# Angle measurement from colour survey

Tags: #<Tag:0x00007fb8823cc408> #<Tag:0x00007fb8823cc1b0>

#21

I’d still like to know what the Orientation column represents…

Yes… you can use dy/dx to get the direction

Note that the median Orientation and slope are not the same value.

But it seems to me that using the “dominant direction” option is a much easier way to get the general directionality of linear elements in your image.

#22

Good day Ron DeSpain,

Laura wanted to get the numerical orientation-angles of the yellow needles/indicators overlayed to her image. These angles can be computed as described by me.

Regards

Herbie

#23

Good afternoon Herbie and Ron DeSpain
thanks for replies.
Yes I wanted to compute the angles of the yellow lines of my original image and I found useful the method described by @Herbie.Thank you Herbie, this is exactly what I needed.

However, Ron despain when you say that median orientation and slope are not the same value, what did you mean? When you sau slope, you mean the little yellow lines on the image? I know these two are not the same value, so what’s the difference then? Cause I think this might be something I’ll look into. If I compute the dominat (preferred) orientation of a little region of interest using e.g. Orientation J measure or dominant direction, then I compute the angles of these little yellow lines, it means these two values will be different. So what’s the difference?

Thank you

#24

You are the man Herbie!

I’d like to use the Orientation column…do you know its units?

Thanks
Ron

#25

Ron DeSpain!

You are the man Herbie!

Not sure if that’s polemic …

I’d like to use the Orientation column…do you know its units?

You are free to do so, but did you realize that this column contains only two numerical values?

Obviously the units are radians and the values give you the quadrants of the orientations.

HTH

Herbie

#26

It’s a compliment

Thanks for the info.

Ron

#27

@rondespain Could you please have a look at my previous comment?
I am not sure what did you mean in the last image you posted.

Thanks

#28

Hi Laura

If you want the individual angle of each of the vectors in your vector field image you will have to relate each vector’s position with X and Y in the image and then compute its angle with DX and DY as proposed by Herbie and as I did in the excel spread sheet shown. The X and Y values seem to be associated with the lower right corner of a grid of squares that surround each vector. You can access values in the ImageJ results table using “getResult(“Column”, row)”, but I’m not sure how to get the values from the OrientationJ spreadsheet.

If you want the general (median) direction of lines in your selection then all of those calculations are done for you using the dominant direction option in OrientationJ.

I haven’t messed around with the colored image.

Ron

#29

Laura

If you figure out how to access the spreadsheet data would you please let me know how to do it?

Thanks
Ron

#30

Rondespain,

I am not sure where this “getResults” is. Are you still talking about Orientation J vector field? If so, I just see the “show table” button. Whereas from Orientation J dominant direction I just get a table out of it. So where did you see the “getResults”?
I would tell you how to get the spread sheet but I don’t know.

#31

getResult is a macro function built into IJ, so it only affects you if you’re writing macros…and it doesn’t work with the OrientationJ spreadsheet anyway.

you can select the spread sheet data via click and drag, copy it via ctrl-c, and paste it in excel. you’ll have to type in the first row by hand in excel as the IJ spreadsheet doesn’t allow selection of the first row with the variable names.

Sorry to take so long to get back with you…some times I get an email and sometimes I don’t…don’t know why…

Ron DeSpain