sigh...
there is a far better way to do this then editing lightmaps.
you want night in bloodgulch or any map and make it look great? then do this..
first open your map in hmt.
go to the bitmaps section.
find the cryoglass. its usually at the beginning where a10's bitmaps begin in the bitmap section.
"levels\a10\bitmaps\cyroglass
copy the meta from the cyroglass and place it over the meta for "clear sky blue"
"sky\clear afternoon\bitmaps\sky clear blue"
save it. you may want to also save the stock number your "sky clear blue" meta number was incase you need it back for some reason.
now your going to notice in the sky there are little blue patches in the sky. to solve this use my cyroglass i edited.
my cyroglass:
http://pepness.assassinsdamned.com/misc/cryo.dds
now go to the [sky] tag in hmt. make your settings like mine..
the two numbers in that pic labeled "100" and "120" will control the level of darkness presented in the level. what your actually doing is adding a atmospheric fog to the level for a more realistic look. the lower the number, the darker it will become. editing the lightmaps alone if not done correctly will really mess with the look of level. trust me, ive done about 800 of them in my last project alone and they are not fun to go through and fix.
if you dont have these options your going to need phenoms 60 plugin pack for hmt. its a sticky in the modding discussion thread i think.
here is the final result your going to get. and you did it without editing a single lightmap so you dont mess up your lightmaps in the process and make your textures washed out and bland by darkening them. remember, your making the level darker but it still has to be playable. if its pitch black then your not going to be able to see everything or anyone. and if you take that pitch black night bloodgulch to play in a lobby server your going to get raped cause your the only one seeing the darkness. functionality is the key.
can a mod move this to modding discussion?