Per-model, RO's polygon limit is very low- It's about 2000, and generally you'll probably want to limit it to about 1600-1800. I don't know if there is a limit per map, but I've found in the past that the framerate starts to get very bad around 8-10,000 models on a single map. (Models, not polygons)
It's doubtful you will ever reach that many models on a map intentionally, as even my most detailed maps ever tend to only half half as many models as that (around 4-5000). If you want to make use of complicated, detailed 3D models with higher polycounts, you'll have to split them up into several individual models that you piece together in browedit.
I hope that helps.
You can use hexed versions of newer models to make them work in 586, then you don't need to use 620 at all. I've compiled hexed versions of the newer models in this package here: Download
Credit to Tokei for making these. I just reuploaded it.
This happens when copying textures or things from other maps via Global Height Edit! Clear the lightmap on the map giving you the error. This should fix the problem.
Hey Chem- Sorry to disappoint, but as far as I'm aware, this is simply a product of how lights are rendered in RO, which is not necessarily how they are displayed in Browedit. If you've played the game for a long time, you may not have noticed it on Gravity maps, but when you start making maps of your own, it becomes pretty easy to see! Here are some examples, from the Ayothaya and Glastheim dungeons.
The Problem:
http://i.imgur.com/1xoHg40.jpg Ayothaya Dungeon F2!
Oh no! Rings! While we can't solve the technical side of this problem without some major sourcecode tinkering (I think, anyway), we can draw peoples attention away from this through good map design!
An improvement!
The best way I find to do this is to avoid putting lights out in the open, with no variations in the ground texture or elevation to break up the rings. Laying down multiple lights unevenly is one way to do this. Take a look ingame at Comodo, and you'll see what I mean:
http://i.imgur.com/l2xSCNU.jpg Comodo's beach!
http://i.imgur.com/wS6k2qZ.jpg Something sort of similar I did! (Probably not the best example, but this map was made a year or two ago.)
If you have a lot of lights close together, their edges will blend and you'll be left with peanut shapes instead of rings! Which is... an improvement, I guess?
Textures!
The best solution to this problem may not be applicable to every map, but where you can do this, you should! It's easy to see the rings on a flat surface, or an open area with a single texture repeated. If you place down a more complicated texture, however, it can make the the rings almost impossible to see. Having textures that compliment a light source (Like a bright floor emitting light from itself) can also do wonders to make lights look better ingame. Here are some examples in a new map I'm putting together:
http://i.imgur.com/1LNGqmI.jpg Snazzy blues and greens!
http://i.imgur.com/dOpMqry.jpg The base of the Ferris Wheel is all elevated ground and walls, which I got a bit lucky with!
http://i.imgur.com/iMWsgGV.jpg A lit-up keyboard! If you look closely, you can also see a bit of that light-peanutting I mentioned before. Yes, that is the technical term from now on.
http://i.imgur.com/Ra47Vax.jpg Even Gravity does this! Endless Tower has many great examples of this, especially with the complex floor pattern at the top of the tower. (I'd screencap that but I forgot the map name.)
TL;DR: Can you get rid of the rings? No, but you can make people not notice them. Consider where your light source would be in this little world you're making, explore what you can do with varied textures, ground elevations and effects, and follow this rule of thumb that you might've already caught onto: Big lights tend to have bigger rings, and more intense lights tend to have more rings, but each ring is smaller.
As to why your lights are green? No idea! It looks like all your color values are set evenly, and I'll assume you haven't got any green in the map's ambient lighting either, so that's probably just a distortion product of RO's light rendering.
Sage's post in tha_scene01 (Thanatos Tower Main Entrance) was marked as the answer