Another point I forgot to mention: you may have noticed when in Poseray 
or when rendering in POV-Ray, that the Martian landscape does not have 
the usual left-handed orientation (X-right, Y-up, Z- screenwards) but a 
right-handed one (X-right, Y-screenwards, Z-up). You can easily remedy 
that in Poseray. After you recalculated the normals in the Groups 
folder, first press the 'Flip Y-Z axis' button, then in the Transform 
section, set Scale z to -1 and press the 'Transform' button. Finally, 
export to POV-Ray.

-- 
Thomas

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On 19.08.2017 04:23, Stephen wrote:
> On 19/08/2017 07:04, Sven Littkowski wrote:
>> Intention:
>>
>> Using the "Difference" function to create caves and tunnels inside a
>> square-shaped piece of Martian surface (a hollow mesh object).
>>
>> What are your solutions, to transfer what is now a mesh, into a solid
>> object. I believe these objects need to be solid, in order to create
>> caves and tunnels through Difference into that body.
>>
> 
> 
> You are thinking about it wrongly.
> There are no solid mesh objects. The keyword "hollow" has nothing to do
> with an object not being solid. It is used for media containers.
> You should think in terms of the mesh not having any holes. Then you can
> use it with csg without artefacts. In the animation below I intersected
> the mesh of Ariel (the ghost) was intersected with a cub then filled
> with media. The hollow keyword was used for that.
> 
> http://www.tc-rtc.co.uk/member/imagenewdisplay/index176.html
> 
> When I was creating the df3s for Dhalgren with Thomas. I had a lot of
> trouble with the meshes when they had holes in them. (I had to manually
> edit the slices that make up the image sequence.)
> 
> http://news.povray.org/povray.binaries.images/thread/%3C58343a6a@news.pov
ray.org%3E/
> 
> 
> 
> 
Thanks. The first link requires a username and password, was not able to
see the animation just like that.

Nonetheless, good to know I can still work with division. Will give a try.


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On 19.08.2017 04:34, clipka wrote:
> Am 19.08.2017 um 08:04 schrieb Sven Littkowski:
>> Intention:
>>
>> Using the "Difference" function to create caves and tunnels inside a
>> square-shaped piece of Martian surface (a hollow mesh object).
>>
>> What are your solutions, to transfer what is now a mesh, into a solid
>> object. I believe these objects need to be solid, in order to create
>> caves and tunnels through Difference into that body.
> 
> The solution has been mentioned multiple times already: In POV-Ray, a
> `mesh` or `mesh2` object is considered solid if (and only if) it has a
> (non-null) `inside_vector` parameter.
> 
> The parameter value needs to be a direction, but the actual value is
> usually irrelevant as long as the mesh is closed.
> 
> If the mesh isn't closed and has holes, using an `inside_vector` will
> cause artifacts in CSG operations: Essentially, any hole is extruded to
> infinity in the direction opposite to the `inside_vector` direction,
> except that these extrusions don't have visible surfaces and just
> interact in CSG.
> 
Thanks. Yes, I remember to have read it before. Just, how to define such
a non-zero parameter? I never did that before. As I understand, the
location can be anywhere inside the mesh body.

And in case there are gaps, is there any program that can close any open
gaps in meshes, POV, obj, 3DS, whatever format?

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Am 19.08.2017 um 13:11 schrieb Sven Littkowski:

>> The solution has been mentioned multiple times already: In POV-Ray, a
>> `mesh` or `mesh2` object is considered solid if (and only if) it has a
>> (non-null) `inside_vector` parameter.
...
> Thanks. Yes, I remember to have read it before. Just, how to define such
> a non-zero parameter? I never did that before. As I understand, the
> location can be anywhere inside the mesh body.

I repeat: `inside_vector` is NOT a location, but a direction.

That direction is used in a test to answer the question "is location P
inside the mesh?", but that location P is nothing /you/ need to worry
about: POV-Ray of its own accord will come up with plenty of values for
P that it will want to subject to this test.

As for wondering "how to define such a non-zero parameter", that's the
equivalent of searching the "any" key on your keyboard: Literally /any/
vector parameter other than `<0,0,0>` will do. For example:

    mesh2 {
      ...
      inside_vector y
    }

Alternatively, instead of `y` you could also use `z`, or `x`, or
`<5,4,3>`, or `<sin(42*pi/180),-exp(23),4711>`. Anything for which
`vlength(V)` doesn't return zero. (Presuming, of couse, that your mesh
is properly closed. Otherwise, the best choice in your case is whatever
direction is considered to be "up" with respect to the mesh.)


> And in case there are gaps, is there any program that can close any open
> gaps in meshes, POV, obj, 3DS, whatever format?

I'm pretty sure meshlab is able to do that. Blender also surely provides
a way, though it might take you on a sightseeing trip through the entire
software. For very small gaps where the vertices of adjacent triangles
just don't meet up exactly, PoseRay also provides a tool.

