Hi,

Just testing out some moon maps. Thanks to some semi-recent surveys, we've now
got both albedo and height maps to work with.

You can find the moon maps here: https://svs.gsfc.nasa.gov/4720 (FYI: only the
"uint" versions of the displacement maps seem to work with POV-Ray.)

Happy POVing,

Sam

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Op 09/09/2021 om 03:24 schreef Samuel B.:
> Hi,
> 
> Just testing out some moon maps. Thanks to some semi-recent surveys, we've now
> got both albedo and height maps to work with.
> 
> You can find the moon maps here: https://svs.gsfc.nasa.gov/4720 (FYI: only the
> "uint" versions of the displacement maps seem to work with POV-Ray.)
> 
> Happy POVing,
> 
> Sam
> 
> 
Those maps are getting better over the years... as also the use of them. 
Very nice that little touch of Earth glow in the shadows!

-- 
Thomas

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Thomas de Groot <tho### [at] degrootorg> wrote:
> Op 09/09/2021 om 03:24 schreef Samuel B.:
> > Just testing out some moon maps. (...)
> >
> Those maps are getting better over the years... as also the use of them.
> Very nice that little touch of Earth glow in the shadows!

Thank you Thomas. It actually renders very quickly, sans bloom.

Unfortunately, the bump maps appear to be 8-bit grayscale, not 16-bit. Even
though IrfanView reports a 16-bit format, my tests in POV-Ray showed major
terracing artifacts like you would expect from a lower bit depth. (Not seen here
because I kept the resolution below a certain size). I should probably try the
maps them out in other programs to see if POV is at fault, although I doubt it
is...

Sam

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> Thomas de Groot <tho### [at] degrootorg> wrote:
>> Op 09/09/2021 om 03:24 schreef Samuel B.:
>>> Just testing out some moon maps. (...)
>>>
>> Those maps are getting better over the years... as also the use of them.
>> Very nice that little touch of Earth glow in the shadows!
> 
> Thank you Thomas. It actually renders very quickly, sans bloom.
> 
> Unfortunately, the bump maps appear to be 8-bit grayscale, not 16-bit. Even
> though IrfanView reports a 16-bit format, my tests in POV-Ray showed major
> terracing artifacts like you would expect from a lower bit depth. (Not seen here
> because I kept the resolution below a certain size). I should probably try the
> maps them out in other programs to see if POV is at fault, although I doubt it
> is...
> 
> Sam
> 
> 
It could be in 16 bits format, but with the lower byte zeroed.

zeroed lower byte, then, you'll see sharp spikes instead of a curve.

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Alain Martel <kua### [at] videotronca> wrote:
>
> > Op 09/09/2021 om 03:24 schreef Samuel B.:
> > Unfortunately, the bump maps appear to be 8-bit grayscale, not 16-bit. (...)
>
> It could be in 16 bits format, but with the lower byte zeroed.
>
> zeroed lower byte, then, you'll see sharp spikes instead of a curve.

Well, something's going on, as you can see in the attached image.

I just tried it out in Blender, and it looked okay at /first/, but it's hard to
tell since for some reason Blender inverts the bump map for half the moon. (The
problem areas lay within the more null areas inside the inversion zone, and are
thus difficult to examine.)

Sam

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"Samuel B." <stb### [at] hotmailcom> wrote:
>
> I just tried it out in Blender, and it looked okay at /first/, but it's hard to
> tell since for some reason Blender inverts the bump map for half the moon. (The
> problem areas lay within the more null areas inside the inversion zone, and are
> thus difficult to examine.)

Here's the Blender test. I don't see any obvious terracing (but for some reason
the normal gets flipped on the lower left portion). Maybe POV-Ray is mishandling
the tiff file?

Sam

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Op 11/09/2021 om 02:36 schreef Samuel B.:
> "Samuel B." <stb### [at] hotmailcom> wrote:
>>
>> I just tried it out in Blender, and it looked okay at /first/, but it's hard to
>> tell since for some reason Blender inverts the bump map for half the moon. (The
>> problem areas lay within the more null areas inside the inversion zone, and are
>> thus difficult to examine.)
> 
> Here's the Blender test. I don't see any obvious terracing (but for some reason
> the normal gets flipped on the lower left portion). Maybe POV-Ray is mishandling
> the tiff file?
> 
> Sam
> 
And if you save the tiff as tga or png (using IC which I prefer), what 
happens?

-- 
Thomas

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"Samuel B." <stb### [at] hotmailcom> wrote:
> Hi,
>
> Just testing out some moon maps. Thanks to some semi-recent surveys, we've now
> got both albedo and height maps to work with.
>
> You can find the moon maps here: https://svs.gsfc.nasa.gov/4720 (FYI: only the
> "uint" versions of the displacement maps seem to work with POV-Ray.)
>

Hi Sam, it's great to see you posting on the newsgroups again.

That's a beautiful image-- especially with the added Earth glow, as Thomas
mentioned.

So the 'unsigned 16-bit' file is the displacement map you used (with its
apparent 8-bit precision, and some reversed normals!); thanks for the info.

Have you tried placing a 2nd Sun light_source on the other side of the Moon, to
see what happens with the normals in the normally 'shadowed' half?

It's interesting that the website's description of the color map says it was
made with a gamma of 2.8; do you have any idea why that would be so (rather
than, say, 2.2)?

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Hi(gh)!

On 10.09.21 01:40, Samuel B. wrote:

> Unfortunately, the bump maps appear to be 8-bit grayscale, not 16-bit. Even
> though IrfanView reports a 16-bit format, my tests in POV-Ray showed major
> terracing artifacts like you would expect from a lower bit depth. (Not seen here
> because I kept the resolution below a certain size). I should probably try the
> maps them out in other programs to see if POV is at fault, although I doubt it
> is...

Is there anywhere on the Web a tool to convert 16-bit PNGs to 16-bit 
(red/green) POV-Ray heightfields?

Or any other way to handle 16-bit png in POV-Ray, i. e. so that 
eval_pigment() actually reads in 65536 rather than 256 different gray 
values?

See you in Khyberspace!

Yadgar

Now playing: Love Now Till Eternity (Asia)

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"Samuel B." <stb### [at] hotmailcom> wrote:
> "Samuel B." <stb### [at] hotmailcom> wrote:
> >
> > I just tried it out in Blender, and it looked okay at /first/, but it's hard to
> > tell since for some reason Blender inverts the bump map for half the moon. (The
> > problem areas lay within the more null areas inside the inversion zone, and are
> > thus difficult to examine.)
>
> Here's the Blender test. I don't see any obvious terracing (but for some reason
> the normal gets flipped on the lower left portion). Maybe POV-Ray is mishandling
> the tiff file?
>
> Sam

Thanks a lot for reporting the issue, do you think you could share a
(simplified?) blend file or if needed zip with dependencies for the bug ?

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