On 8/16/2017 2:44 AM, Sven Littkowski wrote:
> On 15.08.2017 03:34, clipka wrote:
>> The mesh files provided by NASA are certainly just the surface, and
>> since it's not the entire planet but just a tile (or so I guess),
>> turning it into a solid 3D volume isn't trivial. You'll need to proceed
>> as follows:
>>
>> (1) Generate the mesh INC file.
>>
>> At this point, all you have is a mesh patch object, i.e. a genuinely
>> non-solid sheet.
>>
>> (2) To the mesh, add an `inside_vector` specifying whatever direction is
>> supposed to be "up" with respect to the tile.
>>
>> At this point, you have a chimera between a solid and a patch: It now
>> has a well-defined inside (namely every point that is "below" the tile,
>> i.e. the tile extruded "downwards" toward infinity). The surface
>> definition is still patchy though (pun intended), so right now you won't
>> see any effect, because POV-Ray can only render surfaces, not volumes.
>>
>> Note however that this chimera is already good enough to start "digging"
>> using CSG.
>>
>> (3) Intersect the mesh with another object, e.g. a box, defining the
>> dimensions of the "massive block" you want.
>>
>> Make sure that for any point on the box that is supposed to be "below"
>> the landscape, if you trace a line in the direction given by the
>> `inside_vector`, it should properly intersect the mesh (note that
>> grazing it might not be enough).
>>
>> This step will add surfaces to the "sides" and the "bottom" of your
>> block of landscape, so that they can be seen as well. If that's not a
>> thing you need, this third step is entirely optional.
>
> Thanks.
>
> When talking about that "inside_Vector", I refer to Clipka's information
> he gave me, when I mentioned that I wanted to have solid shapes (and not
> hollow meshes) for POV-Ray.
>
> My understanding of Clipka's information was, that I should open the STL
> meshes in Blender and that I would find there an option to add that
> mysterious "inside_vector".
>
> When you all read Clipka's instructions, what is your understanding? I
> still want to assume his information is correct.
>

How I read the instructions you posted above is:
Open the STL file in Blender and export the mesh as an Obj or 3ds 
object. Convert that using PoseRay to use the mesh in PovRay. (or use 
the PovRay exporter to export it to a pov file directly by rendering it. 
(You will need to deselect the "delete" flag in the Render tab of the 
properties screen, camera icon)

> Please continue to provide assistance to me in regards to make my NASA
> STL meshes solid. Thanks.
>

https://blender.stackexchange.com/questions
Is a good site to ask Blender questions unrelated to PovRay.


> ---
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-- 

Regards
     Stephen

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On 16.08.2017 01:28, Stephen wrote:
> On 8/16/2017 4:24 AM, Sven Littkowski wrote:
>> On 15.08.2017 05:25, Stephen wrote:
> 
>>> What you can do is activate the PovRay rendering addon then render the
>>> scene. This will allow you to open the generated .pov file and extract
>>> the mesh2 object. You can then edit it manually to add the
>>> inside_vector.
>>> In blender the shortcut for making the normals consistent is (in edit
>>> mode or it will open a new scene file) Ctrl + n or to make them face
>>> inward is Ctrl + Shift + n
>>>
>> How can I activate the EDIT mode in Blender? I am really a beginner with

>> Blender.
>>
> 
> There is a lot of learning and Blender does not use the usual shortcuts.
> 
> Keeping your eye on the top status line that will tell you how many
> objects you have selected. (That is the info screen which is normally
> positioned at the top with only the status line showing.)
> "a" toggles selecting all or none. Right click your object to select it.
> "Tab" toggles between Object and Edit mode. Or you can use the drop down
> on the bottom status line of the 3D view.
> Again "a" toggles selecting all or no vertices, lines or faces.
> Ctrl Z or Object > Undo history can be useful. ;)
> 
> It is good practice to always press Ctrl N when you have finished
> editing. Otherwise you might get strange shadows in your render.
> 
> But as Mr has pointed out inside vector is not supported in Blender. 
> 

Thanks, got the editing mode. :-)

I really have to all this step-by-step. :-(

You wrote: "In blender the shortcut for making the normals consistent is
(in edit mode or it will open a new scene file) Ctrl + n or to make them
face inward is Ctrl + Shift + n".

