We use both VM and Surfer, and my interpretation of the 'spiky' comment
relates to the contour objects as opposed to the histogram. We have
found that for many of our needs kriging is necessary to achieve smooth,
evenly spaced contouring. This is the only area where VM falls short
and where we turn to Surfer. Even then we typically bring the results
back into MapInfo. If VM incorporated kriging as a modeling option it
would be all we'd need.
Will Mitchell
Geographic Services Coordinator
The Environmental Company, Inc.
Charlottesville, Virginia
804-295-4446
[EMAIL PROTECTED]
>-----Original Message-----
>From: James Harvie [SMTP:[EMAIL PROTECTED]]
>Sent: Monday, February 01, 1999 5:56 PM
>To: Mapinfo L
>Subject: MI VM vs. Surfer (or other)
>
>>Personnaly I use VM and find the interface (version 2.0) quite OK, but
>>the interpolation algorithms yield surprising results : when
>>transforming contour lines (say elevation 1,2,3,... to 10) into points
>>and creating a grid surface based on these points, the cell values
>>distribution is incredibly "SPIKY", with huge concentrations of cell
>>values around integer values (while we could expect a smooth
>>distribution from regularly spaced contour lines).
>
>I assume that the "SPIKY" behaviour you are speaking of is that shown in the
>histogram displayed in the Colourizer dialogue. If this is the case, then
>the spikiness is really just an artifact of the default histogram interval
>used in the graph function. As you know, with histograms, it is possible to
>get very different looking graphs of the same data simply by adjusting the
>width of the sampling interval. This could be improved by allowing the
>user to set the number of intervals as desired. We'll consider this for the
>future.
>613-224-2020 << File: ATT00061.html >>
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