Acre

The acre is an area measurement used in land sizes.  One square mile (one mile by one mile) is equal to 640 acres.

 

ArcCatalog

ArcCatalog can be used as a standalone program or in conjunction with ArcMap.  The program is a geospatial file explorer program that allows viewing of geospatial files and the metadata.  In addition some file manipulation is possible.

Arc

ArcMap

ArcMap is a commercial geospatial mapping program for the desktop that is a product of Esri.

 

ArcGIS Server

ArcGIS Server is an enterprise level software created by Esri, that functions on a server class machine and can stream numerous different data types, which include Google format, Map Sevice (non-editible) and Feature Services (editible).

 

Arcpy

Arcpy is the python library that contains most of the Esri ArcMap commands and can be used in Python scripts.

 

Attribute Table

An attribute table in geospatial program is a database containing rows and columns each row would be a unique geospatial item.  Each column can have a unique format, such as a number or text (note there numerous other types of formats).  For example an attibute table for a state county map would have one row representing each polygon of each individual county.  The remaining fields would contain unique information such as land area, income, population, etc.  Each attribute can be selected to display different information.

 

Basemap

A basemap is usually the lowest layer, a raster, and the user cannot edit the layer.  For example the base layer might be a map with roads and other geographical features that user puts value added upon.  The user can also create their own basemap layers.

 

Buffer

Buffering is the process of creating a surface about a point, line, or polygon.  In general a distance is a seleced distance away from the selected object.  For example a buffer about a point will be circle, about a line it would be parallel to the line with rounded ends and about a polygon it would be a shape of the polygon a uniform distance away from the original object.  Buffers can also be done inside of a polygon surface.

 

Cadastre

A surveying term is also spelled cadaster, it is a description of a parcel of land, which includes but not limited to the location and area.  The cadaster contains documented survey measurements such as how many feet from a known point in what direction a boundary is located.  This in general is the official document for legal purposes.  Source: https://en.wikipedia.org/wiki/Cadastre

Also

Cartography

Cartography is the study of making maps.  A map should be appealing to the eye, convey the appropriate information, and use the appropriate projection of the surface of the earth.  Cartography is a relationship of science and art.  The design of a map is a multiple step process that requires both technology and manual operations.  Multiple software may have been used to create the final product.  Maps can be both either dynamic or static. A static map has no features change related to scale and thus only one design is required, while a dynamic map will change as the user changes the scale and the designer must be aware of how the image will look at every scale range.

 

Census Tract

A polygon feature, a census tract is complete enclosed within a single county, thus every county of the United States has at least one census tract.  A census tracts have approximately the same population.  They can be subdivided into blocks and block groups.  Census tracts are used extensively in demographical research.

 

Clip

The process of creating a new file by taking a subset of another file by using a polygon boundary file.  For example of you have a state map of rivers and want the rivers only within a given distance from a point.  A polygon curface can be created aroud the point and a clip performed and the new file will contain the rivers a given distance from the selected point.

 

Conic Projection

A conic projection of the earth land masses uses the concept of an imaginery cone covering the earth and projecting of the earth's surface onto the cone.  If the cone is un-wrapped and laid flat you would have a conic projection of the earth's land masses.

 

Contour Lines

A contour line represents normally a polygon surface which the line having a common value, a contour line might represent a temperature, air pressure or an elevation.  In geospatial technology a contour line is used to represent an elevation measurement and everything on the line is at the same elevation.  These contour lines are normally referred to topographic lines.  The separation between the topographic lines are controlled both by the user and also the instrumentation that was used to create the data.

 

Coordinate System

Is a system of measurements, a coordinate system will have two or three measurements associated with it.  Every point on the surface of the earth is part of a coordinate system.  Some coordinate systems are in feet, meters, or miles while other systems are in degrees, an angular measurement, which may use fractional degrees or degrees, minutes and seconds.

 

csv

This is a file type includes comma deliminated information.  Normally this is a basic text file type which can be viewed in notepad or a spreadsheet program.  As the name indicates each item is seperated by a comma.  The first row of information is the header and the remaining information is the data.  This formate is good as a way of transfering information that might be tabular joined to a shapefile.

