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SpaceEngine Planet Classifications
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| SpaceEngineer | Date: Thursday, 29.12.2011, 19:13 | Message # 46 |
 Author of Space Engine
Group: Administrators
Russian Federation
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| Quote (DevonX) But this dont cover if the planet is habitable or not.
Life is an "option" for a planet - it will be mentioned in class description as words "with life". Also, additional words can be:
- With life
- Volcanic
- Tidal-locked
gpaw5765, Chris, you are close to system that I am search for!
I think composition reading should be based on minerals that can be found on a planet's surface, and data on the mean density of the planet. There are two rasons for this:
1) Actually we can't directly detect minerals in a planet's interior, only on its surface. We say that Earth has an iron core, because the mean density of Earth is about 5 g/cm3 - it can't be for example, ice. We say that Ganymede has a silicate core, because its mean density is about 2 g/cm3, and the surface is composed of ice - so its interior should be composed of ice and/or silicates.
2) In game, the player will not be interested on composition of planet's interior - so long as he cannot have access to it for mining. So his interests will be focused on the surface and not very deep in crust interior.
So there's the dilemma. For example, take a "Snowball Earth". This is a rocky planet with an iron core, with relatively small oceans on its surface (10-4 of the total planet's mass). Based on surface type classification, and if water is liquid, this planet should be classified as "Temperate silicate wet terra". But if all oceans are frozen, and all continents are covered with glaciers and snow, it will looks like an icy planet, and should be called "Cold icy arid terra" (here "arid" means that this icy world would have no hydrocarbonate "hydrosphere"). But this is confusing - the planet is "built" with iron and silicates; water or ice is only a small thin peel on its surface. The planet's mean density is about 5 g/cm3 - this immediately gives the idea that it cannot be an icy world. We should take into account the internal structure of a planet. So in the first example it will be "Temperate silicate wet terra", and in the second case a "Cold silicate frozen terra".
I suggest adding a class Supergiant or Superjovian for gas giant that is more massive than 3-5 Jupiters (by analog of Superterra). And maybe an adjective ("Terrestrial") is more suitable than a noun ("Terra"). So, the mass classes will be:
- Asteroid
- Selena / Dwarf
- Subterra / Subterrestrial
- Terra / Terrestrial
- Superterra / Superterrestrial
- Subgiant / Subjovian
- Giant / Jovian
- Supergiant / Superjovian
- Brown dwarf <-- this is actually a star
Temperature classes maybe like the current system or even as a more shorter version:
- Hot
- Warm
- Temperate
- Cold
- Very cold
Internal structure type ("Ices" is either water/ammonia/methane and other volatiles, and can be subdivided on several subclasses):
Core:
- Iron
- Silicates
- Ices
Mantle:
- Iron
- Silicates
- Ices
Crust
- Iron
- Silicates
- Ices
Surface types: This is the most difficult part. One can base this classification on most remarkable impurity to crust material ("ocean"). For example, Earth and Mars have silicate crust and water as an impurity, Titan has a water crust and hydrocarbons as an impurity.
- Water (either liquid and ice)
- Hydrocarbons
- Ammonia
- Carbon dioxide
- ??? (I know that many common substances can form "hydrosphere", according to temperature and pressure conditions).
We should notice that the same planet may have several impurity substances on its surface. For example, Mars has frozen water in the form of frozen seas, permafrost and ice caps, and frozen carbon dioxide in ice caps. Earth has either liquid and frozen water. Tidally locked planets can have exotic mixture of volatiles on its frozen dark-side.
Add here are the words that describe the agregate state of this impurity:
- Liquid
- Frozen
And abundance:
- Wet
- Arid
Next, maybe to add a classname for atmosphere?
- Crushing (Venus, gas giants)
- Dense
- Normal (Earth, Titan) - bad word
- Thin (Mars)
- Negligible (Triton, Pluto)
- No atmosphere
Additional class word - "temporary" or "periodic" or "sublimative". For example, Mars and Pluto have temporary atmosphere that freezes in winter on ice caps and sublimes in summer.
