On 09/12/13 15:26, Stephen wrote:
[...]
> For Grass I often use Rune S. Johansen's GRASS TEX include file.
> I was going to post the link but when I try to go to it, Access Denied.

Ooh, nice. It fakes grass using a single pigment rather than using lots
of primitives, so it's cheap for big areas. I'll have a go --- any ideas
how it looks at a distance? I doubt I'll get the camera closer than a
few hundred metres to the ground. And there's lots of other useful stuff
there I can steal^H^H^H^H^H research...

-- 
┌─── ｄｇ＠ｃｏｗｌａｒｋ．ｃｏｍ ─────
http://www.cowlark.com ─────
│ "There does not now, nor will there ever, exist a programming
│ language in which it is the least bit hard to write bad programs." ---
│ Flon's Axiom

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Update (just managed to catch the dawn light on the trees!), with some
vastly improved textures (not that you can see them because it's so
dark). There are three problems:

(a) nasty aliasing in the waves at the bottom --- I suspect this only
shows up because it's a 400x300 test render, but is there a good way to
make this look less bad in general?

(b) the Earth's gone brown --- this *might* be a real effect; I think
the sky is sucking the blue out of it;

(c) unpleasant banding in the sky.

The sky is a relatively straightforward Rayleigh media stolen from the
Terrapov project; code follows. Any suggestions on how to fix the
banding? I'm *this* close to doing a final render for someone...

#local Bottom_Of_Atmosphere = Nominal_Terrain_Radius + Atmosphere_Base;
#local Top_Of_Atmosphere = Bottom_Of_Atmosphere
	+ Atmospheric_Depth;

#local Base_Rayleigh_Power = 6.7;
#local Rayleigh_Factor = 1 / Atmospheric_Scale;
#local Rayleigh_Scale = 0.5;
#local Rayleigh_Power = Base_Rayleigh_Power * Rayleigh_Factor;

#local Rayleigh_Density =
	density	{
            #local height_from_centre =
	        function(x, y, z) {
	            sqrt(x*x + y*y + z*z)
	        }
	
	    #local height_from_surface =
	        function(x, y, z) {
	            height_from_centre(x, y, z) - Bottom_Of_Atmosphere
	        }
	
	    #local gravity_factor =
	        function(x, y, z) {
	            (1/3) * Bottom_Of_Atmosphere / height_from_centre(x, y, z)
	        }
	
		function
		{
			Rayleigh_Scale * exp(-Rayleigh_Power * height_from_surface(x, y, z)
            )
            	}
	}

#local Rayleigh_Colour = rgb <0.2061, 0.3933, 1.0>;

#local Rayleigh_Media =
	media {
		method 3
		samples 31
		scattering {
			RAYLEIGH_SCATTERING
			color 2.3 * Rayleigh_Colour / Atmospheric_Scale
			extinction 1
		}
		density {
			Rayleigh_Density
		}
	}

#local Sky_Object =
	difference {
		sphere {
			<0, 0, 0>, Top_Of_Atmosphere
		}
		sphere {
			<0, 0, 0>, Bottom_Of_Atmosphere
		}
		
		pigment	{
			rgbt 1
		}

		hollow
		
		interior
		{
			media
			{
				Rayleigh_Media
			}
		}
	}

-- 
┌─── ｄｇ＠ｃｏｗｌａｒｋ．ｃｏｍ ─────
http://www.cowlark.com ─────
│ "There does not now, nor will there ever, exist a programming
│ language in which it is the least bit hard to write bad programs." ---
│ Flon's Axiom

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Attachments:
Download 'newmoon.jpg' (24 KB)

Preview of image 'newmoon.jpg'

Am 10.12.2013 01:41, schrieb David Given:
> Update (just managed to catch the dawn light on the trees!), with some
> vastly improved textures (not that you can see them because it's so
> dark).

I really, really love the lighting in this scene!


> There are three problems:
>
> (a) nasty aliasing in the waves at the bottom --- I suspect this only
> shows up because it's a 400x300 test render, but is there a good way to
> make this look less bad in general?

UberPOV's anti-aliasing mode 3 does a very good job with such stuff.


> (b) the Earth's gone brown --- this *might* be a real effect; I think
> the sky is sucking the blue out of it;

That is to be expected indeed; same effect as the sun going orange near 
the horizon.


> (c) unpleasant banding in the sky.
>
> The sky is a relatively straightforward Rayleigh media stolen from the
> Terrapov project; code follows. Any suggestions on how to fix the
> banding? I'm *this* close to doing a final render for someone...

Use jitter on the media samples.

If this makes the sky look too noisy, go for UberPOV's anti-aliasing mode 3.

