red lines, faults as thin green lines and polylines as thin orange dotted lines. In the move /
zoom mode, the display can be moved using cursor keys and zoomed by shortcut keys
PgUp or PgDn. If only basic objects have to be moved / zoomed, Ctrl with these keys can
be used too. The step of moving and zooming can be changed with shortcut keys "1", "2",
"3", "4" or "5".
Additional displays can be performed using the items in the Display menu.
- Labels and z-coordinates of XYZ points can be displayed using the menu item La-
bels (shortcut key N) Z-coordinates (shortcut key K), respectively.
- The menu item Color scale (shortcut key Alt+S) displays points (and labels and / or z-
coordinates, if they are displayed) in colours indicating their z-values.
- Mesh scale (shortcut key Ctrl+S) enables to display a square mesh showing distances
(if the mesh has to be labelled, shortcut key Ctrl+E can be used). The suggested size
of the mesh can be altered by the user in the presented dialog.
- Refresh (shortcut key R) is intended for restoring the basic display.
- Objects in the background (see 4.2.8 Background) can be displayed using the Back-
ground menu item (shortcut key O).
- Background colour can be switched between black and white using the menu
item B/W background colour (shortcut key Ctrl+R).
- If there are cross-sections saved in the file NAME.RZY (see 4.2.7 Cross-section dis-
play), they can be displayed using Saved cross-sections (shortcut key Ctrl+C).
4.2.2 Transformation of coordinates
The coordinates x and y of the basic map objects (points, boundaries, faults and polylines)
can be transformed. Transformation functions are contained under the main menu Trans-
formation:
- The first one (Move to beginning of coordinate system, shortcut key Alt+0 (zero))
moves coordinates of the basic map objects into the beginning of the coordinate system
– this means that the minimal x-coordinate and the minimal y-coordinate is zero.
- The next two, Transformation x[i]=MaxX-x[i] (shortcut key Alt+Z) and Trans-
formation y[i]=MaxY-y[i] (shortcut key Alt+Y), mirrors map objects according to
the x axis or the y axis respectively.
- Coordinates x and y can be interchanged using the item Interchange x and y coordin-
ates (shortcut key Alt+Z).
- All objects can be rotated - counter clockwise using the menu item Rotation counter-
clockwise (shortcut key Alt+U) or clockwise using the menu item Rotation clockwise
(shortcut key Ctrl+U).
- The Scaling and translation menu item invokes the dialog box enabling to scale and
translate all coordinates by specified constants.
- The last item Save objects is intended for saving all objects into corresponding files
(see 3.8 Formats of input and output files).
4.2.3 Interpolation
The main menu item Interpolation enables to specify map objects, set interpolation para-
meters, run the interpolation process, compute isolines and so on. The subsequent para-
graphs describe these functions.
46
4.2.3.1 Objects for interpolation
The first item in the Interpolation sub-menu contains a selection of map objects, which
have to be entered into the interpolation process. They are Points, Added points, Polylines,
Faults and Boundaries (see section 3.6 Map objects).
4.2.3.2 Interpolation parameters
The quality of the surface generated by the program SURGEF can be changed in the dialog
box invoked by Interpolation parameters menu item:
Fig. 4.2.3: Dialog box for the specification of interpolation parameters.
The first parameter Filter (the default value is 500) is intended for reducing input points if
the number of points is very large and if there are points with a small horizontal distance
between them. Usage of the parameter Filter was explained in paragraph 2.2.1 Filtering of
points XYZ.
The parameter Smoothness (see paragraph 2.2.7 Smoothing) enables to control smoothness
of a generated surface. The larger the value, the sharper interpolation is obtained. Typical
values are:
0,00 - 0,30 for smooth interpolation
0,40 - 0,60 for normal interpolation (default value is 0,50)
0,70 - 1,50 for sharp interpolation.
A sharp/smooth model at local extremes can be improved by extending the smoothing para-
meter. Beginning from SurGe version 5.50, the smoothing parameter can have two formats:
1) number 0,00 - 9,99, which is equivalent to the above described smoothing parameter
2) number 100,00 - 999,99, where the first two digits divided by 10 determine a so called
shape factor, which has an influence on the shape of the surface in the surrounding of sharp
local extremes. The smallest value 1.0 means, the shape will not be changed and any greater
value (1.1 - 9.9) means that the local extreme will be sharper. The remaining digits have the
original meaning.
Remark: If the smoothing parameter has the first format, the shape factor has the default
value 1.0.
