LOD’s (Distance Levels)

I had a look at a model sent to me by Ian and found a solution (work-around?) for the problem he is having.

Normally I advise against merging objects, but there appears to be an exception. The model Ian sent me had separate objects for the roof, sides and front/rear. When I merged these objects into a single object the Reduce operation worked properly. The reduction algorithm tries to retain the shape of the object, but if the shape is not clearly defined it has troubles.

Note that, just because objects are merged doesn’t mean that they can’t be unmerged. The trick is to not compact the object after merging. If you leave it uncompacted you can recover your individual objects simply by deleting the object merge layers.

If you are curious to know what the LODs are going to look like try using the Reduce operation on each andquot;objectandquot;.

The reductions are:

Level 0 – 100%
Level 1 – 80%
Level 2 – 66%
Level 3 – 54%
Level 4 – 43%
Level 5 – 33%
Level 6 – 23% (and all objects outside the main group are removed)

Note that if you don’t like any of the generated levels, you can delete them manually from the S file. It is relatively straight forward. I am sure someone has written instructions somewhere (but I don’t recall where). It is also easy to change where the distance level comes into effect.

Richard

Hello

Is there any info on how 3CD handles the LOD’s
(distancne levels) for an .S file? I have a couple of cars
that the roof tops are disappearing at 100 meters, and
I don’t want them to be dropped for at least 500 meters,
or more.

Is there someway I can tell 3DC what I want to be drop
at what levels?

Thanks
Patrick

I was about to post this similar problem. I created these red and grey vans this week using v5.7 and this is what happens at 100m or so. The van body sides and ends are plain rectangular faces and their objects are in the top level of the main group heirarchy, but one triangle of the pair forming the rectangle disappears!

Please Richard, what is going on?

You know Richard will tell you to crease it. That seems to fix almost everything. <!– s:D –><img src="{SMILIES_PATH}/icon_e_biggrin.gif" alt="" title="Very Happy" /><!– s:D –> Sorry, I couldn’t resist.

What about using the face selection tool and selecting the diagonal line from corner to corner and then the andquot;cutandquot; tool (looks like scissors)? andnbsp;This might get 3dC to treat the entire side as one piece.

Thanks for the suggestions, but I crease everything before I finish a model these days, and in 3DC the sides and ends are just plain rectangles.

Any other suggestions please?

What we need is a full blown LOD manager… andnbsp;hint hint

<!– s:) –><img src="{SMILIES_PATH}/icon_e_smile.gif" alt="" title="Smile" /><!– s:) –>

Patrick

There is another problem with the automatic LOD generation that I have just found out about.

That is that the train object quality slider selects a lower polygon level model which does give some slightly strange results. The top picture is with the train quality control at max and the lower picture is with the setting at 2.

I would echo the earlier request and would appreciate some guidance on how the LOD levels are worked out by the program and how to avoid losing magor parts of the model so early.

Cheers
Kevin

Just crease it. That will fix it andnbsp;

Actually, that looks like a bug in the automatic generation of distance levels. You may want to try updating your version of DirectX to the most recent version. It could help.

Ian, are you getting any warnings about texture usage when you export?

Richard

No warnings, and the vans only use a single texture file.

I am currently using directx 8.1.

Kevin

I’ve been thinking about this a little bit (just a little bit), because although the automatic DL creation in 3DC seems to be good, people like me (sorry Richard) always have reason to want to see exactly what’s going on, or control it.

With that in mind, would it be possible to export a model with distance levels (thus setting up the DL code in the .s file), but create our own low-poly versions and export those? andnbsp;Then, copy the shape information from the nearest DL block in the low-poly .s file to the appropriate DL block in the main .s file.

Would such a work-around be possible, or is there more complexity in there than that?

If I recall correctly, the LOD stuff is pretty complicated. I’ll have a look at all of this in the next while.

Richard

If Richard ever takes a vacation, I’ll be glad to step in. There only seem to be a couple stock answers that are really needed for most of these questions. :

While we’re on his favorite subject, is there a reason that straightening frames/normalizing groups has to un-crease everything? I read in the plug-ins/scripts description for normalize groups script that you must re-crease everything after using it. That’s a whole lot of re-creasing.

Lastly, can you straighten a single frame for just one object? Because if you fix one frame, then add the objects to its group, they will be fixed to, because they will accept the first object’s frame as their own. Is that right?

I noticed a problem with the LOD in MSTS, too. I built some simple houses and to save on the polycount I deleted polys that could not be seen in the game. Some of the buildings andnbsp;with removed backsides or sidewalls showed a unwelcome behavior. The fronts split up in two triangles (that’s the way it has to be I’m told) but only one of the triangles showed textured, the other was invisible. I could avoid this phenomenon exporting the buildings without LOD which is no problem, they aren’t too complicated so that LODs wouldn’t matter much.

Yes, the LOD functions works best on andquot;solidandquot; objects. i.e. with andquot;hiddenandquot; faces not removed. That actually could be the cause of some of the odd behaviour that has been reported.

If you are curious to see what the auto-LOD generation will do to you model try the andquot;Reduceandquot; operation on the parts that make up your model (just click andquot;cancelandquot; not OK <!– s;) –><img src="{SMILIES_PATH}/icon_e_wink.gif" alt="" title="Wink" /><!– s;) –>)

Richard