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The procedure would be the same as in the first case, but after assigning the ground material back to the base objects, you should use the Maxwell texture controls from the Scene Manager > Material tab to change the texture size as, if you use the SketchUp controls, the density map would also be modified. Here I used a crosshatch pattern for the ground geometry while keeping the previous density map (note I changed the crosshatch pattern size in the Scene Manager window and its size in render no longer matches what is seen in the viewport):
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