Am 23.05.2016 um 09:19 schrieb Thomas de Groot:

> I agree with Kenneth: while the rules are there to be followed
> strictly... they need also to be broken when artistic needs call for it
> and yield interesting results.

I'd like to put it this way:

Rules are there to be respected -- every one of them, always, and
without exception.
But there is a difference between respect and obedience.

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On 23-5-2016 14:55, clipka wrote:
> Am 23.05.2016 um 09:19 schrieb Thomas de Groot:
>
>> I agree with Kenneth: while the rules are there to be followed
>> strictly... they need also to be broken when artistic needs call for it
>> and yield interesting results.
>
> I'd like to put it this way:
>
> Rules are there to be respected -- every one of them, always, and
> without exception.
> But there is a difference between respect and obedience.
>

Absolutely. While I /respect/ the rules in every traditional way and for 
every traditional purpose, I certainly shall /disobey/ them if, for any 
reason, I can reach my goal through another way.

And let us be frank: if you were not told in the example under scrutiny, 
you would not know. :-)

-- 
Thomas

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On 23-5-2016 14:45, Ive wrote:
> OK. While I still do not understand why the word "artistic" does popup
> within a context I consider a purely technical problem (it almost seems
> like a curse in these NG, as soon as someone mentions "gamma" inevitable
> someone else replies "but for artistic reasons" as if one would have
> anything to do with the other as I have tried to explain with the ironic
> Vermeer example).

In my view because creating an image is not just /only/ or /purely/ a 
technical problem. To get the end result I want I shall not hesitate to 
twist the rules. The technique is but a means to me towards an 
"artistic" goal. That may sound very extreme but I can assure you that I 
am very obedient towards the rules in general but I sometimes need to 
punch them in the face :-)

> Anyway, I simply do not believe you have used the
> "straightforward/correct" way. So step by step: you are using a linear
> gradient to generate the depth-map image within POV-Ray. Right? Then you
> make sure that POV-Ray writes the depth-map image in linear color space
> by using the appropriate file output options (or, much easier use
> OpenEXR as output file format). Right? Then, when using the image again
> in POV-Ray you add gamma 1.0 to the image_map statement. Right? And in
> case you really need to edit the depth-map outside of POV-Ray you make
> sure that the used editor does not apply gamma correction when opening
> or saving the image file (hint: AFAIK this is not possible with Gimp,
> but can be done e.g. with Photoshop). Right?

I have done all that exactly to prescription (except I forgot about exr 
indeed) and initially have not edited the image, and still it does not 
give the result I want. My solution now would be to forget about most of 
the head and concentrate the output exclusively to the face. It would 
not matter as only the central part of the image is important for the 
final isosurface. I have not tried that thoroughly yet but I will.

> Anything else will give you an distorted result and/or a loss of quickly
> estimated 85% of detail information.

Agreed.

>
>> I, modern Vermeer, do not paint the earring but glue the photograph of
>> one in its place (collage) :-)
>>
> This *is* called artistic nowadays I guess, but this is certainly not my
> field of expertise.

Nor mine really but the field is larger than what we may consider 
familiar or appropriate. The ready-mades of Surrealism can either be 
considered brilliant concepts or a hoax.

-- 
Thomas

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Before I am condemned to the stake, here are my latest results, using an 
exr depth_map (attached).

Two attached result images: SB_rockhead1a with, in the corresponding 
section:
exr "Mapping_test.exr" gamma 1.0 interpolate 2

and SB_rockhead1b with, in the corresponding section:
exr "Mapping_test.exr" gamma 3.0 interpolate 2

The latest of course is what I want. I plead innocent M'Lord.

-- 
Thomas

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Attachments:
Download 'mapping_test.exr.dat' (126 KB) Download 'sb_rockhead1a.png' (410 KB) Download 'sb_rockhead1b.png' (366 KB)

Preview of image 'sb_rockhead1a.png'

Preview of image 'sb_rockhead1b.png'

On 5/24/2016 8:49 AM, Thomas de Groot wrote:
> Before I am condemned to the stake, here are my latest results, using an
> exr depth_map (attached).
>
> Two attached result images: SB_rockhead1a with, in the corresponding
> section:
> exr "Mapping_test.exr" gamma 1.0 interpolate 2
>
> and SB_rockhead1b with, in the corresponding section:
> exr "Mapping_test.exr" gamma 3.0 interpolate 2
>
> The latest of course is what I want. I plead innocent M'Lord.
>

Change your plea to not guilty you are innocent. :-P

I prefer the gamma 3.0 image.

