How to photograph for a texture?

I have done limited texture photography myself, so I can't claim to be an expert, but there are some things you need to watch out for. Also, post processing is unavoidable.

You could use cheap-ish cameras for the job, however cameras on the cheaper end suffer more from artefacts such as barrel distortion, chromatic aberration, and CCD noise, etc. There are ways to overcome these problems, but a midrange to good camera helps.

For best results, use as much indirect lighting as possible. Make sure the scene is well lit, because it helps increasing the signal to noise ratio in the result. Camera flash is generally bad in dark light conditions, as it produces a central hotspot in the resulting image. For example, if you take a picture of a white wall with flash, you will notice that the image corners are always darker. Essentially this is low frequency "noise", which can be mitigated by applying a high pass post-processing filter and then by renormalising the contrast. Using flash is particularly bad for shiny surfaces, such as marble floors, etc. Either use indirect lighting or an indirect camera flash, if you have one available.

You will need to play with the zoom to minimise geometrical distortions in the image. It's better to physically move closer or further to the subject as opposed to relying on the zoom too much. You will need correct for barrel or pincushion distortions in the post processing stage. This is especially important if you want to create a texture that contains straight lines (eg. brick wall texture, floor boards, etc).

Finally, you will need to make your textures tile-able. If you have a repeating brick pattern, the texture seams will need some photoshop work. I believe there are some tools to automate this to some extent, but I can't think of any (maybe someone else can?).

These are a few tips from my own personal experience:
- Take photos of surfaces that are not directly lit by any light source, like in shadowed areas or during overcast days
- Adjust the colors in photoshop to remove the ambient lighting (.e.g. remove the blueish tone caused by the sky lighting) to obtain the pure surface color
- Obviously you should aim the camera as perpendicular as possible to the surface to avoid any perspective distortion
- If possible, take the photos from a distance or high places to get a wide sample of the surface so the surface repetion doesn't become too evident in the game
- When taking photographs of tiled walls or geometric patterns you may notice "fish eye" distortion caused by the lens (straight lines showing a bit curved) which you may need to compensate with some tricky photshop editing

The post processing can be done quite easily in photoshop with some practice.

Thanks a lot for all the useful tips. I'm going to give a try to this experiment.

of course, as flat on as you can get to nearly orthogonal is the angle to pick, but thats obvious

Im just sick of looking for textures on the internet and they are all angle shots, and I cant use them, nice photos of shop building fronts with some heightmaps manually crafted off the photos can give you a result like this ->

Here's an article from UDN I've found to be pretty interesting: taking better photos for textures.

BTW, some of the tricks I mentioned earlier was featured on gamasutra ages ago:

http://www.gamasutra.com/view/feature/3073/the_power_of_the_high_pass_filter.php