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On 9-12-2013 19:52, David Given wrote:
> On 09/12/13 15:26, Stephen wrote:
> [...]
>> For Grass I often use Rune S. Johansen's GRASS TEX include file.
>> I was going to post the link but when I try to go to it, Access Denied.
>
> Ooh, nice. It fakes grass using a single pigment rather than using lots
> of primitives, so it's cheap for big areas. I'll have a go --- any ideas
> how it looks at a distance? I doubt I'll get the camera closer than a
> few hundred metres to the ground. And there's lots of other useful stuff
> there I can steal^H^H^H^H^H research...
>

It looks very good at a distance and even close up it is more than 
acceptable, so you should not have any problems there.

Thomas

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David Given <dg### [at] cowlarkcom> wrote:
> On 09/12/13 15:26, Stephen wrote:
> [...]
> > For Grass I often use Rune S. Johansen's GRASS TEX include file.
> > I was going to post the link but when I try to go to it, Access Denied.
>
> Ooh, nice. It fakes grass using a single pigment rather than using lots
> of primitives, so it's cheap for big areas. I'll have a go --- any ideas
> how it looks at a distance? I doubt I'll get the camera closer than a
> few hundred metres to the ground. And there's lots of other useful stuff
> there I can steal^H^H^H^H^H research...
>

I have used a couple of times for TC-RTC competitions.
In neither of them did I pay much attention to the grass as my attention was on
other aspects if the image </excuses>

http://i.imgur.com/Fg92iNR.jpg

This one the path is defined in the macros, I think. Anyway it is almost a
direct steal from the example file.
BTW Please don't mock my Auntie Jessie. :-)

http://i.imgur.com/x3QpXKM.jpg

Stephen

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On 10-12-2013 9:39, Stephen wrote:
> David Given <dg### [at] cowlarkcom> wrote:
>> On 09/12/13 15:26, Stephen wrote:
>> [...]
>>> For Grass I often use Rune S. Johansen's GRASS TEX include file.
>>> I was going to post the link but when I try to go to it, Access Denied.
>>
>> Ooh, nice. It fakes grass using a single pigment rather than using lots
>> of primitives, so it's cheap for big areas. I'll have a go --- any ideas
>> how it looks at a distance? I doubt I'll get the camera closer than a
>> few hundred metres to the ground. And there's lots of other useful stuff
>> there I can steal^H^H^H^H^H research...
>>

Also from the TC-RTC comes this image where I used Rune's grass macro, 
with the 'path' variation and the flowers: 
http://www.tc-rtc.co.uk/imagenewdisplay/stills/index418.html

This goes from near to far and view remains good. The 3D effect of the 
grass is mainly controlled by the distance between the ground 
height_field and the 'fake' grass, which is a copy of the height_field 
in fact. Note however, that I added some 'real' grass patches.

Thomas

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The lighting is so nice. :O

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Update: this is with media jitter 0.1. I found that with too much jitter
the sky would go noisy and spoil up the lovely clarity effect (and also
hide the superb 6000x3000 starfield texture). I did experiment with
UberPov's anti-aliasing mode 3 but couldn't make it behave --- I'd
either get sparkles on the water or jaggies on the mountains, and either
way it would take an age. I'll also experiment with radiosity and see if
that makes a difference.

Also I should have rendered this as EXR and tone mapped it, curses curses.

The Earth needs to be *brighter*. Except that it's illuminated by the
sun, so I don't have direct control over it. The cloud layer is diffuse
1, so it should be reflecting brightly, but it seems not to be.

(I should point out that this model isn't just this landscape: I'm
rendering the *entire moon* here. I can change the camera position and
time of day arbitrarily, including shots from out in space.)

-- 
┌─── ｄｇ＠ｃｏｗｌａｒｋ．ｃｏｍ ─────
http://www.cowlark.com ─────
│ "There does not now, nor will there ever, exist a programming
│ language in which it is the least bit hard to write bad programs." ---
│ Flon's Axiom

Post a reply to this message

Attachments:
Download 'newmoon.jpg' (88 KB)

Preview of image 'newmoon.jpg'

Le 13-12-10 10:50, David Given a écrit :

> The Earth needs to be *brighter*. Except that it's illuminated by the
> sun, so I don't have direct control over it. The cloud layer is diffuse
> 1, so it should be reflecting brightly, but it seems not to be.
>

Are you talking about Erath's clouds or the closer Moon's clouds.
If the later, did you try using backside illumination?
Just change the cloud's finish to diffuse 0.5 0.5 as a start point.


Alain

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Alain <kua### [at] videotronca> wrote:
> Are you talking about Erath's clouds or the closer Moon's clouds.
> If the later, did you try using backside illumination?
> Just change the cloud's finish to diffuse 0.5 0.5 as a start point.
>
>
> Alain

That's a very cool feature now POV-Ray supported. Here is its description:

http://news.povray.org/povray.binaries.images/thread/%3Cweb.4a71339a7f799d0174340c00%40news.povray.org%3E/

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