 +1
Under review

Polar plot point interpolation

bsguedes 5 years ago • updated 5 years ago
Hi,

I'm trying to translate a XY chart into a polar plot. I have a collection of points in a given time that are represented on the XY chart (chart 1) with time on the X axis and the angle (in function of time) on the Y axis.

When I try to plot the equivalent polar chart, I expect to have the time on the radius and the angle on the angle axis. However, Oxyplot connects the points using a direct line between each two subsequent points, like the attachment image I've uploaded (on the 'wrong' label, chart 4).

I would expect that this interpolation would create an arc between each pair of points (char 3): this way, we don't go 'back in time' (you can notice this behaviour on the orange section of one of those lines that I marked on the attachment image... the interpolation that oxyplot does implies that on a XY chart we would have something like the chart number 3... notice that we go backwards in that interpolation too).

Is there a way to consider this kind of interpolation on the polar chart (chart number 2)? Forgot the attachment: http://i.imgur.com/qdDZ9Jx.png Under review
Have you tried setting the "Smooth" property on the LineSeries to true? Hi objo, thanks for the answer!

Unfortunately it does not return the expected chart. If I set Smooth to true, I have this:

http://i.imgur.com/UjQenrZ.png

As you can see, I still have the  "series going backwards" problem. thanks for testing! Yes, smooth is interpolating the final transformed points and will not help here. In this case I think we need to interpolate before applying the polar axes transforms. I think there should be a similar problem for logarithmic axes. It could be handled by the LineSeries, but I think the problem is to find how many interpolated points are required... I think a workaround is to interpolate yourself before adding the points to the LineSeries. Add a ScatterSeries with the original points for the markers. There is something interesting going on when I set Smooth to true. Even though the series is not respecting the time constraint, the tracker is not following the series! It is following the exactly path that I wanted in the first place.

http://i.imgur.com/PmbOkMs.png

It may be difficult to view this as a static image, but when I advance the tracker I never go backwards, like I was trying to do (this will only happen with smooth = true). So this interpolation is being done already some place, it is just not plotted as a series.