[Tioga-users] monochrome image

[Roy Mayfield]

> On Dec 12, 2006, at 8:13 AM, Edwin wrote:
> 
>> I'm actually thinking about using make_contour and then just t.fill to  
>>
>> fill the resulting area. I think this should work well
>>
> 
Bill Paxton wrote:
> 
> 
> Hi Edwin,
> 
> Unfortunately, you may not be happy with the results if you do a fill 
> with the contours.
> 
> I've used the "industry standard" contour finding algorithm, and it 
> seems to work okay for stroked contours.  But if you take a very 
> close-up look at the contours you'll see that they are doing goofy 
> things with lots of tiny zigs and zags and a large number of breaks, 
> none of which are really necessary.  (Try printing out the number of 
> gaps in a typical contour -- you'll be amazed!)
> 
> If you can suggest a better contour finding algorithm, we could give it 
> a try.  But I'm afraid this is one of those problems that turns out to 
> be a lot more difficult that it looks at first.
> 
> Here's the link to a description of the current routine:
> http://local.wasp.uwa.edu.au/~pbourke/papers/conrec/
> 
> --Bill
> 

Hi Bill,

I'm not a contouring whizbang but have been pleased with the results 
from the GRI graphing package (http://gri.sourceforge.net/).  Dan Kelley 
(Oceanography Dept, Dalhousie University) is the primary author and has 
been fine-tuning this GPL'd software for about 15 yrs now.  The contours 
that it produces don't seem to be jagged or broken like those from the 
CONREC routine that you describe, especially when one of 3 types of 
smoothing are specified.  When I pull the contours into xfig (via 
pstoedit), they come in as continuous polylines and I can select the 
entire line with one click.  Dan has also taken a shot at labeling the 
contours.  They aren't perfect in all cases, but are surprisingly, um, ok.
-- Roy