Parameter Accuracy (the default value is 1) is the percentage value from the difference
z2−z1
. The role of this parameter was described in paragraph 2.2.8 Iteration cycle.
Enlargement is the grid size enlargement described in section 3.10 Running SURGE-
F.EXE. If it is greater than 98, the program SURGEF computes it internally.
47
The parameter Linear tensioning enables to set the degree (0-3) of linear tensioning (see
2.2.6 Linear tensioning and 3.4.2 Degrees of linear tensioning). The default value is 1.
In most cases the number of iterations can be decreased (see 2.2.8 Iteration cycle) by the
transformation
a⋅P
i , j
b P
i , j
, where constants a and b minimize the term
∑
i=1
n
a⋅f X
i
, Y
i
b−DZ
i
2
The resulting surface is somewhat smoother, but the number of iterations is decreased by
cca 30%. The check button Faster convergence enables this feature.
The pull-down list Pre-defined parameters contains the list of interpolation / approxima-
tion modes and enables to set appropriate parameters for a selected mode. The modes and
pre-defined parameters are:
Mode Filter Smoothness Accuracy Linear tensioning
Trend Surface 30 0,1 90 0
Smooth approximation 200 0,2 20 0
Smooth interpolation 500 0,2 1 1
Normal interpolation 500 0,5 1 1
Sharp interpolation 500 200,7 1 1
LES interpolation 1000 -0,5 1 1
Digital model of terrain 1000 200,7 1 3
Important note: The Trend surface and Smooth approximation set a special multiplier for
the SMOOTHING parameter otherwise estimated by SURGEF. To deactivate this setting,
the Normal interpolation item should be selected.
4.2.3.3 Interpolation
The interpolation / approximation process is started using the Calculate grid menu item.
Firstly, the parameter file PAR.3D is created and then SURGEF is run in a new console
window. The content of a typical console window running SURGEF is described in section
3.10 Running SURGEF.EXE.
4.2.3.4 Increasing the density of the grid
There is the possibility to double the grid (using the menu item Double grid) once or more
times. Z-values of newly created grid nodes are computed by means of quadratic interpola-
tion. A doubled grid provides better isolines and it can be used for the creation of an extra
smooth surface. Of course, each doubling creates a file four times greater in size.
4.2.3.5 Calculation of isolines
Before displaying, isolines must first be calculated. The calculation is invoked by the menu
item Calculate isolines. The following dialog appears:
48
The meaning of individual items in this dialog is apparent, but four points should be em-
phasized:
- Only the isolines having a level divisible by the divisor will be labelled.
- If a small difference between isolines is selected, the calculation can last from several
seconds to minutes.
- The calculated isolines are stored in the binary file NAME.VRs where the s is a suffix
(see paragraph 3.8.1 Convention for file names) and then they are immediately dis-
played.
- If the surface is later created with different interpolation / approximation parameters,
the isolines should be recalculated to correspond to the actual surface.
An example of printed isolines is in figures 2.4.2b, 2.4.2c and 2.4.2d.
4.2.3.6 Blanking grid outside the boundary
The function Blank grid outside boundary is intended for cancelling values of the grid
nodes located outside the boundary. To obtain isolines only inside the boundary, the calcu-
lation of isolines must be then performed again. Examples of this function are in sections
5.4 Wedging out of layer and 5.6 Digital model of terrain.
4.2.3.7 Cutting off extreme values
The function Substitute below enables to substitute all z-values of the surface, which are
less than a specified constant, by this constant. For example, negative values of the grid
nodes can be substituted with zero. A similar function has the menu item Substitute above.
An example of this function is in section 5.1 Zero-based maps.
4.2.3.8 Mathematical calculations with grids
The menu item Math calculation with grids starts a dialog box enabling to perform some
calculations with all nodes of grids. It is assumed that the first operand is the actual surface
and the second one is a previously created surface defined by the suffix. If the second oper-
and is not defined (the suffix is empty), it is assumed to be a constant (specified in the fol-
lowing dialog box). The result of the operation is indicated by one character with the fol-
lowing meaning:
Operand Result
~ Negation
+ Addition
- Subtraction
* Multiplication
: Division
m Minimum
M Maximum
a Average
$ the first operand; if the second is greater than the first, then average
% the second operand; if the second is greater than the first, then average
w weighted average (the weights are specified in the following dialog box)
d derivative computed as the size of gradient vector
49
Examples of these functions can be found in sections 5.4 Wedging out of a layer and 5.5
Maps of thickness and volume calculations.
