Tell me everything about bump maps.

Ummm... see above.

I know what they are (having skinned for Sims 2), but how does one get them in the game? Are they a greyscale with white high and black low, or the embossed looking kind? I want to know specifically for clothing. Are they yet another channel on the targa format file? Do many users even HAVE the ability to see them, or turn that on in the graphics options??

There are two forms of bumpmaps that work here. Traditional bumpmapping, as it exists in real world 3D, isn't in Second Life. At all.


The current options available are:

1) For prims and clothing, you can "bake" a bumpmap into a texture by using the tools provided by Photoshop/PSP/GIMP. This will create a faux lightsource and grain using the grayscale values of the image, and works fairly well for texture support.

2) You can also use the "bumpmap" feature prims have. It allows for a few changes, but compared to traditional bumpmapping, the effect it renders doesn't look too good. You can use the "Brightness" or "Darkness" option for an in-world effect similar to Point 1.

Compare with traditional bump mapping, which allows a user to specify their own unique files for the actual surface and bumpmap separately.

You're probably better off with option number one in Second Life anyway, since the actual feature is only half-finished (likely due to the primitive nature of lighting here). By default, support for the bump map feature for prims is also toned very far down, and I doubt many users have them enabled in-world at very high distances.

Hmm. Thanks for the quick reply!

Okay, since I'm doing clothing I'll go with #1. It's a greyscale image, that makes sense. Is it a new layer on the channels of the file, or something else? What do I have to call the layer?

Usually it's a filter, no matter what program you use. In the GIMP, it's under Filters > Map > Bumpmap, but I'm guessing you're using Photoshop or a different program.

Not sure where the option is exactly there, but you should be able to set it with a filter on any color or grayscale image; it'll just treat color as a shade of gray.

Clear as mud?

To expand on Jeffrey's good info, if you are using Photoshop, here are the instructions for creating an embedded bump map, taken directly from the Photoshop help files:

Using a Lighting Effects texture

The Texture Channel in the Lighting Effects dialog box lets you use a grayscale texture such as paper or water to control how light reflects off an image. You can use any channel in your image (including a channel copied from a different image) as a texture, or you can create your own texture. For an embossed text effect, use a channel with white text on a black background, or vice versa.

To use the Texture Channel in the Lighting Effects dialog box:

1. If necessary, create an alpha channel in your image and add texture. To use a texture from another image, copy and paste the image into a new channel. (See Creating alpha channels (Photoshop).

2. In the Lighting Effects dialog box, choose a channel from the Texture Channel menu: the image's Red, Green, or Blue channel or any channel added to the image.

3. Select White is High to raise the white parts of the channel from the surface. Deselect this option to raise the dark parts.

4. Drag the Height slider to vary the texture from Flat (0) to Mountainous (100).


IMPORTANT: If you do it this way, do NOT include the thexture channel in the file you upload to SL. After you make the bump map, delete the texture channel. Otherwise, SL would treat the texture map as a transparency map, which obviously would not be pretty. Also, if you don't know where to find the Lighting Effects dialog box, it's Filter -> Render -> Lighting Effects.


Alternately, you could also play aroud with the Bevel & Emboss settings on the layer blending options (my preferred method). Right click on the name of your layer and click "Blending Options". You'll see lots of different tools and settings for giving layers unique looks. If you build your image in sections, this can be quite powerful.

Excellent. I think I'm sufficiently armed with knowledge to tackle bump maps.

I'm curious if people turn on the ability to see them, though?

Oh well, I'll make clothes that look good with and without them.

I'm confused by this last post of yours. I'm getting the feeling we've been talking about two different things. I thought you had wanted to know how to simulate bumpiness on a texture, something done in Photoshop (or whatever your graphical editor of choice is), and not something anyone in SL would have to turn on in order to see.

The bumps that people can turn on and off are the shiny/bumpy objects setting, and the avatar bump & cloth setting. The bumpy objects options in SL are very limited, so most people don't use them, but since the on/off switch for it is the same one as for shine, most people do have it turned on.

If you're talking about bump maps for avs, then I'd suggest you start by looking at the ones that already exist. You can find them in your Program Files\SecondLife\character directory. You can modify them if you wish, but keep in mind it will take longer for people to be able to see your av properly if you do. In my opinion, it's not worth the effort. I really don't know how many peple have avatar bump turned on, and it's a big pain in the ass to have to modify the SL directory structure every time you change avatars, which is what you'd need to do in order to make it effective. It's best just to leave it alone.

For clothing, the bump maps are applied via the wrinkles slider, which is something almost no one uses. I've never seen any point in customizing it.

Until SL gets better at utilizing custom bump maps, and much better at lighting, neither of which are likely to happen for a very long time, I'd suggest sticking with the kind of simulated, baked-in bumping in your textures that Jeffey and I were talking about, and leave the SL bumps alone.

Just to clarify this point, here's an excerpt from a few town halls ago:

/3/4a/48100/1.html



Also, the other problem with rendering bumpmaps is the fact they have an "active distance" setting that's usually set very low by default (about 10 - 20m or so on my card). Unlike shiny, you cannot see the bumpmap at all until your camera is that close to the object. It's another one of those "things" that makes that solution less viable.

Hmmm. I guess I'll wait until they give us more options for it.

Yes, I was talking about adding another channel for a bump or normal map to the avatar's clothing texture. Though using the lighting effect in Photoshop will do the same thing anyway, so I'll probably just play around with that.