Transcript Analysis of different gridding methods using “Surfer7”

Analysis of different gridding
methods using “Surfer7”
Michigan
Technological
University
presentation by
Fehmi Kamcili
February 10, 2001
Fig.: Shaded Relief and Contour map
Analysis of different gridding
methods using “Surfer7”
Table of content
• Introduction
• Grid Files
• Grid Methods
1. Inverse Distance to a Power; 2. Kriging;
3. Minimum Curvature; 4. Modified Shepard’s Method;
5. Natural Neighbor; 6. Nearest Neighbor;
7. Polynomial Regression; 8. Radial Basis Function;
9. Triangulation w/ linear Interpolation
• Best Results
• Conclusion
Analysis of different gridding
methods using “Surfer7”
Introduction
• Surfer 7; Feb. 2000
Surface mapping system
Golden Software, Inc.
• Differences in created
grid-files visualized by
overlaying wireframe
and contour maps
Fig.: Wireframe and Contour Map
• Vernon/Rosebuch oilfields in Isabella county, Michigan
with 245 well Data-Points (Lat-Long of Top Dundee)
Analysis of different gridding
methods using “Surfer7”
Grid Files
Fig.: Contour and Post Map
• gridding by specifing
source file
-Spreadsheets (Excel)
-manually in Surfer
(Worksheet)
• gridding method
• accuracy of grid
• faults and breaklines
• creates “file.grd”
Analysis of different gridding
methods using “Surfer7”
Grid Methods
Fig.: Wireframe Map
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Inv. Distance to power
Kriging
Minimum curvature
Modified shepard’s
Natural neighbor
Nearest neighbor
Polynomial regression
Radial basis function
Triangulation w/ linear
interpolation
Analysis of different gridding
methods using “Surfer7”
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Fig.: Power: 2
Inverse Distance to a
Power
• weighting average
interpolator
• Power parameter
between 1E-38 & 38
“0” = planar surface;
great weighting power
= less effect on points
far from the grid node
during interpolation
Analysis of different gridding
methods using “Surfer7”
Fig.:
Power: 8
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Fig.: with
smoothing: 0.01
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Inverse Distance to a
Power
• exact or smoothing
interpolator
• generate "bull's-eyes”
-smoothing reduce
this effect
• very fast method for
gridding
-till 500 Datapoints
Analysis of different gridding
methods using “Surfer7”
Kriging
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Fig.: Point Kriging
• by entering path & file
name production estimated
standard deviation grid
• express trends
suggested in your data
• Point or Block
-Block is using
average valuessmoother; not perfect
• specify & add as
many variogramcomponents as wished
Analysis of different gridding
methods using “Surfer7”
Minimum Curvature
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Fig.: default
• smooth but not exact
• recalculation of grid
node values until
reached less of max.
Residual value, or
max. Iteration
• Set Internal and
Boundary Tension
• Relaxiation Factor
Analysis of different gridding
methods using “Surfer7”
Fig.: 1
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Modified Shepard’s
Method
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Fig.: 2
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• Like IDP Method
• exact or smoothing
• Weighting and
Quadratic Neighbors
parameters specifies
size (number) of local
neighborhood
• Fig.1: Q13/W19;
Fig.2: Q40/W60
Analysis of different gridding
methods using “Surfer7”
Natural Neighbor
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Fig.: default
• Natural Neighbor
interpolation
algorithm uses a
weighted average of
neighboring
observations, where
the weights are
proportional to new
added polygons
Analysis of different gridding
methods using “Surfer7”
Nearest Neighbor
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Fig.: default
• assigns value of the
nearest point to each
grid node
• useful when data are
already evenly
spaced
• this method is
effective for filling
missing values
Analysis of different gridding
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Fig.: 1
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Fig.: 2
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Polynomial
Regression
• used to define largescale trends &
patterns
• not real interpolator
(does not predict
unknown Z values)
• Fig.1: Simple planar
surface; Fig.2: Bilinear saddle
Analysis of different gridding
methods using “Surfer7”
Radial Basis
Function
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Fig.: 5. Thin plate spline
1. Inverse Multiquadric
2. Multilog
3. Multiquadric
4. Natural Cubic Spline
5. Thin plate Spline
• 1.; 2.; 4.- error
• 5.- good; 3.- best
Analysis of different gridding
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Radial Basis
Function
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Fig.: 3. Multiquadric
• all exact
interpolators
+ smoothing factor
• = variogram in K.
(mathematically
specifies spatial
variability of data set
& resulting grid file
Analysis of different gridding
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Triangulation w/
linear Interpolation
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Fig.: default
• creates triangles by
drawing lines
between data points
• exact interpolator
• for evenly distributed
data over grid area
-sparse areas result in
distinct triangular
facets on map
Analysis of different gridding
methods using “Surfer7”
Best Results
Kriging is exact, has many options & modifications,
but needs knowledge
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Fig.: Point Kriging
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Analysis of different gridding
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Best Results
Radial Basis Function is exact, shows nice views
& is uncomplicated
Fig.: Radial Basic
Function; Multiquadric
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Analysis of different gridding
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Conclusion
• I did not consider all aspects & details
• Surfer is very powerful for the 3D-Visualization
• Surfer 7 works:
-fast & without consuming much disk space
-uncomplicated with Object manager
• All processes (gridding, mapping) can be automated
with writing programs in Visual Basic
• Help content is very useful & describes also background
information