4.2.3.9 Data analysis
The Data analysis menu item runs only the first part of SURGEF.EXE to get essential in-
formation about filtering, grid sizes and expected maximal gradient. Then it displays the
following dialog box:
The first and second items inform about the number of points before and after the filtration
process. If the grid size is smaller than the Minimal grid size set by filter, there is a high
probability that the iteration process will not converge. The Suggested grid size is a grid
size suggested by SURGEF.EXE. The Comment contains a verbal description of data ana-
lysis results and some suggestions.
The edit box Filter enables to change the actual setting of the filter (and, for example, to
run Data analysis again to observe its influence). The Target grid size has two purposes:
1. If interpolation with a trend surface is performed, this grid size will be used without re-
spect to the state of the Use check box.
2. If the check box Use is switched on, this grid size will be used for the next interpolation /
approximation and for the next data analysis.
The items Normal, Linear, Convex and Auto in the Trend surface group box are intended
only for interpolation with a trend surface (see the next paragraph).
4.2.3.10 Interpolation with a trend surface
Interpolation with a trend surface runs SURGEF.EXE two or three times. The first run
creates a trend surface with a small grid having the following properties:
- the grid size of the small grid is between 80 and 160 or between 40 and 80 or between
20 and 40 – it depends on the selection of the Preservation of extrapolation trend
parameter 1, 2 or 3 in the provided dialog box
- the Target grid size (see the previous section) is the 2
n
multiple of the small grid size.
The second (third) run reads the created grid of the trend surface doubled n-times and then
performs a modified interpolating algorithm as described in section 3.10 Running SURGE-
F.EXE. Using this procedure the trend surface is involved in the interpolation, meaning that
the resulting surface keeps a proper trend in areas without points. It is recommended to per-
form data analysis before interpolation with a trend surface and to set a desired Target grid
size.
50
An example of interpolation with a trend surface is in paragraph 2.4.3 Conservation of an
extrapolation trend and in section 5.2 Extrapolation outside the XYZ points domain.
4.2.4 Display of surface
2D displays of the created surface can be performed using the following items in the Dis-
play menu.
- Isolines can be displayed (assuming that they were calculated) using the
item Isolines or by the shortcut key I.
- The surface can also be represented as a colour raster map using Colour Map (short-
cut key C).
- The menu item Shadowed relief (shortcut key Alt+Q) enables to display a shadowed
colour map improving the 3D feel of the display (see figure 4.2.4); the angle and in-
tensity of the shadow is specified in the presented dialog.
- The colour of the base objects (points XYZ, labels, z-coordinates, boundaries, faults
and polylines) can be switched using Change colour (shortcut key Ctrl+A) in order to
achieve better visibility of these objects on the colour map.
- There are three items related to the gradient display. The first one, Gradient in nodes,
shows gradient as short oriented line segments starting at the nodes of the grid. The
second one, Gradient in isolines, shows similar line segments starting along the
isolines (only if isolines have been calculated). In both cases the user can change (in
the provided dialog box) the multiplier constant (default 100) specifying the length of
the line segments and the frequency (default 2). For example, frequency=2 means, the
gradient line segments will start in every second node. When the function Gradient
lines is selected, the program enters digitisation mode. In this mode the cursor has the
shape of a little cross and the cursor keys move the cursor (and not the map). The
gradient lines (starting from the cursor position) can be displayed using the shortcut
key Alt+G.
Fig. 4.2.4: Difference between colour map and shadowed colour map display.
4.2.5 3D display
The menu item Display / 3D view is intended for displaying and viewing the created sur-
face in 3D from different angles and different elevations. In this case the surface is firstly
51
stored to the file NAMEF.GRs and then is read again. Before reading the surface, there is a
possibility of changing the step of reading node values. The default step value is 1, which
means, that all grid nodes will be displayed. A value of 2 means, that every other grid node
will be displayed and so on. Higher values enable to display a sparser grid.
Cursor keys can be used for moving the 3D view around the screen, shortcut keys PgDn
and PgUp are intended for zooming.
In the 3D view mode there is a special menu having the following items:
- The surface can be displayed without colours (Display wireframe surface, shortcut
key S), with colours (Display colour surface, shortcut key C) or as a shadowed colour
surface:
- Shortcut key E displays the surface with pure colours and clears all shadows.
- Shortcut key Alt+Q adds shadows with angle and intensity specified in the presen-
ted dialog. It can be used several times with different angles and intensities to
achieve nice lighting effects.
