Comparison with other methods


The program SurGe contains an interpolation / approximation method named ABOS (Approximation Based On Smoothing), which is described in User's manual. The quality of the resulting surface is affected by the parameters Smoothness and Accuracy. The effect of these parameters and the comparison with commonly used methods is illustrated in the next picture. It is obvious that ABOS can create surfaces comparable both to Kriging and Minimum Curvature methods.

Cross-sections through created surfaces provide another interesting comparison.

The mathematics of ABOS is very simple in comparison to the mathematics of commonly used interpolation / approximation methods, such as Kriging, Radial Basis Functions or Minimum Curvature methods. For example, the Kriging method needs to compute an experimental variogram, to fit the variogram model and to solve the system of linear equations. If the number of input points is large (say thousands), the number of linear equations is also large and cannot be solved in an acceptable time - in such case, additional parameters influencing the quality of the resulting surface must be specified - search radius, number of search sectors, maximal number of points in each sector and so on.

The mathematical complexity is related to the computational time - Kriging needs for example 115 seconds for interpolating 9500 points into a grid of 200x400 nodes, while ABOS needs 10 seconds (time was, of course, measured on the same computer).
The result of both interpolations is shown in the next picture. While the surface in regions with no data is smooth in the ABOS case, Kriging created, in these regions, strange jumps resulting from the search algorithm. The Radial Basis Functions method has the same problem.

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- There is a possibility to display alternative coordinates using so called georeferencing technique - see here.

- SurGe was successfully tested in Linux (Ubuntu) using WINE - see here, how to install it.

- SURGEF now reads an external grid (see How to utilize an existing grid in the SurGe Tutorial) in ASCII format (see here) compatible with SURFER (Golden Software) - if the binary file NAMEf.GRs containing an external grid is not found, SURGEF searches for the file in ASCII format NAME.GRs and reads it, if the file exists.

- fix of insignificant bug in SURGEF.
- SurView now enables to display axes and to measure horizontal distance. Display of labels and z-coordinates was enhanced.
- map can be moved or zoomed using the mouse in both modes of SurGe (move/zoom mode and digitization mode):
   - While Ctrl key is pressed, the map is moved according to the mouse cursor movement.
   - While Shift key is pressed, the map is zoomed as the mouse cursor is moving from the left to the right.
   - Mouse wheel can also be used for zooming

- bug fixed in the boundary created as a convex envelope - memory allocation of auxiliary array was insufficient.

- SurView now enables to display points position and point labels or z-coordinates. Note that the maximal number of displayed points is 10000 - the rest is ignored.

- Microsoft removed hardware acceleration of the most GDI  (Graphics Device Interface) functions in Windows 7. As a result, the GDI (responsible for tasks such as drawing lines, polygons and so on) is five times slower in comparison with Windows XP. That is why I was forced to implement so called double buffering in SurGe display, which utilizes BitBlt function for fast display of graphics. BitBlt is one of a few GDI functions remaining hardware accelerated in Windows 7.

- programmer's nightmare:
64-bit version of SURGEF crashed on certain data set. It was caused by standard C function realloc, which behaves differently in the 32 and 64-bit version.
The bug was fixed - please download the corrected version of SurGeF64.zip.

- 64-bit version of SURGEF interpolation engine (SurGeF64.zip) is now available for 64-bit Windows operating systems. It is about 20% faster than 32-bit version.

- bug fixed in computation of polyline points
- bug fixed in printed isoline labels

- most dialogs now contain context-sensitive help.

- bug fixed in isoline computation and isoline digitization.

- GRIDCONV.EXE utility is utilized for importing some of common grid formats (see How to import other map/GIS grid formats in SurGe Tutorial).
- GRIDCONV.EXE utility now replaces DEMGRD.EXE, ARCGRD.EXE and GRSGRD.EXE (see Conversion command line utilities).

- new main menu in SurView

- new in SurView:
   - selection of color palette
   - display of color scale

- several new color palettes was created: Globe.pal, Polar.pal, Steel.pal and Topo.pal
- editor of color palette for raster maps and 3D view (see Color palette in User's Manual)

- version 6.50 released

- new 3D OpenGL surface viewer SurView was created as a stand alone utility, suitable namely for displaying of the large broken grids. Main features are:
  - display of shadowed surface with optional change of light height position and light intensity
  - move, zoom, rotation and z-scaling using shortcut keys or by mouse dragging
  - parallel (orthogonal) or perspective projection
  - switch between  color + shadow / only shadow / only color  display modes
  - switch between wireframe and filled surface

- change of my ordinary mail address - see Main page

- SURGEF.EXE was compiled with GNU Fortran v. 4.4.0. Now it is about 7% faster.

- output of isolines as ASCII file (see the menu item Output / Isolines as ASCII file) now contains 11 decimal places.

