{"id":2330,"date":"2018-01-04T00:01:14","date_gmt":"2018-01-04T00:01:14","guid":{"rendered":"http:\/\/spaceengine.org\/?p=2330"},"modified":"2018-01-03T23:36:23","modified_gmt":"2018-01-03T23:36:23","slug":"custom-models-for-asteroids","status":"publish","type":"post","link":"https:\/\/spaceengine.org\/news\/blog180104\/","title":{"rendered":"Custom 3D models for asteroids"},"content":{"rendered":"

The new feature<\/a> - static (uncontrollable) ships, space stations and planetary bases - are handled by SE as a fake \"satellites\" with a custom 3D models. They uses a Keplerian orbits as a normal planets or moons do, or a static position relative to the parent body, but are rendered by a ship model instead of a ball with an adaptive terrain mesh. But the same mechanism can be used to render asteroids with a custom 3D model instead of a cubemap elevation maps<\/a>, needed to create a planetary body. In this case object is displayed in SE interface as a normal asteroid of dwarf moon, but its model is replaced with a custom \"ship\" model.<\/p>\n

This is recently discovered interstellar asteroid 1I \/ `Oumuamua<\/a>:<\/p>\n

\"\"<\/a>

Oumuamua at its closest approach to the Earth<\/p><\/div>\n

The model is the same as in the ESO press release<\/a>. It was gently given to me by its author Luis Cal\u00e7ada. The model has very big polycount and no textures, so it needs some improvement.<\/p>\n

\"\"<\/a>

Oumuamua orbit and position today<\/s> on 28 Dec 2017, when I made this screenshot<\/p><\/div>\n

\"\"<\/a>

View from its perspective today<\/s> on 28 Dec 2017, when I made this screenshot<\/p><\/div>\n

This is 67P \/ Churyumov\u2013Gerasimenko<\/a> comet. Model is not very good, and also has no textures. I have to find a better one.<\/p>\n

\"\"<\/a><\/p>\n

You may add \u02bbOumuamua to SE 0.980\/0.980e by this script (name the file Oumuamua.sc and save it to data\/catalogs\/planets). Of course, in 0.980 Oumuamua will be rendered as a procedurally generated asteroid model.<\/p>\n

\n\/\/ First detected interstellar object
\nAsteroid\t\"Oumuamua\/'Oumuamua\/1I|2017 U1\/1I|2017 U1 ('Oumuamua)\"
\n{<\/p>\n
ParentBody \"Sol\"<\/p>\n

\/\/ This will work in 0.990
\n\/\/Model \"planets\/Asteroids\/Oumuamua.sss\"<\/p>\n

DiscMethod \"Imaging\"
\nDiscDate \"2017.10.19\"<\/p>\n

Radius 0.115
\nAbsMagn 22.08
\nAlbedoGeom 0.1<\/p>\n

RotationPeriod 8.1<\/p>\n

Orbit
\n{<\/p>\n

Epoch 2458059.5
\nMeanMotion 0.6802
\nSemiMajorAxis -1.2798
\nEccentricity 1.19951
\nInclination 122.69
\nAscendingNode 24.599
\nArgOfPericenter 241.70
\nMeanAnomaly 36.425<\/div>\n

}<\/p><\/div>\n

}<\/p><\/div>\n

As you can see, there is only one new parameter in the script - Model<\/b>, which specifies a path to the ship scheme file<\/a> (relative to the models\/ virtual subfolder). This mean that any normal ship model can be used for asteroids, including modular SE ships. The only difference that it is saved in the models\/planets\/ folder, instead of models\/spacecraft\/. This way 'Oumuamua's model will be ignored by the Ship manager (i.e. will not be displayed there as a ready-to-use spacecraft).<\/p>\n

Before trying to assign a custom model to 'Oumuamua, I've experimented with a triaxial elliposoid<\/a> shape for planets. So far planets and stars in SE are oblate spheroids, i.e. flattened spheres. Their oblateness controlled by the Oblateness<\/b> parameter in script and editor. There were no way to make a prolate (egg-like) shapes. Now I've changed oblateness a vector, i.e. now one can specify something like Oblateness (1.0, 0.6, 0.8)<\/b>. So it's possible to make a prolate shapes, like in close binary<\/a> stars, and also a triaxial ellipsoid shapes. This is needed for objects like Haumea<\/a>, Varuna<\/a> and even Mimas (almost all \"spherical\" satellites are triaxial ellipsoids).<\/p>\n

\"\"<\/a>

Dwarf planet Haumea has an odd shape, and... rings!<\/p><\/div>\n

A three-component Oblateness<\/b> is not a very convenient way to describe a shape, so I've added a new parameter Dimensions (x, y, z)<\/b>, used to describe sizes (diameters) of an object by its three primary axes. You may sometimes see such descriptions in Wikipedia articles. For example, Haumea dimensions are 2322\u2009\u00d7\u20091704\u2009\u00d7\u20091138\u2009km.<\/p>\n

Discuss this post on the forum<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"

The new feature - static (uncontrollable) ships, space stations and planetary bases - are handled by SE as a fake \"satellites\" with a custom 3D models. They uses a Keplerian orbits as a normal planets or moons do, or a static position relative to the...<\/p>\n","protected":false},"author":2,"featured_media":2332,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-2330","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news"],"_links":{"self":[{"href":"https:\/\/spaceengine.org\/wp-json\/wp\/v2\/posts\/2330","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/spaceengine.org\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/spaceengine.org\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/spaceengine.org\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/spaceengine.org\/wp-json\/wp\/v2\/comments?post=2330"}],"version-history":[{"count":8,"href":"https:\/\/spaceengine.org\/wp-json\/wp\/v2\/posts\/2330\/revisions"}],"predecessor-version":[{"id":2357,"href":"https:\/\/spaceengine.org\/wp-json\/wp\/v2\/posts\/2330\/revisions\/2357"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/spaceengine.org\/wp-json\/wp\/v2\/media\/2332"}],"wp:attachment":[{"href":"https:\/\/spaceengine.org\/wp-json\/wp\/v2\/media?parent=2330"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/spaceengine.org\/wp-json\/wp\/v2\/categories?post=2330"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/spaceengine.org\/wp-json\/wp\/v2\/tags?post=2330"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}