POV-Ray : Newsgroups : povray.advanced-users : Camera scaling and focal_blur? Server Time
28 Mar 2024 05:47:47 EDT (-0400)
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From: Mike Horvath
Subject: Re: Camera scaling and focal_blur?
Date: 12 Feb 2018 16:03:42
Message: <5a82012e$1@news.povray.org>
On 2/12/2018 2:02 PM, Alain wrote:
> Le 18-02-10 à 22:36, Mike Horvath a écrit :
>> I've been reading this
>>
>> https://en.wikipedia.org/wiki/Miniature_faking
>>
>> and have been wondering how to achieve the effect in POV-Ray. 
>> Obviously, there is no true scale in POV-Ray, so there's no need to 
>> "fake" the effect. But I don't know how to construct the correct camera.
>>
>> Any ideas?
>>
>>
>> Mike
> 
> Use a larger aperture. Something like
> vlength(Camera_Location, Focal_point)/4
> 
> If that's not enough, use a smaller divisor.

Yeah, I got it working. But it doesn't look as good in POV-Ray as it 
does in photography. I'll post some test renders soon.


MIke


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From: William F Pokorny
Subject: Re: Camera scaling and focal_blur?
Date: 13 Feb 2018 10:05:17
Message: <5a82fead$1@news.povray.org>
On 02/11/2018 06:56 PM, Kenneth wrote:
> William F Pokorny <ano### [at] anonymousorg> wrote:
> 
>>
>> ..for a technique using a not yet adopted parser change which allowed
>> image_maps to be used directly in density {} blocks.
>>
> That is *definitely* an interesting and useful idea (as is your current
> workaround.) Any idea if this image_map thing is going to be included in a newer
> v3.8.x alpha or beta?
> 
> 
I've no idea. I've since closed the image_map specific pull request. As 
a request it was submitted - as suggested - in place of another adding 
image_maps and pigment_maps to density { }. I myself use the latter 
branch with both enhancements and maintaining the image_map one was 
always extra work for me as I 'git re-based' my branches over time.

In general, I've pruned back on the github pull requests I leave sitting 
in the queue though I still publish any branches I think reasonably 
solid that others building their own POV-Ray might find useful.

Having a lot of pull requests backed up on github itself becomes a 
burden to the build test machines, it slows me down on re-basing and it 
generates a lot of email noise especially for the most connected 
developers.

Aside: I am sometimes frustrated by the pace at which changes are 
adopted - while also understanding it. We must have knowledgeable gate 
keepers and planners for the code base and they have only so much time. 
Christoph, especially, has often enough saved me from my own ignorance 
or improved upon an idea and my actual implementation. We need the pinch 
point, the bottleneck for change - and to reasonably pace change given 
many have development code efforts running alongside the master branch. 


Bill P.


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From: Alain
Subject: Re: Camera scaling and focal_blur?
Date: 13 Feb 2018 19:06:34
Message: <5a837d8a$1@news.povray.org>
Le 18-02-12 à 16:03, Mike Horvath a écrit :
> On 2/12/2018 2:02 PM, Alain wrote:
>> Le 18-02-10 à 22:36, Mike Horvath a écrit :
>>> I've been reading this
>>>
>>> https://en.wikipedia.org/wiki/Miniature_faking
>>>
>>> and have been wondering how to achieve the effect in POV-Ray. 
>>> Obviously, there is no true scale in POV-Ray, so there's no need to 
>>> "fake" the effect. But I don't know how to construct the correct camera.
>>>
>>> Any ideas?
>>>
>>>
>>> Mike
>>
>> Use a larger aperture. Something like
>> vlength(Camera_Location, Focal_point)/4
>>
>> If that's not enough, use a smaller divisor.
> 
> Yeah, I got it working. But it doesn't look as good in POV-Ray as it 
> does in photography. I'll post some test renders soon.
> 
> 
> MIke

As the ratio aperture/focal_length increase, you also need more samples. 
Otherwise, the image will get very noisy.


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From: Bald Eagle
Subject: Re: Camera scaling and focal_blur?
Date: 13 Feb 2018 20:55:01
Message: <web.5a8396e13abb6b9e5cafe28e0@news.povray.org>
Can you

a) mimic and actual camera lens with glass / ior?

b) look through a clear sheet that has a perturbation or normal that gets
progressively stronger toward the edges?

c) look though a partially transparent image map of the scene that somehow gets
rotated a little further the farther out toward the edge you get?

d) otherwise use overlapping image maps to imitate the photographic "circle of
confusion"?


