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View Full Version : Displacement- why does this happen?



IMI
12-29-2007, 01:00 PM
I got this house object from the content of the Essential LightWave v9 book and thought I wanted to texture and render it. I have only just begun with that, but one of the first things I tried after getting it into Layout was to make a displacement for the ground.

It's all wrong, and yes, I have to make the driveway a separate object. I wasn't planning on doing this when I still had it in Modeler. And, yes, I plan on putting trees and other stuff in it, and setting up better lighting. :)

Now that the disclaimers are out of the way, you can see that the displacement is displacing everything, not just the ground object. The ground object (which is a sub-patch and modified quite a bit from the original) is in its own layer, making it (so I've always thought) a separate object. BTW, I greatly exaggerated the effect to make it more obvious, but even the smallest amount shows up in the house, too. It's particularly noticeable the way the roof is detaching itself from the walls. Would be good in a hurricane animation, but not here. ;)

So how do I prevent everything in the scene from being displaced? I only want it on the ground, but might try it on other objects, too. The ground layer is not parented to the house or any other layers. Nothing is parented to anything else.

I'm guessing it could be done if I made the ground a separate object unto itself, and not a layer, but I haven't tried it yet. For future reference though I'd like to know why this happens, if it's supposed to happen like this, and what, if anything, can be done to prevent it?

Thanks. :)

SplineGod
12-29-2007, 01:14 PM
They can be layered. Where are you applying the displacement?
You can separate the objects into layers to prevent it or have them in one layer and use weight maps to mask out certain areas.

IMI
12-29-2007, 01:19 PM
Thanks Larry. :)
It is layered, though. I'd upload the scene if the object were mine, but it's not.
The ground is a layer separate from the house layer, and it's the ground only, to which the displacement is applied. See the screenshot attached.
I hadn't thought about weight maps, will try that. Good idea, really.

IMI
12-29-2007, 01:34 PM
Ok, I see what happened. Not sure how it happened, but it did. User Error.
I opened it back up in Modeler, and somehow the roof got mixed in with the Ground layer. I think it was because i copied it to a separate object to work on it, then pasted it back in to the same layer as the ground, accidentally. :foreheads

Problem solved, yes, I'm an idiot. :D

gerry_g
12-29-2007, 06:22 PM
Also looks like you need to crank up the subdivision in the render settings for subD objects they're very jaggy

Mr Rid
12-29-2007, 06:26 PM
I prefer to avoid layered opbjects where possible. Ive run into too many weird issues with plugins and parts and surfaces getting confused.

IMI
12-29-2007, 07:02 PM
Also looks like you need to crank up the subdivision in the render settings for subD objects they're very jaggy

Oh, I did. It's up to 6 now, which seems pretty good. I had just started, and then I exaggerated the effect to make it more obvious for the screenshot.
I'm fairly new to using procedural displacement on regular, non UV objects. I know how to do it with ZBrush and a texture map, but for this object I didn't want to spend an hour painting a texture. The end result is actually very subtle, but noticeable enough. Much easier than regular old "bump". For that matter, it's more realistic and quicker to render than something in the bump channel. I can't believe I put off learning displacement as long as I have.
Now I wonder if it's possible to bake a displacement into an image map with the Surface baking Camera.

IMI
12-29-2007, 07:04 PM
I prefer to avoid layered opbjects where possible. Ive run into too many weird issues with plugins and parts and surfaces getting confused.

Yeah, I'm rapidly coming to see that's true. When I have objects that aren't going to have moving parts, or parts I might want to reposition or rotate, I'll use layers.
If I do have moving parts, I make them entirely separate objects because it's easier than moving the pivot points for each thing.

Mr Rid
12-29-2007, 07:52 PM
...I can't believe I put off learning displacement as long as I have.
Now I wonder if it's possible to bake a displacement into an image map with the Surface baking Camera.

The old school trick is to apply a black to white gradient to a displaced object and render it as a flat/orthographic image.

I have found displacement to be about the most overlooked tool for all manner of interesting effects, especially when animated or using sequences. I have stumbled into many weird dispalcement tricks to baffle. Normal Displacement is a whole nother fun world.

gerry_g
12-30-2007, 05:59 AM
Oh, I did. It's up to 6 now, which seems pretty good.

Last time I messed around with a terrain I tried a level of 10 and it still wasn't that good, also I deformed and froze a first mesh from height field data and added displacement afterwards so as to have more control over what I ended up with, (see pics) I was using the per polygon setting here.

IMI
12-30-2007, 06:07 AM
The old school trick is to apply a black to white gradient to a displaced object and render it as a flat/orthographic image.

I have found displacement to be about the most overlooked tool for all manner of interesting effects, especially when animated or using sequences. I have stumbled into many weird dispalcement tricks to baffle. Normal Displacement is a whole nother fun world.

If you don't mind, what do you mean by "apply a black to white gradient to a displaced object"? You mean, in the Color channel, so the high points are white and the low points are black?

Yes, displacement seems to have endless possibilities, very cool indeed. I see though it's easy to quickly bog down LW with too high of a subpatch level. I don't know if it was an error in LW, but I was playing with an object that didn't have any excessive polygon count, but it sucked down 4 gigs of ram like a man in the desert who has found a glass of water.
I was particularly intrigued by Willian Vaughan's Pin Displacement video he uploaded a couple of weeks ago, and played around with that somewhat. Loads of possibilities with a technique like that.

IMI
12-30-2007, 06:13 AM
Last time I messed around with a terrain I tried a level of 10 and it still wasn't that good, also I deformed and froze a first mesh from height field data and added displacement afterwards so as to have more control over what I ended up with, (see pics) I was using the per polygon setting here.


That looks great, gerry_g. I'll have to try that. I hadn't considered height field maps.
I'll post a pic of how my yard turned out - I'm still working on it, but it's not going to be too upclose, so 6 seems to be doing a decent enough job. No major detail, just roughing up the smoothness of it a little.