IMAQ edge find

I have a system that will be scanning a specific area of a solar cell (see good-broken.jpg). The region of interest (see region of interest.jpg) is what I would like for an IMAQ edge find to operate. The dark area in the middle doesnt allow for accurate readings, so I would like to have the system not scan that specific region. But it is not a big issue of it stays.
Essentially, I would like to have a pixel intensity meter in the region of activity. By having a IMAQ edge find locate the edges of the solar cell and scan the intensity values within it.
Any help would be greatly appreciated
Thanks you
Attachments:
region of interest.jpg ‏67 KB
good-broken.jpg ‏61 KB

Attached is a VI that filters the solar cell's edges. This isn't perfect, but you can use the resulting object centers and bounding boxes to define the ROI you need.
Attachments:
ImgFilter.vi ‏145 KB
VisionAssistFilterScript.vascr ‏4 KB

Similar Messages

Edge detection using IMAQ Find Edge/IMAQ Edge Tool 3

Hi,
I have several images with useless background around a rectangular ROI (coordinates unknown!). So I tried using the two VIs mentioned above in order to detect these edges so that I can remove them. Regretfully, this does not work as planned.
IMAQ Find Edge usually finds an edge, but not where it should be. The edge detection is earlier than I want it to be.
IMAQ Edge Tool 3 sometimes does not find an edge at all, sometimes it finds the edge perfectly. Here I use the 'get best edge' option, which delivers the best results with all the images I tested it with.
All the other options are also not changed while running the VI with the images I have.
Does anyone have intimate knowledge of these VIs' algorithms, how they work, how they can be manipulated, ... ?

Hi,
Can you upload an example image?
That would clarify what you're trying to do?
Most of the time a change of mindset solves the problem.
Kind regards,
- Bjorn -
Have fun using LabVIEW... and if you like my answer, please pay me back in Kudo's
LabVIEW 5.1 - LabVIEW 2012

USB Camera Flicker, and Showing Edge Finder Results

Attached are 3 files. The vi (simple.vi), the variable library and the project file. Hopefully it reassembles easily.
One issue I am having is that the image 'flickers', and it seems to be creating havoc with the vision tools. What is also strange is that every once and a while, it seems a 'raw' image (meaning color) slips in, which may actually be the flicker problem. I am using a USB camera to capture the video.
I thought of using a shift register, which helps a little, but the problem persists. I have a feeling it is something dumb I am missing.
Also, I am trying to figure out how to get the 'Imaq Simple Edge' to show up on the screen, like the 'Imaq Find Edge' does. I am assuming there is a Boolean somewhere I am missing. I would like to use this to see if the edges are where they are supposed to be, as well as if the lines are drawn in the right place. This is mainly for debugging purposes. What I have been using in the interim is the Vision Assistant to see if the calculated values line up with where they should be. It would be much nicer to have it in the VI.
In case you are curious, what I am trying to do is find 4 discs on any of 3 pins. The camera and target are not locked together, so I am using the top, bottom and left edges to locate the base, then calculate where the pins should be, then draw edge find lines to see if they are there. Ultimately the logic (not included yet) will allow me to determine which disc is where.
I tried pattern matching, but this setup is too 'random' for it in testing. The basic vision setup in this vi seems to work, and is similar to what I have used in industrial applications in the past.
Thanks for any help.
Rich
Attachments:
Simple.vi ‏216 KB
Variables.lvlib ‏17 KB
Tower.lvproj ‏8 KB

Thank you for the feedback.
I tried the 'Snapshot' option, and the graphic overlays disappeared. Ultimately, this doesn't matter, but while I am still tinkering, it is useful to have it displayed.
What seems to have fixed it, is I removed the shift-register, and got rid of the Imaq Cast. Instead, I am using the 'IMAQ Create' to make the grayscale image. This has gotten rid of the twitch, as far as I can tell, allows the overlay, but the image displayed is color (not a big deal). Attached is the updated VI/
I still can't figure out how to get the overlay for the Edge Detector lines. Attached is a picture of what I would like to display with the edge finding lines (the little green squares).
I am assuming the Edge Detector is less processing intensive than the Find Straight Edge. This is the reason I am using Edge Detectors to find the discs. If this is incorrect, I can probably use the find Straight Edge to find the edge I am looking for.
Attachments:
overlay.JPG ‏112 KB
Simple.vi ‏216 KB

