When fighting dragons their textures often turn to some kind of low-res version during the combat, which is both ugly and kind of immersion breaking. They look fine before the combat starts and when killed. Anyone who knows what's causing this and how it might be fixed? ATM I'm using Bellyaches HD Dragon Replacer, but I'm pretty sure I had this when using the vanilla textures as well. Meanwhile, I'll try switching to the HQ version of Judas' Enhanced Vanilla Dragons to see if that helps.

does it happen with the whole dragon, or is it just the blood veins through his wings?

those have issues, that are well known. the USKP should have these fixed, though it isn't a 100% fix.

the blood veins are some kind of additional see through layer, and the engine does that low pixelated error depending on the angle and distance (it's an engine bug actually)

USKP has improved vein textures, so the issue happens a lot less often, but there are no guaranty that it is 100% gone.

No, it's the whole dragon. It switches to low-res textures (or it looks like that anyway) during combat, then it switches back. As said, I think I had this issue with vanilla as well - IIRC, that was the reason I tried out dragon texture replacers in the first place. Also, I think I didn't have the issue when using Judas Ultra texture replacers, but I stopped using them just a week ago when toning down my texture replacer load because of CTD:s. But now the issue is back again. I'll try using Judas HQ version.

This mod http://skyrim.nexusmods.com/mods/36059//? attempts to fix the problem your having. It has to do with most dragon models having LOD textures that sometimes pops in and out like your describing.

Thanks, I'll try that! Seems like a logical explanation as well. I fought the same dragon twice with Judas textures instead of Bellyaches and didn't have the issue, but perhaps that was just luck.

EDIT: Hm, TES5Edit found one ITM record plus has these warnings with that plugin:

I wonder if that's something to avoid? I think I'll skip it for now.

I think it's an engine bug that causes these LODs to appear. In one game I had a similar error, but with water LODs in Whiterun.

I'm not using it myself, since the problem goes away if you save and reload when you encounter the bugged dragon (I should have mentioned that in the first post probably...).