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Vital
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Odd pattern on Oceania moon...

01 Jan 2017 08:05

So just a few minutes ago I came across this, and I have a suspicion that this is a bug along with a cool formation, but take a look:
scr00053.jpg

scr00054.jpg



This is the moon [color=rgba(255, 255, 255, 0.701961)][color=rgba(255, 255, 255, 0.701961)][size=100][font=Whitney, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif]RS 0-7-485154-1812-114-5-25780-106 2.2[/color][/font][/size][/color]
It has some odd poles I've never seen on any other oceania..
It seems as though the glacier is low enough to have the "underwater" color palette in places. There isn't water but it looks like there should be, which is why this is probably a bug.


Nonetheless it it's patterns are beautiful from space.
scr00055.jpg
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LordShadoko
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Strange sightings

08 Jan 2017 01:34

I don't really know where to put that, as there isn't an "anomalies" thread yet, so...I'm running the 0.98 version of space engine by the way. 
I found some rather strange things and I wonder if they are bugs or not. 

I'm fairly sure the first one ain't a bug, more of a limitation of the engine. It's an oceania in a binary system ; it's tidally locked with the smallest star, an orange dwarf, thus having the characteristic of a tidally locked oceania with open waters and a big storm on the illuminated side ; however, the second star is close enough to illuminate the planet as well, so the other side is made of open waters as well, but without the clouds. Not really realistic, I guess, but interesting nonetheless, it's the first time I see this. 

Image

This one is really a bug, I think. It's also a binary system, with a red giant (IIRC) and a white dwarf...which appears to be a disc, in fact. 

Image

Image
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An'shur
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08 Jan 2017 09:04

The white dwarf thingy is not a bug, but an accretion disk of matter orbiting around the dwarf itself. I have found a similar system, to see what I have on mind, lower the exposure.

Image
Image
Image
Image
 
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problemecium
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Strange sightings

08 Jan 2017 12:09

IMO those discs are a bit excessively bright. I get that the center should be really hot and luminous, but when it's blinding white all the way out to the edge it looks wrong somehow. If it needs to be that hot at that distance for realism then the white dwarf discs should be made to extend farther out.
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Watsisname
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Strange sightings

08 Jan 2017 16:36

When reality looks wrong, change reality? ;)

The temperature of an accretion disk with respect to radius generally follows [math]

Which as a plot, looks like this:
Image

If the disk is hot enough that it emits x-rays (wavelengths between 10-8 and 10-11 meters), then the peak temperature must be hundreds of thousands to millions of Kelvin.

Suppose as in the screenshot that the peak temperature of the disk near the white dwarf surface (about 10,000km out) is about 5 million Kelvin.  Then at twice that radius, the temperature is still about 3 million K.  At 10 times that radius it's about 900,000K.  At 100 times that radius? 150,000K.  You get the picture.  Even at large distances it's still so hot as to be glowing in ultraviolet!  And since luminosity follows temperature to the fourth power, that's a huge luminosity even compared to a typical star, and it would be absolutely blinding.

How far out would we have to extend the disc such that the temperature is merely 5000K and thus peaking in visible light?  That would be ten thousand times the white dwarf's radius!  That's 100 million kilometers -- greater than the distance from the white dwarf to the star it's accreting from!

So that's reality.  White dwarf accretion disks are stupidly bright all the way out!  Trying to extend the disk so that the outer edge isn't stupidly bright would result in a disk that is stupidly unrealistically big.  The only reasonable correction to make it "look right" would be a massive exposure compensation, where everything else including nearby stars are black, as is shown in An'shur's screenshots.
 
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DoctorOfSpace
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08 Jan 2017 16:51

While SpaceEngine strives for realism, even it has dimmed accretion disks by default.  Sometimes you need to make adjustments to reality in favor of presentation.
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spaceguy
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Strange sightings

08 Jan 2017 18:18

Watsisname wrote:
When reality looks wrong, change reality? ;)

The temperature of an accretion disk with respect to radius generally follows [math]

Which as a plot, looks like this:
Image

If the disk is hot enough that it emits x-rays (wavelengths between 10-8 and 10-11 meters), then the peak temperature must be hundreds of thousands to millions of Kelvin.

