'Invisible' leak?
So, last night I compiled what was to probably be the final compile before release of my map, 'The Electric Castle'. Expecting it to take a few hours I left it overnight, but when I got up this morning I had a quick look through the compile log to see it took... 8 minutes. Great. The number of direct lights has also reduced from around 5,000 to 600 odd. Thinking I had a leak I loaded up the pointfile but nothing. And sure enough, all the light bounces had still been calculated.
I did a quick play through and something is clearly wrong with the lighting; some of the plastic surfaces (the ones with the circles on) have turned matt black, and there are a few square black patches just on standard test chamber floor.
If anyone has heard of similar problems and could point me on the right track then it'd be greatly appreciated, Thanks.
I've never had this problem with making maps before. Are you using entity lights, texture lights or both? Are you using HDR lighting?
Probably all I can suggest is to make sure the surfaces that are going black are either world brushes or func_details.
What is a "direct light"?
It sounds like you could be over one or more maxobjects limit.
Holy shit! 600 lights, wtf are you making, the Vega strip? You do not need that many lights. Even ep2 maps don't reach that number, the highest you should ever go is 60 or 70.
No, I think it means the number of light patches for doing the vrad radiosity simulation. Like if you had a light entity that would be one direct light, but if you had a 32x32 texture light with 16 units per luxel that would be 2x2=4 direct lights.
Thanks for the responses, everyone.
Firstly, Fusion, I'm using a majority of texture strip lighting for the recessed lights, with some entity lights with a high constant to even things out, and yes I'm using HDR lighting. I had a quick double check of the brushes, and they're all func_detail 
, apart from one which has to be tied to a moving object, but that's been not black before ^^
Thanks for the link YouMe, hopefuly I'll be able to throw it at that link later today.
And Fusion answered the other two questions for me. Thanks.
On an awesome sidenote, I saw the Rentests, Logicportals and Chamber 21 on the demo disk of this months issue of PC Gamer in the UK 
Whoa. Are you serious?
Super serious; they had a special on mods this week, there was some LOTR conversion for a Total War game, some HL2 mods and about 5 portal maps. (Those were the only ones I recognised from TWP). So congrats to everyone who made them!
Is it this issue, which has an article about "DIY Portal Test Chambers"?