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Why is the snow yellow?

Postby sgofferj » Sat Dec 24, 2011 6:10 pm

I noticed already in the beginning when I was playing with the settings, that the snow is yellow in large parts of the area (flying around EFTP)...
I don't suppose, the developers thought, Finns relieve themselves a lot outside and thus made the snow for Finland mainly yellow...

But how comes this? I have barely seen yellow snow or yellow light reflexes on snow in reality. Red/orange, yes, in dusk/dawn, but never yellow.
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Re: Why is the snow yellow?

Postby HHS » Sat Dec 24, 2011 9:30 pm

No idea, but this is only with the default materials.xml. If you try 2.5.0/2.6.0 materials-dds.xml, you should see white snow.
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Re: Why is the snow yellow?

Postby someguy » Sat Dec 24, 2011 9:41 pm

"Watch out where the huskies go..."
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Re: Why is the snow yellow?

Postby sgofferj » Sat Dec 24, 2011 9:53 pm

I just today upgraded to 2.5.0 from git and downloaded and installed the latest fgdata. So I would think, I have the latest materials-dds.xml.

That's what it says about snow:
Code: Select all
    <material>
   <name>SnowCover</name>
    <texture>Terrain/snow1.png</texture>
    <texture>Terrain/snow2.png</texture>
    <texture>Terrain/snow3.png</texture>
    <texture>Terrain/snow4.png</texture>
   <xsize>2000</xsize>
   <ysize>2000</ysize>
   <shininess>1.2</shininess>
   <rolling-friction>0.15</rolling-friction>
   <friction-factor>0.3</friction-factor>
   <bumpiness>0.1</bumpiness>
    </material>
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Re: Why is the snow yellow?

Postby Thorsten » Sun Dec 25, 2011 9:57 am

Last time I was there, the area around Tampere wasn't permanently covered in snow, so the terrain will not have the landclass 'SnowCover' and the entries you cite are rather irrelevant. Either you have loaded winter textures, or the snow is shader-generated.

Can you simply post a screenshot? Looks like a low arctic sun lighting issue - the light does get yellowish for a while. Looking outside, the current conditions in Finland seem to be well described by winter textures rather than shader - dirty snow with lots of vegetation visible...
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Re: Why is the snow yellow?

Postby sgofferj » Sun Dec 25, 2011 3:47 pm

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Re: Why is the snow yellow?

Postby sgofferj » Sun Jan 01, 2012 3:30 pm

There is partially "normal" snow and lots of "yellow" snow... How does FG determine what to put where? And I'm still wondering about this yellow tone. It looks more like desert sand than snow ^^.

Image

Image
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Re: Why is the snow yellow?  

Postby Thorsten » Sun Jan 01, 2012 3:44 pm

How does FG determine what to put where?


Actually, you do - it's shader generated snow, and since shaders aren't co-ordinated, the transition shader has a different snow effect from the landmass shader, they make different assumptions about lighting, they do not agree with permanent snow,... So every landclass which uses transition effects gets one type of snow, every landclass which doesn't gets another kind of snow.

Try --materials-file=materials-dds.xml, this should use a more consistent shader set. Or switch off transition effects and keep only landmass shader. Or disable all shader-generated snow and use --season=winter at startup - looks much nicer in my opinion anyway if all is snow-covered.

The issue itself seems to be that

1) sun is very low, thus
2) the light is yellow to organge, and since
3) one shader assumes that snow inherits the light color, the snow gets yellow (or probably red at sunset)
but since
4) another snow shader does not make that assumption but keeps it in grey shades instead, you get the color mismatch

If you feel lucky, you can go edit the shaders :D
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Re: Why is the snow yellow?

Postby sgofferj » Sun Jan 01, 2012 9:46 pm

Changing the materials file did it.
Let's talk in 5 years or so again about me fiddling with shaders :D.
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Re: Why is the snow yellow?

Postby someguy » Sun Feb 05, 2012 1:55 am

I installed 2.6 RC1, and made dds copies of the snow and glacier textures that didn't already have them. But, some of the glaciers are still that horrible yellow-green. Yes, I added --materials-file=materials-dds.xml to my startup parameters.

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Re: Why is the snow yellow?

Postby Thorsten » Sun Feb 05, 2012 12:25 pm

I installed 2.6 RC1, and made dds copies of the snow and glacier textures that didn't already have them. But, some of the glaciers are still that horrible yellow-green.


Because you didn't understand the problem - dds or not has nothing to do with it. Please read the thread again.
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Re: Why is the snow yellow?

Postby someguy » Sun Feb 05, 2012 4:40 pm

OK, it seems to be the misguided Transition shader, and my only choices are to turn it off or live with yellow glaciers:

Image

Wouldn't it be better if it left glaciers alone instead of trying to "help" them?
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Re: Why is the snow yellow?

Postby 439Tiger » Mon Feb 13, 2012 2:31 am

I have a question.

I thought the "Environment Window" would be the place to include "--season=winter" but it does not seem to be the case,it does not appear in the command line:

Image

Where should I add it?
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Re: Why is the snow yellow?

Postby Gijs » Tue Feb 14, 2012 4:46 pm

On the last page of FGRun, there's a "season" dropdown, right under "Time of day" ;)
The "Environment" tab in the Advanced dialog is for OSG_ENVIRONMENT variables.
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Re: Why is the snow yellow?

Postby 439Tiger » Tue Feb 14, 2012 11:08 pm

Doh!!! :shock:

I was looking for something too complicated, and it was right in my face. :oops:

Image

But this actually opens another question for me. I lived in the area where I took the shot for 15 years, the bay is frozen as it should be. This time of year the ice should be around 1 M thick.

My question is about the amount of snow. I have the snow line at 0 M but the quantity of snow is insufficient for the area, you shouldn't see green anywhere.

Is there a regional setting where I could set a parameter to determine snow cover? This is a very low snow year for us and we still have over 30 cm + of snow on the ground.

Image
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