intensity Graphs inc

[FredFred]

Hello to all,

I am trying to develop an intensity plot for a 255x255 map (meaning xy).

My issue with this is that i'm plotting the intensity for each 1x1 box and the intensity will be based on a color scale that would go from 0-5volts (blue-green-yellow-orange-red). If the data coming in falls withing this scale, it will plot in that graph, that certain color.

I can't seem to do this. Can anybody help?

-FredFred

[altenbach]

If I understand you right, you want something that looks like an xy graph but the trace should have variable color. Yes, you need an intensity graph, because regular xy graphs have only one color/plot.

An intensity graph uses a 2D array input (255x255 in your case). Start out with all zeroes. The only thing you need to do is to fill array elements at the desired index pair (x, y)  with a number related to your voltage (z). The color scale is easiest done with a property node (see example mentioned below).

Have a look at my example from a while ago. I'm sure you can simplify it to suit your needs. Let me know if you get stuck. 🙂

[FredFred]

Gracias! Muchas Gracias Mr. LabVIEW Champ!

[altenbach]

I made a quick example based on my suggestion above. For simplicity I assume that you have an x-value for each pixel. It would be very simple to also plot arrays with fewer or more points, just scale to a new range then use "interpolate array" to obtain a value at each pixel.

Of course you might also look into using a picture indicator. The nice thing is the fact that it is always mapped 1:1 to screen pixels.

Message Edited by altenbach on 07-19-2005 08:33 AM

[H2Oyeah]

I am doing something very similar.  I am trying to scan a sample on a microscope and raster the stage around and collect the intensity from the sample in the form of voltages.  In the end I want to create an image with the voltage displaying as the z-axis and x and y being the position.  I examined the previous examples and I think I have an idea how to use them but I don't know how or were to apply my collected intensities or how to make sure that the x and y values change as the stage moves.

Thanks for any help.

[FredFred]

Hola H2Oyeah,

Since you are looking for a plot with Z being intensity and X&Y being position, I recommend using a 3D plot. What you can do is create a 2D array for which you load the intensity values for each column and row (X and Y) and submit this array to the 3D plot. See attached image. In regards to the stage moving, can you be more clear?

Regards,

FredFred

[H2Oyeah]

For the stage movement I am having the stage move one pixil, stop, take a intensity measurement, and then move to the next position to do the same over.  Right now I have the stage move positive x, up one y, then -x, up one y, etc.  The actual numerical position of the stage is not important.   I am just want to make sure that the intensity reading fill in the array in the proper corresponding x, y position.  Is this better?  the 3D graph is a good idea though.  I will try that.

Thanks

[FredFred]

H2Oyeah,

"For the stage movement I am having the stage move one pixel, stop, take a intensity measurement, and then move on to the next pixel to do the same over."

You want to do this and still retain the previous data on the plot?

If so, you can create the 2D array with the set number of pixels and just load the intensity values to each XY position and just update the 2D array as you receive more and more data....

FredFred

[H2Oyeah]

That is what I want to do but I am not sure how to do that.  I do not have a lot of experience with arrays.  thanks again.

[FredFred]

OK look at the following image,

This is my parameter…

Pixels = 9

Row & Column = pixel location, 0 to 8

What I am doing is initializing my array with a value of 0 for intensity and the dimension as the square root of the total number of pixels, (i.e 3x3 = 9). This sets my array to be in 3x3 form.

Afterwards, I load my array into the replace array subset function and I feed in the intensity value I want to change.

 

This should get your foot in the door.  

Hint:

Play around with the vi and with arrays, it will help you out a lot!

To update the array with new values, you can use a while loop along with a shift register to reload your array.

FredFred