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When a mesh is created the engine places spheres at the particles' positions. The radius of these spheres determines the mesh's surface and can be adjusted for each particle sequence individually: with a small amount of particles a higher radius is needed to blend the spheres and achieve a closed surface. With lots of particles, the radius can be decreased, because the particles are close together.Sphere radius is just one criteria, and it defines whether the mesh will be thick and have the appearance of mud, or if it fits the underlying particles tightly.
The other important parameter is polygon size. This value is responsible for the spheres' resolution: the more polygons, the smoother the mesh, and the more details you will finally get:
Both, “Radius” and Polygon size” are the main factors to describe a mesh's appearance. All the other parameters are used to fine-tune the mesh. For a complete workflow description, please read the → “Particle-Based Meshing” tutorial.
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For 3DS the workflow is almost the same, but you have to use the → “Preview Object” instead of the “Display” panel; for Softimage there is the → "RkViewer".