Here's some tips for creating realistic textures:
First, get a decent paint program that supports layers.
I reccomend Photoshop.
Next, get yourself some photographic source material. Metal, brick, dirt.
Now, cut out a section of your source material which is square, and then scale the image to 512x512, or 256x256. Textures hsould always be powers of 2.
Now, copy your texture to a second layer, and blur it by 64 pixels. Then make that layer black and white. Then invert it so white is black. Then make the layer "soft light" or if you don't have that, try multiply. Fade the layer until the lighting over the image looks fairly even.
Now that you've evened out the lighting, use the offset filter in your paint package to offset the texture by half it's width and height, with wrapping turned on. The edges of the texture should now be in the middle.
Use the clone brush to copy peices of the texture from the corners and paint with them over the middle to remove the visible seams. The healing brush in the latest version of photoshop is especially good for this.
Now you have a seamless texture which should tile without too many ugly repeating light patterns or seams.
If you're trying to do stuff wirh brick you'll need to distort the image before you do the offset step to try and line up the lines in the image from one side to the other. Having the grid turned on will help. Painting over the seams will then be easier. Also make sure when you crop the initial image you choose edges that will either have whole or half bricks there or else you'll never be able to make seamless brick.
Now here's the fun part. Let's assume oyu've made a seamless metal texture. All you need to do now to make it interesting is add beveling and holes. To do that, you make a layer on top of it, and then make some 50% grey shapes in there. Then you use the bevel modifer to make these shapes appear to indent inwards or outwards. SHARP bevels will generally look more professional and realistic than soft bevels. So don't make the bevels too rounded unless you're going for a specific effect. Now that you have a beveled grey square that looks like it goes in or outward, set the layer to soft light. Or if you don't have soft light, copy the layer, and make one copy multiply, and one copy screen. You can also use dodge and burn but you'll have to turn the layer transparency way down or it will look like crap.
Finally, add holes. To make holes, first make a grey beveled shape. The brightness of the middle will be unaffected. Btw, sometimes you might want to make your bevel grey a bit darker to make the low part of the bevel a bit darker than the high part of the main texture cause it adds depth... Okay so now you have a bevel. Now make another layer on top of the bevel and make a black shape to fit the middle. Voila. "Hole"
Here's another tip. Pay attention to lighting. For wall tiles, make the bevels have light from the top of the texture, down. So inner bevels should have the bright part on the bottom. In most levels, light comes from the sky. But for floor tiles, you don't want to do that. In fact, you may not want much beveleing at all, but you can try to have a little. Foor tiles are lit from a number of directions so a bevel in any one particular direction might be exactly the opposite direction of whatever light source happens to be in the room. So bevels on floors are generally a no no. Instead, try making black holes. But under the black hole layer, make white holes with a slight blur, and then set those to screen or dodge and fade the layer a lot. That will make the area around the black hole appear to be scuffed metal.
Finally, let's assume you did not start out with a metal texture but instead started out with a plain grey background. Well, just stick a metal texture over everything and set it to multiply. Then adjust the brightness and contrast until you get a good effect. Make it really bright and you'll get a nice dirty look to your metal. But if you up the contrast, and brighten it up you can make some bits be very dirty and other bit be clean.
Adding dirt in this way is the key to making realistic looking textures. You can also use an alpha map to paint dirt only into the corners of the texture or only dripping from the holes in a wall.
You can also paint in streaks and stuff coming down from holes and that works well. Jut make lots of random lines going down and the blur them, and then maybe up the contrast of that layer assuming you painted on a white background and the layer is set to multiply. That will de blur them a bit if you up the contrast. But the blurring will help the lines to run together.
Phew. Well that's a lot of details but that's pretty much how I make my textures.
First, get a decent paint program that supports layers.
I reccomend Photoshop.
Next, get yourself some photographic source material. Metal, brick, dirt.
Now, cut out a section of your source material which is square, and then scale the image to 512x512, or 256x256. Textures hsould always be powers of 2.
Now, copy your texture to a second layer, and blur it by 64 pixels. Then make that layer black and white. Then invert it so white is black. Then make the layer "soft light" or if you don't have that, try multiply. Fade the layer until the lighting over the image looks fairly even.
Now that you've evened out the lighting, use the offset filter in your paint package to offset the texture by half it's width and height, with wrapping turned on. The edges of the texture should now be in the middle.
Use the clone brush to copy peices of the texture from the corners and paint with them over the middle to remove the visible seams. The healing brush in the latest version of photoshop is especially good for this.
Now you have a seamless texture which should tile without too many ugly repeating light patterns or seams.
If you're trying to do stuff wirh brick you'll need to distort the image before you do the offset step to try and line up the lines in the image from one side to the other. Having the grid turned on will help. Painting over the seams will then be easier. Also make sure when you crop the initial image you choose edges that will either have whole or half bricks there or else you'll never be able to make seamless brick.
Now here's the fun part. Let's assume oyu've made a seamless metal texture. All you need to do now to make it interesting is add beveling and holes. To do that, you make a layer on top of it, and then make some 50% grey shapes in there. Then you use the bevel modifer to make these shapes appear to indent inwards or outwards. SHARP bevels will generally look more professional and realistic than soft bevels. So don't make the bevels too rounded unless you're going for a specific effect. Now that you have a beveled grey square that looks like it goes in or outward, set the layer to soft light. Or if you don't have soft light, copy the layer, and make one copy multiply, and one copy screen. You can also use dodge and burn but you'll have to turn the layer transparency way down or it will look like crap.
Finally, add holes. To make holes, first make a grey beveled shape. The brightness of the middle will be unaffected. Btw, sometimes you might want to make your bevel grey a bit darker to make the low part of the bevel a bit darker than the high part of the main texture cause it adds depth... Okay so now you have a bevel. Now make another layer on top of the bevel and make a black shape to fit the middle. Voila. "Hole"
Here's another tip. Pay attention to lighting. For wall tiles, make the bevels have light from the top of the texture, down. So inner bevels should have the bright part on the bottom. In most levels, light comes from the sky. But for floor tiles, you don't want to do that. In fact, you may not want much beveleing at all, but you can try to have a little. Foor tiles are lit from a number of directions so a bevel in any one particular direction might be exactly the opposite direction of whatever light source happens to be in the room. So bevels on floors are generally a no no. Instead, try making black holes. But under the black hole layer, make white holes with a slight blur, and then set those to screen or dodge and fade the layer a lot. That will make the area around the black hole appear to be scuffed metal.
Finally, let's assume you did not start out with a metal texture but instead started out with a plain grey background. Well, just stick a metal texture over everything and set it to multiply. Then adjust the brightness and contrast until you get a good effect. Make it really bright and you'll get a nice dirty look to your metal. But if you up the contrast, and brighten it up you can make some bits be very dirty and other bit be clean.
Adding dirt in this way is the key to making realistic looking textures. You can also use an alpha map to paint dirt only into the corners of the texture or only dripping from the holes in a wall.
You can also paint in streaks and stuff coming down from holes and that works well. Jut make lots of random lines going down and the blur them, and then maybe up the contrast of that layer assuming you painted on a white background and the layer is set to multiply. That will de blur them a bit if you up the contrast. But the blurring will help the lines to run together.
Phew. Well that's a lot of details but that's pretty much how I make my textures.