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Possible bug in Intensity Graph while using interpolate colors on a Log scale (LV2013)

Hi,

 

When attempting to plot data on an Intensity Graph, using a log scale (in particular in the range 1E-9 to 1), with defined color markers, and interpolate colors option 'off' the data plots exactly as expected.

 

However, when you turn the interpolate colors option 'on' the graph displays the correctly interpolated colors on the ramp, but NOT does not map the data to these colors correctly.  It seems to map the first few layers correctly, but not the entire plot, As shown in this image.  The color ramp displays the interpolated colors correctly, but the actual data is not mapped to this correctly.

 

ColorInterpolation.jpg

 

After playing around with various properties of the Intensity Graph, it appears that if you switch on the interpolate colors, and then turn on the "ignore color array" property, it then shows a correct color scale (at least one that matches the now plotted data)

 

I cannot find any reason why this is happening and think it is a bug with the control.  I've also submitted this to service request as a bug, but also wanted to submit it here to see if anyone out there had any thoughts on this...

 

I've found a work around of basically generating the 'log' data and color scale values before sending it to the control, and then plotting the data on a linear scale.

 

I have attached a small VI which shows an example of this behavior.

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I agree that this is probably a bug.  There are several other problems with standard graphs and log mapping, so this does not surprise me.

 

Lynn

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I cannot find the post, but I complained about that in very ancient forum times. When the z axis is logarithmic, the color scale needs to be linear in the log of the values. You should simply use the method on the right.

 

The same happens also with e.g. the scale of meters (see picture). In a better world, the scale should look the same for both!

 

 

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What was your service request number? I can check on the Status of that CAR for you.

 

Rob B
FlexRIO Product Manager
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unfortunately, they didmt provide me with a CAR number....though they did say that they created one...

 

also Im not understanding the solution/work around suggested by altenbach.  do you have an example of what you mean?

 

 

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jyoung8711 wrote:

also Im not understanding the solution/work around suggested by altenbach.  do you have an example of what you mean?


I meant you should use your code version that works (labeled "expected graph behavior").

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@altenbach wrote:

jyoung8711 wrote:

also Im not understanding the solution/work around suggested by altenbach.  do you have an example of what you mean?


I meant you should use your code version that works (labeled "expected graph behavior").


ah. gotcha! a bit inconvenient/annoying but certainly better than nothing.

 

thanks!

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Hi jyoung8711,

 

I just sent you an email about the CAR I created, but thought I would post the CAR number here for everybody else who has similar issues. The CAR number is: 453407.

Kevin S
Applications Engineer
National Instruments
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