This script-fu turns a "flat" image into isometric image. This helps to draw floors. It can also scale image with few options (ratio, a second layer with interpolation and opacity)...
You can find "02 - Isometric Floor" in Filters>2D Isometric-Fu>
Why is there "a second layer with interpolation and opacity" for scaling?
There is always a first layer without interpolation to try to keep the grain texture. This is practical for stone for example. The opacity of this layer is always 100%.