Yeah, if you're doing stuff for poser, only the DPI for the final rendered images matters, and only then if you're doing them for print. In every 3D application, the resolution of a texture is referred to as the per-pixel dimensions. A 512x512 iamge map is considered low resolution, where soemthing along the lines of 4000x4000 is high resolution. 1600x1600 can be considered high-resolution depending upon the detail is applies to to the mesh and the way the mesh is designed. High-resolution is pretty much a relative term in 3D depending upon what the mesh itself needs.