how can create a 3d level from a 2d floor plan ?

i want to use a image ( floor plan ) ( pdf or gpj ) as a referenceto my 3d level, like having it in the bottom and build on top of it, and how to fix the scale ( i have some measurements on the plan that i want to use to make it look realistic)??
thanks in advance

Basically, import the floor plan ( PNG is better ) as a texture. Make a material and just plug the texture directly into the color node on the material. Drop the material on a cube in your level and you can work on top of the cube, as a guide.

You will have to juggle the size of the cube to get a working area you’re happy with, but also put a TextureCoordinate node feeding into the texture in the material, because you will want to tweak the UV scale to get the texture to look right on the cube.

that was so helpful, thank you