Method for measuring distance of a irregular curved profile

[Mahesh_stud]

Hi All,

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I am trying to measure a curved profile of a surface(2D) to determine the surface availability at different rate of testing. I have attached an image for a rough picture. Actually I have a reference geometry and performed two tests to determine the behavior. They two had different profiles at top portion. So I considered an axis for reference geometry and drew radial lines with 15deg angle difference each and marked those points as 1 (15 deg anticlockwise from vertical axis),2(30 deg anticlockwise from vertical axis),3,... and measured length of the radial lines which gives the distance of the top profile at different points(L1 at pt1, L2 at pt2...). I did the same on my first test results and got the lengths L1',L2'...and with second test lengths L1",L2".... Now I estimated the deviation of the profile by calculating the error like this test1: Error = ((L1-L1')/L1)*100% test2: Error = ((L1-L1")/L1)*100% As the number of experiments increases it is a bit tedious to divide lines based on angles and measure the deviation of the top profile and hence would like to look for an alternative. One approach would be to eliminate the axis and split the complete area with square grids and get the coordinates (x,y) and find the error, but this seems not too good. Could any one please suggest an easy method to do find out the difference in the top profile? Thanks in advance

[Trurl]

I don’t follow your method, but what I think you are trying to do is have an equation explain an unknown, irregular graph or shape. That would be gold dust that would allow any graph to be easily described.

 

I think of it as 3D Studio Max. You are drawing a shape that is irregular from pieces of “molded” shapes. The drawing file in Max must be mathematically described, but is not an elegant equation describing the contours.

 

But remember when you draw you draw starting with the basic shapes. As in your transformation from one graph to the other, it appears you have no reference graph. Perhaps you should try a known, defined graph and try to modify it to from the “transformed graph.” Remember in subjects like electricity, much descriptions are transformations of the Sine curve.

 

I am not a math expert, obviously. However, I now you must simplify this problem. I don’t understand the transformation you did in your drawing. However, do not let that stop you, because how you explained it may be entirely different that the method I understood. But as I have personally learned, explaining the math problem is as important as finding the answer.