POV-Ray: Newsgroups: povray.binaries.images: POVEarth: Tristan da Cunha: gaps between mesh2 triangles: POVEarth: Tristan da Cunha: gaps between mesh2 triangles

POV-Ray : Newsgroups : povray.binaries.images : POVEarth: Tristan da Cunha: gaps between mesh2 triangles : POVEarth: Tristan da Cunha: gaps between mesh2 triangles		Server Time 29 Jul 2024 22:29:36 EDT (-0400)

From: Jörg 'Yadgar' Bleimann
Date: 30 Jun 2013 15:00:40
Message: <51d08058@news.povray.org>

Hi(gh)!

Meanwhile, I managed to produce some first crude ground based views of 
Tristan da Cunha (from Inaccessible Island towards the main island) at 
"pedestrian height". i. e. 1.7 metres above the ground. The ocean 
currently is a simple dark blue global sphere (to be replaced by some 
semi-transparent basic water texture later on), the sky a simple 
sky_sphere with a gradient aligning with the local normal vector (to 
replaced either by Bruno Cabasson's or Christoph Hormann's atmosphere 
model), also the terrain texture soon will be replaced by a Blue Marble 
satellite mosaic texture (scaled from originally 240 x 240 to 3601 x 
3601 pixels, as this is the original data resolution of the underlying 
ASTER DEMs.

But now a problem shows up which I faced already some years before: gaps 
between the single mesh2 triangles! I remember having dealt with this as 
early as 2004 and, with help from Mike Williams, also satisfactorily 
solved: just by translating the center of the Earth (and thus the mesh2) 
by an amount which places the mesh2 vectors at coordinates of relatively 
small orders of magnitude (i. e. not millions but rather thousands or 
even only hundreds of POV units). Back then it worked fine (as you can 
see with my "Flight over Afghan mountains" animation: 
https://www.youtube.com/watch?v=abgq4Zo_nOw ) - but now it doesn't anymore!

Regardless which overall scaling factor I use (in the attached image 
sequence from 1 down to 0.0001), the gaps never completely disappear... 
instead, at very small values, increasingly portions of the mesh are 
shadowed which should be illuminated.

Can be anything done about this - or is this an inaccuracy of POV-Ray 
which is entirely unavoidable?

See you in Khyberspace!

Yadgar

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Preview of image '2013-06-30 tristan da cunha from inaccessible island, pedestrian view, take 2.jpg'

Preview of image '2013-06-30 tristan da cunha from inaccessible island, pedestrian view, take 3 (scaling factor 0.1).jpg'

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Preview of image '2013-06-30 tristan da cunha from inaccessible island, pedestrian view, take 5 (scaling factor 0.001).jpg'

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Preview of image '2013-06-30 tristan da cunha from inaccessible island, pedestrian view, take 8 (scaling factor 0.0008).jpg'

Preview of image '2013-06-30 tristan da cunha from inaccessible island, pedestrian view, take 7 (scaling factor 0.0005).jpg'

Preview of image '2013-06-30 tristan da cunha from inaccessible island, pedestrian view, take 6 (scaling factor 0.0001).jpg'