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General SE questions
HarbingerDawnDate: Saturday, 04.05.2013, 15:32 | Message # 166
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Quote (apenpaap)
Is comet brightness only based on the core or does the tail also get entered into it?

It's based on both; maybe there's something weird going on in that case.





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DarkcloakDate: Saturday, 04.05.2013, 20:09 | Message # 167
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Quote (HarbingerDawn)
But generally speaking everyone has the same universe.


Ooooh, cool, thank you. smile So, then, what about the 3D meshes for moons and asteroids? They're not actual files, are they? Or are they bundled in files that can't be edited? I've always wondered about those irregularly shaped objects. Because I wouldn't expect those to be procedurally generated. Unless, of course, they are. I feel so intelligent right now only not really. biggrin
 
apenpaapDate: Saturday, 04.05.2013, 23:50 | Message # 168
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I'm pretty sure the asteroid shapes are procedural too. I think it all works through some very big and complicated forumulas that use the location of the system's sun as their variable.




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midtskogenDate: Sunday, 05.05.2013, 06:59 | Message # 169
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Here's a more extreme example of air density: RS 8404-1357-8-4052580-50 2

Air density is 399 g/cm³... The atmospheric pressure is almost 7000 atm. Such absurd densities seem pretty common.





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kairunotabiDate: Sunday, 05.05.2013, 07:20 | Message # 170
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In the future, can we get better nebulas like this?



It's composed of layers of photos of the actual IC1396







Edited by kairunotabi - Sunday, 05.05.2013, 07:21
 
WatsisnameDate: Monday, 06.05.2013, 08:41 | Message # 171
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Quote (midtskogen)
Here's a more extreme example of air density: RS 8404-1357-8-4052580-50 2

Air density is 399 g/cm³... The atmospheric pressure is almost 7000 atm. Such absurd densities seem pretty common.


Yeah, they sure do. I think your suggestion of weighting the air density to the bulk planet density is a good one; it'd cull extreme values to values that make sense in the context of the planet, while also leaving low values mostly unaffected. An alternative could be to use the semi-empirical approach set by the solar system, where air density (in g/cm3) is approximately 1/1000 the air pressure (in atm). Perhaps with some randomization to account for the composition.

There are a few ways to calculate density, some are easier than others. One is to use the equations of hydrostatic equilibrium (dP/dz = ρg, where ρ and g vary with z but variance in g may be negligible) and the scale height of the atmosphere, but solving for ρ from that isn't trivial. Easier way to do it is ρ=(MP)/(RT), where M is the molar mass, P is the pressure, R is the gas constant (8.314 J*K-1*mol-1), and T is the temperature in Kelvin. Have to be careful with M and P though, to be sure they're dimensionally consistent. For Earth's atmosphere at sea level (and assuming no water vapor) this gives 1.22 kg/m3.

Actually, that should be the easiest way to do it, and it could be implemented with what we have in the program right now since we already have everything we need. Check this out:

For the hot desert planet I posted originally, the surface pressure is 363atm, the average molar mass is 2.06g/mol, and temperature is 439K. Do the calculation and this gives 0.021g/cm3 for density, which makes much more sense. smile

edit: Sorry, typo -- meant g/cm^3 in my answer there, not g/m^3.

Added (06.05.2013, 11:41)
---------------------------------------------
For ease of use, the above calculation for air density in g/cm3 may be written as thus:



where P is in atm, M is in g/mol, and T is in Kelvins, as SE gives them.






Edited by Watsisname - Monday, 06.05.2013, 05:43
 
midtskogenDate: Monday, 06.05.2013, 08:54 | Message # 172
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For fun, if I use your formula and imagine a pure radon atmosphere and the same temperature and pressure, I still get density in the rock and metal range. 2.23 g/m³. (Of course, this atmosphere would rain lead and almost entirely decay within weeks). Likewise, tuning the other parameters, like having extremely high pressure or low temperature, will also make the equation spiral out of control. But an upper limit can be set (planet density or something lower as I suggested) to suppress such effects. It's totally unphysical, but since the chemical composition isn't specified, there is much freedom.

An even simpler way to avoid clearly unrealistic values is simply not to state the air density. The pressure and surface temperature alone give a rough indication of the conditions.





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WatsisnameDate: Monday, 06.05.2013, 09:48 | Message # 173
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Yup. The equation assumes that the conditions can be approximated by the ideal gas law, which for planetary atmospheres is a very good assumption. It fails when intermolecular forces become significant, such as under extremely high pressure and low temperature, or for very large molecules, or where phase transitions are about to occur.

At thousands of atm of pressure and low temperature you're probably not dealing with a gas anymore, anyway.





 
pepe8999Date: Tuesday, 07.05.2013, 02:41 | Message # 174
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Hi people, can someone explain me how i install version 0.97, i first unrar the version 0.96 in disk C, then i unrar version 0.96.2 in the folder of space engine, and overwrite, everthing work right, i star SE and it say version 0.96.2, but now, i unrar the version 0.97 in the folder, overwrite and is still the version 0.96.2, it says something of a SYSTEM folder that not exist in the folder of space engine. Please help.




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apenpaapDate: Tuesday, 07.05.2013, 02:43 | Message # 175
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Don't install 0.97 in the same folder as 0.96; it makes a mess of things. Install it to a different folder or delete the 0.96(.2) folder entirely before installing and it should work.




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anonymousgamerDate: Tuesday, 07.05.2013, 02:46 | Message # 176
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You're supposed to unzip into a new folder.

....I presume you're this guy? http://www.reddit.com/user/ShroomKing





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pepe8999Date: Tuesday, 07.05.2013, 03:31 | Message # 177
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Quote (apenpaap)
Don't install 0.97 in the same folder as 0.96; it makes a mess of things. Install it to a different folder or delete the 0.96(.2) folder entirely before installing and it should work.


Thank you!!

Added (07.05.2013, 06:31)
---------------------------------------------
I am having a lot of crashes, anyone with the same problem?

My specs, I7 3770K 3.5 ghz 8 GB RAM 1600 mhz ati hd 7750 1 GB windows 7 64 bit




I7 3770K 3.5 ghz 8 GB RAM 1600 mhz ATI HD 7750 1 GB Windows 7 64 bit
 
HarbingerDawnDate: Tuesday, 07.05.2013, 04:08 | Message # 178
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pepe8999, do not make the same post in more than one place. Also do not create a new thread unless there is no existing thread where your post would fit.




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apenpaapDate: Tuesday, 07.05.2013, 07:28 | Message # 179
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Quote (pepe8999)
I am having a lot of crashes, anyone with the same problem?


I used to, but not any more. Go to [Your SE install folder]/config/main.cfg and change VideoMemoryMaxPercent to 70 and VideoMemoryStartupDetect and VideoMemoryDynamicDetect to True and change LoaderMode to 1. That fixed as good as all my crashes.





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VoekoevakaDate: Tuesday, 07.05.2013, 10:05 | Message # 180
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Is there a way to export a system without exporting the asteroids and the comets ?




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