Depends on what you mean by "massing". Russian armed forces have about 771,000 active troops, most of which are concentrated in the Western part of the country. The Southern Military District, which borders Ukrainian Donbas and now includes Crimea, has at least 72,000 permanently stationed troops, and last year managed to host military exercises for 120,000.
I don't know where your 150,000 figure comes from and why it is important, but to me it sounds like a perfectly reasonable common-sense estimate of how many troops Russia could rapidly deploy into Ukraine.
As to why you don't see super high resolution, neatly labeled satellite photos of them in the media like the ones in OP, refer to my previous post.