Tangents on a flat surface

Question

Currently I am trying to do some bump mapping but would like to know how to find the tangents of a flat surface. I have already defined my normals but not sure about tangents, I have drawn a diagram and would like some confirmation on whether this is correct or not.

T representing tangent and N representing normals enter image description here

Hi Michael I was wondering if my diagram is correct for tangents? — DorkMonstuh, Apr 25 '13 at 20:29
I did answer this comprehensively at http://stackoverflow.com/a/5257471/524368 — datenwolf, Apr 25 '13 at 22:12
To be fair, he wanted to know if his picture was correct, though your explanation is very nice and indepth. I figured another pretty(er) picture would help more than the actual matrix math. BTW, nice answer. — Michael Dorgan, Apr 25 '13 at 22:19

score 3 · Accepted Answer · answered Apr 25 '13 at 21:05

Here is a link for you showing pretty pictures for tangents and explaining why certain directions for tangents are chosen. Keep in mind that any vector that is perpendicular to the normal is a valid tangent (an entire circle of vectors around the normal that will travel along the tangent plane.) Therefore, your diagram is technically correct. The tangent (and bitangent) vectors aren normally chosen to move along the positive U and V direction of the texture at right angles to each other though to simplify bump/normal mapping. See the link.

Tangents on a flat surface

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