Q. What is an FAQ?

Frequently Asked Questions. A list of questions and answers commonly used on the web to provide the same information to many users.

Q. What is Geography?

The study of the earth and its features and of the distribution of life on the earth, including human life and the effects of human activity.

Q. What is Remote Sensing

The measurement or acquisition of information of an object or phenomenon, by a recording device that is not in physical or intimate contact with the object. Data may be acquired through a variety of devices depending upon the object or phenomina being observed.

Q. What is GIS?

A geographic information system (GIS) is an organized collection of computer hardware, software, geographic data, and personnel designed to efficiently capture, store, update, manipulate, analyze, and display all forms of geographically referenced information. GIS is distinguished from other information system technology in its ability to perform common database operations and statistical analysis, as well as complex visualization and geographic analysis. These unique capabilities make GIS valuable for explaining events, predicting outcomes, and planning strategies.

Q. What is a .E00 file?

.E00 are ARC/INFO Export files, or interchange files, that can be used to transport coverages, INFO data files, text files such as AML macros, and other ARC/INFO files between various machine types. An interchange file contains all coverage information and appropriate INFO data file information in a fixed-length ASCII format.

Q. What is a Shapefile file?

A vector data storage format for storing the location, shape, and attributes of geographic features. A shapefile is stored in a set of related files and contains one feature class.

Q. What is a Vector file?

A vector file is a data storage format for storing the location, shape, and attributes of geographic features. A shapefile is stored in a set of related files and contains one feature class.

Q. What is a Raster file?

An abstraction of the real world where spatial data is expressed as a matrix of cells or pixels, with spatial position implicit in the ordering of the pixels. With the raster data model, spatial data is not continuous but divided into discrete units. This makes raster data particularly suitable for certain types of spatial operation.

Q. What is ESRI?

ESRI (pronounced either EZZ-ree or EE-ESS-AHR-EYE, its employees only call it EE-ESS-AHR-EYE, though) abbreviates the name of Environmental Systems Research Institute, Inc., an organization based in Redlands, California which produces Geographic Information System software. They are the biggest manufacturers and sellers of geographic information systems in the world with large offices in both the U.S. and UK and smaller offices elsewhere. ESRI uses the name, ArcGIS to refer to its suite of GIS software products, which operate on desktop, server, and mobile platforms. ArcGIS also includes developer products and web services. This is the main GIS software package that MARIS uses on a daily basis.

Q. What is ERDAS?

The leading provider of Geographic Imaging products and related services to clients worldwide. ERDAS' business encompasses software development, sales, technical support and training for numerous geographic imaging products, custom applications development and project consulting services. The software runs on the most popular platforms: Windows and UNIX. The products are tightly integrated, highly customizable, and easy-to-learn-and-use.

Q. What is MrSid?

MrSID is an acronym for Multi-resolution Seamless Image Database. More information is available at LizardTech.

Q. What is TIFF?

TIFF is a tag-based image file format that is designed to promote the interchange of digital image data. The TIFF format originated in 1986 when Aldus Corporation and leading scanner vendors worked together to create a standard file format for images used in desktop publishing. The first version of the specification was published in July, 1986. Version 6.0 of the specification was completed in September, 1995, and is available on Adobe's Web site. TIFF provides a general purpose data format and is compatible with a wide range of scanners and image-processing applications. It is device independent and is used in most operating environments, including Windows, Macintosh, and UNIX. This non-proprietary industry standard for data communication has been implemented by most scanner manufacturers and desktop publishing applications. Adobe continues to evaluate and incorporate TIFF enhancements that are useful within publishing applications, maintaining backward compatibility whenever possible (e.g., even applications written in the fall of 1986 can read many modern TIFF 6.0-compatible images).

Q. What are Spatial Data?

Data used with geographic information technology have different characteristics than data required in conventional data base systems. GIS uses spatial data which, quite simply, includes anything that takes up geographic space or has geographic distribution.

Q. What data is available from MARIS?

MARIS maintains vector and raster data. The vector data is organized into two distinct ways:

  • Statewide Files - indicates the extent of the themes area of coverage is continuous over the whole state.
  • County Files - the themes area of coverage exists by individual counties for each county in the state.
Raster data is avaible either by county or selected areas.

Q. What is a map projection?

A mathematical formula that transforms feature locations from the earth’s curved surface to a map’s flat surface. A projected coordinate system employs a projection to transform locations expressed as latitude and longitude values to x,y coordinates. Projections cause distortions in one or more of these spatial properties: distance, area, shape, and direction.

Q. What map projection does MARIS use?

MARIS uses the Mississippi Transverse Mercator (MSTM) projection.

Q. What is the MSTM Projection?

The MARIS Technical Center (MTC) and the Mississippi Department of  Transportation (MDOT) jointly developed a map projection for Mississippi called  the Mississippi Transverse Mercator (MSTM) Projection. When viewing geographic  data on a statewide level, the MSTM projection alleviates the multiple-zone conflict inherent in UTM and State Plane systems.The problem with both of these  systems is that each divides the state into an east and west zone that cannot be  digitally displayed together.

The MSTM projection is a customized Transverse Mercator projection designed  to more evenly distribute convergence and scale-factor, and is based on the  North American Datum of 1983 (NAD83). The projection parameters of the MSTM  projection are as follows:

Scale Factor: 0.9998335
Central Meridian: -89 45' 00''
Central Latitude: 32 30' 00''
False Northing: 1,300,000 meters
False Easting: 500,000 meters
Projection Units: meters
Spheroid: GRS80
Datum: NAD83

(click image)

This projection is used by both MTC and MDOT for the development and storage of geographic data. The MTC can and does receive and distribute data in a number of other projections, however, the MARIS Technical Center and MDOT encourage the use of the MSTM projection.

More information regarding the development of the MSTM projection and its projection parameters may be obtained by contacting MARIS at 601-432-6128.

Q. How do I add MSTM projection to my shapefiles?
A. Download mstm.exe to c:\arcgis\arcexe9x\Coordinate Systems located on your PC. (This is a self-extracting zip file)

  1. Open ArcToolbox
  2. Click on the Data Management Tools tab
  3. Click on Projections
  4. Click on define projection wizards (shapefiles,geodatabases)
  5. Click on folder icon and navigate to shapefiles you want to add info to
  6. Click Next
  7. Click Select Coordinate System
  8. Click Select (the Coordinate systems directory should show up)
  9. Click on mstm.prj then click on Add
  10. Click on apply then OK
  11. Click Next
  12. Click Finish
You will notice that a prj file for each shapefile has been added to your directory. Download this pdf document with more detailed instructions. This file includes screen shots which makes the file size approximately 5.2mb.

Q. How do I define raster projections in ArcGIS 9.x?

Download mstm.prj to c:\ProgramFiles\arcgis\Coordinate Systems located on your PC.
(Internet Explorer users right click on link and Save Target As...
Netscape users left click on link and Save it to Disk)

  1. Open ArcMap
  2. Click on ArcToolbox Icon
  3. Click on the Data Management Tools tab
  4. Click on Projections and Transformations tab
  5. Click on Define Projection tab
  6. Click on folder icon and navigate to raster images you want to add info to
  7. Click Add
  8. Click Select Coordinate System
  9. Click Select (the Coordinate systems directory should show up)
  10. Click on mstm.prj then click on Add
  11. Click on apply then OK
  12. Click OK
  13. Click Close
This will allow you to view the raster image in MSTM with vector or other data in other projections without having to re-project the raster image.

Q. Where is the USGS Map Index?

Click here.

Q. What if my SHAPEFILE gets corrupted?