Art Spotlight: Artificial Extraterrestrial Objects

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In Art Spotlight, we invite Sketchfab artists to talk about one of their designs.

A very good day to you, Ladies and Gentlemen. My name is Grant Borodin (Sketchfab’s tashtego). I live in Novosibirsk, Russia, and work for Vito Technology company as a designer and 3D artist. The models I was asked to tell you about was made for two apps: virtual planetary Star Walk 2 and solar system model Solar Walk 2. There is a lot of things in them: stars, planets and planetoids, moons and moonlets, asteroids and cometsconstellations and nebulas– and, last but not least, spacecrafts of diverse nature: spaceships, satellites, stations, telescopes, deep space missions, etc.

Those constitute the main body of my work, so let’s move to the point and talk about them.

References

All the aforementioned content, spacecraft included, has one common feature: they are real objects (or were  real objects anyway), so from designer’s point of view there is not a lot of space for imagination, but, at the same time, a great need of good references – both 2D and 3D. And yes, in this case 3D reference is preferable because of a complexity of the matter. For example, Mars 3, the first module to accomplish soft landing on Mars:

Of course you can conjure something out of this and hope that nobody ever have seen the real thing (in fact this is  precisely what I have done), but this is not a very admissible way.

So let’s see what we have in the field of available 3D resources.

The major reference point is the  NASA 3D library. It’s vast and representative (for example all the planets’ textures used in my collection are courtesy of NASA), but it contains only (well, 99.9%) NASA spacecrafts, obviously. All the other agencies – Roscosmos, ESA, JAXA, CNSA and even famous National Aerospace Development Administration of North Korea – are rather shy. In this case there are space enthusiasts’ works, for example Celestia Motherlode and Orbit Hangar and some others. If spacecraft you need is well known and let’s call it fashionable, you can hope to find it there, if not – alas, your last resort is google image search.

Important side note about third party 3D models: even if we put all copyright and ethical questions aside (and we did not), direct use of them is absolutely impossible. They always are too simple or too heavy, contain a strange geometry, broken normals, and pose a lot of problems in texturing. It’s always easier to make your own model than try to fix some existing models. So they may be used strictly for reference.

I’m talking so much about references just because this is the most difficult problem in this area. Once you’ve got them in any adequate form, the work is pretty straightforward: model, unwrap, texture, export.

The style of the model is dictated by a compromise between accuracy and capacity of mobile devices. We can’t afford the liberty of zillions polygons and 8k textures, so I’m trying to keep polycount somewhere in the 10k-30k range, avoiding any superfluous detailing. This limit is not very good for really complex craft, like ISS, but generally it’s ok.

Let’s take Soil Moisture Active Passive mission as an example.

Modeling

This one was build without 3D reference and based on images and movies only. There are less than 9k tris in it. I work in Blender 3D, but the principles is quite common. As for the modeling: do as you like, but keep it simple and always use autosmooth feature with sharp edges marked. Bevel the edges wherever possible, it’s a good method to mask low-polyness.

Typically I start to unwrap as i model – there is a lot of identical elements and it’s wise thing to unwrap the first created element and then just duplicate it with UV just in place.

UV Maps

We used two UV maps: the first for color, specular and bump channels, the second – for ambient occlusion:

Do you see the mess? Well, me too and I’ll explain that later.

The first map is unwrapped manually, the second one with blender’s Smart UV project feature and then tweaked a bit.

Materials and Textures

As Blondie and Tuco Benedicto Pacifico Juan Maria Ramirez keep saying: you see, in this world there’s two kinds of materials, my friend: those are insulated and those are not. Insulation is widely used in space industry. For us, designers, it’s just monochrome (gold, silver, black or yellowish white) and evenly crumpled material. Sometimes it’s shine, sometimes not. The mess i’ve mentioned above is formed by the faces belonging to gold foil insulation of SMAP. I just unwrap this part as seamlessly as possible, adjust the scale and let the seamless normal map texture do the rest. The second material is more accurately unwrapped:

These are three textures: color, specular and normal map respectively. They are quite simple and I just cook them in Inkscape vector editor (normal map passes through appropriate filter in GIMP later). You see, all human spacecraft is built in clean rooms, so they are exceptionally clean and devoid of those picturesque battle scars, burns, rusted armor plates and such. Maybe later, when we’ll find some aggressive interstellar bugs and start fighting with them for the galactic supremacy, this situation will change, but until then I see no point to use more advanced solutions.

The last channel – ambient occlusion – is used by all materials. Unlike the other three it’s baked right in blender.

Whoops, I forget about third material – that semi-transparent wireframe-like thingy on top, the radar, which is just a transparent net, made in Inkscape too.

All the materials are PBR, simplified a little (without roughness), with slightly different specular levels. Most of the crafts have only two or even one material, that is, we have only four 512×512 textures per each to maintain a decent quality.

Basically this is it. After all this work done you’ll need to triangulate N-gons, check normal’s direction and export model to FBX.

Sketchfab

Apart from being today’s greatest 3D showroom on this planet and AFAIK in this galaxy, Sketchfab may be very useful for debugging your models without the need to bundle them in whatever engine you use. Some glitches I have told you about (N-gons, normals etc), which are hardly noticeable in Blender, became obvious after uploading here. Also Sketchfab allows us to share WIPs easily, which is especially important for remote workers like me.

In effect I’m very grateful to Sketchfab team for their excellent work.

About the author

Seori Sachs

Community Person!


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