This is a masterpiece, I love it. Thus, this is short. I am not the good one to write a critique about technique, because this is far too high level for me, but i can talk about colours : this gold-sand-yellow, with that summer-sky-blue, are definetly awesome. I can see clouds moving across the sky while Shaï-Hulud tries to escape...
The only things i could notice are on the vision of the scene. in my old memories of the books, several clues are strange in that scene. Arrakis is a desert : even if these clouds are really beautiful, i wonder if there could be so many on a "desertic" planet. I am not really fond of helicopters, i had pictured them as "mechanic birds" (maybe thanks to the Cryo game, huh).
Anyway, i really feel Shai-Hulud's power on this pic. Great
You are right about the thopters, the helicopters are silly! I will fix this when I have time and think about a proper design.
If I remember correctly the author sometimes described clouds in his books, and if you consider that the planet is slowly transforming with vegetation and occasional rain then it might even make sense. I do get your point though!
Thank you for your great critique, I appreciate it!