I did some experimenting with images and gamma using PaintShop Pro (does 
not auto gamma correct) and height fields.

Changing the gamma in the image changes the position of where the detail 
is brought out. Or so it seems to me.
If that is the aim then it is a bonus that it can be done inside 
Pov-Ray. Rather than using an external process that will slowdown the 
workflow.



-- 

I will not let ignorance stand in the way of opening my gob.

Regards
     Stephen

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On 24-5-2016 10:41, Stephen wrote:
> On 5/24/2016 8:49 AM, Thomas de Groot wrote:
>> Before I am condemned to the stake, here are my latest results, using an
>> exr depth_map (attached).
>>
>> Two attached result images: SB_rockhead1a with, in the corresponding
>> section:
>> exr "Mapping_test.exr" gamma 1.0 interpolate 2
>>
>> and SB_rockhead1b with, in the corresponding section:
>> exr "Mapping_test.exr" gamma 3.0 interpolate 2
>>
>> The latest of course is what I want. I plead innocent M'Lord.
>>
>
> Change your plea to not guilty you are innocent. :-P

Oups, yes, that would be more correct indeed!

>
> I prefer the gamma 3.0 image.
>
> I did some experimenting with images and gamma using PaintShop Pro (does
> not auto gamma correct) and height fields.
>
> Changing the gamma in the image changes the position of where the detail
> is brought out. Or so it seems to me.
> If that is the aim then it is a bonus that it can be done inside
> Pov-Ray. Rather than using an external process that will slowdown the
> workflow.
>

Exactly. I prefer not to mess with external processes and in this case 
the final result can be controlled better inside POV-Ray.

-- 
Thomas

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On 5/24/2016 12:19 PM, Thomas de Groot wrote:
>
> Exactly. I prefer not to mess with external processes and in this case
> the final result can be controlled better inside POV-Ray.

I tend to change the image but that is because of the tools I use. In 
this instance the image is being used as a data source, to be 
manipulated. So I don't see that there is a problem. Colour to position, 
no break in the photorealism rules, there. ;)


-- 

Regards
     Stephen

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On 24-5-2016 13:46, Stephen wrote:
> On 5/24/2016 12:19 PM, Thomas de Groot wrote:
>>
>> Exactly. I prefer not to mess with external processes and in this case
>> the final result can be controlled better inside POV-Ray.
>
> I tend to change the image but that is because of the tools I use. In
> this instance the image is being used as a data source, to be
> manipulated. So I don't see that there is a problem. Colour to position,
> no break in the photorealism rules, there. ;)
>

The problem is in the eye of the beholder :-)

-- 
Thomas

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On 5/25/2016 7:42 AM, Thomas de Groot wrote:
> On 24-5-2016 13:46, Stephen wrote:
>> On 5/24/2016 12:19 PM, Thomas de Groot wrote:
>>>
>>> Exactly. I prefer not to mess with external processes and in this case
>>> the final result can be controlled better inside POV-Ray.
>>
>> I tend to change the image but that is because of the tools I use. In
>> this instance the image is being used as a data source, to be
>> manipulated. So I don't see that there is a problem. Colour to position,
>> no break in the photorealism rules, there. ;)
>>
>
> The problem is in the eye of the beholder :-)
>

And that problem would be a "beam"?

Sorry, I could not resist. :)

-- 

Regards
     Stephen

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On 25-5-2016 10:45, Stephen wrote:
> On 5/25/2016 7:42 AM, Thomas de Groot wrote:
>> On 24-5-2016 13:46, Stephen wrote:
>>> On 5/24/2016 12:19 PM, Thomas de Groot wrote:
>>>>
>>>> Exactly. I prefer not to mess with external processes and in this case
>>>> the final result can be controlled better inside POV-Ray.
>>>
>>> I tend to change the image but that is because of the tools I use. In
>>> this instance the image is being used as a data source, to be
>>> manipulated. So I don't see that there is a problem. Colour to position,
>>> no break in the photorealism rules, there. ;)
>>>
>>
>> The problem is in the eye of the beholder :-)
>>
>
> And that problem would be a "beam"?
>
> Sorry, I could not resist. :)
>

Lol! I don't know. Too many rays in the Pov I guess.

-- 
Thomas

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