 

Database

A database is a grouping of information that is composed in rows and columns. The database allows for mathematical calculation but the equation is used once and is gone, it is not saved in the individual cell like in a spreadsheet.  The columns represent fields and each row has a unique ID number that contains information about a specific piece of information with the attirbutes contained in each field.  Logical queries can be done on specified fields.  The information in each field is formated such as number, text, etc.

 

Data Frame

A data frame is a term used by Esri, it contains items such as map projections, coordinate systems, as well as the arrow being displayed.  A map may display multiple data frames.  Cartographers refer to this as Map Body.

 

Digital Elevation Model (DEM)

A DEM contains information about the elevation of the surface of the earth.  The elevation data is normally referred to as the 'z' value.  By having accurate elevational data a three dimensional model of the surface earth can be constructed.  The accuracy of the information will vary and dependent on how the data was collected.

 

Digitizing

Is a process of taking analog data into electronic digital format.  Before the information can be digitized it must be referrenced to the surface of the earth.  For example a paper map can be scanned and created as a picture format, the information from the image  can be converted into a vector format either through heads up digitization or by an algorathim.

 

Domain

There are multiple uses of this word.  In this case a domain is a listing of potential attributes for a speicific field in a database.  For example the street names in a city might be part of a domain.  Therefore, all users would select a member from a list, this eliminates typographical errors and make field data collection easier.  The same domain can be used for more applications saved in the same database.

 

Dynanic Zoom

The process of turning on and off layers and labels dependent on their zoom scale.  For example a city might be displayed as a point when zoomed at the state level, but as a polygon when at the county level.  This occuring automatically makes the map much more functional.  The same type of zooming is posible with labeling so that a statewide map is not cluttered with every town in a state, but at the county level all the small towns and villages are displayed.

 

Electromagnetic Specrum

The electromagnetic spectrum is a family of energy from radio waves to gamma waves.  The information has both wave and particle properties.  Many of the different energies are used in remote sensing.  Visible light, infrared (near and thermal), radio waves and ultraviolet are all used in geospatial technologies.

 

Ellipsoid

An ellipsoid is a three dimensional shape which through one plane an ellipse is projected and through a perpendicular plane a circle would be projected.  The earth is not a sphere due to the rotation on its axis.  The polar regions are compressed and the equatoral regions bulge.

 

Geocoding

Geocoding is the process of changing a street address into a coordinate location on a map.  Geocoding is done by comparing a spreadsheet or csv file with a locator file to try and locate the position of the address.  The quality of the geocoder directly impacts the quality of the data points.  Each address becomes a point in a geospatial file.  This is done by using all components of the address including the street address, city, state and zip coder.  In the proces, first the state is compared to limit the information used, then the city and zip code, next the name of the street is searched for in the information that remains. Each street segament in the locator file, has an address range, which represents a block, then an estimation is done on the postion depending on length of the block and number of address contained on the block.

 

Geodatabase

A database is a collection of information that can be easily accessed.  A geodatabase is specifically designed for mapping.

 

Geodesy

Relates both mathematics and earth science together in the study of the earth's shape, with influences such as rotation and gravitational pull.

 

Geoids

Geoids is the theoretical shape of the earth's oceans would take under an equal gravitational pull at all points and rotation, without the consideration of tides and wind.   Source: https://en.wikipedia.org/wiki/Geoid

 

Georeferencing

Is the process of taking an image and referencing the image to the surface of the earth.  This in general is done by aligning points from the image to a projected map.  The more corresponding points selected the better the alignment of information.  The alignment can be done from a linear method or a more complex mathematical function.  Once the image is aligned a digitization process is required to create vector imformation.

 

Hillshades

Is the process of building a solid model that can be viewed from multiple angles and elevations to determine what a surface would look like.

 

Label

In mapping a label is used to designate a location on a map.  Labels can be either dynamic or static.

 

Latitude

A line of latitude is perpendicular to Longitude and is parallel to the equator which is the zero line of latitude.  Latitude is measured north or south of the equator and have values from 0 to 90 degrees.  The north or south pole has a latitude of 90 degrees and is a point.

 

Layer Files

A layer file is composed of vector information as well as symbolism.  The vector information is shapefile type information such as line segment length and direction.  The symbology is composed of items such as color, symbol, thickness and informational break points.  The layer file points to the shapefile for the geometry.  If the shapefile is moved the layer file becomes broken and must be re-associated. 

