overlaid intensity graphs

[Shades]

I have two 2-D arrays.  I need them overlaid onto one intensity graph.  Each array of data needs to be displayed with different colors.

[falkpl]

you could and the arrays this will "mix" the intensity of each pixel.  Or you could use a pixel map instead of an intensity map (easiest if the arrays are the same size) and treat one array as the blue channel and one as the red or green channel of RGB and add the arrays pixel by pixel (you can even use an alfa channel to blend channels).  What is the data you are trying to display?

[Shades]

Each 2-D array is the same size (about 400 by 1500 I believe).

The arrays are ionogram signal-return intensity graphs.  Large splotches on the graph represent signal returns at a certain frequency and at a certain altitude (of the ionosphere).  Here's our database if you want to see them:

http://www.hipas.alaska.edu/ionosonde/history.asp  (some of the info in the about file is inaccurate -- ignore that.)

Were are upgrading to two modes of receiving (X-mode and O-mode).  So I need to be able to display X-mode splotches in one color range and O-mode splotches in another.

[Justin D]

Shades,

I don't think there's any easy built in way to do this with intensity graphs.  There is however a way to do it that's a little challenging.  It involves adding an offset to one of your data sets and setting a custom color range for your intensity graph.  For one of your graphs add an offset that's greater than or equal to the largest intensity values in your other graph (making sure not to add this offset to the cells that have an intensity of zero).  So lets say for example you had 2 2D arrays whos values ranged from 0-100.  Lets call them arrays A and B.  Add 100 to each value in array A (except when the array value is zero).  Then add array A and array B (assuming they are the same dimensions).  You then need to go into a loop and set the zscale.markervals[] property.  Lets say we want array A to be blue in the plot and array B to be red.  We want our array of clusters to look like the following...

0    black

1    very faint red

...

99 very dark red

100 black

101 very light blue

...

200 very dark blue

When all is said and done, you will have both of the plots on the same graph in different colors.  You will just have to remember that if you want the numerical intensity of any of the offset plot's points you will have to subtract the offset first.

Hope this helps,

Justin D.

Applications Engineer

National Instruments