newbie, looking for a digital caliper tool

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newbie, looking for a digital caliper tool

unxzst
Hi all, I have a task of measuring the distance between dark lines on an
image. I'm sure this has been done before, but I can't find where.

What I need is a digital micrometer. A pair of lines that can be rotated,
moved and spread to get relative measurments between to pairs of lines is
all thats neede.

Here's the scope: a reflective coating on a Fizeau-Tolansky micrometer will
have fringes 2730Å apart, an area with no coating will show up as shifted
fringes. I need a pair of rotatable parallel lines to measure the distance
between the normal and shifted fringes, and calculate the relative
dispalcement. I'm trying to make this usable by people with minimal
computer understanding, and <100Å accuracy.
 
My problem: minimal java understanding. Just the tools included in ImageJ
are enough for an accurate measurment, but this needs to be very user-
friendly, and I can't find anything that is so. Please send my way any
links to related material, Java tutorials on creating a sort of digital
caliper, related work, anything! It will be greatly appreciated.
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Re: newbie, looking for a digital caliper tool

Justin McGrath
Wouldn't drawing with the line tool then using measure work?  It will
create a table of lengths, which is pretty user friendly.

If you wanted to get fancier and get a length that you're fairly sure
is perpendicular, you could find the angles of the parallel lines
(either by the user drawing with the line tool or through some image
processing technique), then calculate the length of the line segment
perpendicular to them.  With a macro, you could have it so that the
user needs to only draw two lines.  If you can find the angles with
image processing, then you could eliminate all user input.  The Hough
transform is one that can find lines, but I don't think there's a
plugin for ImageJ.  If all of your lines are vertical, you can do a
much simplified Hough transorm pretty easily.

A rotating calipers tool seems needlessly complicated.

Justin

On Wed, Jun 4, 2008 at 9:50 AM, Andrei <[hidden email]> wrote:

> Hi all, I have a task of measuring the distance between dark lines on an
> image. I'm sure this has been done before, but I can't find where.
>
> What I need is a digital micrometer. A pair of lines that can be rotated,
> moved and spread to get relative measurments between to pairs of lines is
> all thats neede.
>
> Here's the scope: a reflective coating on a Fizeau-Tolansky micrometer will
> have fringes 2730Å apart, an area with no coating will show up as shifted
> fringes. I need a pair of rotatable parallel lines to measure the distance
> between the normal and shifted fringes, and calculate the relative
> dispalcement. I'm trying to make this usable by people with minimal
> computer understanding, and <100Å accuracy.
>
> My problem: minimal java understanding. Just the tools included in ImageJ
> are enough for an accurate measurment, but this needs to be very user-
> friendly, and I can't find anything that is so. Please send my way any
> links to related material, Java tutorials on creating a sort of digital
> caliper, related work, anything! It will be greatly appreciated.
>
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Re: newbie, looking for a digital caliper tool

unxzst
In reply to this post by unxzst
Thanks, Justin.

I've been crawling up this same wall, what seems user friendly to us, may
be inexplicaply complex to someone that is not computer-savvy: the end-
user. I am shooting for minimal complexity:

Step 1: position/size/rotate caliper lines with keyboard.
Step 3: press Enter to take measurment.

The problem with the images is that they are fairly warped, and deciding
the right measurment through user input seems the logical choice.

for example: http://i51.photobucket.com/albums/f356/Unxzst/DSCN1560.jpg
http://i51.photobucket.com/albums/f356/Unxzst/DSCN1487.jpg


On Wed, 4 Jun 2008 11:31:28 -0500, Justin McGrath <[hidden email]> wrote:

>Wouldn't drawing with the line tool then using measure work?  It will
>create a table of lengths, which is pretty user friendly.
>
>If you wanted to get fancier and get a length that you're fairly sure
>is perpendicular, you could find the angles of the parallel lines
>(either by the user drawing with the line tool or through some image
>processing technique), then calculate the length of the line segment
>perpendicular to them.  With a macro, you could have it so that the
>user needs to only draw two lines.  If you can find the angles with
>image processing, then you could eliminate all user input.  The Hough
>transform is one that can find lines, but I don't think there's a
>plugin for ImageJ.  If all of your lines are vertical, you can do a
>much simplified Hough transorm pretty easily.
>
>A rotating calipers tool seems needlessly complicated.
>
>Justin
>