What are the exact terms of use? "Free to use" can mean many things like "you can't make commercial things, you can't re-sell, you can't re-distribute".

We recommend one or a combination of these licenses:

• CC-BY 3.0
• CC-BY-SA 3.0 
• GPL 3.0 
• GPL 2.0 
• CC0

Very impressive collection, but as qubodup said, pretty useless without a clear license. If you mean they are free to use for anything but would want a link back as said in the page footer, then CC-BY 3.0 is ideal. If attribution would just be nice to have but not required, then CC0 basically puts them into public domain. Personally I would not encourage using GPL as the (only) license as it is meant for software, not art.

The textures seem to be all very high quality, I would suggest to use CC-BY 3.0 or CC0, if you want to see others use your textures a lot, but everything more complicated will likely keep most people away from using them.

If you chose CC-BY 3.0 you could put your name or your site as attribution requirement, so people will have to put your name or site in the credits, if they use your textures.

With CC0 there is no requirement to credit you, but quite many people are nice and do so anyway, so in practise there is not so much difference between them, even with CC0 you remain the author.

Basically yes, but include a link to the license text (http://creativecommons.org/licenses/by/3.0/) and who to attribute. Creative Commons has a handy generator here: http://creativecommons.org/choose/?lang=en which produced e.g. this HTML code:

<a rel="license" href="http://creativecommons.org/licenses/by/3.0/"><img alt="Creative Commons License" style="border-width:0" src="http://i.creativecommons.org/l/by/3.0/80x15.png" /></a><br />These textures by <a xmlns:cc="http://creativecommons.org/ns#" href="http://seamless-pixels.blogspot.com" property="cc:attributionName" rel="cc:attributionURL">hhh316</a> are licensed under a <a rel="license" href="http://creativecommons.org/licenses/by/3.0/">Creative Commons Attribution 3.0 Unported License</a>.

Which looks like this:

These textures by hhh316 are licensed under a Creative Commons Attribution 3.0 Unported License.

(Edits after original post: tweaked wording, fixed link)

Wow, thanks alot.

Pretty nice textures... just need to be run though a normal and spec map tool like crazy bump ;)

What tool are you using to make them seamless? Could you make a small tutorial?

Actually that would be very nice if someone having the license for crazy bump to produce them.

Well there is this: http://opengameart.org/forumtopic/someone-willig-to-update-insane-bump-p...

not sure how well it compares to the crazy bump output, and it still has a few minor bugs...

There is a normal map plugin for gimp or a free alternative called njob, where you have more control about how large your bumps should be.

Otherwise it is not very useful to generate normal maps for others, since it depends a lot on taste. Only in special cases, for example baked normal maps or other difficult effects it is useful to pre make them for others.

http://www.smart-page.net/smartnormal/

@riidom: it has one big proble. It has to undo the light using that normal map to obtain diffuse texture.

Also doesn't give you specularity maps and uses Adobe Air with is about the most crappy and dead/unsupported format ever (especially on Linux).

Edit: Ok you can use the Flash based web-version... but I hate relying on web-based service.

I started using the diffuse map for specular map also in most cases, it is not much disginguishable and even looks better in many cases.

How it works seems to be quite irrelevant to me, as long as it works. About problems under Linux I cant tell anything, sorry.

Also, auto-generation of specular maps is generally no good idea, because it is hard to guess what should be glossy and what not. I would rather do that in a 2D-editor.

For web-services.. it is nice as long as they are there, in general the whole story is not exactly reliable, I agree in that point. It is just a very quick way of doing a normal map.

There is another limitation, I remember, about texture size. The guy in #blender mentioned that really big textures wont work, so one has to probably scale down to 1024² or similar.

tl;dr: Yes, it is not perfect :)

cemkalyoncu, I dont really understand what you mean by obtaining the diffuse map; this is what we start with, I would consider it given?

In the above examples the light an shadows you would normally find is a photo texture are already removed somehow (the original author has not explained is technique yet). But tools like Crazy Bump try to algorythmically "flatten" the photo and thus remove some shadows from the then thus created diffuse texture (e.g. that is where that name comes from: no shadows as if lit by diffuse light).

In gimp: Dublicate layer, set mode to extract fibre and set opacity to 50%, this will simulate a tool removing the shadows, maybe not perfect, but works.

For diffuse maps, Julius explained it pretty good. For faking it, have you seen the output of crazy bump? There is a solid reason why program says: Puny humans are instructed to wait!

 I dont see any lighting problems on hhh316' textures, they are diffuse, so why are we talking about that? And why is everyone all of a sudden comparing this webtool I linked to, with crazybump? If somebody wants crazybump, I suggest to just buy it.

I'm done with this thread, except the original post, which is awesome and doesnt deserve such silly discussions.