What is the meaning of "making normals consistent", and of "make normals
face inwards"? I need to understand this. And ... sorry for all my
questions. :-)

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On 8/16/2017 9:33 AM, Sven Littkowski wrote:
> Thanks, got the editing mode.:-)
>

Good :-)

> I really have to all this step-by-step.:-(
>

The best way until you don't need to think about it.

> You wrote: "In blender the shortcut for making the normals consistent is
> (in edit mode or it will open a new scene file) Ctrl + n or to make them
> face inward is Ctrl + Shift + n".
>
> What is the meaning of "making normals consistent", and of "make normals
> face inwards"? I need to understand this. And ... sorry for all my

I am still learning too. You need a different way of thinking using a 
mesh modeller than to using Pov. But the Blender community is very 
helpful so for blender issues GIYF. ;-)
Maybe this link will help.

https://docs.blender.org/manual/ja/dev/modeling/meshes/editing/normals.html


This has nothing to do with your original post, btw.


-- 

Regards
     Stephen

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Stephen <mca### [at] aolcom> wrote:
> On 8/16/2017 9:33 AM, Sven Littkowski wrote:

> > What is the meaning of "making normals consistent", and of "make normals
> > face inwards"? I need to understand this. And ... sorry for all my

> https://docs.blender.org/manual/ja/dev/modeling/meshes/editing/normals.html

Blender probably has some very nice code to make sure that all of your triangles
in your mesh have all the sides "pointing the right way" - rather than having
some of them (using a coin analogy) tail side up rather than head side up.

See what that might look like below:

http://news.povray.org/povray.binaries.images/thread/%3Cweb.57b4f3192c2caea5e7df57c0@news.povray.org%3E/?ttop=413577&to
ff=50

you can probably test for this in your scene by defining both a texture{} AND a
contrasting interior_texture{}.

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On 8/16/2017 12:58 PM, Bald Eagle wrote:
> Stephen <mca### [at] aolcom> wrote:
>> On 8/16/2017 9:33 AM, Sven Littkowski wrote:
>
>>> What is the meaning of "making normals consistent", and of "make normals
>>> face inwards"? I need to understand this. And ... sorry for all my
>
>> https://docs.blender.org/manual/ja/dev/modeling/meshes/editing/normals.html
>
> Blender probably has some very nice code to make sure that all of your triangles
> in your mesh have all the sides "pointing the right way" - rather than having
> some of them (using a coin analogy) tail side up rather than head side up.
>
> See what that might look like below:
>
>
http://news.povray.org/povray.binaries.images/thread/%3Cweb.57b4f3192c2caea5e7df57c0@news.povray.org%3E/?ttop=413577&to
> ff=50
>
> you can probably test for this in your scene by defining both a texture{} AND a
> contrasting interior_texture{}.
>
>
As far as Blender goes. I am only an egg. I have not gotten round to 
needing that yet. But I know what you mean.
Because Blender displays the scene using OpenGL it is obvious if a face 
is A for Elbow when using a material or texture viewport.

Oh! I see you were replying to Sven but I'm not going to waste my typing. :)


-- 

Regards
     Stephen

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Sven Littkowski <I### [at] SvenLittkowskiname> wrote:
>
> You wrote: "In blender the shortcut for making the normals consistent is
> (in edit mode or it will open a new scene file) Ctrl + n or to make them
> face inward is Ctrl + Shift + n".
>
> What is the meaning of "making normals consistent", and of "make normals
> face inwards"? I need to understand this.

