You'd expect Ronnie Deziel to be disappointed that passersby on 93 North can no longer see the massive whale mural on the Planet Self Storage building. After all, he's the artist who painted the three killer whales way back in 1998. But progress is progress, and the new, multi-story residential building that's gone up just off Exit 18 in the South End has mostly blocked the landmark from view. "What can you do? That's the world today. There's new construction," said Deziel. "It's not like I have air rights to it." True enough. But Deziel is nonetheless very fond of the mural, which measures 125 feet tall and 100 feet wide, and he's in town giving it a touch-up. Actually, he's repainting the whole thing, an endeavor that will take several days and 100 gallons of paint. "I'm not changing it, really," he said, "but I am adding a couple of things, like a sea turtle and maybe a sperm whale in the distance." Deziel, who's doing the work himself, said he should be finished by the end of the week.