Bump Mapping Tutorial
by Crechebaby

Required:
Bodyshop
Adobe Photoshop
A finished skin.

Estimated time: 2 minutes.

Bump mapping is used to make a skin look more three dimensional, and avoid the "painted on" look that some textures can have. They're very simple to make, and add a great deal to a skin's quality, so don't overlook them.

This particular method of bump mapping includes one more step than most methods do. However, I feel it produces superior results.

For this tutorial, I'm assuming we have already created the skin we want to bump map. You will need to have the .bmp files for this project opened up in your paint program. If bump mapping is enabled for the skin, you will have three .bmp files. The alpha, the texture, and a grey image that is the bump map. It will also have the words "NormalMap" in the file name.

Note: If you don't see that 3rd "NormalMap" file, bump mapping is not enabled for this skin. You can very easily enable bump mapping for most skins using this tutorial by Muehlie on Mod The Sims 2. The only exception to this is skins on meshes made with any of Wes_h's Milkshape plugins, which at the moment does not support bump mapping.

For this tutorial, I'm going to create a bump map for this skin, created by Kim here at Sim Chic. I am, of course, altering the skin with permission from the creator.

It's a lovely skin, but it's a little one dimensional, and it has that painted on appearance. In order to fix these problems, open up your alpha file. Select the "magic wand" tool.

At the top bar, you'll see some options for this tool. I usually have the tolerance set to "32" for most jobs, and for this purpose in particular, make sure that the "Contiguous" box is unchecked. This will allow you to select all of the white areas with one click. If your alpha has any grey areas that don't get selected, you can either add them to your selection by holding down the SHIFT key while you click, or by turning your tolerance up.

Here, I have all of my white areas selected, plus the little bit of grey on my shoes.

This is important:
If your skin does not have shoes, or some other white area touching a corner of the screen (for instance, if you are adding a bump map to a tank top or swimwear, etc, or if the white area for your shoes doesn't quite touch the corner), you will also need to select a little piece of the very top corner of your screen (right or left). This step is only necessary if you don't have any white areas touching one of the four corners of your image.

Use your rectangular marquis tool:

... and (while holding down the SHIFT key, so you don't lose anything you've already selected), select a little square in the upper right hand corner of the image. Make sure you select all the way to the VERY edge.

Now, when you have everything selected, go to your "Select" drop down menu at the top of the screen, and click on "Save Selection".

This box will pop up, asking for a name:

Just click on "OK", and it will save it as "Alpha 1".

Select the "View" drop down menu at the top of the screen, and make sure there is a check mark next to "Snap".

Now switch over to your texture file.

Using the "Select" drop down menu at the top of the screen, find "Load Selection" and click on it.

A box will pop up, asking which selection to load. Just click "OK".

The selection you saved from your Alpha will appear over your texture. Copy this, using either Edit > Copy, or CTRL+C

Now, open your bump map image. It should be completely grey. If there are any markings on it, erase them first. Then use "Paste" to paste your selection onto the image (Edit > Paste, or CTRL+V).

As you can see, it didn't quite paste on in the right spot. Just slide the image down, and it will snap into place. This is why we turned the "Snap" option on, and why it's important to have some part of the original selection touching one of the four corners of the image. It needs to be positioned exactly.

Now, just as with any other bump mapping method, use Image > Adjustments > Desaturate to turn the layer into shades of grey. Your bump map should now look like this:

You'll notice that the pants are actually darker than the shade of grey in the background. This isn't what we want. Use your marquis tool to select only the pants (front and back). Then use the Image > Adjustments > Brightness/Contrast slider to brighten up the area you've selected. Increase the brightness as much as you need to in order to make the pants significantly lighter than the background. Doing this will sometimes wash out some of the details, so you may want to also increase the contrast.

Now, after increasing both the brightness and the contrast, my bump map looks like this:

If you need to, you can also change the background to a darker shade of grey. The point is for the edges of the clothing to be much lighter than the background color. In the image above, you'll notice I have some little strips of black along the sides of my jeans in the front, and on the right sides of my tank top. This is okay--those parts don't show. The really vital areas are the neckline, the hem of the tank top, and the waistband of the jeans. These are the areas that need to stand out against the Sim's skintone in order to prevent them from looking like they've been painted directly on.

Now, flatten your layers, save the bump map file, and check things out in Bodyshop. Depending on your preferences, you might want to play with the Brightness/Contrast a bit more. Don't be afraid to really push your bump maps--interesting textures make for interesting skins.

Here's the before and after of Kim's skin, side by side:

It's obvious to tell which one we've bump mapped. The skin has alot more texture, and--most importantly--the clothing doesn't look painted on. Check out the straps on the tank top, how they appear raised. They actually look like straps!

And thats it :) Thanks for reading.

~ Crechebaby