Tips and Techniques for Creating Seamless Textures
When it comes to texturing, one very important technique you'll need to have a strong understanding of is creating seamless textures. When texturing large areas like roads, walls and roofs especially in video games you'll need to be able to tile a single texture across the entire length of the geometry, because it can take a huge amount of time to create one huge material texture for something like a brick wall. The challenge with this technique is that you must make sure the viewer will not be able to tell when one texture starts and the next begins. This article will cover some very important techniques for creating truly seamless textures.
What is a Seamless Texture?
A seamless texture is usually a photograph of something like a brick wall that can be repeated as many times as needed without any breaks or seams, each corner of the image must be able to meet up and match perfectly with the other. If you were to take a photograph of a brick wall and try to tile it across the geometry it wouldn't work because the left side of the texture would not be able to match up with the right side. To successfully make tileable textures, all four corners of the texture must match up with the opposite corner. For example, the top of the image must match with the bottom. To achieve this you must do some photo manipulation in a program like Photoshop to create a seamless texture that can be tiled across a surface as many times as needed.
Snapping the Right Photo
There are many different websites out there where you can find seamless textures. While these are fine and the textures will most likely work for your project it's better to just take the photographs yourself. There are a few reasons for this. The first one being that you may have to purchase these seamless textures, which can start to add up, especially when on a budget. Even if purchased you'll need to pay very close attention to the user agreement, because you don't want to infringe on any licensing laws. The second reason being is that you know exactly what needs to be taken and how. If you need to create a seamless texture for a brick wall, go out to your city and snap some photos. Try to build up your library so you'll have images you can pull from when you need other textures. If you're going to take the do-it yourself approach and take your own photographs then there are a few very important things to keep in mind for snapping the perfect photo. The first thing you need to ensure of is that you're facing parallel to the subject. You don't want to be viewing it at an angle and you also don't want to have the camera rotated at all. You want to try and take the photograph as straight on as you can. If the photo was taken at an angle then this can cause some strange distortion in the texture and will be nearly impossible to tile correctly. Here is a great example of a bad angle, you can see because of the view that the photograph was taken there is a slight perspective where the bricks further away are smaller. This would be a very difficult photo to use as a material seamless texture. The last thing you'll want to make sure of is the lighting in the shot is nice and even. You don't want to have any hot spots in the image. If you're outside try to find an area where the lighting is even across the surface which will make it much easier when having to tile the textures. To learn more about the proper way for snapping photographs to use as textures in your 3D models be sure to read Five Tips to Improve Your Photography for 3D Textures.
Creating Your First Seamless Texture
Once you have the photo taken now it's time to bring it into a program like Photoshop where you can do the proper manipulation. In order for the photo to be able to tile correctly you'll want to crop it as a square. So for example, 1024x1024 or 2048x2048. Once the image is cropped to the right size you'll need to select a small area of either the right or left side of the image with the selection tool and Layer Via Copy and drag the new copy to the other side of the image. You should notice a pretty big seam where the copy meets up with the original; this can be fixed very easily by using the eraser tool with a very low hardness and opacity and erase the seam and blend it better with the image below, this should make the seem hardly noticeable. Now that you've copied the right side of the image to the left, when tiled both these sides will meet much better. You can repeat this process for the top edges as well. There may be some small seams when you try to tile the photograph in Photoshop, but you can go in and buff them out by using something like the Clone Stamp tool. Depending on your photograph the process may be a little different, but this is a great technique to use to quickly create a nice looking tileable seamless texture.
Using the Patch Tool to Hide Seams
Another great way to hide seams in your texture is to use the Patch Tool in Photoshop. The Patch Tool allows you make a selection around an area of your photograph and copy the selection to where ever the seam is and Photoshop will do a great job of blending these two images together. This technique for hiding seams is best used for photographs that are abstract, for instance, a gravel driveway or a section of grass. So make sure the type of photograph you're working with will benefit from using the Patch Tool approach to hiding the seams. Creating seamless textures is a vital technique to know especially when texturing environments. While this post only covered one approach to creating repeating seamless textures there are many different methods that can work. If you want to dive deeper and learn the different techniques for creating seamless textures be sure to check out Creating Seamless Textures for Games.