Pixel height: 175/100 = 1.75 cm
Boulder(1) length: 255 px x 1.75 cm = 446.25 cm
Boulder(1) height: 85 px x 1.75 cm = 148.75 cm
To get the width we have to look at the other image. The underside of the boulder is definitely no smaller than 4 feet so I will use it as a low end with 6 and 8 feet as mid and high ends.
Boulder(1) width(s): 4 feet, 6 feet, 8 feet
Boulder(1) weight(s): [length(feet) x height(feet) x width(feet)]150 lbs/2000 lbs = total tons
Low End: (14.65 x 4.88 x 4)150/2000 = 21.45 tons
Mid End: (14.65 x 4.88 x 6) = 32.17 tons
High End: (14.65 x 4.88 x 8) = 42.9 tons
Boulder(2) length: 67 px x 1.75 cm = 117.25 cm
Boulder(2) height: 27 px x 1.75 = 47.25 cm
To get the width we have to assume that Oro is sitting on a top portion no smaller than 2 feet as his legs and butt completely fit on the surface with room to spare. So, I will use 2 feet as a low end, 2.5 feet as a mid end, and 3 feet as a high end.
Boulder(2) width(s): 2 feet, 3 feet
Boulder(2) weight(s): [length(feet) x height(feet) x width(feet)]150 lbs/2000 lbs = total tons
Low End: (3.85 x 1.55 x 2)150/2000 = .89 tons
Mid End: (3.85 x 1.55 x 2.5)150/2000 = 1.12 tons
High End: (3.85 x 1.55 x3)150/2000 = 1.3 tons