Maybe atmosphere classname should have additional words describing 2-3 its major components:
- Carbon dioxide
- Nitrogen
- Oxygen
- Water (wapor)
- Hydrocarbons
- Ammonia
- Helium
- Hydrogen
So, classnames of our planets (I'm not sure if gas giants should have a hydrosphere description):
Mercury: Warm iron-iron-silicate subterra, (no hydrosphere), (no atmosphere)
Venus: Warm iron-silicate-silicate terra, (no hydrosphere), crashing carbon dioxide atmoshere
Earth: Temperate iron-silicate-silicate voulcanic terra with life, frozen-liquid water ocean, normal nitrogen-oxygen atmosphere
Mars: Cool iron-silicate-silicate subterra, frozen water-carbon dioxide ocean, thin carbon dioxide periodic atmosphere
Moon: Temperate iron-silicate-silicate selena, (no hydroshpere), (no atmosphere)
Io: Cold iron-silicate-silicate voulcanic selena, (no hydroshpere), temporary sulfur-dioxide atmosphere
Jupiter, Saturn: Cold silicate-metallic hydrogen-gas giant, global liquid hydrogen-helium ocean, crashing hydrogen-helium atmosphere
Uranus, Neptune: Very cold silicate-ice-gas subgiant, global liquid hydrogen-helium ocean, crashing hydrogen-helium atmosphere
Europa: Cold silicate-water-ice selena, (no hydrosphere), (no atmosphere)
Ganymede, Callisto: Cold silicate-water-ice subterra, (no hydrosphere), (no atmosphere)
Titan: Very cold silicate-water-ice subterra, liquid hydrocarbons, nitrogen-hydrocarbon atmosphere
Triton: Very cold silicate-ice-ice selena, (no hydrosphere), negligible nitrogen-methane atmosphere
Pluto: Very cold silicate-ice-ice selena, frozen nitrogen, negligible nitrogen-methane periodic atmosphere
Some possible planets:
Gliese 581 c: Temperate silicate-water-water superterra, global liquid water ocean, normal nitrogen-water armosphere
Solaris: Temperate iron-silicate-water terra, global liquid water ocean, normal nitrogen-water armosphere
Carbon planet: Cold iron-silicate-hydrocarbon superterra, liquid hydrocarbon ocean + frozen carbon dioxide, dense hydrocarbons-carbon dioxide atmosphere
I think these are too long for descriptions, they should be shortened and simplified. Words like "desert", "arid", "wet" should be used somewhere. Also, I still hope use word "terra" for Earth twins...
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| DevonX | Date: Thursday, 29.12.2011, 19:50 | Message # 47 |
 Space Pilot
Group: Users
Norway
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Status: Offline
| @SpaceEngineer I understand it better now and i agree that the word terra should not be a size parameter and more like a definition on a planet that is earth like.
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| curiousepic | Date: Thursday, 29.12.2011, 22:32 | Message # 48 |
 Space Pilot
Group: SE team
United States
Messages: 141
Status: Offline
| I like having that level of description, SE, it's close to what I had in mind earlier, building the classification bottom-up instead of top-down.
But I agree these are too long for practical use. It starts to blur the line between "type of planet" and" full statistical analysis".
For the type names, it should be constructed from the components that are of the most interest to an explorer. Ideally, the engine would use the system you just proposed, but allow the player to toggle certain types of info on and off. For some people, the interior composition doesn't matter, or they only care if it has an atmosphere or not, not about the type of atmosphere. Etc.
But if you must shorten overall, you can start by ignoring the core and mantle composition, and reducing element names to their chemical shorthand (Si, H2O, CO2 ice, etc).
My ideal preferences for visual design of the mothership and technology in SE
Harry Potter and the Methods of Rationality
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| curiousepic | Date: Saturday, 07.01.2012, 04:44 | Message # 49 |
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Space Pilot
Group: SE team
United States
Messages: 141
Status: Offline
| What is the current temperature ranges for the diffrent temp names? I just found a "temperate" terra at 263 which is below freezing, after a "warm" terra at 312 which is hot, but closer to temperate in my book.
What is the temperature at which a planet is too cold to have a liquid ocean?
My ideal preferences for visual design of the mothership and technology in SE
Harry Potter and the Methods of Rationality
Edited by curiousepic - Saturday, 07.01.2012, 05:08 |
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| SpaceEngineer | Date: Saturday, 07.01.2012, 14:42 | Message # 50 |
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Author of Space Engine
Group: Administrators
Russian Federation
Messages: 4800
Status: Offline
| Quote (curiousepic) What is the current temperature ranges for the diffrent temp names?
It is described in first post.
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| Red_River | Date: Wednesday, 11.01.2012, 00:28 | Message # 51 |
 Astronaut
Group: Users
Canada
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| Periodic Table of Exoplanets
this doesn't include moons and moonlets.
