How do YOU create resolution LODs?

[abs 2]

...and I'm not talking about right-click, create new lod, or whatever the option is. ;)

What is your process to lower the poly count on a model to create the lower res lods? Do you do it in o2? Is there an automated tool you use?

I'm really curious to get feedback from the community about this. As for my process: I don't...hence the reason for this post. :)

Abs

[JDog 11]

Unfortunately I haven't made res lods for the carrier yet (it would be quite a task time-wise, seeing how many models it is). But I have made 3 levels for the Sea Sparrow launcher I made. Really I just started deleting components that I don't think can be noticed at distance or lowering the quality of other components. This was my first time but it seemed to work out great in-game with a drastically lowered polycount. When I was testing it I made the lower quality LOD a different color so I could tell when it switched, and I could not see a difference in model quality at that range. Anyway this may not be what you're looking for but here's what I did for each LOD on the sea sparrow:

First LOD:

Second LOD: Remove all small details like the bolts on the base and z-brace, remove handles on plate covers, delete every other edge on all cylinders to reduce smoothness, delete all missile pylon detail

Third LOD: Leave only the basic shapes, this one's pretty self-explanatory as to what's removed

Caps LODs: Obvious enough

As far as I know/do, it's mostly an issue of removing components that can't be seen at range, and lowering the quality of other (usually be deleting edges). I'm sure there are other methods, especially for organic shapes, but in the end its still just removing edges while keeping as much of the object's shape as you can. Hope that's something of what you were looking for :)

[abs 2]

Yep, that's a good guide! Do you do all this before or after you've finished texturing? I'm wondering how it affects your UV layouts.

Abs

[rstratton 0]

it can be done without affecting the uv's, but its not easy to do in oxygen 2.

[JDog 11]

Yea I did all the uv mapping for LOD 0, making the others didnt change the mapping at all, not like I added any new polygons to it.

[soul_assassin 1750]

indeed uv mapping should be done in the best quality model only. UVs will only start getting distorted far enough that the texture should not be distinguishable anymore and in any case its easier to fix 3 maps than make 6 new ones. The most important thing in element deletion is try not to delete elements that effect the silhouette of the overall model, so parts that stick out from sides should be reduced and not deleted. Objects that are flush on surfaces or really small can be deleted safely. Another thing to keep in mind are objects that have contrasting colors as well as very black AO under them. At distance black spots would seem to appear on the model.

I personally do reduction by simple manual edge removal, welding etc. The tools in max 2011+ make this very easy, for example pattern edge selection allows to select every second segment edge on cylinders very fast. Also don't forget: select edge + Backspace deletes the edge but leaves the vertices. Selecting and edge and pressing Ctrl+Backspace removes the remaining verts as well.

---------- Post added at 10:51 PM ---------- Previous post was at 10:47 PM ----------

Yea I did all the uv mapping for LOD 0, making the others didnt change the mapping at all, not like I added any new polygons to it.

well when you reduce from 14000 to 250 you are bound to have distortion :)

Edited August 26, 2011 by Soul_Assassin

[PuFu 4600]

For complex geometries (will kill the topology though) and fast (read not really optimal all the time) the ProOptimizer Modifier in max can do wonders - protect borders, keep UV boundaries options should be used.

The rule of thumb for res LOD is:

LOD1 = 1/2*LOD0

LOD2 = 1/2*LOD1

and so forth

as i have seen Jdog has his LOD1 1/3 of LOD0.

Reason is that if you remove too much geometry from the thing with each iteration, the transition between LODs will be a lot more apparent

[[aps]gnat 28]

So, if your main resolution lod is only 3000 (for example) poly count and 2 or 3 sections ...... is it even worth cutting lower res lods?

I ask (well, its really me stating my opinion ! ) because with some of my own models, I've tested on a medium spec PC with 4000+ Veiw Distance and added over 50 ( ! ) of them to a map, then tested the performance.

9 out of 10 times its NOT the Resolution lod that slows performance even an inch, its almost always inbuilt scripting that may be within the addon that clips FPS.

At this point in the PC / CPU evolution, ArmA2 seems to have little problem with medium poly count models IMHO.

If I do worry about polys, its almost always only the "round stuff". Wheels, pipes etc

[max power 21]

I usually down model by collapsing edge rings or removing edge loops. Usually I create an unoptimised but UV'd res LOD 0, leaving all of the little centre vertexes on the lids of cylinders, etc, to facilitate procedural edge selection (by loops or rings), downmodel that, then optimize LOD0.

I do all of the modelling in max. Each time I set up a new LOD I start a new layer and copy the previous res LOD into that layer. I set up cameras on these layers using the biki information on LOD switching as a rough guide to set their distance from the model. I then animate the camera to do some orbit moves from different angles, and I use the animation slider to control the camera position. I then use that camera as a guide to remove/downmodel anything I can't see at that distance.

[PuFu 4600]

Obviously, manual reduction is better because you have more control on what is going on. I forgot to add the the manual reduction tools in max the one designed specifically for LOD, which is the MultiRes, besides the ProOptimizer

@Gnat:

The best practice is to provide the engine with more res LODs, even if the LOD0 polycount is low.

The performance gauge is texture related (or in fact the section count - as i am sure you are already aware, not the poly count).