- error in isoline computation corrected.
- better diagnostics in input data procedures.

- bug fixed in internal filter.

- Gallery of surfaces created and displayed by SurGe was added to web pages.

- SurGe documentation now contains animated GIF showing interpolation process. See User's Manual

- transmission of grid size between SurGe Project Manager and SurGe was not correct.

- Linux users may try to use SURGEF interpolation engine as a console application (see Main Page.).

- number of input points is limited only by available computer memory. SurGe was successfully tested with 5000000 points.
- new algorithm of internal filter - now it is about 7 times faster (5000000 points are filtered within 5-15 seconds).
- reading of input data is more than two times faster thanks to the new routine ATOFL for reading real numbers in ASCII format.

- version 6.30 released

- cosmetic enhancement of the cross-section display.

- new sections in the SurGe Tutorial: How to simulate wedging out of layers and Maps of thickness and volume calculation

- new section in the SurGe Tutorial:  How to directly convert seismic reflection times to structure depth.

- running of new SurGe instance with selected map detail - see section Detail of map in the SurGe User's Manual.

- text specification in the background mode. See section Background in the SurGe User's Manual.

- derivative of surface can be computed as the size of gradient vector - see Math calculation with grid.

- using of SURGEF in applications was extended. Follow this link for more information.

- interpolation with trend surface was extended. See Interpolation with trend surface in the User's Manual.

- all points XYZ now may have the same z-coordinates.

- bug fixed in gradient lines computation

- display of shadowed relief (shortcut key Alt+Q) is three times faster.

- output of grid in the ArcGIS format - see the menu item Output / Grid as ArcGIS file.
- new command line utility ARCGRD supporting import of grid in ArcGIS format.
- supported map formats are listed in the new section in Support for other map formats.

- cosmetic enhancements of 3D view display and print.

- bug fixed in DEMGRD utility.

- version 6.10 released

- iteration process in SURGEF.EXE can be stopped by Esc key. In this case the actual iteration step will be completed before the stop.

- new algorithm of internal filter - now it is about 10 times faster.
- maximal number of input points was increased from 100000 to 300000.

- SURGEF.EXE now uses dynamical allocation of memory in spite of the fact, it is compiled by FORTRAN 77. Grid size is limited only by available memory.

- a view point in the 3DVIEW mode can be changed by mouse movement, if the left button is pressed. 

- SurGe now automates the interpolation based on a trend surface. This feature improves extrapolation properties of resulting surface in areas not containing points XYZ (compare the two pictures below). Details are in the section Interpolation with trend surface in the User's Manual and in the SurGe Tutorial in sections How to obtain trend surface and How to utilize trend surface for improving extrapolation. This new function is under the Interpolation menu.

- new item under the Interpolation menu was added - see the section Data analysis in the User's Manual.

- information about upper Filter limit in the documentation is obsolete and was corrected to 9999. Special value 0 means that only the points having the same x and y coordinates will be filtered.

- name of GRASS output files was corrected - see the User's Manual.

- boundary in the digitization mode can be created as a convex envelope of XYZ points. See the section about Boundary in User's Manual. Practical usage of convex envelope is described in the section How to modify the size and the shape of the grid area in the SurGe Tutorial.

- SURGEF.EXE enables to create a boundary as a convex envelope of XYZ points. See Using SURGEF in applications.

- new dialog Scaling and translation (see the menu item Transformation) enables to multiply and/or translate any combination of coordinates. It is recommended to save transformed coordinates (use the menu item Save objects) and to perform new interpolation, because after any transformation of coordinates the surface does not correspond to changed data. 

- version 5.90 released

- a click on mouse right button in move/zoom mode now enables to select the way, how to perform interpolation. For details see SurGe Tutorial.

- dialog box Interpolation parameters now contains the list of pre-defined parameters suitable for desired type of interpolation / approximation. For details see SurGe Tutorial.

- new interpolation mode (LES interpolation) suppresses an exceeding of local extreme values. It is suitable for zero based maps.

- correction of wrong boundary display in case of extremely great enlargement of map.

- command line utilities supporting import of DEM, GRASS and Shapefile data formats can be now downloaded as a separate file. Details are in SurGe conversion utilities.

- the maximal length of point labels was increased from 10 to 23.

- in the digitization mode it is now possible to measure horizontal distance. See How to measure horizontal distances in the Surge Tutorial.

- computation of cross-section was improved and the error message Too small distance between cross-section points was removed, because now there is no reason for it. Maximal number of cross-section points was increased from 99 to 333.

- minor bug in FMEW fixed.

- installation program now detects, if your CPU supports MMX and SSE2 instructions (for example Pentium 4, Pentium Centrino, Xeon, ...). If yes, the program installs SURGEF.EXE utilizing these instructions. Then the interpolation is about 25% faster.

