"Trevor G Quayle" <Tin### [at] hotmailcom> wrote:
> A lot of objects in a CSG can be very slow, espscially if using intersection or
> difference.  Perhaps try using blobs as I did for a golf ball some time ago,
> which ends up rendering a lot faster.  You can either create the whole planet
> as a single blob entity, or just the craters (still create all the craters as a
> single blob item though) and union/difference them with the planet.


I was not expecting (and greatly appreciate!) the quick responses to my problem.
 Since this is the second time (2 out of 2) that the use of blob objects for
creating craters has been mentioned as a possible solution, I would like to try
this approach.  I can understand how "negative" blobs could be used to simulate
the smooth dimples of a golfball, but the rim of an impact craters wall is
usually sharp, jagged and abrupt. the same is true for the more complex
features of the inside of very large impact craters such as central peaks and
peak rings.  Is is possible to get such "sharp" effects and still use blobs?

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Removing tons of objects from a main object will result in a very slow
render. I don't think there's currently any way around that.

  If you can create a single mesh from your cratered planet, that would
render very fast.

-- 
                                                          - Warp

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Warp <war### [at] tagpovrayorg> wrote:
> Removing tons of objects from a main object will result in a very slow
> render. I don't think there's currently any way around that.
>
>   If you can create a single mesh from your cratered planet, that would
> render very fast.
>
> --
>                                                           - Warp

Yes, no real way around it, sometimes manually bounding can give a little speed
boost, but not much.  The original object can be broken into smaller pieces as
well and manually bound, but this can be difficult to implement very well, at
least for a significant speed improvement.

But, removing a single blob entity consisting of several blobs is considerably
faster than removing the equivalent in spheres, if the objects can be made of
blobs (using the basic formula in the docs, you can mathematically get the
blobs the same size as spheres of a specific radius)

A mesh would likely be far quicker (at rendering) and likely far more versatile.

-tgq

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This doesn't look like a Windows-specific problem ;-)

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COMPATT nous apporta ses lumieres en ce 2008/01/08 21:29:
> "Trevor G Quayle" <Tin### [at] hotmailcom> wrote:
>> A lot of objects in a CSG can be very slow, espscially if using intersection or
>> difference.  Perhaps try using blobs as I did for a golf ball some time ago,
>> which ends up rendering a lot faster.  You can either create the whole planet
>> as a single blob entity, or just the craters (still create all the craters as a
>> single blob item though) and union/difference them with the planet.
> 
> 
> I was not expecting (and greatly appreciate!) the quick responses to my problem.
>  Since this is the second time (2 out of 2) that the use of blob objects for
> creating craters has been mentioned as a possible solution, I would like to try
> this approach.  I can understand how "negative" blobs could be used to simulate
> the smooth dimples of a golfball, but the rim of an impact craters wall is
> usually sharp, jagged and abrupt. the same is true for the more complex
> features of the inside of very large impact craters such as central peaks and
> peak rings.  Is is possible to get such "sharp" effects and still use blobs?
> 
> 
Create the planed as a blob. Use negative blob components to dig the rough 
outlines of the craters into the planet.
Once that's done, add, with an union, all your craters with ther sharp and 
jagged edges and peaks.

-- 
Alain
-------------------------------------------------
EVERYTHING HAS A GENDER

You may not know this but many nonliving things have a gender...

A Hot Air Balloon is Male, because, to get it to go anywhere, you have to light 
a fire under it, and of course, there's the hot air part.

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Thanks again for all the help.

When I created the planet using a blob then subtracted out negative blobs the
size of crater floors, the rendering of the planet including my crater objects
increased immensly. Now when I create the moon using the entire 8000+ crater
database it only takes 2.5 min to render the whole 2048x1024 image!!!

Now I can focus on reducing the parse time for the files (which is over 4 hours)
I already know how to do that part by pre-processing the crater data so POV-Ray
will not have to test each crater against all of the already existing ones for
the overlap condition. This is not to hard to do using C++ I just didn't want
to waste time trying to reduce parse time when it would still take almost a
week to render the scene after parsing was over.

If I can end up reducing parse time half as much as I have the rendering (with
the help of all your advice)This macro may even be useful in animations.

I had planned on adding blobs to the macro down the road for making craters on
irregular shapes like asteroids.  It never occured to me I could use a blob
object for the spherical planets and moons as well.

Thanks so much for providing the missing puzzle piece!!

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"COMPATT" <com### [at] hotmailcom> wrote:
> Thanks again for all the help.
> I already know how to do that part by pre-processing the crater data so POV-Ray
> will not have to test each crater against all of the already existing ones for
> the overlap condition. This is not to hard to do using C++ I just didn't want
> to waste time trying to reduce parse time when it would still take almost a
> week to render the scene after parsing was over.
>
> If I can end up reducing parse time half as much as I have the rendering (with
> the help of all your advice)This macro may even be useful in animations.
>
> I had planned on adding blobs to the macro down the road for making craters on
> irregular shapes like asteroids.  It never occured to me I could use a blob
> object for the spherical planets and moons as well.
>
> Thanks so much for providing the missing puzzle piece!!

Ah, looks like you're facing the placing non-intersecting spheres, O^n
conundrum.  We had a bit of a go at this in a couple threads last year with
very good results (in the order of 10-20x speedup depending on parameters).

Original discussion:
http://news.povray.org/povray.binaries.images/thread/%3C4468e90a%40news.povray.org%3E/?ttop=257697&toff=1000

Resulting techniques posted here:
http://news.povray.org/povray.advanced-users/thread/%3C446b33a3@news.povray.org%3E/?ttop=255728&toff=100

One of the successful techniques was by me, so feel free to post any questions.
Warp had a completely different technique, but with similar speedup times here
as well, feel free to ask him questions, but I can't guarantee the response ;)
-tgq

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"Trevor G Quayle" <Tin### [at] hotmailcom> wrote:
> Resulting techniques posted here:
>
http://news.povray.org/povray.advanced-users/thread/%3C446b33a3@news.povray.org%3E/?ttop=255728&toff=100

Try again...
http://news.povray.org/povray.advanced-users/thread/%3C446b33a3@news.povray.org%3E/?ttop=255728&toff=100

-tgq

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"Trevor G Quayle" <Tin### [at] hotmailcom> wrote:
> "Trevor G Quayle" <Tin### [at] hotmailcom> wrote:
> > Resulting techniques posted here:
> >
http://news.povray.org/povray.advanced-users/thread/%3C446b33a3@news.povray.org%3E/?ttop=255728&toff=100
>
> Try again...
>
http://news.povray.org/povray.advanced-users/thread/%3C446b33a3@news.povray.org%3E/?ttop=255728&toff=100
>
> -tgq

I'll try without the http...

news.povray.org/povray.advanced-users/thread/%3C446b33a3@news.povray.org%3E/?ttop=255728&toff=100

If this link doesn't work, just search for "Random placement of non-intersecting
spheres" from May 2006 (hmm, maybe it was 2 years ago) in povray.advanced-users

Man I suck at this...

-tgq

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All three link attempts worked for me.

But try tinyurl.com for next time.

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