Why do I need so much geometry?!

#1

Hi,

I’m trying to generate small water ripples on a surface grid.

I’m using a Fractal Texture node, plugged into the displacement slot of the surface’s material.

I want to repeat the fractal texture across each grid unit many times, so that I can drastically cut down on the number of units being used for the ocean surface (especially considering the ocean needs to run to the horizon in all directions from the center of the scene) but still have many ripples on the ocean (very detailed even when in close).

The problem is, I can only repeat the fractal texture across any given grid unit a few times. If I up the repeats past say 4 or 5, it does nothing. The shape of the waves changes by inceasing the number, but the quantity does not increase.

As of right now, the only way I’ve been able to attain the amount of ripples I want is to up the grid count… which completely ruins the point of using a displacement map (aka keep down the poly count).

Any help would be grealy appreciated!

Thanks,

Matt

#2

I should also note that I assume it has something to do with geometry approximation. Unfortunately, I can’t really mess with that either.

I screw with the numbers in geometry approximation until I see one change, and then after that, that’s all the changes XSI will make. I can change numbers till the cows come home, but once XSI shows the first approximation change, it WILL NOT update the render region to reflect the newly changed parameters after that. Sooo annoying.

Matt

#3

what version of XSI are you using ?

what are your geometry approximation settings, and what parameters are you trying to change?

#4

6.5

and I I finally got a geometry approximation setting that I like through trial and error. But I don’t really understand how I got there.

I’m using the Parametric setting:

max. displace=4

step=2

#5

Glad you got it working.

Parametric is non adaptive. In other words, it simply subdivides the geometry the same no matter if the geometry is close up or far away.

If you need a more optimized approximation because you’re running into memory problems it might be better to use Length / Distance / Angle, or Fine for very detailed displacement.

#6

I have a grid that is extending to the horizon. I’m getting gross artifacting because there’s so much detail near the horizon.

Would LDA gradually cut out detail over distance on the one model? If so, any idea’s on the best way to set it up? I don’t really know what the values mean.

Thanks!

Matt

#7

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