[Gmsh] 3D graph

Jake Chrzanowski jmchrz at gmail.com
Wed Mar 1 21:31:44 CET 2006


 Hi,

I've been reading about the program your working on, Gmsh, and was wondering
if it had the functions I need for a project I'm working on:

I'm trying to create a 3D graph to represent an image and the distance that
image is away from a source.  I was looking at your GLT program to do this.
I was wondering if your Gmesh program had the necessary functions I needed
to do this?  If so, can you point me in the right direction on what the
functions I need would be?  Below I described a little more in depth of what
I'm trying to do.
First, I'll give you a little detail on our overall project so you have a
better idea of what I'm
dealing with.

We're trying to measure the distance of an object using two cameras.  Two
identical cameras are positioned near each other with a separation
distance and focusing angle.

The Image-Processing Computer applies filters to conform the images so
that meaningful features stand out in contrast to non-meaningful features
(i.e. shadows, textures, glare, and reflections).  The computer uses a
vast array of image-processing algorithms to find key features in the
images.  Cross-correlation is performed between the features in both
images to determine the line-of-site angle and separation distance.  With
that found, triangulation is performed to determine the distance that an
object(s) is away from the cameras.
-------------------------------------
Now, once we have determined the distance, we want to have a 3D graph
display the object's distance away from the camera (part where I'd like to
use Gmesh), as they come into focus. (i.e.  The graph will be continually
updating at 10 frames/sec along
with the cameras) I have attached a general 3D graph .bmp file to show you
kinda what I'm looking for. (Obviously, the graph won''t portrude negative
as the .bmp file since the camera only look in one direction)

What I'm thinking is I will basically take in two parameters.

  1) The coordinates of the edge detected (horizontal and vertical pixel
location).  Edges won't be detected in the entire area ( i.e. a wall
focused in too closely will ideally show no edges).  The graph will
only be concerned with areas that edges were detected.

  2) The other parameter that needs to be taken in is the computed
distance from the cameras of the detected edge.  This is the parameter
that will determine how far the graph protrudes out in the z direction.


Ideally, I would like for portions of the graph to change colors
corresponding to a certain distance detected (i.e. 0-1 feet red, 1-2 feet
orange, etc...).

Also, something that isn't needed (but would make the graph look a lot
better), is if I could use some interpolation functions so areas that
were encompassed by edges would protrude out, too, instead of just the
edges.

Sorry about the length of this email.  I just wanted to give you a good
idea of what I'm looking for.

I also attached a picture (" picture2.bmp") that had gone through an edge
detection program.  The white lines are detected edges.  Everywhere else
in the image now has a pixel intensity of 0.

I'm looking for a library to help me accomplish all or most of these
things listed with the 3D graph. I am an amateur at computer programming
, so the simpler the better (I'm an electrical engineering major, we don't
get a chance to learn too much about how to program).  Anything you can help
me with I would really appreciate.

Thanks a lot for your time and I'll look forward to your response.

--
Sincerely,

Jacob Chrzanowski

Electrical Engineering Student, NDSU
jmchrz at gmail.com
(701) 866-3120
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