 

Layers

In most geospatial mapping system layers are used.  Layers can be stacked and selected to be visible or not.  In general a point layer is on top of all line layers, and lines are on top of all polygon layers and a raster generally the lowest layer and known as the basemap.

 

Layer Package

A layer package file is similiar to a map package.  A layer package can be one or more layers and the associated data that have been packaged into a single file for easy transfer of information without the loss of symbology and other characteristics  of the layer.  In general it will be much smaller than a map package.  A layer package can be opened directly in ArcMap by dragging from ArcCatalog.  This is referring to an Esri format.

 

Legend

A legend provides information to the viewer about the symbols and colors used on a map.  In general it will have an example of the feature and descriptive name.  For example it might have secondary roads shown with a short black line and then named State Roads.  In addition the legend can explain ramp colors used to represent a feature but with a set of division, such as income broken into five classifications.

 

Line

A line is a vector which has length and direction but no thickness.  A line is displayed with a width, style and color, but that is for display purposes only.

 

Line of Sight

The Line of Sight allows a user to determine what would be visible and not due to education.  Generally the user can offset the observers elevation and the height of the target.

 

Longitude

A line of longitude runs from pole to pole and measured east and west of the prime meridan.  Lines of longitude are measured from 0 to 180 degrees east or west of the prime meridan.  The 180 degree line has no east or west designation and at most points is the international date line.

 

Map Body

See Data Frame.

 

Map Package

A map package is a single file which contains all of the map information of a map project file including the data which is not stored in a map project file (mxd).  This is a way of sharing information from one user to another, the file size map be very large.  The map package should be expanded outside of ArcMap.  This is an Esri format.

 

Mercator projection

A Mercator projection of the earth's land masses is done by placing an imagery cylinder around the earth touching at the equator.  If the land masses are then projected onto the cylinder and the cylinder then unrolled, the results is a Mercator projection.  The lines of longitude would be parallel to each other as would the lines of latitudes.  The latitude and longitude would form a grid pattern crossing each other perpendicular.  Far northern and southern latitudes would be very distored.

 

Merge

Merging is a processes of combining to look shapefiles together and the creation of a new shapefile.  For example if you have two counties and you want to combine them together to create single new file, the process would be merge.

 

Meridian

A meridian is a line of longitude.  Before time zones meridians were lines in which were used to calculate local time.  Many large cities have north-south streets near the center of the city that were used for local time calculation.  Therefore cities would have different time calculations, since the calculations were based on the position of the sun.  Noon was the time that the sun was due south on the meridian. 

 

Metadata

Metadata is information provided about a layer that assists the user in a better understanding of how the layer was constructed, the purpose of the layer and the projection of the data.  All layer files should have metadata associated with them to make them more usable by other individuals or when a layer is reused for a new project.

 

MXD or project file

A MXD file type is an Esri project file type.  The project file contains information about all the shapefiles used in a mapping project.  This includes property information about individual shapefile such as color or line weight, break points of data and symbolism. The actual data files are not saved in the project file but the location of the information is saved.  Thus if information is moved, the file becomes disassociated with the project file.

 

NDVI

Normalized Difference Vegetation Index uses near infrared in the analysis of vegetation.  Normally false color imagery is used in conjunction with this method.  Vegetation emits large amounts of near infrared.  The calculation for NDVI utilize the difference between near IR and visible divided by the sum of near IR and visible.

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Near Infrared

Near is the area of the electromagnetic spectrum that is of longer wavelengths than red light.  Usually referred to as near IR.  These wavelengths are used to determine the amounts of vegetation in remote sensing.

 

Oblate Spheroid

The earth is not a sphere, which means all objects are an equal distance from the surface, even if we forget about mountain ranges and the depths of the ocean.  The earth actually bulges in the equatorial regions and is flattened at the poles.  This is caused by the rotation of the earth on it's axis.  The particles of the earth at the equator are trying to leave tangentially to the surface of the earth, the centripetal force of the earth structure is holding the earth together.

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Oblique Imagery

Oblique images occurs when a three dimensional surface are viewed from a non-perpendicular angles and gives a three-dimensional  appearance.  In aerial photography those objects further from the center of the flight paths have more oblique nature, instead of seeing just the roof top of the building the sides are also visible.  This can be eliminated by overlapping the images andusing more flight pathes, which increases the cost.  There are other applications in which oblique images are made intentionally, this normally is accomplished by using a multiple camera platforms.  One of the applications for oblique imagery is measuring the height of buildings directly.

