[HELP] Normal map issue in gimp

[nokiaslave]

Hi. Recently i retextured Jojjo's armor in GIMP for my own purposes and everytime i cast spell on my charr or there's some other glow on me, i get this freckled effect on my armor. I guess it has to do something with Normal maps, but i dont know whats the problem. Pls i need some advice how to fix it

[Ghogiel]

I am not certain..

 

It could be lack of mipmaps, but that usually does other things in oblivion, like not rendering at any distance from the camera except right up close. But a sparkingly effect will happen if there are no mipmaps and the game does render the map, in layman's terms, the point of mipmaps is to always provide a texture that is relevant size/resolution to the objects distance from the camera, if no mips are provided then the full map will be forced to render despite the fact that it may occupy a very small portion of the screen. When a large texture is forced to render in such a small space, it might be trying to cram a million pixels of texture into a few hundred pixels of screen resolution, and rendering artefacts occur, and those artefacts are a sparkling effect.

 

It could be you haven't normalised the normal map, ie make all the normal lengths =1. Some games normal map shader will normalise the map on the fly, ie anything that is using swizzled or BC3/5 normal maps will definitely renormalises as it has to recompute a whole channel on the fly in realtime. the end result rendered in game is a normalised map.

 

anyway I only say that as Ob quite possibly doesn't normalise it's maps on the fly, it only uses regular 3 channel normal map compressions, Anyway one of the issues with unormalised maps can be a flckering/sparkling effect. pretty sure I used custom normal lengths in my maps actually and never seen any artefacts.. not that I remember.

 

not sure what else it could be off the top of my head.

Edited May 29, 2011 by Ghogiel

[LHammonds]

Check the alpha channel in your normal map...which is the specularity.

 

I don't think the glow map would affect this though.