- Shortcut key W displays the surface with the actual settings of shadows (after rota-
tion, zoom, …).
- The horizontal angle of the view is changed by Rotate counterclockwise (shortcut
key A) or Rotate clockwise (shortcut key Shift+A).
- The vertical angle can be changed by Rotate up (shortcut key B) or Rotate down
(shortcut key Shift+B). The items Increase z-scale (shortcut key Z) and Decrease z-
scale (shortcut key Shift+Z) are intended for increasing and decreasing the superelev-
ation, respectively.
- The item Display / hide labels (shortcut key K) switches on/off the display of point
labels.
- Background colour can be changed using B/W background colour (shortcut key
Ctrl+R).
Step of angles, moving and zoom can be changed with shortcut keys "1", "2" and "3". The
horizontal and vertical angles of view can also be changed by clicking and holding the left
mouse button and moving the mouse.
4.2.6 Digitisation
Digitisation is intended for manipulating basic map objects. After selecting one of the items
Points, Boundaries, Faults or Polylines in the menu Digitisation, the program enters di-
gitisation mode with a special menu. In this mode the cursor has the shape of a little cross
and cursor keys change the position of the cursor (and not the position of the map as in the
basic move / zoom display mode). The step of the cursor movement can be changed with
shortcut keys "1", "2", "3", "4" or "5". Of course, the location of the cursor can be changed
using the mouse too. While the cursor is being moved, the main window bar shows the co-
ordinates of the cursor.
4.2.6.1 Points
The menu Points enables to add or delete points XYZ or change their z-coordinate. A new
point is specified by the cross cursor position when the left mouse button or the shortcut key
B is pressed. The point next to the cursor position is deleted using the right mouse button or
the shortcut key Ctrl+B. The shortcut key Shift+B is intended for setting a new z-coordin-
ate of the point, which is next to the cursor position.
52
4.2.6.2 Boundaries
The menu item Boundaries is intended for creating and correcting boundaries. Boundaries
are handled as a horizontal polyline.
The shortcut key Ctrl+H ends the definition of one boundary and starts a new one. A new
point of the boundary polyline (including the first one) is defined by the position of the
cursor when the shortcut key H is pressed. The last entered point can be deleted using the
shortcut key D. The shortcut key U is intended for closing the boundary (for creating a
boundary as a closed curve). Any point of the boundary can be marked using the shortcut
key Shift+H and then moved to a new position by the shortcut key M. The last item under
the menu Boundaries creates a boundary as a convex envelope (convex hull) of points
XYZ. The number entered in the following dialog box enables to scale the convex envelope.
Using this feature the size of the interpolation function domain can be changed and grid val-
ues outside of the convex envelope can be removed – see section 5.6 Digital model of ter-
rain.
4.2.6.3 Polylines
Spatial polylines can be digitised using the menu Polylines.
The shortcut key Ctrl+L ends the creation of one polyline and starts another. A new point
is defined using the shortcut key L, the last entered point can be deleted using the shortcut
key D. As in the case of the boundary, the polyline can be closed using the shortcut key U.
When defining a new point, the corresponding z-coordinate must be specified in the
provided dialog box. If the z-coordinates of the polyline are to be the same, there is the pos-
sibility to predefine a constant z-coordinate using the shortcut key F. This function can be
cancelled using the shortcut key Ctrl+F.
Any point of the polyline can be marked using the shortcut key Shift+L and then moved to
a new position by the shortcut key M.
If a polyline is created, it is necessary to set its number of internal points. In fact, SURGEF
does not work with polylines directly – it works only with the points, which are evenly dis-
tributed along the polyline. To specify the number of these points, move the cross cursor
near the polyline and press the shortcut key P. Then in the provided dialog box enter the
number of internal points (typical values are 50 - 200).
4.2.6.4 Faults
The menu item Faults enables to edit sequences of line segments (in horizontal plain), at
which the resulting surface has to be discontinuous. Each fault is defined by a pair of points.
A new point of the fault is specified by the cursor position when the shortcut key Z is
pressed. The fault can be deleted using the shortcut key D – the one whose centre is closest
to the cursor position. The position of the fault end point can be changed by the shortcut key
Shift+Z.
4.2.6.5 Isolines
In the digitisation mode there is also the possibility to modify isolines. The first func-
tion, Mark isoline (shortcut key X), serves for selecting an isoline. After selection, the
isoline is represented by a sequence of white points. If the display is (due to operations)
damaged, it can be restored using the menu item Redraw modified isoline (shortcut key
A).