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From: Mike Horvath
Subject: Re: Camera scaling and focal_blur?
Date: 13 Feb 2018 23:39:34
Message: <5a83bd86$1@news.povray.org>
On 2/13/2018 8:54 PM, Bald Eagle wrote:
> Can you
> 
> a) mimic and actual camera lens with glass / ior?
> 
> b) look through a clear sheet that has a perturbation or normal that gets
> progressively stronger toward the edges?
> 
> c) look though a partially transparent image map of the scene that somehow gets
> rotated a little further the farther out toward the edge you get?
> 
> d) otherwise use overlapping image maps to imitate the photographic "circle of
> confusion"?
> 
> 
> 

I don't know how to do any of these things. It would probably be easier 
to just do post-processing in Photoshop.



Mike


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From: Mike Horvath
Subject: Re: Camera scaling and focal_blur?
Date: 14 Feb 2018 01:27:20
Message: <5a83d6c8$1@news.povray.org>
On 2/13/2018 11:39 PM, Mike Horvath wrote:
> On 2/13/2018 8:54 PM, Bald Eagle wrote:
>> Can you
>>
>> a) mimic and actual camera lens with glass / ior?
>>
>> b) look through a clear sheet that has a perturbation or normal that gets
>> progressively stronger toward the edges?
>>
>> c) look though a partially transparent image map of the scene that 
>> somehow gets
>> rotated a little further the farther out toward the edge you get?
>>
>> d) otherwise use overlapping image maps to imitate the photographic 
>> "circle of
>> confusion"?
>>
>>
>>
> 
> I don't know how to do any of these things. It would probably be easier 
> to just do post-processing in Photoshop.
> 
> 
> 
> Mike

I forgot about the fact that my scenes have some tall objects, and the 
Photoshop post-processing doesn't work properly in cases like this.

Will a transparent glass really make much of a difference?


Mike


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From: Alain
Subject: Re: Camera scaling and focal_blur?
Date: 14 Feb 2018 11:55:43
Message: <5a846a0f@news.povray.org>
Le 18-02-13 à 20:54, Bald Eagle a écrit :
> Can you
> 
> a) mimic and actual camera lens with glass / ior?

Yes. Tou place an object shaped as the desired lense with the desired 
ior just in front of the camera. You can also add some dispersion.
This have been actually used.

> 
> b) look through a clear sheet that has a perturbation or normal that gets
> progressively stronger toward the edges?

You can use camera perturbation or use some actual transparent object 
with a perturbed normal or some actual displacement.
Then, it's just a question of modulating the pattern.
There are some samples scenes that show how it can be done.

> 
> c) look though a partially transparent image map of the scene that somehow gets
> rotated a little further the farther out toward the edge you get?
> 
> d) otherwise use overlapping image maps to imitate the photographic "circle of
> confusion"?
> 
> 
>


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From: Kenneth
Subject: Re: Camera scaling and focal_blur?
Date: 14 Feb 2018 17:20:00
Message: <web.5a84b5923abb6b9ea47873e10@news.povray.org>
"Kenneth" <kdw### [at] gmailcom> wrote:

I just noticed a dumb error I made-- some switched vector coordinates:
>
> Now, with a more complicated camera position:
> original camera position: <3,13,-9>
> original focal point: <0,0,0>
>
> With scale 2:
> new camera position: <...? ...> (I'm too lazy to figure it out)
> new focal_point set to: <-13,-3,9>
>

With scale 2, it should be...
new camera position: <...? ...> (I'm too lazy to figure it out)
new focal_point set to: <-3,-13,9> // the CORRECT vector

I hope my mistake didn't totally confuse the idea...


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From: Mike Horvath
Subject: Re: Camera scaling and focal_blur?
Date: 21 Feb 2018 06:28:16
Message: <5a8d57d0$1@news.povray.org>
On 2/13/2018 8:54 PM, Bald Eagle wrote:
> Can you
> 
> a) mimic and actual camera lens with glass / ior?
> 

I'm surprised no one has created a library of simulated cameras/lenses 
already. POV-Ray has been around for, what, two decades?


Mike


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From: Thomas de Groot
Subject: Re: Camera scaling and focal_blur?
Date: 21 Feb 2018 07:19:10
Message: <5a8d63be@news.povray.org>
On 21-2-2018 12:28, Mike Horvath wrote:
> On 2/13/2018 8:54 PM, Bald Eagle wrote:
>> Can you
>>
>> a) mimic and actual camera lens with glass / ior?
>>
> 
> I'm surprised no one has created a library of simulated cameras/lenses 
> already. POV-Ray has been around for, what, two decades?
> 
> 

Edouard Poor...


-- 
Thomas


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