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From: Jörg 'Yadgar' Bleimann
Subject: Re: POVEarth: Tristan da Cunha: gaps between mesh2 triangles
Date: 30 Jun 2013 16:09:10
Message: <51d09066@news.povray.org>
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Hi(gh)!
On 30.06.2013 21:28, Stephen wrote:
> Just a short in the dark, Jorg.
> Blender has the functionality to fill a hole in a mesh with faces.
>
> http://wiki.blender.org/index.php/Doc:2.4/Tutorials/Modeling/Meshes/Fill_Faces
>
>
> It might help and it is free. ;-)
Yes, I heard of Blender (and sometimes even used it) - but this is
probably not the solution, as "technically", the mesh is complete, i. e.
no triangles are missing. It must be an accuracy or epsilon problem...
See you in Khyberspace!
Yadgar
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From: Stephen
Subject: Re: POVEarth: Tristan da Cunha: gaps between mesh2 triangles
Date: 30 Jun 2013 16:25:10
Message: <51d09426@news.povray.org>
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> Hi(gh)!
>
> On 30.06.2013 21:28, Stephen wrote:
>
>> Just a short in the dark, Jorg.
>> Blender has the functionality to fill a hole in a mesh with faces.
>>
>> http://wiki.blender.org/index.php/Doc:2.4/Tutorials/Modeling/Meshes/Fill_Faces
>>
>>
>>
>> It might help and it is free. ;-)
>
> Yes, I heard of Blender (and sometimes even used it) - but this is
> probably not the solution, as "technically", the mesh is complete, i. e.
> no triangles are missing. It must be an accuracy or epsilon problem...
>
> See you in Khyberspace!
>
> Yadgar
>
As I said. It was a shot in the dark.
--
Regards
Stephen
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From: Thomas de Groot
Subject: Re: POVEarth: Tristan da Cunha: gaps between mesh2 triangles
Date: 1 Jul 2013 03:03:12
Message: <51d129b0@news.povray.org>
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It seems to me that the triangle are floating, the vertices not being
joint properly together. If that is true, the solution is simple: load
the mesh2 into Poseray, go to Groups, push the button labelled Weld
vertices, save as mesh2 again.
Additionally, beware indeed of epsilon issues. Put the camera a little
bit higher from the ground.
Thomas
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From: Jörg 'Yadgar' Bleimann
Subject: Re: POVEarth: Tristan da Cunha: gaps between mesh2 triangles
Date: 1 Jul 2013 04:56:21
Message: <51d14435$1@news.povray.org>
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Hi(gh)!
On 01.07.2013 09:03, Thomas de Groot wrote:
> It seems to me that the triangle are floating, the vertices not being
> joint properly together.
I think they should, as this is the code for the mesh2:
#declare Earth_Slice=
mesh2
{
vertex_vectors
{
xdim*ydim
#declare row=0;
#while (row<ydim)
#declare col=0;
#while (col<xdim)
#declare clrvect=eval_pigment(map, <1/(xdim*2)+col/xdim,
1-(1/(ydim*2)+row/ydim), 1>);
// #warning concat("<",vstr(3, clrvect, ",",7,2),">")
// #warning concat(str(col,2,0)," ",str(row,2,0))
#declare hval=clrvect.red*65280+clrvect.green*255;
#declare hval=-deadsea+rng/65535*hval;
// #warning str(hval, 1, 2)
(rd+hval)*<sin(radians(-longstart-col/xdim))*cos(radians(latstart-row/ydim)),
sin(radians(latstart-row/ydim)),
cos(radians(-longstart-col/xdim))*cos(radians(latstart-row/ydim))>*sf
#if (!(row=ydim-1 & col=xdim-1)) // no comma after last vector
,
#end
#declare col=col+1;
#end
#declare row=row+1;
#end
}
face_indices
{
(xdim-1)*(ydim-1)*2
#declare r=0;
#while (r<ydim-1)
#declare c=0;
#while (c<xdim-1)
<r*xdim+c, r*xdim+c+1, (r+1)*xdim+c>,
<r*xdim+c+1, (r+1)*xdim+c+1, (r+1)*xdim+c>
#if (!(r=ydim-2 & c=xdim-2)) // no comma after last vector
,
#end
#declare c=c+1;
#end
#declare r=r+1;
#end
}
texture
{
pigment { color rgb <0, 0.8, 0> }
finish { ambient 0.1 diffuse 1 brilliance 0.4 }
}
double_illuminate
translate ApproxLook*sf
}
> If that is true, the solution is simple: load
> the mesh2 into Poseray, go to Groups, push the button labelled Weld
> vertices, save as mesh2 again.
Poseray? Is it free?
> Additionally, beware indeed of epsilon issues. Put the camera a little
> bit higher from the ground.
In my current scene, the camera is placed at "pedestrian eye's height",
i. e. 1.7 metres above ground. But the problem remains with any camera
height - the gaps then show up as black dots on the terrain!
See you in Khyberspace!
Yadgar
Now playing: Master of Sensation (Eloy)
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From: Stephen
Subject: Re: POVEarth: Tristan da Cunha: gaps between mesh2 triangles
Date: 1 Jul 2013 05:57:56
Message: <51d152a4$1@news.povray.org>
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> Poseray? Is it free?
