The input material I took photos of the grass in my backyard to create a grass texture. The camera was held at shoulder height pointing down. I cropped the image into a 1:1 image. Try to keep the image as big as possible. Do not scale it into your desired dimension yet! Make it tileable! There are two methods to make the image tileable/seamless. The easiest way to create a tileable texture is to use the “Make Seamless” tool (Filters->Map->Make Seamless).