There are several algorithms mentioned on that page. Do you need the diameter, width, or something else?
Oh , I did not realize that .Actually first i implemented diameter algorithm [ http://hpaste.org/49925 ] and tested it on couple of test cases . Its working fine then i tried to implement " The minimum area enclosing rectangle for a convex polygon" using four calipers but i don't know whats wrong code.
Do you have some example data and what wrong result you get? For any test input [ which i tried ] it outputs 4 . If its implemented correctly then it will accepted here with slight modification [ http://www.spoj.pl/problems/WLOO0707 ] since it asks for square area. Couple of test cases which i tried .
ghci>final [ P 1 1 , P 2 2 , P 0 100 , P 0 1 ]
Loading package array-0.3.0.0 ... linking ... done.
Loading package bytestring-0.9.1.5 ... linking ... done.
4.0
ghci>final [ P 0 0 ,P 5 1 , P 9 2 , P 12 3 , P 14 4 , P 15 5 , P 16
7 , P 17 10 , P 18 14 , P 19 19 ]
3.9999999999999982
ghci>final [ P 2 ( -3 ) , P (-1 ) 2 , P 0 5 , P (-5) (-1) , P (-4)
( 2 ) , P 4 0 , P 1 3 , P 4 3 , P (-3) (-4) , P 0 (-2)]
4.0
Thank you
Mukesh Tiwari
On Aug 6, 10:32 pm, Tillmann Vogt
Am 06.08.2011 13:12, schrieb mukesh tiwari:> Hello all , Hi
I am trying to understand rotating calipers [ http://en.wikipedia.org/wiki/Rotating_calipers] but i am not sure if understood this algorithm correctly . I tried to use the almost same algorithm given on wiki but with four calipers to solve the problem [http://cgm.cs.mcgill.ca/~orm/rotcal.html].
There are several algorithms mentioned on that page. Do you need the diameter, width, or something else?
My approach is find xminP, xmaxP, yminP ymaxP and their corresponding calipers will be ( 0 * i - j ) , ( o * i + j ) , ( i + 0 * j ) and ( -i + 0 * j ). I implemented the algorithm in Haskell but its not working . I am not sure if i have followed the wiki algorithm correctly and could some one please tell me what is wrong with implementation. It would be great if some one can explain this algorithm in pseudo code which explains the rotating caliper and their implementation details . In case of indentation , see here [http://hpaste.org/49907] . Thank you Mukesh Tiwari
I tried your code on one of my libraries. The convex hull function seems to works correctly (I could send you a screenshot). I hope this narrows the search down. Do you have some example data and what wrong result you get?
In one of my libraries (http://hackage.haskell.org/packages/archive/collada-types/0.3/doc/htm...) there is a function:
streamAnimation :: [(Float,Float,Float)] -> [SceneNode] -> [Animation]
that can visualize a stream of points by an animation. I use this sometimes for debugging.
-Tillmann
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