IMAQ edge tool 2 "First + last edge" - returns position only of the first edge

I`m using "IMAQ edge tool 2.vi" with Process set to detect "First and last edge. It`s obvious from Edge infromation indicator that it returns only one point coordinates. Where are the coordinates of the last edge detection?
Note: it detects edges along the long green horizontal line, so there are definitevely at least 2 edges.
Thanks for advice.
Martin
Solved!
Go to Solution.
Attachments:
screenshot.JPG ‏42 KB
vi_screenshot.JPG ‏40 KB

Hey Martin,
This may sound silly, but what happens if you scroll to the next entry in your cluster? Right now you are displaying the information for your '0' edge on the front panel. What happens if you index to the '1' edge in your cluster and hence look at the information on the second edge. Is the cluster blank when looking at the 'zero' edge? If it is, perhaps the settings on your find edge step are too strict and the step doesn't pick up on a second edge.
If the problem persists, perhaps posting your sample vi and a sample picture will help clear things up.
Hope this helps!
-Ben
Hope this helps.
-Ben
WaterlooLabs

How can you detect irregular edges using the IMAQ add on?

Im currently trying to use the IMAQ add-on for LabView to detect the edges of an irregular image. I have attached the image I am trying to detect the edges of. I have tried using everything in the "locate edges" sub-pannel (i.e.. imaq find edge, imaq find circular edge etc.) but none of them have yielded any favorable results. I think the "IMAQ edge tool 3 IV" might be what im trying to find however I don't understand how to get any usable data out of it.
Thank you, all comments and help are greatly appreciated.
Attachments:
waveguide.png ‏516 KB

Hi Dander,
I am not sure exactly what types of edges you are trying to acquire, but I used one of the examples from our Example Finder and was able to detect edges on your image. I will say that with the image that you are using, the edges are not very well defined, so you may not get a 100% accurate measurement. The example that I was using uses the IMAQ Edge Tool 3 VI and the example can be found by going in LabVIEW to Help>>Find Examples... From there, you will go to Toolkits and Modules>>Vision>>Functions>>Edge Detection Example.vi. After that, you will remove the build path function and input a path to the image. I hope this helps!
Kim W.
Applications Engineer
National Instruments

Imaq line guage

Hi -
I want to overlay the edge points found using the IMAQ Line Guage VI, very similar to how it is done in the 'Edge Detection Example.vi'.
However, the only outputs for the IMAQ Line Guage VI are distances. I can use the IMAQ Edge Tool 3 to get edge information to overlay, but it is unclear to me that the edge information provided by the IMAQ Edge Tool 3 is consistent with the calculations in IMAQ Line Guage VI. I do need the sub-pixel accuracy.
Can someone let me know how we can do this with IMAQ Line Guage?
As another note, I tried using IMAQ Edge Tool itself but was obtaining some very strange results for distances, which is why I turned to IMAQ Line Guage, which is giving me good results.
Thanks,
Don
Solved!
Go to Solution.
Attachments:
overlay edge points.PNG ‏13 KB

OK. The caliper function finds edge pairs along a specified path in the image. So I tried this but am getting an error that not sure how to handle. Here is my strategy. I am drawing a line on the Vision Image and using the ROI property node to extract ROI descriptor. I use the same edge parameters that I had been using with the Distance fx. Below and attached are the screenshot and VI if you have any suggestions. I am sure we are close. I only want the first and last edge. Distance and coordinates so I can overlay the latter onto the line where edges are detected.
Error -1074395318 occurred at IMAQ Caliper Tool
Possible reason(s):
IMAQ Vision: You supplied an insufficient number of points to perform this operation.
Attachments:
caliper with overlay.vi ‏23 KB

Is there a way to force rotobrush in CS5.5 AfterEffects to a specific contour that the automatic edg

Is there a way to force rotobrush in CS5.5 AfterEffects to a specific contour that the automatic edge finder will not recognise? Such as a light color car moving in front of a light color building.*

> Now Adobe, listen up.
You can submit feature requests (and bug reports) here: http://www.adobe.com/go/wish
More on feedback for After Effects: http://adobe.ly/93d6NF

Automating Edge Detection?

I have a question about the IMAQ edge detection VI. I am designing a VI that will be counting edges in an image many times in succession. My question is that since the area in question will not change as the image changes, is it possible to just measure along the same line every time? Can I select a start and end pixel location for the edge detection? At this point I have to click and drag a line and it is very tedious for the amount of images that will be measured.
Thanks,
Mack

Hi Mack24,
Which tool are you using for edge detection? The shipping example "Edge Detection.vi" allows you to specify a ROI of a line to detect edges against.
The example can be found under Toolkits and Modules->Vision->Caliper->Edge Detection.vi
-N
National Instruments
Applications Engineer

How do I properly use imaqCentroid() ?