- section Using SURGEF in applications in User's Manual was updated.

- computation of the matrix NB  is now more than three times faster for surfaces with faults.

- computation of DZ values near faults was corrected. This problem caused bad convergence if there were points XYZ too near to faults.

- section Output in User's Manual was updated.

- new shadowed display mode in 3D view:

- error in faults definition is now described in the User's Manual.

- new section in the User's Manual describing a possibility to call SURGEF.EXE from user applications.

- filter built in the program SURGEF is now more than two times faster. For example, 30000 points can be filtered within 5 seconds.

- shadowed relief display (shortcut key Alt+Q) improves a 3D feel of raster color map - compare the next two pictures.

- points (and labels and / or z-coordinates, if they are displayed) can be displayed (using the shortcut key Alt+S) in colors indicating their z-values. See the next picture:

This function is enabled only if raster color map or isolines are not displayed.

- the speed of interpolation algorithm has increased by cca 25%.

- SurGe Tutorial was extended - see new chapter Print.

- cross-section display was enhanced and bug in the description of layers was fixed.

- two Excel macros were created for Excel users. The first one enables to write selected block of data into ASCII file, the second one creates auxiliary file #EXCL#.DTA and runs SurGe on this file. See SurGe and Excel in documentation.
- SurGe now exits properly, if one of input files has wrong format.

- new shortcut key Ctrl+E enables to display a mesh and labels, while previously implemented shortcut key Ctrl+S displays only a mesh. Ctrl+E also displays axes, if there is enough space on the left or/and bottom side of the map. If there is not enough space, use arrow keys for moving of the map. See menu item Display / Mesh labels.

- version 5.70 released

- shortcut key Ctrl+F3 enables quick creation and preview of map
- if 0 0 (zero space zero) is typed as a response to SURGEF prompt
 SMOOTHING [ 16]: 0 0    then only per partes constant interpolation is performed

- implementation of new tensioning algorithm (see the User's Manual for details).  
     - interpolation process is two times faster in average (the speed was tested on data sets provided by SurGe users):
     - linear tensioning has four degrees (0-3). The level 3 corresponds to the level 2 in the previous version.
     - shape of generated surface near to faults is apparently better.
- estimation of number of smoothing and tensioning repetitions was enhanced and default values ensure good quality of generated surface outside the convex envelope of points XYZ.

- the estimation of grid size in SURGEF.EXE was improved.

- algorithm of Faster convergence was improved.

- in the working directory there can be two new files for common definition of color / isoline levels, NAME.CL and NAME.LV. See the User's Manual for details.
- fixed problem with color scale, if values out of boundary are blanked.

- fixed problem with mouse cursor in the move/zoom mode.
- SURGEF.EXE now computes average deviation 1/NB*abs(DZi) at each iteration step and displays overall time of interpolation.

- new menu item Output / Z-values at points was added. It reads X and Y coordinates from the specified input ASCII file, computes corresponding Z value and writes the result (X, Y and Z values) into specified output file. The input file must contain X and Y coordinates in the first two items of each row. The rest of row is copied into output file.
The format of the input file rows must be:
X  Y  [any-text]
The format of the output file rows is:
X  Y  Z  [any-text]

- fixed problem with installation directory, if the name of the directory contains spaces.

- SurGe Project Manager did not work on some computers with Windows95 and Windows98. The problem was fixed.

- SurGe Project Manager now enables to create copy of actual subproject or actual map.
- fixed problem with mouse cursor blinking in the move/zoom mode.

- the background is printed, if it was displayed
- fixed problem with blinking display, if the "Show window contents while dragging" is switched on (see the system setting of "Effects" in the desktop "Properties").

- the raster color map is printed, if it was displayed

- the axes in the printed map can be switched on / off - see the dialog box for map printing.
- bug fixed in the initial setting of the mesh scale.

- version 5.50 released

- Surge Project Manager was extended. Now it contains pre-defined grid size and buttons for editing color map levels and isoline levels.
If the grid size in the X direction is zero, SURGEF.EXE suggests appropriate value.
If the grid size in the X direction is positive and the grid size in the Y direction is zero, SURGEF.EXE accepts the first value and suggests appropriate second value.
If both values are positive, SURGEF.EXE accepts them.

- new level of linear tensioning was involved into SURGEF.EXE. Now there are three levels of linear tensioning:
0 ... no linear tensioning - corresponds to the "Linear interpolation" switched off in the previous version
1 ... medium linear tensioning - corresponds to the "Linear interpolation" switched on in the previous version
2 ... strong linear tensioning - new level of linear tensioning.
If the second level is used with the small number of smoothing (say from 1 to 5), the SurGe can be used for so called digital model of terrain - as an example see the digital model of a stone quarry in the next picture.

