| Re: Editing Shapefile [message #69774] |
Sun, 14 February 2010 15:53 |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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Adakite writes:
> So, What I am trying to do now is quiet tricky, I know! I would like
> to open and display this shapefile, containing elevation information
> (this is already done actually), so as to edit it by two ways:
>
> (1) able to change "by hand" the elevation attribute of each curve
> inside the shapefile displayed (e.g. when I select with mouse a
> specific coutour line, get a text box pop-up with elevation attribute,
> and the edit it and save.
>
> (2) still mouse selected countour line in this shapefile, so as to
> obtain discret points lying along the countour line. Then I once I
> selected one of these points I would like to move it on the map
> (meaning that the countour line will be reshaped/remodeled).
I would say all of this is *possible*, but it certainly
doesn't fall into the "easy to do" category. For an example,
you could view the AnnotateWindow application. Draw a polygon,
now click inside the polygon to select it. Handles appear
at each vertex, which you can move, etc.
http://www.dfanning.com/catalyst/annotate.html
My goal was to make these kinds of user interactions
easy to accomplish. I would say I probably failed
miserably in that regard. These objects are complicated
and much more difficult to program than I expected them
to be.
Getting the selection right might be the most difficult
thing. If you are lucky your contours might be easy
to select with the mouse, but my experience with luck
is that it usually runs against me. I would be tempted
to come up with some other selection method (contour
levels in a pull-down menu?)
Once you have the contour selected, ARCSAMPLE from the
Coyote Library might help you establish "control" points
which can be manipulated and moved. You don't want too
many of these, but you don't want too few either.
Once you have control points, I think you can probably
find your way home. Moving the point is not so difficult,
if you have done some thinking about the problem ahead
of time. It will help if each contour line is its own
"object", I think, so it can be drawn individually.
You might consider using ISOCONTOUR to draw your contour
plots.
Humm. Now that I am thinking of all the difficulties again,
it might be a better idea to figure out a way to sneak away
for cheap margaritas. :-)
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")
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