| Author |
 Topic  |
|
|
Johnnye
9 Posts |
 Posted - 02 Feb 2009 : 18:51:55
|
Hi,
I'm evaluating your product for polar charting...
Is it possible for a Polar chart to have negative magnitude (X-axis) values? I'm working from you PolarLineAndScatterChart example, and it doesn't seem possible.
Also, is there a way of resizing the chart when the control is re-sized in a way that maintains an aspect ratio of 1.0 (i.e. to keep the polar chart area a circle)?
thanks
|
|
|
Johnnye
9 Posts |
Posted - 02 Feb 2009 : 22:04:54
|
In relation to my second question: as an example, if you change the Dock property of tabControl1 and polarLineChart1 in your PolarCharts example to 'Fill' then run the application, when you resize the window, the plotted data seems to resize ok (keeps its aspect ratio) and seems to be synchronised to the polar axes horizontally but not vertically.
Is there a way of maintaining the axes aspect ratio when resizing, so that they match the plotted data? Otherwise the chart becomes unusable. |
 |
|
|
quinncurtis
1164 Posts |
Posted - 02 Feb 2009 : 23:36:50
|
The plotting routines only work with positive magnitudes. It would be easy enough to run through the data and convert negative magnitudes to positive with a 180 degrees phase shift (just add or subtract Math.PI to the polar angle value).
There is currently no option to force the polar charts to maintain a fixed aspect ratio, regardless of how you resize the chart. We will be adding that in subsequent revision, due out in a month or two. |
|
|
|
Johnnye
9 Posts |
Posted - 03 Feb 2009 : 01:32:51
|
ok, thanks for your quick reply. If I buy a licence now will I also get the new revision when it comes out?
I have another question - is it possible to align the polar axes so that 0 degrees is at the top and the polar axis increments clockwise? |
|
|
|
quinncurtis
1164 Posts |
Posted - 03 Feb 2009 : 08:56:25
|
You will be able to download updates (new revisions)of the software for two years after purchase.
We don't plan on any options to align 0 degrees at the top of the graph, nor to have counter clock rotation. I don't think it can be considered a true polar plot in those circumstances, but something "like" a polar plot. What application is this? sounds like wind direction, or something similar.
The data transformation would be trivial, i.e. newpolarangle = -(originalpolarangle - Math.PI/2). Changing the radial axes labeling would also be trivial, you could do it if you had the source code, or you could just have our special services group do it for a nominal fee.
|
|
|
|
Johnnye
9 Posts |
Posted - 03 Feb 2009 : 18:33:28
|
The application is an antenna characterisation test system, plotting gain against azimuth, with 0 degrees the 'boresight' of the antenna.
The gain (i.e. magnitude) figures can be positive and negative, so the limitation of positive magnitudes only could be a problem - unless I can easily draw annotations (both polar and radial) on the chart. Do you have any examples of adding such annotations to a Polar chart? |
|
|
|
quinncurtis
1164 Posts |
Posted - 03 Feb 2009 : 19:12:45
|
Handling negative magnitudes is trivial. Just run through the data, if a magnitude is negative, make it positive and add PI to the polar angle.
Adding ChartText using polar coordinates is what you would expect from the documentation for ChartText.
double polarmag = 1.5;
double polarang = Math.PI;
ChartText polartext = new ChartText(pPolarTransform, theTitleFont, "Polar annotation",
polarmag, polarang, ChartObj.POLAR_POS);
chartVu.AddChartObject(polartext); |
|
|
|
Johnnye
9 Posts |
Posted - 03 Feb 2009 : 20:13:45
|
True, but I can have both positive and negative values in the same chart, so I would have to add an offset to all data points to bring them positive. This is ok, but the axes won't be displaying the original values.
So I was thinking that if I could add my own circles to the chart (i.e. draw my own 'grid') that might be a way around this. Is there a way of adding circle and line annotations to the polar chart? |
|
|
|
Johnnye
9 Posts |
Posted - 03 Feb 2009 : 20:24:06
|
| ...I guess I could just create more SimpleDataSets to draw these lines! |
|
|
|
quinncurtis
1164 Posts |
Posted - 03 Feb 2009 : 21:39:19
|
We don't really understand your comment about the offsets. If a magnitude is negative, making it positive and adding PI to the polar angle produces the exact same point graphically.
The polar point (-1, 0) is mathematically the same as the polar point (1, PI).
|
|
|
|
Johnnye
9 Posts |
Posted - 03 Feb 2009 : 23:01:54
|
I have gain data that is typically in the range -40 to +20 dB that is measured at various angles as the antenna is rotated, and this needs to be plotted against azimuth on a polar chart.
|
|
|
|
Johnnye
9 Posts |
|
|
quinncurtis
1164 Posts |
Posted - 03 Feb 2009 : 23:22:22
|
| As we said, that is not what our polar plots look like. We can't tell you how to make the QCChart2D polar plots produce the antenna graph you show. If you want a chart that looks exactly like your example, you either need to get a QCChart2D Developer package, and the QCChart2D source code, and make the necessary changes to the underlying polar plot classes; or hire us to do the same. The later would be much more cost effective. Let us know if you would like a quote. |
|
|
|
Johnnye
9 Posts |
Posted - 03 Feb 2009 : 23:43:02
|
| ok, yes a quote would be great. Let me know if you need any more info. |
|
|
| |
Topic |
|
Polar Plots