Edited by Red_River - Wednesday, 11.01.2012, 00:40 |
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| SpaceEngineer | Date: Wednesday, 11.01.2012, 10:05 | Message # 52 |
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Author of Space Engine
Group: Administrators
Russian Federation
Messages: 4800
Status: Offline
| Quote (Red_River) Periodic Table of Exoplanets
This is very close to the SE system! (except subdivision by subterra-terra-superterra).
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| Teto | Date: Monday, 06.02.2012, 18:35 | Message # 53 |
 Space Tourist
Group: Users
France
Messages: 28
Status: Offline
| Hi ! 
I'm new here, and I'm so amazed by the engine that I want to participate in a way.
I've read most of this thread and I want to suggest something:
- Let the developer to decide what he wants for the classification. Each people has his own vision of classification, if he wants to design a realistic universe or a fantasy's one.
So I suggest this method :
- Developer develops his planet classification by tree, done by repertories.
- Those would have this form:
1 Planet
-> 1.1 gas
-----> 1.1.1 Hot
-----> 1.1.2 Warm
-----------> 1.1.2.1 whatever
-----> 1.1.3 Cold
-----> 1.1.4 ...
-> 1.2 Liquid.
-> 1.3 Rocky
-> ...
And so on. And it's just an example, the structure could be something else.
In each repertory you'd find a configuration file with all elements needed to describe closely and precisely what sort of planet it is. The structure of this file is well known (your choice) but basically it would look like a .sc file.
After that a small application (made by you of course  ) compiles the tree and the files into a catalog or something, read by engine when it starts.
Why repertories and not a "big" file already written by developer ? Because with this solution, other files could be added after, to be used by a changed/improved engine (to add behaviors, specifications and so on) without touching the old files. Furthermore, this structure is more useful to improve/maintain for a developer.
So YOU do your own classification, and if I want to improve it, or to change it completely to describe the Star War Universe  it's very simple.
I was thinking about this proposal because what does it mean "tempered" or "liveable" ? For who ? If I make a game with Alien who can live in an Icy planet, 20 °C would be very hot for him. Also a fish should be embarrassed by a rocky planet. You get the idea. (So I could add other files to describe things like : I'm an Alien A, this planet for me is NOT liveable, but my ship can fly on it).
In a sense, the classification is more a script than a deep feature of your engine. And most of the time it won't be perfect for a game developer anyway, he would change things.
It's just few thoughts.
Anyway, please continue, it's a great engine you're making !
Teto.
Edited by Teto - Monday, 06.02.2012, 18:37 |
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| SpaceEngineer | Date: Monday, 06.02.2012, 21:20 | Message # 54 |
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Author of Space Engine
Group: Administrators
Russian Federation
Messages: 4800
Status: Offline
| Hi Teto, it is a great idea! I hadn't thought about it. I will look at SE code and check if it is possible to implement.
However, a small concern: how to manage multiple classifications made by users?
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| Teto | Date: Tuesday, 07.02.2012, 14:18 | Message # 55 |
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Space Tourist
Group: Users
France
Messages: 28
Status: Offline
| What do you mean ? I don't understand. 
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| Starchild | Date: Friday, 10.02.2012, 18:25 | Message # 56 |
 Observer
Group: Newbies
Poland
Messages: 1
Status: Offline
| Hi Space Engineer, have you thought about making some editing tools that would give you possibilities to edit objects like in program called Universe Sandbox?
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| SpaceEngineer | Date: Saturday, 11.02.2012, 01:40 | Message # 57 |
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Author of Space Engine
Group: Administrators
Russian Federation
Messages: 4800
Status: Offline
| Quote (Teto) What do you mean ? I don't understand.
I mean, what SE should do if users make their own classifications and want to use them together? How to use "Calssification 1" together with "Calssification 2" and "Classification 3"? to switch them in the menu?
Quote (Starchild) Hi Space Engineer, have you thought about making some editing tools that would give you possibilities to edit objects like in program called Universe Sandbox?
This is not necessary, as long as in game players can't modify space objects.
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| Teto | Date: Monday, 13.02.2012, 10:31 | Message # 58 |
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Space Tourist
Group: Users
France
Messages: 28
Status: Offline
| Quote (SpaceEngineer) I mean, what SE should do if users make their own classifications and want to use them together? How to use "Classification 1" together with "Classification 2" and "Classification 3"? Switch them in the menu?
