Le 17-10-25 à 14:57, Stephen a écrit :
> On 25/10/2017 17:31, Bald Eagle wrote:
>> "cbpypov" <nomail@nomail> wrote:
>>> Hi,
>>>
>>> I'm trying to render a high quality "cover art" for a physics thesis
>>> (nanophotonics). I have basically two questions:
>>>
>>>    1. What is the best way to generate a "glowing field distribution"?
>>>    2. What is the best way to illustrate a light ray or "photon path" 
>>> coming from
>>> an emitter, say a small glowing sphere
>>
>> I would say that you should look at Paul Nylander's work
>> http://www.bugman123.com/index.html
>> as he's and engineer, and has done an awful lot of very professional 
>> quality
>> scientific visualization with POV-Ray.
>>
>>> For 1): Say I have field values in 3D that I could assign to desired 
>>> colors and
>>> brightness values. So that that I have e.g. a list of (x, y, z, R, G, B,
>>> brightness).
>> .....
>>> So how can I achieve something like
>>> this?
>>
>> You use an EMISSIVE media.
>> I'd also consider generating your field as a df3 file, and then you 
>> can "sculpt"
>> the media density with that df3 information.
>>
> 
> DF3s are probably the way to do it. One drawback is that PovRay uses 
> df3s as a monochrome input. So you would need three of them to R G & B 
> images. jr might be able to help you with the df3 format as he is 
> working on a set of df3 utilities.
> 
> The code I use for rendering in colour with df3s is:
> 
>          #declare PF = 64  ; // multiplication factor
> 
>      #declare Df3_Material0 =
>      material{
>        texture {
>          pigment {
>            colour rgbft <1.000,1.000,1.00,0.000,1.000>
>          }
> 
>        }
> 
>        interior{
>          //ior                 1.000
>          //caustics            0.000
>          //dispersion          1.000
>          //dispersion_samples  7.000
>          //fade_power          0.000
>          //fade_distance       0.000
>          //fade_color          rgb <0.000,0.000,0.000>
Those can, and should, be omited.
>          media {
>            method     3
>            // intervals  10
MUST stay at 1. Don't use intervals is best.

>            //samples    1, 1
// May be omited : Use 10 samples by default
// Second value NOT used.
>            //confidence 0.900
>            //variance   0.008
>            //ratio      0.900
// All 3 NOT used with method 3
>            absorption rgb <0.000,0.000,0.000>
>            emission   rgb <1.000,0.000,0.000>     * PF
>            aa_threshold 0.050
>            aa_level    4
>            density {
>              density_file df3 "Your_red.df3"
>              interpolate 2
>            }
> 
>          }
> By default, method 3 use only 1 interval and 10 samples.
Using more that a single intervals will dramatically increase the time 
required by your render.
If you need more sampling, simply increase the samples vlue.
As only a single interval is used, only the first samples value is ever 
used. A second valus, if present, is silently ignored.
Also, confidence, variance and ratio, are used to distribute samples 
within various intervals, they are not used, and silently ignored.

intervals 1 samples 500
is much faster than
intervals 10 samples 5
for 10 times as many samples.

Post a reply to this message