They are surveyors datums. Between the two groups of these they are building a monster of a building which was four stories high before it got to ground level and has gone up a further 20/30 levels. The surveyor on the job checks regularly, with his theodolite, to see if the ground is sinking.
This little building just to the left almost out of shot. It is being built next to that little building in front of the nice silver one. The datums are set up on either side of it. So not a light show at all, Poo!