Thomas de Groot wrote:
> "John VanSickle" <evi### [at] hotmailcom> schreef in bericht 
> news:4835644f$1@news.povray.org...
> 
>> The macro may need tweaking.  The rippling in the left-hand side of the 
>> image appears to be an artifact.
>>
> 
> I have been wondering about that. It appears indeed in the close up height 
> field blocks.

The macro (IIRC) calculates the number of pixels spanned in any 
direction by the heightfield, and sets the height field's resolution to 
that value.  It may be that when the line of view is parallel or 
near-parallel to the diagonal of the height field, that this is not 
quite enough.  Increasing the resolution of the HF (probably by no more 
than 40%) should fix this.

The ripple may also be the result of aliasing, in which case the same 
remedy--increasing the HF resolution--is called for, but there would 
also need to be aa + jittering in the render for the rippling to be 
eliminated, if this is the cause.

Regards,
John

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"John VanSickle" <evi### [at] hotmailcom> schreef in bericht 
news:483a9de9@news.povray.org...
>
> The macro (IIRC) calculates the number of pixels spanned in any direction 
> by the heightfield, and sets the height field's resolution to that value. 
> It may be that when the line of view is parallel or near-parallel to the 
> diagonal of the height field, that this is not quite enough.  Increasing 
> the resolution of the HF (probably by no more than 40%) should fix this.
>
That is correct. I have introduced a multiplicator to the Details parameter 
in the macro, which does a nice job, especially for larger images.

> The ripple may also be the result of aliasing, in which case the same 
> remedy--increasing the HF resolution--is called for, but there would also 
> need to be aa + jittering in the render for the rippling to be eliminated, 
> if this is the cause.

Tentatively, I introduced the smooth option in the macro, just to see what 
it does. The rippling is further generated I think by the pigment I used, 
where a downscaled wrinkle is present. The effect is somewhat lessened if  I 
scale it a bit up. However in larger renders, one clearly sees the mesh of 
rectangles so increasing the resolution works best.

All in all, using the macro is just to find the settings which will work 
best together, which is fun to do.

Thomas

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