When working with or adding meshes, I've seen UV Spheres and Icospheres being presented to me. What are the differences between them, when should either be used and is there anything I should take into consideration if I want to have them render cleanly?

up vote 57 down vote accepted

The major fundamental difference is how each sphere is modeled. The UV sphere, somewhat like latitude and longitude lines of the earth, uses rings and segments. Near the poles(both on the Z-axis with the default orientation) the vertical segments converge on the poles. This sphere is useful for projecting terrain onto planets and/or complex modeling as it is readily subdivided even after being created, and maps onto equirectangular projections (plate carrée) readily.

The icosphere uses a different approach. A polyhedron is made with triangles which are placed(at various subdivision levels) as an icosahedron (thus the name) and more finely-subdivided solids. All faces have the same area, which may be useful for certain types of UV mapping containing non-organic textures. An example that comes to mind is an isocahedral die or billiard balls where stretch must be minimized near the point where the number is printed onto the ball.

Comparison of spheres
A conparison of UV and icospheres. UV spheres are on the left. Going downward, the subdivision levels are increased. 10 rings, 3 segments; 16/8, and 32/32 for UV spheres, and subdivision levels 1,2, and 3 for the icosphere. Default BI material is used, and light is directly behind camera.

Source: Wiki page and experimentation with UV mapping.

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    I guess nothing is stopping me from mapping an equirectangular map to an icosphere, right? Because I can always compute (lat, lng) for each vertex of the sphere, regardless of its triangulation. – Sibbs Gambling Jun 19 '17 at 21:59

Since you are asking what the difference is I thought I'd point out one of the most important differences between the two kinds of spheres in relation to modelling.

Basic difference
Comparison using many subdivisions

UV spheres are best used in situations where you require a very smooth, symmetrical surface (the more subdivisions the better). However, they do relatively poorly when realistic topology is your key goal. UV spheres are not the best for organic natural shapes, because of their symmetry and the use of quads.

ICO spheres are best used for objects such as:

  • Geodesic Domes
  • Planets with realistic terrain
  • Rough surfaces, such as golf balls.

If symmetry is important, use UV spheres because ICO spheres are asymmetrical.

Displace on
A displacement modifier on the ICO sphere yields more satisfying results. With a higher number of subdivisions the difference between ICO and UV sphere won't be as noticeable. Generally, though, the ICO sphere looks more realistic and much smoother.

Displace settings
Displace modifier settings

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    +1 Very useful information! I never really knew what the ico spheres were good for before, thanks! – Gwen May 24 '13 at 18:16
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    Little request. In the second image, could you also show the tops/poles of the spheres, where the difference is more dramatic? Perhaps also a strong shader so we can see the contrasts more clearly? – hexafraction Aug 16 '13 at 21:55
  • Why not use a round cube instead? It doesn't have any triangles and it's low poly at normal settings. – JeremiahTDK Oct 18 '17 at 15:13

A UV sphere has faces with 4 edges, while an Icosphere has triangular faces. This results in the UV sphere having a smoother appearance and the Icosphere having a jagged appearance. However, the more faces you have on them, the smoother the Icosphere looks compared to the UV sphere.enter image description here

  • 3
    the UV sphere in the image above has more than four times the number of triangles in it than the icosphere does. that's hardly a fair comparison. – Spongman Jan 26 at 6:58

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