Suppose as in the screenshot that the peak temperature of the disk near the white dwarf surface (about 10,000km out) is about 5 million Kelvin.  Then at twice that radius, the temperature is still about 3 million K.  At 10 times that radius it's about 900,000K.  At 100 times that radius? 150,000K.  You get the picture.  Even at large distances it's still so hot as to be glowing in ultraviolet!  And since luminosity follows temperature to the fourth power, that's a huge luminosity even compared to a typical star, and it would be absolutely blinding.

How far out would we have to extend the disc such that the temperature is merely 5000K and thus peaking in visible light?  That would be ten thousand times the white dwarf's radius!  That's 100 million kilometers -- greater than the distance from the white dwarf to the star it's accreting from!

So that's reality.  White dwarf accretion disks are stupidly bright all the way out!  Trying to extend the disk so that the outer edge isn't stupidly bright would result in a disk that is stupidly unrealistically big.  The only reasonable correction to make it "look right" would be a massive exposure compensation, where everything else including nearby stars are black, as is shown in An'shur's screenshots.

To me the reason why it looks wrong is because of the lighting effect itself. It looks more of a blurry, pixelated cloud that does not contrast well into the surroundings the closer you get.
 
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Watsisname
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08 Jan 2017 18:18

I agree the visual appearance of the disk is off-putting in the sense of "what the heck am I looking at?" and "I'm pretty sure if I were actually looking at such a thing in nature, it wouldn't look like that."  Of course, if you did really look at one, it would look like *you are now blind*.  But the presentation should be different.  The way it is right now is immersion breaking.

I don't agree with changing the physics -- if nature makes the whole disk blindingly bright, then it should be portrayed in such a way that the viewer understands that that's how they really are.  I agree with making the disk bigger to compensate even less -- it would actually make the problem worse, with the white dwarf and its partner star both engulfed in a huge blinding sea of whiteness.  Besides being unrealistic, it would be even more confusing.
 
I think the best option is an exposure compensation, where everything else smoothly fades out when you get close enough to resolve the disk, and that you can see structure in the disk instead of a solid pure-white blob.  You can already do this manually, but having it done automatically would look nice and hopefully not be so weird and immersion breaking.
 
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Strange sightings

08 Jan 2017 18:35

Watsisname wrote:
I agree the visual appearance of the disk is off-putting in the sense of "what the heck am I looking at?" and "I'm pretty sure if I were actually looking at such a thing in nature, it wouldn't look like that."  Of course, if you did really look at one, it would look like *you are now blind*.  But the presentation should be different.  The way it is right now is immersion breaking.

I don't agree with changing the physics -- if nature makes the whole disk blindingly bright, then it should be portrayed in such a way that the viewer understands that that's how they really are.  I agree with making the disk bigger to compensate even less -- it would actually make the problem worse, with the white dwarf and its partner star both engulfed in a huge blinding sea of whiteness.  Besides being unrealistic, it would be even more confusing.
 
I think the best option is an exposure compensation, where everything else smoothly fades out when you get close enough to resolve the disk, and that you can see structure in the disk instead of a solid pure-white blob.  You can already do this manually, but having it done automatically would look nice and hopefully not be so weird and immersion breaking.

Exposure is honestly the best method to look at details of stars. I think this game should strive for realism, and sadly the lighting suffers due to compensation for the viewer. But we have exposure, so there's no reason to compromise reality over presentation when there are tools to compensate.
What I'm trying to say is, that the lightning in space engine in general is not very realistic in it's graphical portrayal. Accretion disks are not the only ones to suffer, but stars too. I guess turning off auto-exposure helps but it isn't really the same.
 
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Watsisname
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08 Jan 2017 18:43

I know SpaceEngineer has already given a lot of thought to this, so we might imagine the solutions cannot be very easy to implement or else we'd already have them.  Mainly the problem is how to merge auto-exposure with how the rendering system handles color-temperature-luminosity relationships of objects so that it looks good in all situations.
 
spaceguy
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Strange sightings

08 Jan 2017 18:49

Watsisname wrote:
I know SpaceEngineer has already given a lot of thought to this, so we might imagine the solutions cannot be very easy to implement or else we'd already have them.  Mainly the problem is how to merge auto-exposure with how the rendering system handles color-temperature-luminosity relationships of objects so that it looks good in all situations.

