DOUGLAS ARGOS-FILTER ALGORITHM

• Douglas Argos-Filter Algorithm
  • Abstract
  • What's New in v.7.03
  • Software Download
  • User Manual
  • FAQ's
  • Archive
  • Bibliography

ANIMAL MOVEMENT

• • Animal Movement V.2
  • Spatial Tools
  • Population Viability Analyst
  • Oceanographic Analyst

Loading this Extension:  Spatial Tools is an ArcView  program extension which must be run simultaneously with Spatial Analyst.  After downloading, unzip the .avx file directly (or unzip to a temp directory, then copy) to the ArcView EXT32 folder.  Start the ArcView program, click on "file" and go to "extensions".  From the list of available extensions, select Spatial Analyst, then Spatial Tools and click "ok".  The collection of new functions  will now be available through  menu choices, tools, and buttons described below. When installing version 3.2 (10/99), Spatial Analyst will automatically load after selecting the Spatial Tools 3.2 extension.

Note...you must install the g2i.dll file in to the $AVBIN directory (which is now included in the latest version, v. 3.2).

Using this documentation:  Click on the menu bar above to go to the major headings and then click on either the subheading list or the image map of menu choices or buttons.  Click on the return button to get back to the subheading list.

For any questions or problems regarding this documentation, contact elizabeth_solomon@nps.gov.
 

Introduction

Spatial tools is an ArcView extension which provides a collection of grid tools made available through the program's  GUI (Graphical User Interface).  Menus, Tools, and buttons provide access to various spatial modeling and analysis capabilities such as geometric transformations, mosaicking, resolution alteration, data clean-up and spatial analysis.   Spatial Analyst  must be loaded simultaneously.

Requirements: ArcView and Spatial Analyst. This program will work in versions of ArcView on PC, UNIX and Macintosh hardware.  On the PC platform it is recommended that a Pentium or Pentium Pro 200 or faster be used with this program and at least 32 megabytes of memory, since Spatial Analyst must be running simultaneously.

Other grid operations and functions not currently available through Spatial Analyst or Spatial Tools menus can be accessed through the use of the additional extensions and Avenue Requests.  Help for these requests and extensions can be found in the ArcView On-Line Help Documentation and/or at  http://www.esri.com/.
 

Data Format

The majority of functions in Spatial Tools operate primarily on grid theme data (ARC GRID format).  The exceptions are the Profile and Profile with Feature Points operations which require a combination of active grid, line and point feature themes, and  Clip Grid, which requires a selected graphic object as well as an active grid theme to perform the analysis.  The menu choices Set to View and Set from View  each require a separate existing view in the project and the Type in to Link and Type in from Link work  with an existing table (which can be created using the Create Link Table option).

Menu choices are performed on selected (active) feature themes, after which the user is prompted to enter or select from a list of variables.  Tool buttons are utilized by clicking the tool and then clicking in the view to perform the function.
 

Views

VIEW MENU CHOICES

Select a Menu Item

Addition to Version 3.2 menu (10/99):

• Point and Line Visibility Tool

• Make Warp Point Table, Warp Help, and Warp choices have been removed from the Transformation menu.
• New warp functions have been added to the Transformation menu, which include Set From view, Set To View, Set Link Table, Create Link Table, Type in From Link, Type in To Link, and Warp.
• Random Grid has been added to the Analysis menu.
• Profile and Profile with Feature Points have been added to the Analysis menu.
• Grid to Image has been added to the Analysis menu.
• A Delete Link Button  has been added to the view.
• A Rotate Grid Button  has been added to the view.
• The Grid Shift Tool Icon  has been changed.

Select a Tool

TRANSFORMATION MENU

Merge Grids

Mosaic

In the following example, 3 grids were mosaiced to create a new grid with smooth boundaries.

Combine Grids

Clip Grid

Select graphic object

Choose "clip inside" or "clip outside'

The following set of tools are used in the georeferencing/warp operation for grid data sets:
Note...Online help for the warp procedure is available from ArcView's Help Menu

Set From View
Specifies the view to be used as the From View in the Warp operation.

Set To View
Specifies the View to be used as the To View in the warp operation.

Set Link Table
Specifies the Table to be used as the Link Table (a table containing "from" and "to" link coordinates) in the warp operation.

Create Link Table
Creates (and sets) an empty Link Table to be used in the warp operation.

Type in From Link
Allows the user the option to manually type in a "from" link coordinate in to the Link Table instead of clicking in the "From View".

Type in To Link
Allows the user the option to manually type in a "to" link coordinate into the Link Table instead of clicking in the "To View".

