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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