 

Open Source

It is a common belief that Open Source means that the software is free, while many Open Source software are free, what it really means is that code of the software is not closed and can be modified by the user.

 

OpenStreetMap

OpenStreetMap is much like the concept of Wikipedia, in which the user community builds the map.  OpenStreetMap allows for anyone to add information to the map, which will become part of the basemap once accepted.  It does use volunteer editors to check on additions to the map to make sure that they are accurate.  Data can be loaded as individual items drawn by the user who also adds attributes or in a batch format, but that takes an additional level of permissions.  http://OpenStreetMap.org

 

Orthographic Project

An orthographic image is the representation of three dimensional space in two dimensions. 

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Point

A point is a singularity in space, it occupies no physical space and only has a coordinate.  It is displayed with a shape, size, style and color, but that is for display purposes only.

 

Polygon

Is any closed surface that can be filled.  It is created by a line that encloses an area.

 

Projection

A process of displaying the surface of the earth onto a two dimensional grid.  The earth is a rough sphere, not a ball.  It is imposiible to peel the earth's surface and make it a flat planar object, like a piece of paper. Projections are used to project the curved earth onto a flat surface.  All projections will cause some degree of distortions.  A map of the United States, in the northern part of the country will appear different  depending on the projection.  Maps should be projected and all layers should be in the same projection.  

 

Publishing

There are two types of publishing static and dynamic.  A static map is like a paper map or Adobe Acrobat file (pdf), while a dynamic map can be modified such as an online map.  A published map should have a scale, legend, directional arrow, title, and author block.  In addition a boarder about the map and addition information that can make the more user friendly is also suggested.

 

Python

Python is a modern scripting lanaguage that can be used to within or outside of my geopatial programs.  It is used in both ArcMap and QGIS.

 

QGIS

QGIS is an Open Source geospatial technology software that is free and one of the leading Open Source GST softwares in the world.

 

Query

A query is the selection of information based upon a set of criteria.  For example you want display only those census tracts that have a median income greater than $25,000, yu would use a query function to make this determination.  A query in general does not alter the data permanently.

 

Raster

A raster layer is a bitmap layer, a picture, which may or may not be dynamic.  In GST many times the raster layer will be a basemap or an aerial image of a region that is being studied.

 

Relational Database

A relational database is designed to allow multiple editors, a time stamp is written when a record is opened and used to make sure the most recent information is displayed.  Microsoft SQL, mySQL and Orcale are some of the more common relational databases.

 

Remote Sensing

Remote Sensing is the process of taking imagery data from a sensor and determining information about the location.  Remote sensing takes to forms, active and passive.  Passive remote sensing is the collection of reflected data, while active remote sensing is the process of sending a pulse and viewing the reflected information that is received.  Passive remote sensing is looking at a picture of the earth and viewing the imge which is formed by the reflection of sunlight.  Active remote sensing is what occurs with radar, a pulse of electromagenetic radiation is sent from an antenna and the reflected data is received and analyized.  

 

Sanborn Map

A Sanborn map was created for populated areas of the United States, begin in the 1860s, these historical maps were created for communities so that fire insurance rates could be accurately determined.  These maps are an excellent example of urban growth and are extremely useful in historical research of a community.  Many different source exists for the older data which is outside of copyright.  The Sanborn company is still a geospatial company.  http://sanborn.com 

 

Section

A section is one-thirty-sixth of a township.  It is one mile square and contains 640 acres.  In general a section is divided into sixteen 40 acres divisions.  This is a mehtod used to survey land in much of the eastern United States.  A AA

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Shapefile

A shapefile is a file type that is used in Esri ArcMap.  A shapefile contains spatial data to create map elements such as a line or polygon.  The shapefile can be used in database or in a file folder.  The shapefile does not contain information such as color or line thickness.

 

Spatial Join

A spatial join is a process of determine statistical information about objects contained within a polygon.  For example if you have student data which are represented by points and you want to know the number of students living in each county, a spatial join can be done to count the students.

 

Slope

Slope is in general is the elevation change divided by the horizontal distance change.  The steeper the slope the closer the contour lines are togehter on a map.  Understanding the slope of a parcel is important in the understanding the water run off and what the land can be used for.  The slope of a parcel can be calculated from the DEM. is

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Sphere

A sphere is a geometrical object in which a plane cutting into the object parallel to the axis will always generate a circle, the maximum diameter of the circle will occur when the plane passes through the center of the sphere.

