Planet Appearance

[Plasmic Physics]

Just an idea, but could the albedo be linked to the combined luminosity (HLS colour model) and reflectivity of a planet's water, land and atmosphere? This results in a planet with 0 albedo to appear black, with a matte solid surface, and a planet with 1 albedo appears white, with a gloss surface.

And what about linking the air density to the opacity of the atmosphere? This would result in being able to observe how the atmosphere of Venus gradually becomes clearer with lower air pressure. I think that it would also be good to add a disable button for people who like to have it their way.

[Plasmic Physics]

Does any one else think that these are good ideas?

[Gregory]

It would be an excellent idea, yet worth the development.

[Vtron]

This would be a very good idea, and very applicable to places as dark as TRES-2b, and as bright as Enceladus. Another thing that should be added to the appearance, is new textures, to have it be much more diverse. For earth like planets you can have sets like cratery textures, rift-abundant textures, and textures featuring plate tectonics. For the gas giants you can have textures with storms like Jupiter, with clean bands like Saturn, and completely featureless like Uranus.

I also think it would be a good idea for there to be a public texture library, where skilled artists and players use certain programs or tools (such as blender), to make textures that are realistic and yet creative. I say this because I feel like we lost a lot of creative freedom with the textures, all the planets look bland, as the rocky ones all look cracked, and the gas giants look too soft. I think it would be good for there to be a texture library to allow artists and players to make such textures, and then maybe the software engineers of Universe Sandboy may incorporate the elle te that change such as melting, cratering, and storm movement. This would make universe sandbox 2 have the same texture freedom as the first game, yet with the more advanced features.

Let me knoe your thoughts...

[Gregory]

Yup that would all work, though it's quite a work in process, though US2 has gone so far since its legacy versions.
Another thing to add though is the effect rotation ould have on the shape of the planets, such as oblateness, though that's also dependent on materials as we can spin a bowling ball so fast that even still we can't detect any oblateness though if it were really flexible it could become more oblate.

[Plasmic Physics]

Cratered textures would at the very least depend on the age of the host body and on the density of the atmosphere - a thick atmosphere suggests an increased weathering potential which is compounded by the age of the system, which correlates roughly with the age of the host body.

Recent evidence indicate that plate tectonics, including rifting, is only possible in a body with a surface elasticity below a certain maximum, controlled by surface temperature, which excludes Venus; and in bodies with a crustal dynamic friction coefficient below a maximum, typically controlled by water content. However, these requirements are reduced for bodies which are subjected to extraordinary tidal forces.

Perhaps these things, including oblateness, could be estimated rather than being calculated precisely using factors already present in USB like composition, temperature, tangential velocity, density, etc, and using averages to calibrate the equations?

[Gregory]

Yup, all of that sounds true.
Also what’d be cool is an oblateness lock which locks the degree of oblateness to keep it the same regardless of the rotational velocity.
I know that sounds unrealistic, but anything’s possible if you believe it.

[Plasmic Physics]

Do you mean like the lock on the automatic radius calculation? I don't think that it sounds unrealistic - a user may not approve of the accuracy of the simulation's rough prediction for a particular body, and may opt to force an empirical value.

I have an idea of how both tidal deformation and oblation can be modeled. Model a body as a highly symmetrical polyhedral node net (such as dodecahedron), covered in an elastic smoothed 2D skin that can deform with the underlying net, with every node being attracted only to its immediate neighbours. Then have the equilibrium distance between nodes affected by external and internal forces. This would avoid having to deal with hydrodynamics by treating the body as a system of nodes and springs. This is similar to how nano-scientists and statistical physicists deal with surface tension of micro-sizes droplets. Shortcuts are a wonderful tool.

I believe that this could even be used to refine the visuals of how a body breaks apart when it enters a Roche limit or is impacted by another body sending fragments away. You will be able to see how the net is stretched beyond its elastic limit before the fragment separates, leaving a hole that  would slowly fill in as the net reforms it self to replace the lost nodes.

[Gregory]

Now Earth's oblateness is 0.0033528590034 (0.33528590034%) based on measurements.
While some might not notice that from a big perspective, it's definitely 7 pixels larger than its polar diameter assuming it takes up 2160 pixels, so the polar diameter taking up 2160 px of the screen means the equatorial diameter would take up 2167 px of the screen, definitely visible to the naked eye (yet especially for people rotating/tilting the view), though it's definitely not much of a difference.
Still significantly important though.

