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On 2021-01-06 1:44 PM (-4), Alain Martel wrote:
>> Alain Martel <kua### [at] videotronca> wrote:
>>
>>> I tend to use some averaged micro-normals. Around 5 to 10 seems to work
>>> well.
>>> I prefer to use granite as my base pattern.
>>> I also use rather large random translations after the scaling.
>>
>> Granite-- I never thought of that. It is nicely 'random'. My own
>> trials used
>> overlapped and rotated 'linear' patterns... like sine waves or scallop
>> waves for
>> the normals, IIRC. Maybe that was the cause of my Moire patterns?
I suspect so. Think of the regular patterns you see in 4-color
halftones in comic books.
However, Rune Johansen has a brushed metal texture that just averages 2
wood layers. It is quite convincing, even with no blur effect. It was
written for MegaPOV 0.5, but it is easily converted to 3.7/3.8.
http://runevision.com/3d/povgoodies/
> You can also try bozo/bumps/spotted or agate as your base pattern.
I tried crackle once, but it took longer than bumps and didn't look all
that great. Facets coords gives results similar to bumps, without
taking longer.
I have never thought to try granite or agate. Have you tried wrinkles?
> Tip when using averaged textures for complex objects or multiple objects
> with blurred reflection :
>
> Make two copies of your objects with blurred reflection. The first have
> the full averaged texture and the no_reflection attribute. The second
> have only the non-averaged micro-normals and the no_image attribute.
> That way, when that object self reflect, or several objects that have
> blurred reflection inter reflect, the number of rays to trace is kept to
> a reasonable level.
My RC3Metal module in the Object Collection uses this trick. Thanks
again for that idea.
> Also, using averaged textures can be much faster that rendering multiple
> times and averaging the resulting images externally. The render time hit
> only affect the part of the image where there are averaged normals.
> Multiple renders need to render the whole image multiple times, then,
> you have the time needed to post process them.
This was my first plan. But I had written the original scene using
POV-Ray 3.7, so to get the same effect as finish-level Fresnel, I had
used a layered texture. (Trust me, reflection-level Fresnel looked
horrible.) Then when I tried to change the bumpy layer to an averaged
texture, I got the old "Cannot layer a patterned texture over another"
error. Rather than attempt to rearrange the texture, or unravel the
texture to work with 3.8's finish-level Fresnel, I just chose the easy
way out. But yes, I agree that putting in the extra work would probably
have shortened the render time.
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