Camera　calibration　is　a　fundamental　task　in　computer　vision　and　photogrammetry.　This　paper　presents　an　approach　for　automatic　estimation　of　intrinsic　parameters　from　images　by　using　vanishing　points　with　orthogonal　directions.　Firstly,　image　lines　are　extracted　and　are　clustered　into　groups　corresponding　to　three　dominant　vanishing　points.　Second,　camera　parameters　including　the　radial　distortion　are　estimated　by　adjusting　linear　parameters　locating　the　images.　Finally,　the　rotation　matrix　of　the　projection　matrix　is　computed　from　the　vanishing　points,　and　the　image　edges　and　the　translation　matrix　are　obtained　with　the　help　of　additional　translation　motion　between　the　viewpoints.　Our　approach　does　not　need　any　a　priori　information　about　the　cameras　being　used.　Experiments　to　evaluate　the　performance　of　this　approach　on　synthetic　and　real　data　are　reported.　(C)　2009　Society　of　Photo-Optical　Instrumentation　Engineers.　[DOI:　10.1117/1.3070650]