Warp
Starts the warp calculation on an active grid theme.  After creating/setting the "From" and "To" views, creating/setting the link table, and building a list of coordinates in the table, the user must select the "From View", and is prompted to enter the polynomial order to be used, as well as the desired resampling method (Nearest Neigbor, Bilinear, or Cubic Convolution).The new dataset will be added to the "to" view and named "Warp of (original grid theme)".
 
 

Aggregate

The following bathymetry grid was aggregated using maximum values for depth and a cell factor of 3.  The resulting grid been resampled to a coarser resolution.

Grid to Image

Takes a grid or set of grids that were created from a true color image and converts them into a BSQ, BIL, BIP, JPG or TIFF image.
All of the grids must be from the same source image and must be of the integer type.  Cell values cannot exceed 255.

The g2i.dll file must be placed into the bin32 directory to work properly.

CLEAN UP MENU

Majority Filter

In the following example, the majority filter function has smoothed out the data by replacing misclassified cells (dark green areas of vegetation occurring in water) with new values using the most frequently occurring values of neighboring cells.
 
 

Region Group

Extract by Count

In the following landcover grid, the original values which represent  "shadows"  (displayed in black) were set to to No Data by entering a count of 1500.  The new grid represents the original values for all  data with a count greater than 1500.

Nibble

Boundary Clean

Thin

notBinary (TRUE = all values other than No Data are thinned.  FALSE =  only values greater than 0 are thinned).
doFilter (TRUE =  the Grid is filtered to smooth the boundaries between values. FALSE = no filter is used).
sharpenCorners (TRUE = rectangular corners and junctions are preserved. FALSE = all corners and junctions are smoothed).
maxThickness (can be a Number or Nil, that defines the maximum thickness, in map units, of linear features in the Grid. If maxThickness is set to Nil a value 10 times the cell size of aGrid is used).

Resample

Changes the resolution of the active grid by interpolating values using a chosen resampling method (nearest-neighbor, bilinear, or cubic).

• NEAREST NEIGHBOR:  Fastest of the 3 interpolation methods. It is mainly used for categorical data, as it will not change cell values. The maximum spatial error will be one half the cell size.
• BILINEAR:  Determines the new value of a cell based upon a weighted distance average of the four nearest input cell centers. It can be used for continuous data, and will cause some smoothing of the data.
• CUBIC CONVOLUTION:  Determines the new value of a cell based upon a weighted distance average of the sixteen nearest input cell centers. It is used for continuous data and is geometrically less distorting than the Grid achieved by running the nearest neighbor method.  This method require the most processing time.

Random Grid
This function creates a random grid.  The user selects either a uniform random or a normal random grid, and is prompted as to whether or not the values are to be adjusted.

The following histograms illustrate the default values used in creating  uniformly and normally distributed random grids:
 

Uniform: Values are between 0 and 1	Normal:  Mean = 0 and Standard Deviation = 1

Pycnophylactic Interpolation
The program performs pycnophylactic interpolation on a categorical grid.
The analysis variable in the VTAB of the grid should represent a phenomenon that changes continuously over space.

Zonal Geometry Table

Creates a table containing various geometric calculations for each zone in the active grid.

In this example, the selected stream (shown highlighted in yellow) was profiled, using 5 equal divisions.  The chart below shows distance and corresponding elevation values.
 
 

Used to create elevation profiles of selected lines and selected point features.  Requires three active themes, the first a point theme (the feature points), the second a line theme and the third an elevation grid theme.User is queried for how many divisions of merged line.  Outputs a dbf file of distances starting at the lowest inerval point and including all interval points, feature points and corresponding z values.  Dbf table contains a "Type" field indicating whether a distance is an interval point or a feature point.  Outputs a scatter diagram graph (the line profile) of distance from origin vs. z values if no more than baout 50 points are produced.
 
 

Line or Point File Visibility

Conducts a visibility analysis of a line or point file.  This function requires the following fields in the input FTab, which are used to control the visibility analysis. These Fields are SPOT, OFFSETA, OFFSETB, AZIMUTH1, AZIMUTH2, VERT1, VERT2, RADIUS1 and RADIUS2.

If not specified, the default values in the Visibility Tool are are set as follows:
 
 

Creates Warp desired points (creates a "to link" in the "to" view).  Click on the desired location in the georeferenced dataset to start building a list of "to links" (Points will automatically be labelled).  Use the delete links button to remove incorrect links from the table.
 

Shifts the active grid to a new location  by clicking in the view to move its point of origin.Click the tool, then click on the desired location to shift to in the view.
 
 
 

VIEW BUTTONS

Rotates the active grid in a clockwise motion around the lower left-hand corner.

Click the button, then enter the number of degrees desired (and the resampling method to be used if multiples of 90 degrees are not used).  (See previous section on Resampling methods, for a description of the 3 types of interpolation).

In this example, a new grid was created, rotated 90 degrees around the original grid's lower laft-hand corner.
 
 

Bibliography