polar coordinate in imageannotation

Aug 27, 2013 at 1:15 PM
Edited Aug 27, 2013 at 1:16 PM

I want to display a polar image something like:


Can someone give me some pointers where I can start?

thanks a lot.
Aug 27, 2013 at 1:26 PM
The image drawing is restricted to rectangular shapes.
A custom series is required to render this. You should create an image that covers the sector (the pixels outside the sector should be transparent). For each pixel, calculate the polar coordinates, interpolate the value and set the pixel color by the color axis. This sounds like a fun example - should be added to the example library!
Aug 27, 2013 at 2:50 PM
I am not 100% sure how to do what you said.
I am working on it. Hopefully I will spend enough time to make it work.

Thanks a lot objo for this library. By the way, I hope you checked the bug I posted in imageannotation.
Aug 27, 2013 at 11:53 PM
Edited Aug 27, 2013 at 11:54 PM
See the new 'PolarHeatMapSeries' example (under 'Custom series' in the example browser). It is not optimized for performance, but hopefully you can use some of it for your own custom implementation.
Aug 29, 2013 at 9:04 AM
thanks for the example objo.

Interestingly I need x-y coordinates not polar, on the axes. And still no zoom on polar coordinates. I have to zoom since I have too many points and single points are of significant importance for visualization.

I was thinking may be I can make an oxyimage which looks like polar (example) and render it on XY grid.
Aug 29, 2013 at 9:40 AM
It should be possible to do this with one or two extra lines of code - where you transform from the X/Y coordinates to polar coordinates, which are mapped into the data array (I assume your data is in polar form)
Aug 29, 2013 at 9:55 AM
Added a new example. Not optimized for performance.
Aug 29, 2013 at 12:22 PM
thanks again objo. deeply appreciate.

but it is rather slow. I have to find a way to use an image instead of a series. I will use your tips and try to get it to work. I will keep posted if I need some guidelines.
Sep 6, 2013 at 10:17 AM
Edited Sep 6, 2013 at 12:14 PM
Using writableBitmapex, i can make a polar image, for about 50k polygons it is pretty fast. Each pixel is brawn as a polygon. Working on how to render it with oxyplot.


Cant make polygons with float coordinates. writablebitmapex cant be used. Square one.
Sep 6, 2013 at 7:23 PM
This was a fun little example to show the functionality of OxyImage and custom series :) I added an ImageSize property to the example series. Set it to >0 and the heat map will be generated at a fixed size, not adjusted to the size of the plot area.
I added some examples with different image sizes under "Custom series" in the example browser.
Sep 9, 2013 at 1:04 PM
thanks a lot objo.
Oct 3, 2013 at 12:13 PM
how do i get image coordinates (in XY) by mouse click??