Creating curves with equation and controlling the "t" parameter

[cure4u]

I am creating optical components with very hi accuracy and fine tolerance. The calculations of the components are done in ZEMAX optical CAD program. I could use step file export from this program, but I feel that I have no control over the export and import of step files. So I decided instead to create curves from equations. These equations contain very small parameters and are very precise.
The thing is that I can’t control this “t” parameter, which the equation uses. I know that t goes from 0 to 1, but how many steps does it do in between? What is the increment of “t”? I suppose that the “t” increment would change if I change the accuracy, or?
I try to log a call with PTC, but the really didn’t understand my question… the replied that “t goes from 0 to 1”. No shit! Is says so in the text in the editor. But thanks for trying J
Would love to get the “t” under control
Best regards
Daniel Persson
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[bfrandsen]

Daniel,
I have no clue about the step size, but I have found out, that a curve
made from equation is not precise on its derivative. So they are precise
for f(t) but not f'(t), f''(t)... Might influence optic design.

Regards,
Bjarne



"Daniel Persson" <->
26-03-2009 22:31
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"Daniel Persson" <->


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[proecad] - Creating curves with equation and controlling the "t"
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I am creating optical components with very hi accuracy and fine tolerance.
The calculations of the components are done in ZEMAX optical CAD program.
I could use step file export from this program, but I feel that I have no
control over the export and import of step files. So I decided instead to
create curves from equations. These equations contain very small
parameters and are very precise.
The thing is that I can?t control this ?t? parameter, which the equation
uses. I know that t goes from 0 to 1, but how many steps does it do in
between? What is the increment of ?t?? I suppose that the ?t? increment
would change if I change the accuracy, or?
I try to log a call with PTC, but the really didn?t understand my
question? the replied that ?t goes from 0 to 1?. No ****! Is says so in
the text in the editor.  But thanks for trying J
Would love to get the ?t? under control
Best regards
Daniel Persson
(-)
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[cure4u]

Hi Bjarne

It most certainly has an effect my optic surface. I suppose that ProE is making increments along the curve and then creation a spline though the points created. That’s why the f’(t) does not match, I suppose. But if I could get t to make very small steps the deviation between would be very small, I recon.

Br

Daniel

[nkaminakis]

You can have control over the "t" parameter if you want to...
suppose you want a line curve y=10x-32, from 100 to 300.
you set:
x=100+(300-100)*t (t=0, x=100, t=1, x=300)
y=10x-32

if your inteval is [a,b] the x parameter is set as x=a+(b-a)*t, for a,b as
REAL values....
then your y function can be any function of x....

regards,

[cure4u]

Yes, I know how to contoll t in an interval. But how many steps does t take berween (in the example above) x=100 and x=300. That increment of t when the spline is created, that's what I want to control.

Br

Daniel