Using Textures - A Really Basic Question

[Bob James]

I have a really basic question in the use of textures: I want to put grass in my scene, so I find a seamless grass texture. But even though seamless, it has a repeating pattern that, for a full lawn or field, looks like a patchwork quilt. If I change the scale all that does it make it unrealistic for the size of the grass blades.

So, how do you make a lawn or field look as if it has vegetation on it without a repeating pattern?

Acually, the same is true of any texture on any surface: rust or any grunge on metal surfaces, etc.

[Burkhard]

seamless just means the texture frames does not repeat.
The patterns are image based so you will have them overall. You have to go to large images ( thats why good textures are having large MB sizes ) which is unfortunately not good in Sketchup. Another way is to use a prog like imagesynth or pixplant ( or Photoshop, but I do not know how ) to load the seamless texture and change this patterns with a brush tool or similar. - depends on the software you use. Thats what I do.

[Hieru]

You also have to be mindful that your texture is even in both tone and colour as strong variations will result in patterning.

[Bob James]

@hieru said:

You also have to be mindful that your texture is even in both tone and colour as strong variations will result in patterning.

That's the point: I have seamless textures, but any "anomaly" makes a repeating pattern. Every texture "worth its salt" in terms of realism has this problem. Even things like "grunge/dirt" maps. So how do I make objects with textures look "real"?
Once you use another program to "even them out", the realism is lost.

[solo]

Bob,

Unless you have a texture large enough to cover the whole area there will be a repeat, also depends on your camera position, I have noticed many of your renders are birds eye view, that makes it almost impossible to get a seamless realistic grass texture unless you are using a procedural texture.

[Gaieus]

Yes, I think in this case, the "procedural" is the key. Any simple, image based texture will always have some repeat effect.

Bob, are you using these to render mainly? I have learnt this trick back in the Kerkythea forums: Here is a grass texture (more exactly two):
http://sketchup.google.com/3dwarehouse/details?mid=52aeba6fee1da988846ddcb7a97e4c0d&prevstart=0

One is fully opaque and the other one has transparent "blotches" in it. Place them above each other (the one with transparent areas go above the other by 5-10 cm / 2-4". When rendered, it is still better than those simple images (of course, it will never be as good as instanced grass but you cannot instance square kilometres/miles).

[simon le bon]

Interested by the same question, I had found some time ago a tutorial developed for Unreal Development Kit Tutorials.

Tutorials:Adding variation to repeating textures

"Here it is VERY easy to see the repeating, and yes, this could RUIN the believeability"

"This is the final result. Some repeating is noticeable, but to fix this, tweak your diffuse textures to fit your desired look. Also, any grime layers you lay over this can be rotated slightly so they do not repeat along the same axis as the rest of your textures."

I'm far to have understood the complete process, but what I believe the basic is the following:

• take the seamless texture, decrease any obvious color repeating, multiply it four by four, add with post processing a seamless pattern noise, play with noisy bump or normal maps...
  (if someone understand better and in a way we can use it into SketchUP, he will be very welcomed )

No test from me actually

stay tuned,
simon.

[Bob James]

@Pete
I was afraid that was going to be the answer
I still haven't gotten the knack of creating "grunged" metals and paint in Thea's Material Editor.

@Gaieus
Interesting: I'll take a closer look at this. Thank you.
It looks like I'll stick with instancing vegetation models and using Pete's metal materials in Thea.

@simon
The tutorial is just way out of my league. I have Genetica, but never learned how to use it properly. The tutorial program appears to be even more "professional".