Quickly Get Heat Map as Image (Code Review Request)

[JScherer]

My VI is receiving about 5k - 10k rows from a database table with the following information:

X(mm)     Y(mm)    occurrence(#)
0000.00  0000.00      002
0002.00  0000.00      052
0005.00  0000.00      071
.......  .......      ...
9999.00  0578.00      300

I would like to take the data and quickly generate an image that I can overlay drawing elements (circles) that will highlight areas of interest.

Is there any way I can improve this vi to

• Stop using the hidden 3dplot control
• Add an X,Y axis
• Render the image more quickly

[BertMcMahan]

Instead of drawing by points couldn't you just convert your data to a pixel array and use Draw Unflattened Pixmap? I think by default your points will be pixels but you could fuzz each one to include neighbor pixels as well, right?

(I don't use much picture stuff, sorry).

[altenbach]

Just use an intensity graph and quantize the x and y values to a reasonable grid. You can easily do a 2D histogram as described here.

Initialize a 2D I32 array, place in shift register, autoindex on data and use the IPE to increment values at scaled X,Y to array indices. Use a nice color ramp for the z scale.

[altenbach]

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@altenbach wrote:

Just use an intensity graph and quantize the x and y values to a reasonable grid. You can easily do a 2D histogram ...

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Here's what I had in mind...

(you can hide the x and y scales or remap them to actual values using x0/dx if the scaling is different) 

[JScherer]

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@altenbach wrote:

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Here's what I had in mind...

(you can hide the x and y scales or remap them to actual values using x0/dx if the scaling is different) 

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I like the intensity graph, but how would I draw the user's regions of interest on the graph? (eg, a circle r 30 at XY=0,0)

[GerdW]

Hi JScherer,

you can draw those circles into a 2DPicture and use that picture as front image (by property node) of the intensity graph…

[altenbach]

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@JScherer wrote:
I like the intensity graph, but how would I draw the user's regions of interest on the graph? (eg, a circle r 30 at XY=0,0)

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"Plot images" property.

(example to draw a line, but any 2D image tools are of course allowed)

Here's an old example drawing circles on an intensity graph.

[altenbach · Accepted solution]

Simplified example:

(To do: Size graph area such that pixels are square, ensure execution order (draw circles only after axes have autoscaled), Do axis mapping such that data and axes can go from -100 ..+100, etc.)