- update of User's Manual

- update of User's Manual

- sharp/smooth model at local extremes was improved by extending of the smoothing parameter. Now the smoothing parameter can have two formats:
  1) number 0.00 - 9.99, which is equivalent to the original smoothing parameter
  2) number 100.00 - 999.99, where the first two digits divided by 10 determine so called shape factor, which has influence on the shape of 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, the local extreme will be sharper. The remaining digits have the original meaning.
Example: extended smoothing parameter 300.5 means, the original smoothing parameter is 0.5 and the shape factor is 3.0. The cross-section plot illustrates the effect of such shape factor - the gray curve corresponds to the shape factor 1.0 and the green one corresponds to the shape factor 3.0. 

Remark: If the smoothing parameter has the first format, the shape factor has default value 1.0.

- cosmetic improvement of 3D display.

- error in compilation of the FMEW.EXE - wrong compiler switches were used. Sorry for this failure. Now FMEW runs OK.

- as a response to request of many users, project levels in the SurGe Project Manager was extended from 2 to 3 - see the documentation for SurGe Project Manager.

- GFILTR was rewritten as a dialog-based windows application (see description in the Tutorial) and integrated into SPM.

- version 5.00 released

- SurGe now uses free installer for Windows programs "Inno Setup". The installation is quite easy now.

- the first version of SurGe Project Manager (SPM) was released. SPM enables to manage projects and maps, to run SurGe for selected maps, to edit data of map objects (using stand-alone editor FMEW or using any ASCII editor selected by the user), to calculate volumes between two surfaces (using stand-alone program VOLUME) and much more. SPM and FMEW has some limitations for unregistered users. 

- in most cases the number of iterations can be now decreased by the transformation Pnew = A*Pold+B, where P is smoothed matrix (see User's Manual) and constants A and B minimize the term (A*f(Xi,Yi)+B - Zi)2. The resulting surface is somewhat smoother, but the number of iterations is decreased by cca 30%. See new check button Faster convergence in the dialog box Interpolation parameters under the menu Interpolation.
- new dialog box Point and label display setting under Display menu. Replaces menu items under Display / Font size and enables to set all display combinations, which are also available by keys Ctr1+1, ... ,Ctr+4 (font size setting), Ctrl+Alt+L (hide/display labels and/or z-coordinates), Ctrl+Alt+P (display of points) and Ctrl+Alt+T (display of added points).

- new dialog box Objects for interpolation in the menu Interpolation. Replaces checked menu items in the menu File.

- display of points can be changed using shortcut key Ctrl+Alt+P and display of added points using shortcut key Ctrl+Alt+T. These keys switch between modes:
     -  hide all points 
     -  display points as pixels
     -  display points as small rectangles
- display of point labels and/or z-coordinates in map and 3D view can be changed using shortcut key Ctrl+Alt+L. This key switches between:          
     -  hide all labels and/or z-coordinates
     -  display only point labels and/or z-coordinates
     -  display only added point labels and/or z-coordinates 
     -  display all point labels and/or z-coordinates.

- bug fixed in 3D display of labels, if the grid is doubled
- correction of 3D view, if the surface is approximative

- version 4.30 released

- levels of raster color map can be specified in the ASCII file NAME.CLs, where s is a suffix (see User's Manual for details).

- SURGEF now suggests "reasonable" dimensions for grid.

- shortcut keys F2,...,F9 were added into menu item Interpolation.

- bug fixed in the smoothing of the existing grid, if the grid is read from a file

- isoline levels can be specified in the ASCII file NAME.LVs, where s is a suffix (see User's Manual for details).
- bug fixed in isolines calculation

- correction of color map display, if the function "Substitute below" or "Substitute above" is applied
- calculation of the difference vector has been corrected to obtain better information about convergence in case of data with great difference of z-values at very near points.

- change of e-mail address: M.Dressler@centrum.cz

- possibility to change font size using shortcut keys Ctrl+1, ... , Ctrl+4 (see new item in the Display menu)

- bug fixed in formatting of the ASCII grid file
- warning message about no existing grid file at start of program was suppressed
- installation did not contain the file SURGEF.EXE as referenced in documentation, but an identical file with a different name - 3DGRAFF.EXE. Thanks to Avijit Chowdhury for warning! The problem is now corrected in the new installation package.

- flexible formatting in some dialogs
- flexible formatting of records in output ASCII files

- bug fixed in color scale

- color scale enhanced
- correction of axes description in 3D view

- new SurGe presentation at WEB page http://www.digitalgrove.net/Toolbox_mappers.htm. (Thanks to Paul Pingrey!)

- version 4.20 released
- extension of documentation
- correction of minor bugs

- the first publication of SurGe on  the Internet
- version 4.10 released

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