The default sphere from the Sweet Home 3D catalog is a UV sphere as it is created with Blender. You can set a texture to this sphere, for example to create a wooden ball.
But sometimes we want the texture to be different. We we can shift the texture along the X and Y axis in Sweet Home 3D and we can adjust the angle and scale of the texture . But that usually distorts the texture in ways we don't want. For the exmaples I used two different wooden textures and a white marble texture. The wooden textures clearly show how the texture is mapped on the sphere: like disks of wood glued together.
Wrapped and Unwrapped
Since we can't change more than the mentioned options in Sweet Home 3D we have to resort to another application to change the way the texture is mapped on the sphere. The first try is what is called UV unwrapping. “UV†is not an acronym for Ultra Violet, UV's are coordinates on the 2D texture image. Since X,Y, and Z are already used for defining points in the 3D space (vertices) and W is used for quaternion rotations, U and V are the letters chosen for the coordinates on 2D surfaces.
In Blender we can “UV unwrap†the texture mapping of an object. In simple terms that means we unfold the 3D surface image to a flat 2D image. Using that unfolded image give a very different result as is shown on the right side in the image. With the shown textures the result is very different and for some textures useful. For these three I would say that the result is worse than the original. The marble texture... well it looks a little like marble but wrapped or unwrapped it's a mess.
Different Projections
What other options can we try? Again using Blender we can change the projection of the texture on the object. In the image you can see the how different projections change how the texture is mapped on the sphere. I added the sphere with the irises to better show what the cube projection does: the image is repeated for each “side of a cubeâ€.
The sphere and cylinder projections look very similar but notice the stretched knot at the arrow. The cylinder projection is useful when you have a texture image with a text that must be wrapped around the sphere so the text remains a horizontal word. The sphere projection seems the best choice with the marble texture, maybe also the cylinder projection. The “Projection from view†looks like it useless. The image is faded. You don't want the mapping to change the look of the used texture image.
Apparently Blender takes the view into account when you export the object. It exports “as you see itâ€. Notice in the image with the four different projections that the sphere and cylinder projections show the top as if it is tilted a little to the left. The next image shows the sphere and cylinder projection with the view set as “Front Orthoâ€, i.e. front in front and without perspective. This better shows the texture mapping and is more useful as a base for other textures. Now the top really is the top.
Different spheres
These are the options using Blender that present different ways to map a texture on a sphere. The five different spheres (unchanged, unwrapped, cube projection, sphere projection, and cylinder projection) are added to the shapes library. With these you can simply choose a different sphere and see what gives the best result for your texture.
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