Selecting and calculating wood in square meters

Hello !
I’m trying to calculate wood in square meteres from image taken with phone.
Here is an example how other worker does it:
I need to calculate X,Y,Z in square meters.
Thanks in advice !

In that image, the other person has drawn a SketchUp Group that encloses the stack of wood. Then he scaled the model to real world size, probably by clicking the tape measure tool on two points a known distance apart and typing the value (include the units to set the size). Then the Entity Info window shows SketchUp’s calculation of the volume of the solid group. If you want the area of the face, draw a planar shape over it and then Entity Info will show area.

x,y,z sounds more like cubic meters. Although, being American, I am accustomed to the peculiar board-foot unit for “amount of wood,” a quick peek on Google reveals that the metric equivalent to a board foot is indeed expressed in cubic meters, specifically, 1 board foot = 0.00235973722 m³.