Oh, I think I understand.
The structure by repertories is just a easy way to have a tree structure of classification, and (for me) a way to allow easy improvements in the future.
The tree is just a structure for what it is parent, what it is child/leaf. But in each repertory there's a file where it's explained what type of planet it is.
I suppose that the classification is just for gameplay, the engine by itself doesn't care of the classification, it has its own classification for orbits, speed, mass and so on. You can enjoin the language used in the files to be sure that the engine will understand what's going on:
- A planet can only have 3 states : gas, liquid, solid.
- It could be only : a real planet, a moon, an asteroid (a cloud of asteroids too ?).
- It has a mass.
-> It's easy to change that in understandable variables for the engine in a language like :
"$mass" 10000 // in tons
"$state" gas
"$type" planet
-> Yep, it looks like source engine...
Besides that, you have almost an infinite way to class the planet :
- hot, >1000°K, warm, cold, 0-100°K, and so on.
- the main component : rock (what type ?), ice, methane, or an range of components : 80% ammoniac, 10% vanilla ice ( ), 10% whatever.
- its mass.
- the type of landscape.
-> They could be variables not understood by engine, by understood by script developed for the game:
"$temperature" 0-100 // in °K
"$components" {methane,ammoniac,carbon}
"$methane" {liquid,80} //80 means 80%
"$ammoniac" {ice,15}
...
Other things, like climate, atmospheric pressure, atmosphere thickness... can be calculated (I mean, guessed).
So, few parameters in the file are really important because they're needed by engine. The others are just for gameplay/rendering. If you don't want to allow people use your engine to make their own game, maybe my suggestion is useless : enjoin your classification and basta. Otherwise, enjoin the language/structure of the file, and the data will be used in-game via script.
Maybe I'm wrong about things that can be calculated, but you get the idea. 
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| SpaceEngineer | Date: Monday, 13.02.2012, 13:01 | Message # 59 |
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Author of Space Engine
Group: Administrators
Russian Federation
Messages: 4800
Status: Offline
| Ok, can you for example make analysis of this classification and create a list of parameters, needed to implement it? SE doesn't have volcanic, tides, and other parameters yet. I should implement those first. Then we can create a script for this classification and look at how it will work. BTW, is is better to use the SE script format, so I won't need to change the script engine:
Code
Group "Small Body Group"
{
Class "Vulcanoidal"
{
State "rock"
Radius (0, 50) // 0...50 km
OrbitEccentricity (0.2, 1.0) // 0.2...1.0
...
}
Class "Asteroidal"
{
Subclass "Metallic"
{
State "rock"
Composition
{
Metals (0.4, 0.8) // 0.4...0.8
Rock (0.2, 0.6) // 0.2...0.6
Ice (0.0, 0.0)
}
}
Subclass "Silicates"
{
State "rock"
Composition
{
Metals (0.0, 0.3) // 0.0...0.3
Rock (0.6, 1.0) // 0.6...1.0
Ice (0.0, 0.0)
}
}
...
}
...
}
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| Teto | Date: Tuesday, 14.02.2012, 23:08 | Message # 60 |
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Space Tourist
Group: Users
France
Messages: 28
Status: Offline
| OK. I'm not an astrophysicist. So I took time to read the classification, and I don't know if it is used by "professionals". If it's the case, I think that you have a very complete classification, so keep it. I have just few remarks :
- This classification doesn't mention mass of the planets, or range where you can have this or that type. I'm not astrophysicist, as I said, by I know that solar systems has rules with planets/moons, orbits, size, mass and type of planets depends of their number, location and so on. That misses in this classification, but maybe you know what to do. By the way, do you follow those rules when you make procedural solar systems ?
- For each type you have composition of the planet, but again you don't have proportions, thickness of atmosphere, and so on. Maybe it can be calculated.
- If this classification is OK, and you don't want to let modders to change it as they want, I think that the BIG file with all classification is good, and let you to use your script language. But, maybe, keeping the tree by repertories is good to add easily script files (for gameplay, special planets, ...)
Now, my help is the best I can do so far, I don't know how your engine is working (well, a little, if it works like Celestia), but if classification is important (for procedural behaviors, gameplay, rendering), yep, you must be perfect since the beginning (thanks Captain Obvious ! )
By the way, a question off-topic (a little) : Are the planets always spherical ? In Celestia, for example, moon of Pluto is not a sphere, because of its rotation speed (if I remember well). Is it the same thing with your engine ?
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