Prop1 in IGES TYPE 126

Hi,

Type 126 PROP1 states that:
If the curve lies entirely within a unique plane, the planar flag
(PROP1) is set to 1, otherwise it is set to 0. If it is set to 1, the
plane normal (Parameters 14+A+4*K through 16+A+4*K) contain a unit
vector normal to the plane containing the curve.

1. what is the unique plane referred here?
2. what kind of test could decide if the curve lies on this unique
plane?

please correct me if I am wrong.

thanks.

jeff

 

All points on said curve (or all control points) are within
some small number of being on that plane.

How small that "some small number" is probably varies.
But, as you now *know* that it's supposed to be on that
plane you can recompute it on the new system if needed.

In addition to the plane normal parameters you need one
point that is on that plane or the plane it's self. Where is it ....
I'm not going to go drag out the spec to see ....


Different systems use different limits for computing precision.
Consider 16 bit vs. 32 bit and similar ... and on many systems
you could even set where the decimal point was in floating
point computations IIRC .... do you want to maximize the
accuracy for counting pennies with trillions of dollars or
involved computations with absolute values of the data less
than 1?

Probably a poor example but .... all sorts of different
computational accuracies exist.

 

BTW, Why the sudden flurry of questions about IGES from
what may be several folks?
Just curious.

I could go drag out a copy of it .....