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%.
Then there is a second layer with interpolation and opacity of your choice for more precision.
If you check "Isometric floor", the two layers will be merged before being processed.
If the opacity is 0%, the second layer will not be created.
There is an option to keep aspect ratio while scaling. It could be improved...
There is also an option to convert the image to RGB color mode to correct problems of interpolation with indexed color.
SLOW processing for LARGE images! -_-'