POV-Ray : Newsgroups : povray.programming : Binary meshes? Server Time: 19 Dec 2018 11:16:10 GMT
  Binary meshes? (Message 1 to 3 of 3)  
From: Jörg 'Yadgar' Bleimann
Subject: Binary meshes?
Date: 14 Jun 2015 23:43:25
Message: <557e119d$1@news.povray.org>
Hi(gh)!

Still aiming at POVEarth/POVghanistan (and also high-quality renderings 
of other Solar System bodies) - but currently, there is a bottleneck 
when it comes to generating mesh2s from 16-bit (or whatever format) 
heightfields!

The Japanese ASTER mission elevation tiles have a resolution of 3601 by 
3601 measuring points (i. e. pixels in a heightfield generated from 
these data) - but even with 16 GiB of RAM, I had to decrease the 
resolution to 2600 by 2600, otherwise POV-Ray would crash.

Of course this is because POV-Ray generates full ASCII code rather than 
(like with heightfields) binary data to internally represent the mesh2 
object.

Have there ever been any attempts to write a patch to make binary meshes 
feasible with POV-Ray?

See you in Khyberspace!

Yadgar


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From: Le Forgeron
Subject: Re: Binary meshes?
Date: 15 Jun 2015 08:26:15
Message: <557e8c27$1@news.povray.org>
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Le 15/06/2015 01:43, Jörg 'Yadgar' Bleimann a écrit :
> Hi(gh)!
> 
> Still aiming at POVEarth/POVghanistan (and also high-quality
> renderings of other Solar System bodies) - but currently, there is
> a bottleneck when it comes to generating mesh2s from 16-bit (or
> whatever format) heightfields!
> 
> The Japanese ASTER mission elevation tiles have a resolution of
> 3601 by 3601 measuring points (i. e. pixels in a heightfield
> generated from these data) - but even with 16 GiB of RAM, I had to
> decrease the resolution to 2600 by 2600, otherwise POV-Ray would
> crash.
> 
> Of course this is because POV-Ray generates full ASCII code rather
> than (like with heightfields) binary data to internally represent
> the mesh2 object.
> 
> Have there ever been any attempts to write a patch to make binary
> meshes feasible with POV-Ray?
> 
> See you in Khyberspace!
> 
> Yadgar

I lack half the full deck, maybe more:

What are you trying to achieve ?

Why is heightfield not suitable for that purpose ?

Checking the usage of gas-factory to fill a lighter : what would be
the final resolution of rendered images, in term of pixels, compared
to the resolution of input data ? (remember, a final pixel which hold
more than one input data is probably a waste, and holding thousand of
input pixels into a final single pixel is definitely a waste).

(aka: modelling the ball of the pen on a table in a garden in a
suburban area on an island in the middle of an archipelago is waste if
your final image is a map from a satellite view of the half planet
whose resolution would provide about 2 pixels for the city)

If you intend to dive into the view (for animation ?), the VRML
approach might be relevant: different aspects for different distances.
Also used in mipmap for textures in usual CG. You might need access to
the camera informations (either directly or via implied relations to
other values) to select the right body of modelling.

In Povray, mesh (including mesh2) is a collection of any triangles
anywhere in space. It allow great flexibility, including many-folds
terrain.
Whereas heightfield is single-fold horizontal terrain in a unit-cube,
in which the elevation of the points are known only for the one at an
exact grid position, and interpolated elsewhere. (and that
interpolation is not anisotropic : the grid is made of squares which
are cut in two triangles, always along the same axis: rotating the
image by 90° might give a different result)


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From: Jörg 'Yadgar' Bleimann
Subject: Re: Binary meshes?
Date: 15 Jun 2015 13:05:54
Message: <557ecdb2$1@news.povray.org>
Hi(gh)!

On 15.06.2015 10:26, Le_Forgeron wrote:
> I lack half the full deck, maybe more:
>
> What are you trying to achieve ?
>
> Why is heightfield not suitable for that purpose ?

My "heightfield" needs to follow Earth's curvature, so it has to be a mesh2!

See you in Khyberspace!

Yadgar


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