Nope, I know what his problem is.
Cong, where are you getting your cement reference from? And what size are you downloading? Link me and it should help me to help you better.
It could be either one of these things, or both:
1. The reference for your 1024x1024 texture is lower than 1024x1024, and your stretching it out. NEVER stretch an image out. You'll need to use it to create a seamless texture, and tile it. This keeps the resolution and gives you the same quality only bigger.
2. Just because you find a reference of cement, doesn't mean it's the right reference for cement. Why? A lot depends on how close the camera was in taking the reference picture, and then how close the player is going to get to that texture. Your highway here would look great at 200 yards away, but once you get close, you'll see it doesn't look as great as you thought. Detail is lost the further you get from an object. Complicating things more, in the game world, detail is also lost in the texture resolution as well.
Getting into the advanced stuff: You'll need to find the middleground between how close the player is going to get (and how far), and what size resolution you can use while still suspending disbelief (other important factors are how much more resources you can spare. Ideally you want everything to be the highest res you can get it to be. This is of course limited to system specs). Have you ever noclip'd outside of a TF2 (I think TF2 does it) or Unreal III map? The textures on the objects far away are a horrible resolution. Why? You'll never get close, but from far away, it looks real.
But what if the player gets close at one point? Use LOD (level of detail). If your engine supports it, it could load in a smaller resolution file to reduce overhead if your far away, and once you start to get closer, ease into the higher level of detail resolutions.
Hope that helps. Be sure to link me to where you go the texture.
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