Changing coordinate updates waveform chart?

[itschad]

Hi All, hope everyone is having a wonderful 4th of July.

Alright, so I am new to labview and finding my things around the simple things pretty well, but having never taken any sort of programming interest, Im a bit behind in machine logic, so I figured I would ask here. 

EDIT: using labview 2009.  Have Vision package

The research I am doing involves analyzing Electron Speckle Pattern Interferometry (ESPI) images and their fringes to observe fracture points/potential weaknesses in different materials and such.  I have made a simple VI which allows me to draw a line on the ESPI image and output the light intensities to a waveform chart to make it easier to objectively determine the size of the plastic region (area where fracturing is most likely to occur).

What I would like is to be able to draw or set the coordinates of the line initially, then somehow be able to move it vertically -- using either simply my mouse or a numeric controller -- and have the waveform chart update in real time as i do it. 

Any suggestions?  Ive attatched my programs, the one called "line.vi" uses numeric input to determine the line coordinates. 

Also, since i dont sem to be able to attach bitmaps, ive uploaded a sample image here http://img594.imageshack.us/img594/3566/espiimage.png  I dont know why imageshack converted it to a PNG though

thanks all 😄

[GerdW]

Hi itschad,

"Also, since i dont sem to be able to attach bitmaps, ive uploaded a sample image here http://img594.imageshack.us/img594/3566/espiimage. png  I dont know why imageshack converted it to a PNG though"

The image got converted to PNG for the very same reason you can't upload BMPs here: BMP-images are uncompressed and so have a big filze size. Usually PNGs are 10 times smaller - and help reducing bandwidth demand on slow network connections... So for the next time please convert your BMPs to PNG before uploading!

[itschad]

I see.  Thanks for the info, Ill be sure to convert next time.

PS sorry for bad punctuation, I havent figured out where the apostrophe is on japanese laptops yet >_>.

[itschad]

Well Ive got something working pretty good to what I want.  the only things i wish i could figure out are:

any way I can get the "up" and "down" charts to display on the same chart? 

and

any way to keep the charts from like flickering?

Labview 2009

thanks for any help!

[GerdW]

Hi itschad,

"any way to keep the charts from like flickering?"

Yes, sure. Delete those "History" property nodes...

"any way I can get the "up" and "down" charts to display on the same chart?"

Yes, sure. Read the context help of the chart... Before you do that you should unite the two while loops into one. No need for two stop buttons. Then it's also a lot easier to plot both curves on one chart!

[itschad]

Hi GerdW,

   I gave what you suggested a shot, and unfortunately, two things happened that I am unsure how to fix.

First, I just deleted the history nodes in the current version of the program just to stop the flickering.  This made a weird issue where once I select the line, the intensity profile keeps adding itself over and over again onto the end of the chart, so a chart that might initially have been 100 datapoints, just keeps getting longer and longer.

Next, I reloaded the original program and tried to combine the two cases into one while loop and output to a single chart, and this gave me a "Wire connected to an undirected tunnel" error.  

Ive attached the file with the particular error, Im sure its something mundane, but Im a bit rusty on my logic haha.

[GerdW · Accepted solution]

Hi itschad,

did you read the context help of the chart? There it is shown what datatype you need to wire to plot more than one curve on the some chart...

"This made a weird issue where once I select the line, the intensity profile keeps adding itself over and over again onto the end of the chart, so a chart that might initially have been 100 datapoints, just keeps getting longer and longer."

This is how charts work. They keep a history (that you constantly clear). You can set the size of the history buffer. If the default of 1024 points is too much for you you may decrease this to 100 - it's just a right-click away... Otherwise you should use a graph, as a graph only plots the points that are currently wired to it (it doesn't keep a history of previous values).