Geographical concepts
Download
1 / 11

Geographical Concepts - PowerPoint PPT Presentation


  • 191 Views
  • Uploaded on

Geographical Concepts. IDigBio Train the Trainers Georeferencing Workshop Gainesville, Fl 8-12, Oct 2012. Geographical Concepts. 3 main concepts Projection Datum Coordinate system. Geographical Concepts: Projections. Geographical Concepts : Projections. Bonne equal-area projection .

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Geographical Concepts' - shay


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Geographical concepts
Geographical Concepts

IDigBio Train the Trainers Georeferencing WorkshopGainesville, Fl8-12, Oct 2012


Geographical concepts1
Geographical Concepts

  • 3 main concepts

    • Projection

    • Datum

    • Coordinate system



Geographical concepts projections1
Geographical Concepts: Projections

Bonne equal-area projection


Geographical concepts projections2
Geographical Concepts: Projections


What projections do
What projections do

Rectangular projection

Tissot’sIndicatrix of distortion


Projections examples
ProjectionsExamples

Geographic

preserves NS distance

Mercator

preserves shape (terrible for poles, distorts area)


Projections: Take Home Message

  • Projections compromises…

    • Equal-area

    • True shape

    • True scale

    • True direction

  • Select projection to fit your needs



Geographical concepts datums
Geographical Concepts: Datums

Common Datums

NAD27 (North American Datum): system derived from land-based surveys, using Clarke 1886 ellipsoid

NAD83: satellite-based system using the Earth’s center as a reference point; eventually adopted as GRS80 (Geodetic Ref. System 1980)

WGS84 (World Geodetic System 1984): mathematically refined GRS80 used by the US military and default for GPS

For most uses, NAD83, GRS80, WGS84 are equivalent


Geographical concepts coordinate systems
Geographical Concepts: Coordinate Systems


ad