Hi All, 
     Hope someone can help me out here if im not asking too much.
       As an example ill use a brick wall to try & explain myself.  In Carrara, lets say i want to create a simple scene with a virtual brick wall in it, and i've used the units in carrara to make it 6 feet square as in a brick wall im looking at in the real world ( ie, im creating objects in the scene to match the real life dimentions etc ), So here i am with my lovely scale brick wall, obviously, to make it look real im going to have to use a texture map of some kind to apply to it. Actually applying a texture is not a problem, but, to achieve my goal im going to have to take a photo with a trusty digital camera i assume, suck it in to my puter & load it up & apply it. So this is where i fall down, based on how close my carrara render camera is going to be to my wall at render time ( lets say 8 feet for the sake of argument ), how the hell do i work out what resolution / size the image needs to be ? will a 24 bit image of 1024 x 1024 do the job ? will it need to be 2048 x 2048, or bigger even to avoid all the pixels being stretched up to the size of small blocks, then theres the DPI, if i were to render an animation of my wall with intent to show it on a PAL tv screen, how many dots per inch would be required to make it look right ?  Bit of a heavy subject i know, but i'd really like to learn the rules of creating photorealistic texture maps and im sure other PPL will be interested in this too.
    Note: Im fully aware that realism can not just be had from a texture map & that lighting, surface texture, highlights and all the other parts need to me right too, but thats another challenge to play with once i understand the colour chanel texture requirements.
          I suppose there must have been books written on this very subject as its not an easy thing to atchieve in a 3D application. Anyone seen / recommend one of these books ?

Any help would be greatfully appreciated

Take Care All

Paul