 

Spreadsheet

A spreadsheet is a program that can perform simple database type operations, but the primary function is to do mathematical calculations.  The spreedsheet contains columns of information with each field a unique attribute.  Each row in the spreadsheet provides a record with the noted attributes.  The mathematical engine can be used to determine new values based upon other attributes, the equation for these calculations are saved within the spreadsheet.  The information in the spreadsheet is formated such as text, number, currency, etc.  The most popular spreedsheet program is Microsoft Excel, but there are numerous other programs that can be used as long as the data is exported in a format that can be used in your mapping application.

 

Story Map

A dynamic mapping format in which pictures, text (the story) and maps are combined to provide a completely understanding of an area and a subject.  For example looing at the historical markers located within a county, might combine and understanding of the event a picture of the marker and potentially historical pictures as well as a map shown the location of the marker that can be dynamically zoomed.

 

Tabular Join

A tabular join is a process of combining a table with a shape.  The table and the shape must have a common field to create the join and they must be in the same data type.  For example the joining of a census data table in a comma delimited (csv) format with a shapefile of census tracts for the same county as the table.

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Thermal Infrared

Thermal Infrared generally referred to as thermal IR, is longer wavelengths than near IR and represents heat of objects that are generally in the humanistic environment.  For example thermal IR can be used to determine heat loss in a building or persons body temperature.

 

Time Zones

For most of the earth the time zones contains 15 degrees of longitude.  Since there is 360 degrees around the earth and 24 hours in a day, the sun appears to move 15 degrees in one hour (360 divided by 24).  The earth in theory contains 24 time zones (there are few deviation from this concept).  In the United States time zones can be modified by individual states and thus are not acurately based on lines of longitude.

 

Topographic Lines

Theses lines are common referred to as Topo lines and are contour lines of equal elevation.

 

Topography

Topography referes the shape of the earth landforms.

 

Topology

Topology is the interelationship between points, lines and polygons such as the corner of one parcel of land should be the same point for the corner of that parcel which adjoins it.  Therefore, each of these corners are points in space and thus they are the same points even though they are contained within two parcels.  In the same way the property line of the two parcel are geographical a single line represented in two different parcels.  https://en.wikipedia.org/wiki/Geospatial_topology

 

Township

A township is an area that is completely contained within a single county.  There are two types of townships, those determined for surveying and those that are a civil divisions.  A survey township ideally is divided into areas that are six mile by six mile segments.  Each township is then divided into 36 sections each being one mile by one mile or 640 acres.  The sections are divided into 16 equal parts each containing 40 acres.  Civil townships are a unit of government, with different levels of governmental authority.  In the past these civil townships controlled schools, care of the poor and land assessment.  Today these functions in many places have been centralized.  For addition information:  https://en.wikipedia.org/wiki/Township_%28United_States%29n

 

Transverse Mercator Projection

A transverse Mercator projection is done by placing an imagenery cylinder around the earth touching the earth along a line of longitude.  The center of the projection has the least distoration and the farther from the central meridian the greater the distoration. 

 

UAS

Unmanned Aerial System, this includes both the devise as well as the control systems.  The complete system can vary from relatively inexpensive to production grade equipment which can get into the tens of thousands of dollars or higher.

U

UAV

Unmanned Aerial Vehicle, this is just the aircraft, which could be a fixed wing device or a multiple rotator device.  Vehicles of production grade have control systems as well as built in GPS.  Some vehicles have cameras that are part of the vehicle and others have removable cameras.  The sizes of a vehicle can be as small as would fit in your hand to those over 50 pounds.  Generally many of the systems used for remote sensing are less then 55 pounds and are classified as small vehicles.  There are regulations that must be meet to fly vehicles commercially.

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UTM

A Universal Transverse Mercator coordinate system is based on the transverse Mercator projection.  Typically the earth is divided into 60, 6 degree zones, a zone is created for the northern hemisphere and a different one for the southern hemisphere.  This is a good projection system for areas with a more north-south alignment.  The projected corredinate system used should be based on the nearest UTM meridian. . 

 

Vector

A vector is an item that has both length and direction.  Therefore, it can be expanded without loss of resolution.  Shapefiles are composed of vector components.