Hi,
Earlier, I used particle filtering and imaqCalcCoeff(IMAQ_CENTER_MASS_X, Y) to find the center of mass of a black circle printed on a white piece of paper.
Then I would like to try to calculate the center-position using the grayscale image, to achieve sub-pixel accuracy.
I have tried running imaqCentroid() on the image, with a mask surrounding the black circle (the ROI is set to a few pixels larger than the binary particle found at same position).
But the results from imaqCentroid() is much worse than when using blob/particle analysis. The center position is quite different, and there is much more jittering.
I suspect that I need to modify my grayscale image before running imaqCentroid(), but I am not sure which st
eps/functions to use.
Comments?
Thanks,
Torbjørn

Try a white circle on a black background. It will work better. Another option is to invert your current image.
The white pixels carry the most weight (255) when using IMAQ Centroid. The black pixels carry the least weight (0). Right now, you are calculating the centroid of the white strip around your circle. By inverting the image, you will calculate the centroid of the circle.
The best results for IMAQ Centroid are obtained with a white object on a black background. If the lighting is not even or the color/brightness is not even, you will get shifts in your centroid away from the actual center.
I think your results with blob analysis will be better and more consistant than IMAQ Centroid. Another option, if your blobs are all circles, is to us
e Find Circular Edge once you know their approximate location. This uses edge finding to very accurately determine the position of a circular object.
Bruce
Bruce Ammons
Ammons Engineering

DreamWeaver Template change not updating children webpages?

Hi Group,
Sorry for my newbie question here.
I loaded an HTML webpage, and saved it out as a DreamWeaver Template file.
I then created webpages from the template file (( File - New - Page From Template - Site - Template), and made sure that the "Update Page when Template Changes" check box was selected/checked.
I then created several chldren webpages, and saved them as .html files.
I decided to change the navbar system - part of the uneditiabel region in the template - by opening the template file and edit-ing that file, and then saving it as the same DreamWeaver template file.
However, the webpages did Not Update to reflect the navbar changes in the template fle !??!???
Can someone tell me what I'm doing wrong?
I believe it is something that I'm doing incorrectly with DreamWeaver ..
Here is the HTML if anyone is interested.
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No -I haven't been able to get the DW Template feature to work on other sites - this is my first application of it to a website (actually it's the whole reason for getting DreamWeaver... I know it works, I know that I'm doing something wrong.. I just don't know what it is...)
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Extract repeating sequence from tdms

Hi experts,
I have weeks of time series data in TDMS files that are analog logs of a repeating sequence. I need to extract each of the repeating sequences and overlay the waveforms to determine variances between sequences (sample data attached including 5 blocks attached)
The start of each block is defined by the pulse on channel "Bubble Detect Trigger". What I need do is time slice each TDMS between the trigger pulses and overlay all the slices on a chart to see how the other channels line up.
Is there a way of doing this in Signal express or DIADEM?
Help much appreciated.
Solved!
Go to Solution.
Attachments:
TDMS_subset.zip ‏200 KB

Hey Kurt, thanks for your interest.
I'm looking to do a simple overlay. In the attached example tdms there is a group called Timeseries Data, which was captured using SignalExpress and DAQcard. I need to find the edges of the Trigger channel, chop the TimeSeries data up and overlay the repeating sequence. I have done this manually to show the end result in the group called Overlays. By doing this Raw3 can easily be seen to be different from the other sequences.
The analysis is done offline and I need to automate as I have a couple Tb data to process. SignalExpress has some functionality to do edge finding and subset data so I thought that might work, and Diadem is supposed to be great for handling large amounts of data and has scripting so I thought that might work. I just dont know enough about either tool to get the results I need....
Thanks again for your help.
Mark.
Attachments:
Example Analog_Captures.zip ‏707 KB

Need to perform robust feature extraction and tracking to determine the motion of the camera with respect to a stationary background ?

i have tried to use intensity thresholding but the variations make this unreliable. I need to determine a way to efficiently extract reliable features within a ROI (which can be determined by the last known speed of the platform) and correspond these between successive images to determine speed ? Are there any image analysis/image processing gurus out there? I have enclosed a typical image from one of my sequences (please note the faint stripe of light moves with the platform - it is not a stationary feature)
Attachments:
2108_.jpg ‏23 KB

