Big open space type of map: terrible VIS times... does it have to?

I made a quick map for advanced/fun rocket jumping and sticky jumping and water basins to land on if you happen to end up really high in the air.
Targets to land on for accurate landings(air control)... All fun all good.

But even though the geometry is simple, it takes forever to built due to extra long VIS times. I read about how to optimize VIS, but I can't seem to understand how "func_visclusters" work exactly. Because I got a bunch of them, and VIS times are still skyrocketing.

I also noticed that If I keep some sliding planes (super long and large angled brushes for players to slide on and shoot other players while sliding down) the VIS times are much greater.

What's with big angled brushes increasing VIS times and how exactly should I use "visclusters"?
Should they overlap? Should I leave a space between each of them? Is it okay if it goes through some brushes?
If I use too many will it increase VIS times anyways?

Thanks for the help. D

 

AFAIK func_viscluster is mainly for large open outdoor areas where you can grab a huge rectangular block of space (think some of the huge open areas in HL2:Ep2) and declare "this is all empty and every single point inside this box can see the rest of the box".

If VVIS is still taking a while, you probably need to go back to func_detail'ing things. After vbsp is done, you can tell hammer to open the "portal file" which shows all the vis-leaves as zones separated by blue lines.

All sorts of detail here:
http://optimization.interlopers.net/

 

Well, I got a bunch of visclusters, but I didn't know if I had to make them overlap or not, or just touching each other on the same grid line.
Also, what happens if inside a viscluster is a brush? Would this negate the viscluster, or maybe even make it take more time to VIS.

 

I don't know what happens if it contains a brush, but my gut instinct would be to avoid doing it.

 

The brush would be in that visgroup, and if any part of the viscluster is seen at anytime the said brush will be rendered. You may find this related.
http://www.interlopers.net/forum/viewtopic.php?f=2&t=22844

 

The best way to use viscluster is this: compile just your BSP part, then go Map -> Load Portal File, then say "Yes" when it asks to load the default portal file. If you see a bunch of congested blue boxes/lines in a rather open and simple area, put the viscluster in it, then compile BSP again. Load the portal file again, see if you notice a difference.

 

Thanks for your help guys.

I finally made every viscluster overlap a bit and overlap the skybox too, and this cut down VIS from 3 hours, to 25 mins.

 

Is the entire map one area or is it multiple areas, and how large is this map.