen wrote:
>> My brain has gone dead.
>> How do you set up a scene so that a box with an image map is visible
>> when it is only lit from behind. It is visible when the background is
>> not black.
>>
>>
>
> You mean: the box should be /invisible/ with a background other than black?
>
No the other way around. The image should be visible when the background 
is black.


-- 

Regards
     Stephen

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Am 03.04.2016 um 13:14 schrieb Stephen:
> My brain has gone dead.
> How do you set up a scene so that a box with an image map is visible
> when it is only lit from behind.


To _light_ an object from its _inside_, there are two alternatives:

(A) double_illuminate

Using "double_illuminate" in an object will cause incident light from
the back side of a surface to cause the exact same effect as light from
the front side (as far as diffuse illumination is concerned; it does not
cause highlights).

(B) two-parameter diffuse

Using "diffuse FRONT,BACK" in a finish does virtually the same thing,
except that this property is tied to the finish rather than the object,
and allows different brightness levels depening on what side of the
surface the light is coming from.


To _light_ a solid object from its _back_, there are two alternatives as
well (presuming you want a diffuse effect):

(A) dense scattering media

(B) subsurface light transport


> It is visible when the background is
> not black.

Not sure what to make of this sentence.

Maybe I misunderstood your request, and what you're really after is just
coloured transparency? In that case, there's only one "alternative":

(A) filtering pigment

Using "colour rgb SOMETHING filter 1.0" will cause the background to be
visible, but tinted with the specified colour.

To achieve the same effect with an image-based pigment, use "image_map {
... filter all 1.0 }"

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On 4/3/2016 1:39 PM, clipka wrote:
>> It is visible when the background is
>> >not black.
> Not sure what to make of this sentence.
>
> Maybe I misunderstood your request, and what you're really after is just
> coloured transparency? In that case, there's only one "alternative":

That is what I was trying to do but I got the meaning of diffuse A for 
Elbow. :(

Now I have to find out why the colours of the output looks different 
when the camera is at the front or at the back..

Although I have been on the newsgroups I have not been Poving for about 
two and a half years. It is true, if you don't use it you lose it. ;-)
And what has not helped is that I was quite ill in hospital and seem to 
have misplaced a few neurons.

Thanks

-- 

Regards
     Stephen

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On 3-4-2016 17:54, Stephen wrote:
> On 4/3/2016 1:39 PM, clipka wrote:
>>> It is visible when the background is
>>> >not black.
>> Not sure what to make of this sentence.
>>
>> Maybe I misunderstood your request, and what you're really after is just
>> coloured transparency? In that case, there's only one "alternative":
>
> That is what I was trying to do but I got the meaning of diffuse A for
> Elbow. :(
>
> Now I have to find out why the colours of the output looks different
> when the camera is at the front or at the back..

Maybe a little example image would help.

>
> Although I have been on the newsgroups I have not been Poving for about
> two and a half years. It is true, if you don't use it you lose it. ;-)

Yes, that is true.

> And what has not helped is that I was quite ill in hospital and seem to
> have misplaced a few neurons.

Using POV-Ray will grow new ones in the right place.


-- 
Thomas

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On 4/4/2016 7:47 AM, Thomas de Groot wrote:
> On 3-4-2016 17:54, Stephen wrote:


>>
>> Now I have to find out why the colours of the output looks different
>> when the camera is at the front or at the back..
>
> Maybe a little example image would help.
>

Oops! It was an assumed gamma problem. My default scene was still set up 
for 2.2.

I have been meaning to update that file for ages.
As the poet said. "Never put off till tomorrow that which you can put 
off today." ;)

>
>> And what has not helped is that I was quite ill in hospital and seem to
>> have misplaced a few neurons.
>
> Using POV-Ray will grow new ones in the right place.
>
>
I don't need new ones I just need the old ones connected properly.
It is a sair fecht for a hauf loaf.
(Another saying for your linguistic collection ;) )

-- 

Regards
     Stephen

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Am 03.04.2016 um 17:54 schrieb Stephen:
> On 4/3/2016 1:39 PM, clipka wrote:
>>> It is visible when the background is
>>> >not black.
>> Not sure what to make of this sentence.
>>
>> Maybe I misunderstood your request, and what you're really after is just
>> coloured transparency? In that case, there's only one "alternative":
> 
> That is what I was trying to do but I got the meaning of diffuse A for
> Elbow. :(
> 
> Now I have to find out why the colours of the output looks different
> when the camera is at the front or at the back..

Forgot to turn off highlights and/or reflections?

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On 4-4-2016 12:32, Stephen wrote:
> It is a sair fecht for a hauf loaf.
> (Another saying for your linguistic collection ;) )
>

LOL Thanks!

-- 
Thomas

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On 4/4/2016 11:34 AM, clipka wrote:
> Am 03.04.2016 um 17:54 schrieb Stephen:
>> On 4/3/2016 1:39 PM, clipka wrote:
>>>> It is visible when the background is
>>>>> not black.
>>> Not sure what to make of this sentence.
>>>
>>> Maybe I misunderstood your request, and what you're really after is just
>>> coloured transparency? In that case, there's only one "alternative":
>>
>> That is what I was trying to do but I got the meaning of diffuse A for
>> Elbow. :(
>>
>> Now I have to find out why the colours of the output looks different
>> when the camera is at the front or at the back..
>
> Forgot to turn off highlights and/or reflections?
>


No, I did that.
One of the Devs has been mucking about with the gamma.
Can you believe it?

-- 

Regards
     Stephen

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