Yeh, but there has to be some engines S.E can use in order to make this easier.
In the meantime, I keep getting this awful graphical glitch where whenever I get close to star the screen turns black and it stays that way until it I move out (blindly) or restart S.E. It's to the point that the whole thing is unplayable. Help :,(
http://imgur.com/a/zbkGC

Hopefully the lighting could get as great as this.
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(Without the diffraction spikes)
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DoctorOfSpace
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08 Jan 2017 19:00

Watsisname wrote:
Source of the post I know SpaceEngineer has already given a lot of thought to this, so we might imagine the solutions cannot be very easy to implement or else we'd already have them.


He has, he discussed it on the previous forum as well and he and i have discussed it quite a bit. 

Watsisname wrote:
Source of the post Mainly the problem is how to merge auto-exposure with how the rendering system handles color-temperature-luminosity relationships of objects so that it looks good in all situations.


This is a small part of a much larger problem. 

On the surface it sounds simple, but its quite complex.

The important bit is

This also means what SE cannot render accretion disks realistically, at least for now. SE can't render temperatures more than 100,000 K (all higher will have the same color and brightness) and can't render accretion disks of any radius (1000 Schwarzschild radii is limit for now). I am forced to use some cheats like smooth falloff of the disk's outer edge and limiting it's maximum temperature.

Here is a quote from the old forum
http://en.spaceengine.org/forum/26-3022 ... 1447166375
SpaceEngineer wrote:
Accretion disk is indeed overwhelmingly bright. I made some computations using analythic model (alpha-disk model) for accretion disk around Sagittarius A* in the Milky Way center. Using it's mass of 4.2 million solar masses and realistic accretion rate (3 Earth masses per year), I derived this temperature profile:

max temperature at 4.3 Schwarzschild radii - 96,000K
temperautre at 1000 Schwarzschild radii, where SE rendering stops for now - 2600K (still too bright)
temperature at 3600 Schwarzschild radii - 1000K (so rendering radius in SE should be increased 4x times)

Matter at 96,000K have extremely high brightness. According to the [url=https://en.wikipedia.org/wiki/Stefan–Boltzmann_law]Stefan-Bolzmann law[/url], surface brightness is proportional to T4. So 96,000K is 80,000 times brighter than Sun's surface. It will be saturated to white in SE if exposure is more than 0.0001.

Screenshots here showing accretion disk around Sgr A* with different levels of exposure: 1, 0.01, 0.0001:

Image

Image

Image

Temperature in accretion disk around stellar black hole with high accretion rate is even more extreme. For 5 solar mass black hole, eating 0.001 solar mass per year, it will be 330 million Kelvins at 4.3 Schwarzschild radii and 10 million Kelvins at 1000 Schwarzschild radii. Temperature falling down to 1000 Kelvins only at 200 million Schwarzschild radii, or 20 AU from the black hole. This means what stellar black hole's accretion disk can't be such cold, because it's outer edge lies much closer - defined by orbit of the secondary stellar companion, which feeding the black hole with its own matter.

This also means what SE cannot render accretion disks realistically, at least for now. SE can't render temperatures more than 100,000 K (all higher will have the same color and brightness) and can't render accretion disks of any radius (1000 Schwarzschild radii is limit for now). I am forced to use some cheats like smooth falloff of the disk's outer edge and limiting it's maximum temperature.
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LordShadoko
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Strange sightings

09 Jan 2017 00:48

Oh, I see. I should have played with the exposure settings instead of immediatly thinking "hey it's a bug". 
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problemecium
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09 Jan 2017 12:14

I suppose my original post wasn't complicated enough.
I'm fine with the peak/center temperature of the disc being 89 billion zillion Kelvin - black holes in SE do that just fine and I have no beef. The problem is that the disc (at default exposure) is homogeneous white all the way out to the edge where it abruptly cuts off. I'm fairly confident that extending that graph off to the right will reveal a tendency toward zero for the temperature, and accordingly that ideally SE will at some point extend the white dwarf accretion discs as necessary to reveal the colder outer parts.

Sigh. I'd ameliorate the negative tone of this post by posting some recent sightings of my own but alas! When I updated to SE 0.9.8 the installer erased all my screenshots :C
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lemonland
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Strange sightings

09 Jan 2017 12:21

so uh returning to anomalies i found this lemon shaped dwarf moon
Image
i call it Lemonland

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