Yet Earth's crust is 50 km thick in the continental areas and 5 km thick in the oceanic areas, so not exactly 2 dimensional(which would be a thickness of 0).

Now speaking of roche limit, we know it was a theory that large objects break up when too close to other large bodies due to tidal forces, and we witnessed that happen with the breakup of Shoemaker Levy-9 before its collision with Jupiter.
Now some other things (like the ISS for example don't break up by Earth's tidal forces, so not everything breaks up, therefore depends on consistency, mass, and also size, as many bigger bodies experience tidal forces distributed.
Yet Earth isn't a perfect elastic, but a nest of solids and liquids. with the crust being solid (and somewhat brittle) rock and the mantle somewhat solid, but slightly fluid, and the core being a near-spherical chunk.
Therefore within the roche limit, the crust would obviously break apart first before the mantle and core do, and it definitely wouldn't look like spaghetti (it wouldn't stretch a whole lot before you notice any fragmentation or glowing orange of melting and magma exposed, unlike putty, though definitely noticeable).

[Plasmic Physics]

Mmm... Perhaps bodies could be modeled by a double layered net, with the outer net having a higher tensile strength. It would be nice to see a giant, deep crater appear where a chuck of of a body comes away, before the it gradually fills in with magma.The bigger and more fluid (gas and liquid) the body, the faster it would do so. US2 team would probably want to be taking a step by step approach with something like this, and I would be happy with a very rough alpha version of this kind of thing that is refined over a series of micro-steps.

[Gregory]

Yup, and it would take a lot of work to be involved, and bugs are expected, as development continues.
Yet not everything’s the same material though still made of matter.
The above answers are a great step as well.

[Cesare]

This is a very good idea. A 0 albedo should not make the planet appear black and 1 albedo should not make planet appear white either.

However, there is a much better way to put your idea to something which makes more sense. Let me give you an example. A 0 albedo would make the planet look matt, like matt paint, and a 1 albedo would make the planet look glossy, like glossy paint. So, the amount of albedo you add, anywhere between 0 and 1 should make a contrast of matt and gloss. So, if you set your albedo level on any planet at 0.50, then the planet would look satin, like satin paint.

The level of albedo is made to control temperature and greenhouse effects as well as controlling the amount of physical reflection and shininess of an object.

[Plasmic Physics]

Why does albedo not correlate with the surface luminosity of a body, when albedo is defined as a measure of the diffuse reflectivity of radiation; and surface luminosity is defined within colour science as a measure of both the reflectivity and scattering of visible radiation, keeping in mind that 'luminosity as used here, refers to the whiteness/blackness according to the HLS colour model?

[Cesare]

Well, the albedo is a reflectant so light would cause objects to display a different luminosity in levels of shininess.

[Plasmic Physics]

I've done some further research, and found that I may have been confused by the various types of albedo. Bond albedo, which I believe is used by US2, is the total reflectivity (diffuse and specular) of incident radiation. Matte, gloss, and mirrored describe surfaces which varying proportions of diffuse to specular reflectivity, and is thus completely irrelevant to the albedo i.e. a body can be a perfect reflector with an albedo of 1, and can be either matte, gloss or mirrored.

I've also come to doubt the assertion that a white surface intrinsically scatters all visible light, as gloss white surfaces do exist. Therefore, I still believe that luminosity is should correlate very strongly with albedo, because like albedo, luminosity is a total measure of incident radiation, albeit it visible radiation. Thus, under a source of white light, a green surface with a luminosity of 0.5 reflects half of the visible light spectrum in the green region, with the remainder being absorbed. Meaning, a surface cannot reflect all visible light and not be white, or contrarywise, absorb all visible light and not be black.

[Cesare]

Yeah, that correct. Light levels measure in albedos must be added to Universe Sandbox. Different types of albedos must also be added as well. Albedo is more than, not only just temperature level controls.

[Plasmic Physics]

When estimating temperature from bond albedo, one must consider black-body radiation statistics according to Planck's law. Counter to initiative, a cool star radiates most strongly in the infrared region of the spectrum. So the albedo of a body irradiated by such a star has a much more pronounced impact on its temperature, c.f. the albedo of a body irradiated by a very hot star which radiates most strongly in the visible region.