AddXY - v.1.0 - 2.74 KB
AddXY (v1.0) is an ArcView extension that should work with ArcView 3.0 and later. It adds the X and Y values of points (shapefiles or coverages) to their attribute tables. It adds the X and Y values of polygon centroids (shapefiles or coverages) to their attribute tables. It will add the X and Y value of a polygon’s labelpoint to its attribute table. Due to a bug in ArcView, it does not work consistently with node coverages, so this has been removed. The X and Y columns in the attribute table should be created with the same names and precision that the ARC/INFO command “addxy” would create.
When installing ESRI’s ArcView GIS 3.3 on the 32-bit version of Microsoft Windows Vista Ultimate, the following dialog box instantly appears:
It looks pretty bad. Even the title says it’s a severe error! You have to remember, this product was developed back in the Windows 95 days.
There is an easy workaround. Open Windows Explorer and browse the contents of your ArcView CD-ROM and right-click on setup.exe. Click on the Compatibility tab, and click the checkbox next to “Run the program in compatibility mode for:” and leave the Windows XP (Service Pack 2) as is. Now click OK at the bottom of the dialog box to apply the changes and close the box. Double-click on setup.exe and your installation will begin.
Generalize - v.1.0 - 6.09 KB
This Arcview extension provides a dialog-based tool to simplify the currently selected shapes in a polyline or polygon shapefile. This tool is used to generalize, or weed out, vertices that do not add to the desired level of detail in the geometry. A tolerance is specified to check whether or not vertices should be retained.
This script is a simple implementation of the Douglas – Peucker algorithm used in ARC/INFO and PC ARC/INFO. The dialog is initiated from a button in a View GUI.
- The extension does not make a new shapefile. It changes the currently active polyline or polygon shapefile. Changes can be Undone using the standard shape editing tools in Arcview.
- The extension will reduce the quality of the data. Any metadata for the themes should state that the data are modified.
- The extension will generalize all the selected polylines or polygons.
- Results are very dependent on the polyline or polygon geometry. While the shape endpoints are maintained, interior points may be eliminated. Other shapes in a network that may begin or end at an interior vertex may now be dangling. A complex shape may cross itself after being generalized. Neighboring polygons will no longer match edges. Proceed with caution.
- This script does not recalculate lengths or areas. They may have changed as the shapes are simplified. The View.CalculateFeatureGeometry (calcapl.ave) sample script can be used to update the values.
AddXY (v1.0) is an ArcView extension that should work with ArcView 3.0 and
later. It adds the X and Y values of points (shapefiles or coverages) to their
attribute tables. It adds the X and Y values of polygon centroids (shapefiles
or coverages) to their attribute tables. It will add the X and Y value of a
polygon’s labelpoint to its attribute table. Due to a bug in ArcView, it
does not work consistently with node coverages, so this has been removed.
The X and Y columns in the attribute table should be created with the same
names and precision that the ARC/INFO command "addxy" would create.
Thanks to Mark Cederholm for his help in compiling the extension. Written by
Zachary Stauber. Send any questions, comments, complaints to
HydroSHEDS (Hydrological data and maps based on SHuttle Elevation Derivatives at multiple Scales) provides hydrographic information in a consistent and comprehensive format for regional and global-scale applications. HydroSHEDS offers a suite of geo-referenced data sets (vector and raster), including stream networks, watershed boundaries, drainage directions, and ancillary data layers such as flow accumulations, distances, and river topology information.
HydroSHEDS is derived from elevation data of the Shuttle Radar Topography Mission (SRTM) at 3 arc-second resolution. The original SRTM data have been hydrologically conditioned using a sequence of automated procedures. Existing methods of data improvement and newly developed algorithms have been applied, including void-filling, filtering, stream burning, and upscaling techniques. Manual corrections were made where necessary. Preliminary quality assessments indicate that the accuracy of HydroSHEDS significantly exceeds that of existing global watershed and river maps.
The goal of developing HydroSHEDS was to generate key data layers to support regional and global watershed analyses, hydrological modeling, and freshwater conservation planning at a quality, resolution and extent that had previously been unachievable. Available resolutions range from 3 arc-second (approx. 90 meters at the equator) to 5 minute (approx. 10 km at the equator) with seamless near-global extent.
HydroSHEDS has been developed by the Conservation Science Program of World Wildlife Fund (WWF), in partnership with the U.S. Geological Survey (USGS), the International Centre for Tropical Agriculture (CIAT), The Nature Conservancy (TNC), and the Center for Environmental Systems Research (CESR) of the University of Kassel, Germany. Major funding for this project was provided to WWF by JohnsonDiversey, Inc.
HydroSHEDS data are free for non-commercial use. For more information on HydroSHEDS please visit http://www.worldwildlife.org/hydrosheds (homepage at WWF) and http://hydrosheds.cr.usgs.gov (data download and technical information).