View Full Version : Object LoD

02 February 2008, 05:44 AM
Hi! I dont use XSI, have only played with it a bit, but have a quick technical question. Does XSI have LoD groups similar to Maya that work with MentalRay. I ran in to a snag with my thesis work when i discovered that Maya's LoD groups do not work with MentalRay for Maya.
Figured i would ask here because student XSI is a lot cheeper then Renderman and MtoR.

02 February 2008, 08:56 AM
LOD is in the geommetry itself, you apply a poly reduction and it generate LODs for you.
It's the best polygon reduction tool I've ever seen in my life, so I suggest you check it out.

Or are you talking about Geommetry approximation? if yes then well XSI also does better :P
XSI and Mentalray were married until version 5... XSI was pure mentalray so just now that XSI support other renderers... you should expect the best mentalray integration as well.

02 February 2008, 09:01 AM
sorry wasnt clear on LoD use, i have 4 versions of an object very high to low poly. I would like to have the objects switch out depending on the camera distance, like the LoDGroup in maya.

02 February 2008, 10:26 AM
This is a video from showing how PolygonReduction works.
They show LOD's but they talk japanease and their XSI is in japanease so I don't know if you'll understand :P

So it depends on what you want to do but usually you can do one of the following:
- You trow your hires version in XSI, put a model>modify>Polygon reduction, paint weightmaps to the areas you wanna reduce... set everything you want (usually I turn on Quad and Volume preservation).
Then you turn LOD's on.
The LOD stage will define which step you are, usually it will come with 4 steps, you can set the increment (how much each LOD will reduce like 25% or 50%).
Than you right click in the animation divot (the gree incon on the side of the LOD slider) and you put set expression.
The expression window will pop, you click Function > Distance > Center to Center.
you put elem1 and elem2 (something like this: "ctr_dist( hiresMesh., Camera. )*0.1")
this 0.1 depends on the scale of your model.
thats it.

Another option:
- you set 3 different models with different resolution. You import it as referenced models than you make a slider to change the active model depending on the distance from the camera (using the same expression I sent above).

I think the first option is more what you are looking for... It looks complicated but in fact I it's really simple.

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02 February 2008, 10:26 AM
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