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On 19/08/2017 12:09, Sven Littkowski wrote:
> On 19.08.2017 04:23, Stephen wrote:
>> On 19/08/2017 07:04, Sven Littkowski wrote:
>>> Intention:
>>>
>>> Using the "Difference" function to create caves and tunnels inside a
>>> square-shaped piece of Martian surface (a hollow mesh object).
>>>
>>> What are your solutions, to transfer what is now a mesh, into a solid
>>> object. I believe these objects need to be solid, in order to create
>>> caves and tunnels through Difference into that body.
>>>
>>
>>
>> You are thinking about it wrongly.
>> There are no solid mesh objects. The keyword "hollow" has nothing to do
>> with an object not being solid. It is used for media containers.
>> You should think in terms of the mesh not having any holes. Then you can
>> use it with csg without artefacts. In the animation below I intersected
>> the mesh of Ariel (the ghost) was intersected with a cub then filled
>> with media. The hollow keyword was used for that.
>>
>> http://www.tc-rtc.co.uk/member/imagenewdisplay/index176.html
>>
>> When I was creating the df3s for Dhalgren with Thomas. I had a lot of
>> trouble with the meshes when they had holes in them. (I had to manually
>> edit the slices that make up the image sequence.)
>>
>>
http://news.povray.org/povray.binaries.images/thread/%3C58343a6a@news.povray.org%3E/
>>
>>
>>
>>
> Thanks. The first link requires a username and password, was not able to
> see the animation just like that.
> 

Sorry about that. I get logged in automatically.

https://youtu.be/vTQKzpusie0


> Nonetheless, good to know I can still work with division. Will give a try.
> 
> 
> ---
> Diese E-Mail wurde von AVG auf Viren geprüft.
> http://www.avg.com
> 


-- 

Regards
     Stephen

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On 19.08.2017 11:23, Stephen wrote:
> On 19/08/2017 12:09, Sven Littkowski wrote:
>> On 19.08.2017 04:23, Stephen wrote:
>>> On 19/08/2017 07:04, Sven Littkowski wrote:
>>>> Intention:
>>>>
>>>> Using the "Difference" function to create caves and tunnels inside a
>>>> square-shaped piece of Martian surface (a hollow mesh object).
>>>>
>>>> What are your solutions, to transfer what is now a mesh, into a solid
>>>> object. I believe these objects need to be solid, in order to create
>>>> caves and tunnels through Difference into that body.
>>>>
>>>
>>>
>>> You are thinking about it wrongly.
>>> There are no solid mesh objects. The keyword "hollow" has nothing to do
>>> with an object not being solid. It is used for media containers.
>>> You should think in terms of the mesh not having any holes. Then you can
>>> use it with csg without artefacts. In the animation below I intersected
>>> the mesh of Ariel (the ghost) was intersected with a cub then filled
>>> with media. The hollow keyword was used for that.
>>>
>>> http://www.tc-rtc.co.uk/member/imagenewdisplay/index176.html
>>>
>>> When I was creating the df3s for Dhalgren with Thomas. I had a lot of
>>> trouble with the meshes when they had holes in them. (I had to manually
>>> edit the slices that make up the image sequence.)
>>>
>>>
http://news.povray.org/povray.binaries.images/thread/%3C58343a6a@news.povray.org%3E/
>>>
>>>
>>>
>>>
>>>
>> Thanks. The first link requires a username and password, was not able to
>> see the animation just like that.
>>
> 
> Sorry about that. I get logged in automatically.
> 
> https://youtu.be/vTQKzpusie0
> 
> 
>> Nonetheless, good to know I can still work with division. Will give a
>> try.
>>
>>
>> ---
>> Diese E-Mail wurde von AVG auf Viren geprüft.
>> http://www.avg.com
>>
> 
> 
Thanks. Seen. :-)

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On 19.08.2017 10:49, clipka wrote:
> inside_vector y

Hi Clipka, thanks once more. Going to add the line
"inside_vector y" if it is not yet there. Checking.

Will then make some test renders, with testing tunnels into the mesh body.



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On 19.08.2017 17:53, Sven Littkowski wrote:
> On 19.08.2017 10:49, clipka wrote:
>> inside_vector y
> 
> Hi Clipka, thanks once more. Going to add the line
> "inside_vector y" if it is not yet there. Checking.
> 
> Will then make some test renders, with testing tunnels into the mesh body.
> 
> 
> 
> ---
> Diese E-Mail wurde von AVG auf Viren geprüft.
> http://www.avg.com
> 
Good news: the meshes had already a specified "inside_vector".
It was < 0, 0, 1 >

Going ahead with tunnel drilling now...

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I think, I put the three related "Valles Marineris" areas together to
one large rectangular landscape. Quite good fitting, it seems.

If anyone wants to download the source code, here is the URL:
http://www.SvenLittkowski.name/d/MarsVallesMarineris.rar
It's very compressed but still 22 MB in size! But it might be useful, as
you don't have to place anymore all the three individual landscape
squares together. Use the "MarsVallesMarineris1_POV-scene" file to render.

I am working now on the texture, I try to use the color < 0.6235294,
0.2627451,  0.1098039 > for the surface, and < 0.5333333,  0.4196078,
0.2666667 > for the lowest areas (a pigment map). Not finish with this
one at the moment of uploading.

If you like, let's work together for the textures and atmosphere!
Interested?

Afterwards, you can build your own Martian base, or we can do it
together. Would be a nice community project, or a nice competition.

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Oh, and I forgot: I also developed in 2006 a nice and helpful little
tool: PCP (POV-Ray Color Picker).

It lets you choose any color, and gives out the POV-Ray code for that
particular color.  double-click on that color code copies that code into
the memory, and you then can easily copy it into your POV-Ray scene file.

I use it now for the Mars files.

http://www.SvenLittkowski.name/d/PCP.rar
(370 kb only, for Windows)



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