I have used both sufer and VM. Each has its problems and strengths.
VM + excellent, simple interface without loosing flexibility
good features, excellent graphical output and ability to 'fiddle'
good draping and 3D representation - for the right company this may be
enough alone
I feel the software is more intelligent in its design than MI itself
- lacking support of replicable bugs, initially my concerns were at least
dealt with(not solved), the last four attempts have not been replied to
four algorithms for grid generation, inverse distance and rectangular
interpolation are never an option for me(poor results). Triangulation
w/ smoothing is rarely useful. Natural neighbour methodology is my most
frequently used algo., however, it generates many repeatable
errors(using hulls) and sometimes refuses to calculate grid values for
areas that it should be able to.
no 'on contour' labelling option as in surfer, ie, the only label it
gives you is the ability to label using the max/min attribute that it
assigns to each line or poly region. You must manually place EVERY
contour label manually
Surfer
+ KRIGING, produces excellent, believable contours the great majority of
the time(VM, get kriging if at all possible)
you guessed it, on countour labels, for those who like to have the black
and white photocopy useful, this is a great feature
good flexibility and manupulability(eek) of the parameters of the model
- surfer doesn't incorporate the background layer very well, I've never
given it a real honest effort though, in short its not simple
the generated contour plot is not placed in reality, its only a graphic
element on the sheet of paper, so you create a contour plot, drag and
drop it a bit, and post the well values onto the plot, and it doesn't
place the labels in the right spot
it is a real pain to get the data out of surfer and into a mapping
package because of the above. MI 4.5 and Surfer just don't mesh all
that well with the exchange of dxf's. If you mess around with the
transform it can be done though. This is a great disadvantage to VM
that just creates the contours in MI
I'm not the best review of Surfer because I use VM primarily. When VM coughs
and can't produce descent contours, I turn to Surfer. VM seems to be well
thought out and at times I feel as though they suffer from some corner cutting
done by MI. VM is by far better software, if it had Kriging it would be hands
down the winner, however, you can't always get good contours with VM, I'd say
about 10% of the time.
In defence of Surfer, you could purchase Surflink, it takes the surfer data into
MI. But now your dealing with three software companies, each updating and
changing at their own merry pace. I've never tried it.
Also a disclaimer, I work mainly with irregularily spaced data in non-earth
projections. Quite often this data is only marginally suitable for contouring.
For your standard DEM, both are viable and VM is my preference.
Colin Anderson
______________________________ Reply Separator _________________________________
Subject: MI VM vs. Surfer (or other)
Author: Francois Molle <[EMAIL PROTECTED]> at INTERNET
Date: 1/29/99 10:33 AM
I recently saw some messages from someone looking for contouring.mbx.
I wonder if someone has used both surfer (with the MI interface) and VM
and could give us some hints on their respective comparative advantages.
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 tried to get some feedback from NorthwoodGeo on that matter and it's
good to know that they let three of my Emails unanswered. They,
apparently, are not very concerned with their customers and/or unabled
to give comment or (or dismiss) possible flaws of their products.
As anyone observed or understood the "spikes" ?
Pancho
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Tel (University): (66 2) 942.81.75 / Fax(University): (66 2) 942.81.70
Tel/Fax (Home) : (66 2) 287.41.53 / Email : [EMAIL PROTECTED]
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