[osg-ephemeris] Color bands in sky texture

[Terry Welsh]

Say, I thought of something else.  A lot of LCD monitors have bad
color depth (even less than 8-bits per channel).  They might say they
have 8-bits per channel, but they only achieve this through dithering
or other stupid tricks.  So you might want to insure its not your
display that is causing your banding problem...

On Mon, Aug 25, 2008 at 6:19 AM, Kip Carr <kcarr at avtsim.com> wrote:
> Thanks for the feedback Terry, I will check into the shader
> implementation and the floating point texture, though the fp doesn't
> make a whole lot of sense to me (Not a texture expert).  Ill post if I
> come up with any good solution.
>
> Thanks,
> Kip
>
> -----Original Message-----
> From: osg-ephemeris-bounces at andesengineering.com
> [mailto:osg-ephemeris-bounces at andesengineering.com] On Behalf Of Terry
> Welsh
> Sent: Thursday, August 21, 2008 2:54 PM
> To: osg-ephemeris at andesengineering.com
> Subject: Re: [osg-ephemeris] Color bands in sky texture
>
> Hi Kip,
> Sounds like you'll need to run your app on an SGI Onyx with 12-bits
> per channel color.  That should fix it.
>
> No, but seriously, the banding doesn't surprise me.  8-bits per
> channel are really not enough to make gradual color gradations that
> appear smooth to the human eye.  And this problem is exaggerated even
> more on most LCD monitors because of their usually poor gamma
> characteristics.
>
> A better solution for osgEphemeris might be to use a floating point
> texture or to compute the sky color in a shader.  Using a shader would
> probably be a lot more work....
> - Terry
>
> On Thu, Aug 21, 2008 at 11:20 AM, Kip Carr <kcarr at avtsim.com> wrote:
>> Hi All,
>>
>>
>>
>> Had a question concerning the sky texture.  Currently it seems that I
> am
>> able to see the color bands on the texture for the sky.  I have
> attached a
>> png file to show it.  It is very subtle but still noticeable on a
> larger
>> screen (37+).  I was wondering if this is normal or if there was a way
> to
>> make it more granular so it would be less noticeable.  I did check and
> we
>> are running 24bit color in osg so it isn't that.
>>
>>
>>
>> As a side thing the sun and moon both look a bit small and the moon
> doesn't
>> seem to be using the texture, any clues on that as well?
>>
>>
>>
>> Thanks,
>>
>> Kip Carr
>>
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>>
>>
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