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How to trace a image with smooth spline

CADfan

Member
Dear all,
I searched the forum and found many post regarding
spline by various method like XY co-ordinates, free form
etc.,But i couldn't get a point how to trace a image with
smooth spline. Actually i inserted a blade image thro view
option and trace the outline. But if i check the spline
curve smoothness using curvature analysis tool, It shows
the surface more waviness. Can anybody give me some idea
how to make the smooth curve.I have attached image.

Thanks
View attachment 5805
Edited by: CADfan
 
the curve you're showing is obviously not wavy, only the
curvature is fluctuating along the curve. in order to make
it smoother, you should rebuild the curve with as few
points as possible, that means you can probably trace this
portion of the curve you're showing with 4 points and the resulting curve would be both an accurate representation
and smooth. you only need to place more points where the
cruve sharply bend, in that case, place one point just
before the curve bends,on at the bend's peak, and one where
the bend fades into the smooth portion of the curve.
 
Ok, here we go!


Please have a look at the picture attached


2012-12-27_031027_mcad.zip


from top:


1. your picture and curve.


2. my curve using 3 points in my spline, please not the curvature plot.


3. "how its made", please note the cv points i use for modification.


4. Here you can see more in detail what i have done. FIRST , i create 2 "handles" by sketching 2 curves so that i can start my spline at the end of the curve. This way, i can controll the "start angle" of the spline. (and the end angle offcourse). Then i create a spline using 3 points and start to modify the spiline using controllpoints instead of adding more points to the spline. As solidworm says , always try to minimize the number of points in your spline!


//Tobias
 
there is also an option inside Spline "environment"[double click on Spline in sketcher mode] called Fit, with an area called Fit. change default number to something bigger.

Note - spline can change by making new input
 
You can skip the handles and simply dimension the angle
at
the endpoints.

I'd create a vertical centerline at the endpoints. Then
click dimension, and click the spline, the endpoint, and
the centerline (in that order). Click middle mouse to
finish.

Edit: while using my method in conjunction with tobbo's,
I
found that I cannot modify control points when then
endpoints are dimensioned.

I tried to use the handle method instead and still could
not change control points
Edited by: MGortner
 

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