Basically the problem with sparse pictures and point clouds in general is their lack of topology and not precise spatial position. But when you already have the topology (eg with a mesh), you can extract (optimally) a set of points and compute the radius of the splats such that there are no holes in the final image (and their color). That is usually done with the curvature and the normal.
The 'optimally' part is difficult, an easier and faster approach is just to do a greedy pass to select good enough splats.
> Binding New 3D Gaussians to the Mesh
> This binding strategy also makes possible the use of traditional mesh-editing tools for editing a Gaussian Splatting representation of a scene
No images involved, so no training required.