Trace Data Question

**EdSheridan** · 10-20-2006, 01:12 PM

Ok,
Say I have a 512 point frame trace that I want to convert into 128 point trace...I'd just use every 4th point.

But how would you go about converting a 400 point trace down to 128 points? Is there an easy way to do this or it as complicated I think it is?:hammer:

Do I find the lowest common denominator?

**HarryChiling** · 10-20-2006, 02:06 PM

If you are talking about how to programatically do it. Feed your trace points into an array and use a counter to recreate the file pulling out all data that is divisible by 4 (remember to initialize your counter at 1 or add 1 before dividing) Hope this is what you are asking about.

**shanbaum** · 10-20-2006, 02:33 PM

Changing trace formats requires interpolating new points in the spaces between existing ones, unless the new format is a whole-number-fraction of the old (as is the case in converting from 512 to 128).

I don't know how complicated you think that is, but it's not trivial.

I have no idea what Harry's talking about. Harry, what are you talking about?

**EdSheridan** · 10-20-2006, 02:43 PM

My thought was to change the 400 point trace into a 3200 point trace by adding equal points between, then picking out every 25th point (128*25=3200). I think this will work, but I don't know if it's the best way to do it or just the best way my feeble mind can come up with.

**shanbaum** · 10-20-2006, 02:51 PM

Equal points? You could do a linear interpolation between points to produce 3200, but I suspect that you would end up with a rough shape. To get a smooth edge, you have to use a more complex kind of interpolation.

Mind you, it depends on what you're going to do with that - if you're just going to display it, your approach may be adequate.

**HarryChiling** · 10-20-2006, 03:21 PM

Originally Posted by shanbaum

I have no idea what Harry's talking about. Harry, what are you talking about?

I don't know what I was talking about. I didn't read the question all the way through. I though he was going from a 512 to a 128 in which case it is not difficult because he would not be creating points just using the existing points. If you were to go from 400 to 128 that would be a lot more dificult. I was giving a psuedo code example of how to acomplish it, but I did not see the remainder of the question.

**AWTECH** · 10-22-2006, 06:55 PM

Ed:

I think it would be very useful for any of us that want to try to help you to know what accuracy you are trying to achieve.

As one post asks; if you are using these for display that is one answer, while if you are using this to edge you would have to know if you are using z trace data the type of edger. (wheel or blade size may have a bearing on how to create the correct new points.