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Old 28th May 2014, 03:59 AM   #11
zog666 is offline zog666  Australia
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Quote:
Originally Posted by CharlieLaub View Post
See attached for an example of the polar type.
Hi,
I like that graph as well, having the actual angle of the measurement used makes for readability.
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Old 10th July 2014, 04:16 AM   #12
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Quote:
Originally Posted by CharlieLaub View Post
Hi Zog,
depending on how much I get prodded to work on it
Prod
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Old 13th July 2014, 06:42 PM   #13
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I'll get around to it eventually. I have things more or less working. If you don't want/need to simulate the crossover, and just want to be able to plot multiple axis measurements into one of the plots shown in this thread, you can PM me and I can send you the beta version.

The real release the the directivity plot extension will come along with the next version of ACD, but I am working on some other things and am trying to figure out how to overcome some snag so that everything works nicely under both Excel and OpenOffice or LibreOffice Calc.
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Old 4th November 2014, 09:09 PM   #14
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UPDATE:

I was contacted by someone about plotting some measurement data using my ACD directivity extension, so I have revisited this effort again after putting it down for almost a year. I've attached an example of the output from the latest incarnation.

Like many ways to present data, you can influence the overall impression that one gets from a plot by how you choose the scaling. For these polar-heatmap plots, the SPL range over which the colors are assigned is very influential.

In an attempt to come up with an objective way to define the SPL range, I have used the simple average of the "on axis" data plus the standard deviation of that data to set the limits of the colors as follows:
max SPL = average + 1*stdev
min SPL = average - 4*stdev
Above and below these min/max the data is just assigned the min/max color. This stats-based approach is totally empirical, but is based on the assumption that loudspeaker data (on- and off-axis) typically contains less above the on-axis-average data points than below the on-axis-average data points. Keep in mind that the average is for the "on-axis" data, and SPL in general falls below this on-axis level as you move off-axis.

I will need to look at a variety of different types of loudspeakers (closed box direct radiator, horn, open baffle, etc.) to get a feeling of how this would work in general, but I think that this is a good start towards objective plotting.
Attached Images
File Type: png polar_heatmap_stats_approach.png (294.5 KB, 133 views)
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Old 6th November 2014, 07:09 PM   #15
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I like the 3-d graph.
The human mind should be better at processing this graph.
Trying to represent 3 different variables on a 2-d graph is harder than representing the 3 variables on a 3-d graph.
Also if you have to use 2-d what is wrong with using the straight graphs?
You add an extra layer of complexity making it a polar graph.
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Old 6th November 2014, 10:01 PM   #16
pnix is offline pnix  United States
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Jimmy154,

Which 3D graph are you referring to? The surface plot Charlie has shown in post #8? It will be probably harder to read than the polar heatmap.


Charlie,

Do you have a surface plot of the same driver for comparison?
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Old 10th November 2014, 03:46 PM   #17
Elias is offline Elias  Finland
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Quote:
Originally Posted by CharlieLaub View Post
UPDATE:

I was contacted by someone about plotting some measurement data using my ACD directivity extension, so I have revisited this effort again after putting it down for almost a year. I've attached an example of the output from the latest incarnation.

Like many ways to present data, you can influence the overall impression that one gets from a plot by how you choose the scaling. For these polar-heatmap plots, the SPL range over which the colors are assigned is very influential.

In an attempt to come up with an objective way to define the SPL range, I have used the simple average of the "on axis" data plus the standard deviation of that data to set the limits of the colors as follows:
max SPL = average + 1*stdev
min SPL = average - 4*stdev
Above and below these min/max the data is just assigned the min/max color. This stats-based approach is totally empirical, but is based on the assumption that loudspeaker data (on- and off-axis) typically contains less above the on-axis-average data points than below the on-axis-average data points. Keep in mind that the average is for the "on-axis" data, and SPL in general falls below this on-axis level as you move off-axis.

I will need to look at a variety of different types of loudspeakers (closed box direct radiator, horn, open baffle, etc.) to get a feeling of how this would work in general, but I think that this is a good start towards objective plotting.

The angular resolution decreases towards low frequencies in this plottin style.
Is this propriate, depends ?
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Old 11th November 2014, 08:56 PM   #18
pnix is offline pnix  United States
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Quote:
Originally Posted by Elias View Post
The angular resolution decreases towards low frequencies in this plottin style.
Is this propriate, depends ?
Yes, that might be misleading to some but in my opinion a polar heatmap is clearer than a fence plot for example.
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