The selected isoline can be smoothed (Smooth isoline, shortcut key S) as a whole, or par-
tially (Smooth between points, shortcut key V) between the points selected using the menu
items Mark first point (shortcut key Alt+1) and Mark second point (shortcut key Alt+2).
53
There is also the possibility to mark a single isoline point (Mark point, shortcut key
Shift+I) and to move it (Move point, shortcut key M). A certain number (the number can
be changed using Change number n, shortcut key Ctrl+Q) of isoline points can be moved
by Move n points (shortcut key Q). The modified isoline can be saved to the file
NAME.VRz using the menu item Save modified isoline (shortcut key Ctrl+I). Write
marked isoline (shortcut key W) enables to store the selected isoline as the ASCII file IZ.$
$$.
4.2.6.6 Cross-sections
The menu Cross-section enables to specify a polyline in the plane (x,y), which defines the
cross-section through the created surface. The first or next point of the cross-section can be
specified using the menu item Point of cross-section line (shortcut key G). Points are dis-
played in red. A polyline connecting the red points is displayed using the menu item Dis-
play cross-section line (shortcut key E). All specified cross-section points can be deleted
by Delete specified cross-section (shortcut key Ctrl+G) and then a new cross-section can
be defined. In the cross-section mode (see below), there is a possibility to save the position
of the cross-section and name it with a single letter. The function Select saved cross-sec-
tion (shortcut key Shift+G) enables to select one or more saved cross-sections. When the
cross-section is defined, the shortcut key Enter is used for creating the cross-section
through the surface(s) and entering cross-section mode.
4.2.7 Cross-section display
Cross-section mode is invoked by the menu item Cross-section / Display cross-section
(shortcut key Enter) in the digitisation mode. The following dialog box appears:
The suffix convention (see paragraph 3.8.1 Convention for file names) enables to create a
cross-section through several surfaces (layers). In the presented dialog box, the suffix of the
surface and a short description can be specified. The cross-section is constructed through all
specified surfaces and displayed in a 2D plot (see for example figure 2.3).
There is a special menu in the cross-section mode. The title of the plot and description of
axes can be modified using menu items Graph title (shortcut key N), Description of x axis
(shortcut key X) and Description of y axis (shortcut key Y). The range of the y axis can
be changed by Change range of y axis (shortcut key Ctrl+Y).
The last menu item, Save cross-section (shortcut key U) enables to save the position of the
cross-section polyline to the file NAME.RZY for later use in the digitisation mode (see the
previous paragraph). The name of the cross-section must be specified as a single character
A-I.
54
4.2.8 Background
In some cases it is useful to display texts and some characteristic terrain lines and / or ob-
jects to improve orientation in the map. For this purpose, there is a special digitisation level
named Background under the menu Digitisation. Objects of background are handled as
polylines and the following functions (contained in the special menu) for creating, changing
or deleting objects from background can be used:
Start new object (Ctrl+B)
- ends construction of the current object and starts construction of a new one.
New point of object (B)
- a new point of a polyline is specified at the cursor position.
Delete last point (D)
- the last specified point is deleted.
Close polygon (U)
- the next point will be at the same position as the first point of the polyline.
Mark point (Shift+B)
- change the colour of the nearest point of the polyline to the cursor to white.
Move point (M)
- move marked point to a new position.
New text (T)
- specify text string, font size, font thickness, font colour and text orientation.
Change text (Shift T)
- change text string, font size, font thickness, font colour and text orientation.
Three functions are intended for manipulation with whole objects:
Select object/text (S)
- select / unselect the object next to the cursor. The selected object is displayed in purple.
Move selected object/text (Ctrl+M)
- move whole object; the moving vector is given by the marked point and the cursor posi-
tion.
Delete selected object/text (Ctrl+D)
- delete selected object.
All background objects can be saved to the file NAME.BG with the last menu item Save
background (shortcut key W).
4.2.9 Finite difference model grid
The function Model grid in the menu Digitisation enables to create or to modify an irregu-
lar rectangular grid for a mathematical finite difference model, for example MODFLOW.
The program switches into a special digitisation mode with its own menu. In the menu there
is a list of shortcut keys, which can be used for creating an irregular rectangular grid:
Add column (shorcut key X)
- a column line is added at the cursor position
Add row (shorcut key Y)
- a row line is added at the cursor position
Delete column (shortcut key Ctrl X)
- the column near the cursor position is deleted
Delete row (shortcut key Ctrl Y)
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