hi there - here is a ground plane i created some weeks ago:

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# file generated by UVMapper
# NumVerts/NumTVerts/NumVNormals/NumFacets   4/4/0/1
# NumGroups/NumMaterials/NumRegions   1/0/0
# x/y/color/ppu   1024/1024/0/50.00000000

v -1.00000000  0.00000000  1.00000000
v  1.00000000  0.00000000  1.00000000
v  1.00000000  0.00000000 -1.00000000
v -1.00000000  0.00000000 -1.00000000

vt -1 3
vt 3 3 
vt 3 -1
vt -1 -1


g Figure 1
f 1/1 2/2 3/3 4/4
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cut it out - save with a text editor as plane.obj and import it into poser and drop it down to the floor. scale it in x or z direction, rotate it to use as wall or floor. this plane us UV mapped and can take any texture - texture is tiled 2x2 times, so you can scale the plane much bigger than the poser ground without the blurring effect . hope this helps :)