In Part 2 of this series of posts about splines, I mentioned Tolerance as one of the options that we can tweak when doing Spline Freehand.
Tolerance will determine how close the curve will be to the points we define. Tolerance in 0 will force the curve to be interpolated through all the points. This value is tightly related to Increment. But we’ll explain Increment in a following post. For the time being, imagine that while you do the stroke when sketching (with mouse or stylus), AutoCAD is recording the position of your pointer, and keeping some of those values (yes, that’s the increment). According to the amount of points that AutoCAD registers, then Tolerance kicks in. A 0 Tolerance will force the curve to be interpolated through all the points, as I already mentioned. When you change Tolerance to higher values (being 1 the maximum), you will get less points along the spline, which will obviously make it smoother.
Let’s check the following captures.
I made four sketches, roughly similar in terms of the hand’s gesture. They look quite different.
They are ordered according to the Tolerance used. 0, 0.2, 0.5 and 1. My previous explanation should now be really clear. As I move up in Tolerance, the spline gets smoother.
By using CVSHOW command (located in the Control Vertices tab, we can check out the amount of CVs we got from the sketching. I got 115 CVs on the spline with Tolerance=0, and 9 CVs on the one with Tolerance=1. Imagine which is easier to control J
As a best practice, I would recommend to stay closer to 1 than to 0, and always watch the Increment. Since this setting is based on units, it has to be related to what you are drawing, so there are no recipes. If your spline belongs to the side of a consumer product, and depending on the units, the increment needed will be very different to the one you want if you are sketching the roof of a huge convention center.
By the way, the Spline Freehand settings are only available through Command Line.
See you next post, when we’ll cover Increment and make an example.