I have never used Blender, but the analogy in POV-Ray would be this:

A mesh object-- like a simple sphere, for example-- should have ALL of the
triangles' normals facing OUTWARD into the surrounding space, for the sphere to
render correctly. Those would be "consistent normals." Any mesh-creation tool
should do that automatically-- if it's working correctly ;-) But if a triangle
happens to be made 'incorrectly' (that is, the three vector-location-points of a
particular triangle are simply written in the 'reverse order' to what they
should be, looking face-on at the triangle), its normal will actually face in
the opposite direction(!), and will not render correctly. (Or rather, it will
show the INSIDE texture, if the object has one.) BTW, this is a typical mistake
when trying to write triangle vectors *manually*; it's hard to keep track of the
necessary and consistent 'orientation' from triangle to triangle.

Making all the normals "face inwards" would be the opposite of the above. I'm
not clear as to why that would be necessary, but I guess it can be done. (I
don't know if POV-Ray's 'inverse' keyword-- when applied to an object to change
its 'outside' to its 'inside') switches the normals as well; I never thought to
test it.)

Post a reply to this message

On 8/17/2017 4:46 AM, Kenneth wrote:
> I have never used Blender, but the analogy in POV-Ray would be this:
>
> A mesh object-- like a simple sphere, for example-- should have ALL of the
> triangles' normals facing OUTWARD into the surrounding space, for the sphere to
> render correctly. Those would be "consistent normals." Any mesh-creation tool
> should do that automatically-- if it's working correctly;-)But if a triangle
> happens to be made 'incorrectly' (that is, the three vector-location-points of a
> particular triangle are simply written in the 'reverse order' to what they
> should be, looking face-on at the triangle), its normal will actually face in
> the opposite direction(!), and will not render correctly.

Yes, this fits in with my experience.
When you manually edit a mesh you can do it in a way that is ambiguous 
to the modeller. Hence the need to make the normals consistent.


> (Or rather, it will
> show the INSIDE texture, if the object has one.) BTW, this is a typical mistake
> when trying to write triangle vectors*manually*; it's hard to keep track of the
> necessary and consistent 'orientation' from triangle to triangle.
>
> Making all the normals "face inwards" would be the opposite of the above. I'm
> not clear as to why that would be necessary, but I guess it can be done.

If you wanted to make a solid looking pipe. You could create a cylinder, 
copy the outside faces and scale them down to create the inside of the 
pipe. Those normals will still be pointing outwards. To get the inside 
of the pipe to render properly you reverse them to point inwards. For 
example.

> (I don't know if POV-Ray's 'inverse' keyword-- when applied to an object to change
> its 'outside' to its 'inside') switches the normals as well; I never thought to
> test it.)


-- 

Regards
     Stephen

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Stephen <mca### [at] aolcom> wrote:
> On 8/16/2017 4:24 AM, Sven Littkowski wrote:
> > On 15.08.2017 05:25, Stephen wrote:
>
> >> What you can do is activate the PovRay rendering addon then render the
> >> scene. This will allow you to open the generated .pov file and extract
> >> the mesh2 object. You can then edit it manually to add the inside_vector.
> >> In blender the shortcut for making the normals consistent is (in edit
> >> mode or it will open a new scene file) Ctrl + n or to make them face
> >> inward is Ctrl + Shift + n
> >>
> > How can I activate the EDIT mode in Blender? I am really a beginner with
> > Blender.
> >
>
> There is a lot of learning and Blender does not use the usual shortcuts.
>
> Keeping your eye on the top status line that will tell you how many
> objects you have selected. (That is the info screen which is normally
> positioned at the top with only the status line showing.)
> "a" toggles selecting all or none. Right click your object to select it.
> "Tab" toggles between Object and Edit mode. Or you can use the drop down
> on the bottom status line of the 3D view.
> Again "a" toggles selecting all or no vertices, lines or faces.
> Ctrl Z or Object > Undo history can be useful. ;)
>
> It is good practice to always press Ctrl N when you have finished
> editing. Otherwise you might get strange shadows in your render.
>
> But as Mr has pointed out inside vector is not supported in Blender.
>
> --
>
> Regards
>      Stephen

Indeed I added it while reading this discussion but it's currently commented out
as it's related only to CSG that's not implemented yet, best for now is to add
it by hand in the exported file, but next release might have it if I manage.

