EPPS exam 1

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geospatial technology

incorporates diff high-tech systems and tools that acquire, analyze, manage, store, or visualize various types of location-based data (ex: GIS, Remote Sensing, and GPS)

users of geospatial tech

archaeologists, environmental monitering, city planning, forestry, weather prediction, crime scene/mapping, health and human services, military and intelligence, real estate, 3D modeling

geospatial data

location-based data

geolocation

determining where something is in the real world (ex: GPS, IP address, WIFI, Cell Tower data, through phone/tablet/computer)

Projections

transformation of a 3D spherical surface to a 2D plane, introducing distortions to distance/area/shape/direction

Equidistant Projections

map is equidistant in portraying distance from the center to any other place on the map

Equal-Area Projection

map portrays areas over the entire map so every area has the same proportional relationship to the areas on earth that they representation

Conformal Projections

when the scale of the map at any point is the same in any direction; meridians and parallels intersect at right angles, shape is preserved locally

azimuthal projections

preserves direction when azimuths (angles from a point on a line to another point) are portrayed correctly in all directions

Cartesian Coordination System

(X, Y) or East/North, usually specified as decimal numbers that increase from bottom to top or left to right, most often used with maps or GPS and is good at mapping small areas

Spherical Coordinate System

recorded as degrees-minutes-seconds (DMS notation), recorded as Decimal Degrees notation

Why is the earth not a perfect ellipsoid?

because the surface is not flat all around, thus it is a geoid

datum

referencing system that allows the location of lat and longitudes to be identified onto the surface of the earth (2 main eras; those before and those after the satellites geodesy) (Horizontal and Vertical Datum) (Two major vertical datum- North American V.D of 1927 and 1988)

state plane coordinate system

standard set of projections for the U.S., specifices positions in Cartesian Coord sys. for each state. Some states have larger distortions, and it is used in property surveys/subdivisions, construction, and its adopted for GIS. Larger states need several zones and it uses the Lambert Conformal Conic (e/w states) and the transverse mercator projections (n/s states)

datum v projection

datum is a referencing system, projection is a process that converts the lat/long on the earth’s surface to a drawing on a flat piece of paper

UTM Coordinate System

global coord system based on the transverse Mercator Projection, used in U.S., North America, etc.; divides earth into 60 zones

map design goals

clarity, order, balance, contrast, unity, harmony

What to include on a map

TALDOGS (Title, Author, Legend, Date, Orientation, Grid, Scale)

Paper maps

pros: better for certain localities, can be the only option for historic locations

cons: time consuming and good quality maps without errors can be hard to find

georeferencing

taking a paper map or spatial data and transforming it from an arbitrary coord system into a geographic or map projection coord system (digitizing them)

some georefs are metric, defining location using measures of distance, while others are based on ordering (street add) or nominal

Latitude and Longitude

most comprehensive method of georeferencing, allows distance to be computed between pairs of locations, uses a well defined fixed reference frame (based on earths rotation and center of mass + the greenwich meridian)

linear referencing

georeferencing using roads, streets, railroad tracks, highways, river networks

place names

earliest form of georeferencing

Georeferencing methods

1) homogenous transformation through rotation, translation, scaling, skewing (for map projections)

2) through rubber sheeting (used to correctly position distortion images or scanned maps/docs)

Root mean squared error

measures the errors between the measured coordinates of ground control points and the transformed coordinates from the equation

digitize

tracing geographic features from another dataset