This version of the "Surface Interpolator" Extension is a free sample extension for use with
ArcView GIS. Sorry, there is no technical support or any type of warranty/guarantee included
(but I guess you get what you pay for!). 

	This ArcView extension was designed to run on ArcView 3.x with Spatial Analyst v1.1.
It requires that ESRI's Spatial Analyst, the Dialog Designer sample extension, and this extension 
be loaded in the following directories:
	Spatial Analyst- $AVEXT\
	Dialog Designer- $AVEXT\
	Surface Interp-  $USEREXT\

	This extension will add a new Button to the View GUI, from which the user can access
dialogs allowing the interpolation of surfaces using the IDW, Spline, Trend, or Kriging technique.
	For Kriging, the user can choose one of the two Universal methods (linear or quadratic drift),
or one of the five Ordinary Kriging methods (linear, exponential, circular, spherical, or gaussian).
When using Ordinary Kriging, the user is able to view the Semi-Variogram before performing
the surface interpolation. The Semi-Variogram shows the relationship of semi-variance to distance in 
the sample points, and the quality of fit between the actual and fitted values for the method chosen.
Beyond a certain distance (referred to as the 'Range'), variation in the sample point Z-Value is no 
longer spatially correlated. Within the range, variation in z-values is smaller when sample points are
closer. Consult the ArcView on-line help for more information on the Kriging interpolation technique:
search the index with the keyword 'MakeFromVariogram', and then click on the 'Discussion' hypertext
link at the top of the page.
	Semi-Variograms are produced as layout documents, although the user also has the option of
producing a table.

===================================================================================================

There are five primary files included in this package:
  1. Readme.txt - This file
  2. Interp10.avx - Surface Interpolator Sample extension file 
  3. Dialog.avx - Dialog Designer Sample extension file
  4. Avdlog.dll - ESRI Dialog Designer File
  5. Avdlog.dat - ESRI Dialog Designer data File
Additionally, there is a point shapefile that represents elevation sample locations. Bring this
into ArcView as a point theme to test the Interpolator extension (the attribute "Spot" contains the
elevation values).

To install this extension to your system, do the following:
1. Place Interp.avx file in ArcView's C:\ESRI\Av_Gis30\Arcview\Samples\Ext ($USEREXT) folder;

if ESRI's Dialog Designer is not installed on your computer, do the following:
2. Place avdlog.dll file in ArcView's Bin32 folder; and
3. Place avdlog.dat file in ArcView's Lib32 folder.
4. Place Dialog.avx file in ArcView's Ext32 ($AVEXT) folder

To use this extension, at least one point theme must exist in the active View. Click the "Surface Interpolation" 
button (the second to the last, with the 'profile' icon) to open the interpolation dialog. Choose a point theme 
to interpolate the surface from, the field containing Z-Values, and an interpolation method. Additional dialogs 
will come up, requiring more information before interpolating the surface.

Comments and suggestions ...

 
Thad Tilton
ESRI Educational Services
ttilton@esri.com


---> Thanks to:

Marco Boeringa
Gemeentewaterleidingen Amsterdam (Amsterdam Water Supply)
Vogelenzangseweg 21
2114 BA Vogelenzang
the Netherlands
poect8@gw.amsterdam.nl

---> For much of the code that produces the Semi-Variogram Layout.