Post a reply to this message

On 16.08.2017 04:33, Sven Littkowski wrote:
> On 16.08.2017 01:28, Stephen wrote:
>> On 8/16/2017 4:24 AM, Sven Littkowski wrote:
>>> On 15.08.2017 05:25, Stephen wrote:
>>
>>>> What you can do is activate the PovRay rendering addon then render the
>>>> scene. This will allow you to open the generated .pov file and extract
>>>> the mesh2 object. You can then edit it manually to add the
>>>> inside_vector.
>>>> In blender the shortcut for making the normals consistent is (in edit
>>>> mode or it will open a new scene file) Ctrl + n or to make them face
>>>> inward is Ctrl + Shift + n
>>>>
>>> How can I activate the EDIT mode in Blender? I am really a beginner with
>>> Blender.
>>>
>>
>> There is a lot of learning and Blender does not use the usual shortcuts.
>>
>> Keeping your eye on the top status line that will tell you how many
>> objects you have selected. (That is the info screen which is normally
>> positioned at the top with only the status line showing.)
>> "a" toggles selecting all or none. Right click your object to select it.
>> "Tab" toggles between Object and Edit mode. Or you can use the drop down
>> on the bottom status line of the 3D view.
>> Again "a" toggles selecting all or no vertices, lines or faces.
>> Ctrl Z or Object > Undo history can be useful. ;)
>>
>> It is good practice to always press Ctrl N when you have finished
>> editing. Otherwise you might get strange shadows in your render.
>>
>> But as Mr has pointed out inside vector is not supported in Blender. 
>>
> 
> Thanks, got the editing mode. :-)
> 
> I really have to all this step-by-step. :-(
> 
> You wrote: "In blender the shortcut for making the normals consistent is
> (in edit mode or it will open a new scene file) Ctrl + n or to make them
> face inward is Ctrl + Shift + n".
> 
> What is the meaning of "making normals consistent", and of "make normals
> face inwards"? I need to understand this. And ... sorry for all my
> questions. :-)
> 
> ---
> Diese E-Mail wurde von AVG auf Viren geprüft.
> http://www.avg.com
> 
Thanks everyone. But I admit, I am feeling more and more frustrated with
this project - no progress or any success up to now.

Blender is a book with seven seals for me, cannot use it properly. And
the explanations I received, so far, are irritating me as I am not
English. I switched on the POV-Ray plugin, but don't know yet how to
create a POV-Ray scene file with Blender (mesh2).

What I want is this: being able to "dig" tunnels into these Martian
landscapes in my render scenes. I believe, these square-shaped landscape
meshes from NASA should be solid for that, am I right?

Post a reply to this message

Sven Littkowski <I### [at] SvenLittkowskiname> wrote:
> Hi, there is the NASA 3D Resources website, offering various vehicles
> and planetary landscapes as 3D models, formats OBJ and STL.
>
> 1. Is there any OBJ to POV converter?

STL to pov, yes.
https://www.google.com/search?q=stl2pov

OBJ to POV - Poseray
http://www.povray.org/resources/links/3D_Programs/Conversion_Utilities/


I'd probably take the time to do a VERY tiny test scene to get all the comands
and syntaxes worked out, so that you're making it as easy as possible for
yourself.

After that, you can just swap out one mesh for the other.

I find it easiest to use mesh files by treating them as include files.

The triangles in a mesh have a "handedness" - an axial chirality.
Give a "thumbs up" with your left hand, and if you order your triangle vertices
in the order that your fingers curl, then the normal points up like your thumb.

Order them in the reverse direction, and then the normal points in the opposite
direction - "thumbs down"

I'd stop trying to use Blender if you want to render your scene in POV-Ray ----
just convert your OBJ or STL to a mesh, and then do all the fine-tuning in
POV-ray.

AND, as you know, you can post a (small) mesh and your scene file, and then
someone can edit it to get it to work.

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