Yes, it is an excellent program
https://sites.google.com/site/poseray/
--
Regards
Stephen
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From: Thomas de Groot
Subject: Re: POVEarth: Tristan da Cunha: gaps between mesh2 triangles
Date: 1 Jul 2013 07:19:33
Message: <51d165c5$1@news.povray.org>
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> I think they should, as this is the code for the mesh2:
>
> #declare Earth_Slice=
> mesh2
> {
> vertex_vectors
> {
> xdim*ydim
> #declare row=0;
> #while (row<ydim)
> #declare col=0;
> #while (col<xdim)
> #declare clrvect=eval_pigment(map, <1/(xdim*2)+col/xdim,
> 1-(1/(ydim*2)+row/ydim), 1>);
I cannot read that ;-)
Thinking a bit more about this, meshes with loose triangles at least
have their vertices at the /same/ locations; here there seems to be a
gap. Either, this is already present in the original DEMs, or the math
above for the conversion has some errors... Difficult to say.
Poseray is free indeed and it is worth a try. If it does not solve the
issue, then other solutions have to be found. In Poseray, the tolerance
for welding vertices can be adapted. Start with the default; if
necessary increase the value gradually.
Thomas
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From: scott
Subject: Re: POVEarth: Tristan da Cunha: gaps between mesh2 triangles
Date: 1 Jul 2013 08:05:27
Message: <51d17087@news.povray.org>
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> #declare Earth_Slice=
> mesh2
> {
> vertex_vectors
> {
> xdim*ydim
> #declare row=0;
> #while (row<ydim)
> #declare col=0;
> #while (col<xdim)
> #declare clrvect=eval_pigment(map, <1/(xdim*2)+col/xdim,
> 1-(1/(ydim*2)+row/ydim), 1>);
> // #warning concat("<",vstr(3, clrvect, ",",7,2),">")
> // #warning concat(str(col,2,0)," ",str(row,2,0))
> #declare hval=clrvect.red*65280+clrvect.green*255;
> #declare hval=-deadsea+rng/65535*hval;
> // #warning str(hval, 1, 2)
>
> (rd+hval)*<sin(radians(-longstart-col/xdim))*cos(radians(latstart-row/ydim)),
>
> sin(radians(latstart-row/ydim)),
> cos(radians(-longstart-col/xdim))*cos(radians(latstart-row/ydim))>*sf
I would put something very simple like this for debug purposes:
<row,col,hval>
...
> face_indices
> {
> (xdim-1)*(ydim-1)*2
> #declare r=0;
> #while (r<ydim-1)
> #declare c=0;
> #while (c<xdim-1)
> <r*xdim+c, r*xdim+c+1, (r+1)*xdim+c>,
> <r*xdim+c+1, (r+1)*xdim+c+1, (r+1)*xdim+c>
That looks fine to me.
Put your camera in a suitable location for the above debug mesh to show
up, and put a constant coloured background so that you can see the
difference between shadowed areas and areas not rendered properly.
Assuming the above test works then I would gradually build back up to
your equations (maybe first changing the scale to match, then
introducing the trig) to see what causes the problems.
My guess is accuracy because you are dealing with a huge dynamic range
of dimensions.
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From: scott
Subject: Re: POVEarth: Tristan da Cunha: gaps between mesh2 triangles
Date: 1 Jul 2013 08:20:39
Message: <51d17417$1@news.povray.org>
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>> vertex_vectors
>> {
>> xdim*ydim
>> #declare row=0;
>> #while (row<ydim)
>> #declare col=0;
>> #while (col<xdim)
>> #declare clrvect=eval_pigment(map, <1/(xdim*2)+col/xdim,
>> 1-(1/(ydim*2)+row/ydim), 1>);
>
> I cannot read that ;-)
>
> Thinking a bit more about this, meshes with loose triangles at least
> have their vertices at the /same/ locations; here there seems to be a
> gap. Either, this is already present in the original DEMs, or the math
> above for the conversion has some errors... Difficult to say.
Even if it has errors it shouldn't introduce gaps as he is using
face_indices to reference the vertices (all 6 triangles using that
vertex will have exactly the same value, even if it is an incorrect value).
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From: Nekar Xenos
Subject: Re: POVEarth: Tristan da Cunha: gaps between mesh2 triangles
Date: 1 Jul 2013 15:40:03
Message: <op.wzj58xdxufxv4h@xena>
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I would love to visit Tristan da Cunha one day :)
There are so many beautiful and interesting features on this island. My
first impression on Google Earth was "dead, dry and boring" until I took a
closer look.
--
-Nekar Xenos-
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From: Jörg 'Yadgar' Bleimann
Subject: Re: POVEarth: Tristan da Cunha: gaps between mesh2 triangles
Date: 2 Jul 2013 01:39:32
Message: <51d26794@news.povray.org>
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Hi(gh)!
On 01.07.2013 21:39, Nekar Xenos wrote:
> I would love to visit Tristan da Cunha one day :)
Same with me... but it is, at least from Europe, even further away and
more difficult to reach than Afghanistan! And there are many more
interesting islands in the southern temperate and subantarctic zone...
ever heard of Amsterdam Island? It's somehow Tristan da Cunha's
counterpart in the Indian Ocean!
All these islands appear interesting to render within my megalomaniac
POVEarth project... especially when it comes to vegetation and fauna
(any albatross model ready?)!
See you in Khyberspace!
Yadgar
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