EagleSun nous apporta ses lumieres en ce 15/06/2006 09:02:
> Bill Hails <me### [at] billhailsnet> wrote:
>> Hi all,

>> Any Ideas what's causing these artefacts?

>> I'm going for ersatz fluffy clouds, they'll print quite small
>> so the level of detail isn't an issue.

>> It's a blob + media.

>> There's nothing special about the media:


>> #ifndef (CloudScale)
>>     #declare CloudScale = 1;
>> #end

>> #local MCloudColour = rgb 0.95;

>> #local MCloudFinish = finish {
>>     ambient 0.2
>>     diffuse 0.6
>> }

>> #local MCloudTexture = texture {
>>     pigment {
>>         #if (1)
>>             colour rgbt 1
>>         #else
>>             colour rgb 1
>>         #end
>>     }
>>     finish { MCloudFinish }
>> }

>> #local MCloudInterior = interior {
>>     media {
>>         density { MCloudColour * 0.06 / CloudScale }
>>         #if (1)
>>             absorption rgb (1 - MCloudColour) * 8.0
>>         #end
>>         #if (1)
>>             scattering { 3, MCloudColour * 0.1 }
>>             // scattering { 4, MCloudColour * 1.0 }
>>         #end
>>         #if (1)
>>             emission rgb MCloudColour * 0.07
>>         #end
>>     }
>> }

>> #declare CloudMaterial = material {
>>     texture { MCloudTexture }
>>     interior { MCloudInterior }
>> }

>> When I render the cloud in a scene by itself it looks fine,
>> but when I put it alongside other objects in a (not too) complex
>> scene these white flecks appear.

>> --
>> Bill Hails
>> http://billhails.net/

> I've seen this before.... and I suspect they are intersections of several
> objects.  You mentioned an object called "blob".  If they intersect at many
> places, you'll get these lines.  With renderings I have done, the only thing
> I could think of was to change the size or position of the objects by +/-
> 0.001 or 0.005 or some tiny random number, to minimize the number of
> intersections.

> However in your case, it might be better for you to put them into "Union" or
> "Merge".  Merge is slower but may be better in your case... because with
> merge, the objects then actually merge into a single object, which means
> there will be no intersections at all.

> Now come to think of it... I think I'll try that on my renders... trying to
> merge water with the surface of the planet....



A blob is a single, multi components object. It's a kind of special case isosurface
composed of 
various spheres and cylinders. Search fot it in the documentations. It don't contain
any internal 
surfaces and don't intersect itself.

-- 
Alain
-------------------------------------------------
Idolism: Let's bronze this shit.

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