ArcGIS Pro includes a wide variety of editing tools right out of the box. These interactive tools can be used to create, modify, or delete the features and related data on layers in 2D and 3D. You can use the … Continue reading
A common question when using Data Reviewer’s Positional Accuracy Assessment Tool (PAAT) is what sample size should be used when evaluating a geospatial data layer. Sometimes the sample size is mandated by a specification; but when it’s not, Data Reviewer’s Sampling check can be used to provide the sample size. In this blog, I’ll discuss how you can use the Sampling check to generate a statistically valid sample size and then explore two options for using it with the PAAT.
The steps include:
1. From the Data Reviewer toolbar, select the Select Data Check dropdown.
2. Expand the Advanced Checks category and select Sampling Check.
3. In the Sampling Check Properties dialog, select Auto Calculate.
Note: The question you’re looking to answer: given a population size (number of features), what sample size do I need so that I’m “X” percent confident the sample size is statistically significant within a “Y” percent margin of error?
The Esri Grid format for storing raster data has been around for…well, longer than this writer has been doing GIS. But we keep learning about things that need to be added to the documentation. I’m sure those original Grid users could probably tell me more than I ever wanted to know about the format, but here’s a limitation that was news to me.
The name of a Grid has certain limitations, but did you also know that there’s a limit to the number of Grids that can be stored in a workspace? The following lists the theoretical maximum number of Grid datasets that can be stored in a single workspace directory:
- less than 5000 floating point Grids, or
- less than 3333 integer Grids, with VATs (less than 5000 if no VATs), or
- less than 10000 Grid stacks
The preceding numbers are the theoretical maximums. If you have a process that will create interim Grids (and therefore files in the INFO directory) these numbers will be less. Additionally, if you are storing a mix of files, such as Grids and coverages, you will store fewer.
These numbers relate to the number of files in the Grid folder that store information in the INFO directory. The limit is 10,000 (well, 9,999), but it’s not the total number of files in an INFO directory, it’s the number of files pointing to the files in the INFO directory. For each Grid, there are two files in the Grid’s folder pointing to files in the INFO folder: the BND (boundary) files, and STA table (statistics) files (9999/2?5000). When a Grid has a VAT, this also points to files in the INFO directory, so the number that can be stored is reduced again (9999/3?3333). A Grid stack only has a single file which points to the INFO directory (9999/1?9999).
You can get a count of the number of files in an INFO directory using Windows Explorer.
- Navigate to the INFO directory.
- Select all the *.dat files (each Grid file points to a .nit and a .dat file).
- Right-click and select Properties.
This will give you the count of files. Regardless of the data is in the directory (Grids, stacks, coverages, etc.), when that number gets to 9999, the INFO directory is full and you’ll get an error message to the effect of: “Fatal Error: (INFDEF) directory full”. If you happen to come across this limit, you can either create a new workspace to work in, or remove any data that is no longer needed.
There are many ways of representing locations. One of the most common uses angular latitude and longitude coordinates to specify the location of a point. These Geographic coordinates may be expressed in several different notations, including Decimal Degrees (DD), Degrees Decimal Minutes (DDM), and Degrees Minutes and Seconds (DMS). The formula for converting Degree Minutes and Seconds to Decimal Degrees is discussed in the ArcGIS 10 Help. Another common method is to use a projected coordinate system and X and Y coordinate pairs, that is, two sets of numbers in a planar Cartesian system.
Have you ever wondered what is the equivalent ArcGIS desktop command for an ArcInfo workstation command? Have you ever wondered what the equivalent python command is for an AML function or Directive?
The Geoprocessing team has created the following glossaries to allow workstation users find corresponding ArcGIS Desktop commands. In many cases the mapping of functionality and commands between Workstation and ArCGIS Desktop is straight forward and obvious. Sometimes, however, finding the corresponding Geoprocessing tool in Desktop is not straight forward and obvious, and these glossaries are a helpful resource for those of you that are using workstation in conjunction with Desktop.
Workstation to Desktop Glossaries:
- Core ArcInfo Commands to Desktop
- GRID Commands to Desktop
- GRID Functions to Desktop
- AML Functions to Python
- AML Directives to Python
In addition to these glossaries, in 9.4, you will be able to use the new search functionality with Arcmap to search for Workstation commands and the corresponding Geoprocessing tool will be returned if there is a match. These glossaries will be used as a source for populating the keywords to ensure the search mechanism is as accurate as possible.
Keep in mind; we recognize that these glossaries do not show every alternative for workstation functionality within Desktop. As a result, we will continue to update these documents and if you have suggestions or alternatives, please let us know.