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Digitize plots in images

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Hello all,


I wanted to share with you a tool to digitize plots in images using OML and Python. The aim is to convert plots that are introduced in text books like Analysis and Design of Flight Vehicle Structures (Bruhn, 1973):


Such plots are commonly used in industries like Aerospace to calculate constants and other parameters that assess Margins of Safety of components and systems. Finally, we can do a polynomial curve fitting to use these curves and compute these constants without the need to look at the plots everytime they must be applied.


The steps of the attached scripts are:

1) Give the axes bounds, degree of polynomial curve fitting and image whose plot will be digitized

2) Hit Start in the OML script (it will automatically call the Python script)

3) Give a first click with the mouse button to start selecting the corners of the plot

4) Select the corners


5) Give another click to select the points

6) Select as many points as you want


7) Double click with any key to finish the selection

8) Plot is generated and polynomial coefficients are computed and printed






PlotDigitizer.oml ginput_plot.py

João Marabisa, valdir and stmaster like this

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