I tried equalizing your image (Lookup Table: Equalize) and searched for a horizantal edge (Find Straight Edge: Horizantal Edge) with a very high contrast value (100) inside a very big ROI and that seems to work fairly robust. I'm attaching the Vision Builder Script.
Let me know if you have any questions.
Regards,
Yusuf C.
Applications Engineer
National Instruments
Attachments:
script.scr ‏1 KB

VBAI 2010 Fatal Error (NaN to number)

I'm getting a fatal error (see attached banner image) that I have never seen before in VBAI 2010: A NaN value in a calculator step gets interpreted as a large negative number (-2.14E+9) in a subsequent Create Region of Interest Step, which in turn causes the subsequent Edge Finder to trigger the fatal event.
The root cause, in this case, is a missing measurement (a frequent occurence for this and other similar calculator steps in this routine), the x-coordinate for an edge enpoint in previous step, from which I subtract a 2, i.e., I'm trying to set an ROI boundary 2 pixels away from the previous edge found. Typically, when I have a missing measurement in this situation, the subsquent ROI ends up at the image origin (0,0), but VBAI does not crash.
I fully undestand why VBAI crashes with an ROI edge set so far out in "Left Field", but I'm at a loss to explain why an NaN caclulator output get's interpreted as -2.14E+9. When stepping through the routine in Configuration mode and editing the Create Region of Interest step, a message indicates that a "missing measurement is being replaced by a constant" or something to that effect, and the constant turns out to be -2.14E+9, so I assume that this same process takes place in the background when in inspection mode. But what I don't understand is why my routine has never thrown this error before when the measurement was missing, but as of this morning, it throws the error every time!
I've got a temporary work-around (check for NaN in the calculator step and force to zero if needed), but I have a large number of similar sequences to fix and want to make sure I understand why this fatal error suddenly appeared.
All ideas appreciated,
Eric
Solved!
Go to Solution.
Attachments:
VBAI_Fatal_Error.PNG ‏34 KB

This is fixed in VBAI 2011 and newer. It will no longer crash with the updated VDM dlls and in VBAI, if a previous measurement used by the ROI step is NaN, the ROI step will treat it as a missing measurement and the ROI step will fail. The reason NaN gets cast to a huge number is because NaN is only valid for double values, and the ROI coordinates are integers, so when we internally convert the NaN to an integer, it gets interpreted as a large number. Not sure why this would just start happening today though.
Hope this helps,
Brad

Convertir les contours d'une image en tableau

Hello,
I begin in Labview and its Vision module.
I have at present the outline of an image obtained with IMAQ Edge Detection whom I copied in tabular form exploitable under Excel for example.
The problem is we obtain a board (of dimension equal to the size of the image) where the values of cells correspond to the value of pixels.
I would want to know how to modify this board to have simply the coordinates of the points where I have a value superior to a threshold which would be grouped in a board of two columns.
Thank you for your help
Attachments:
prog.PNG ‏9 KB

Hello,
What you can do is use the "Threshold detector.vi" function. It will output the indices of the elements that exeed the threshold for a 1D array you just need to add a for loop to make it work with 2D array.
Best regards,
FYI you should use array instead of board.
Rodéric L
Certified LabVIEW Architect

Detect barcode automatically

Hello All,
Started a new project for my company.
1.    I have a code 39 type barcode which i had generated using labview. (done with the help of forums)
2.    I have to print this image to the printer. (not done)
3.    Using Camera(usb) I want to scan the barcode-Here I want the labview to automatically detect the ROI of the barcode and display the code in the string indicator.
Please help me complete this project.
Here i attach the first part of this project.
Srikanth Chilivery,
Attachments:
code 39.zip ‏479 KB

What sort of background do you expect the barcode to be placed on?
If the patterns outside the barcode is not striped, or checkered, you can use the edge finder to determine an area in the image where the image have a lot of parallel white/black transitions
The result is alot of infinitle lines, that gives you approximately where the edges of the barcode is (width) and angle.
and if you then sample some of those lines you should be able to find the height., and tada a ROI rectangle + angle.
then for robustness increase the the size of that rectangle, and voila, a barcode finder tool is created.
Engineer, M.Sc. Autonomous Systems, Automation and Control of non-linear systems
Project Engineer @ R&D A/S
www.rdas.dk

IMAQ edge find

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