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coordinate reference systems -凯发k8网页登录

representing coordinate reference systems, projecting and unprojecting coordinates, analyzing distortion

a coordinate reference system (crs) provides a framework for defining real-world locations. represent latitude-longitude data using a geographic crs or x-y map data using a projected crs.

transform coordinates between systems using various projection methods. though all projection methods cause distortion, you can preserve attributes such as area, shape, or direction by choosing an appropriate projection method.

functions

crs objects

geographic coordinate reference system object
projected coordinate reference system object
well-known text string

map projection structures

create or reset map projection structure
convert geotiff information to map projection structure
map projection support for axesm-based maps and map projection structures
list map projections for axesm-based maps and map projection structures
geotiff info structure support for projfwd and projinv
select ellipsoids for given utm zone
utm zone from latitude and longitude
choose or identify utm zone by clicking map
project latitude-longitude coordinates to x-y map coordinates
unproject x-y map coordinates to latitude-longitude coordinates
transform azimuth on ellipsoid to direction on map
transform direction on map to azimuth on ellipsoid
clip data at /-pi in longitude, /-pi in latitude
display contours of constant map distortion on axesm-based map
distortion parameters for map projections
project tissot indicatrices on axesm-based map
transform vector map data to new origin and orientation
origin vector to place specific point at pole
origin vector to place north pole at specified point
location of north pole in rotated map

topics

map projections


  • learn about the map projections supported by the toolbox, and their families and properties.

  • most map projections can be categorized into three families based on the cylinder, cone, and plane geometric shapes.

  • map projections are influenced and constrained by five characteristic properties: shape, distance, direction, scale, and area.

  • variable projection parameters control the appearance of map projections. projection parameters include aspect, origin, and scale.

project data


  • transform coordinates from a projected crs to a different projected crs that uses the same geographic crs.

  • project or unproject raster data by referencing the coordinates to a grid, then display the data.

universal transverse mercator (utm) system


  • create a map for a zone in the universal transverse mercator (utm) system.

  • you can interact with a map of the world to select a utm zone and adjust map settings, such as the limits, origin, parallels, and aspect.

  • this example shows how to select a utm zone by specifying the coordinate of a location. you can then create a utm coordinate system using the suggested ellipsoid vector of the zone.

  • this example shows how to display areas that extend across more than one utm zone by using the mercator projection in a transverse aspect.

analyze distortion


  • a map projection transforms a curved surface such as the earth onto a two-dimensional plane. all map projections introduce distortions compared to maps on globes.

  • a standard method of visualizing map projection distortion is to project small circles spaced at regular intervals across the globe.

  • you can calculate quantitative position-specific map error statistics, such as area scale, angular deformation of right angles, and directional scale distortions along meridians and parallels.

rotate orientation of map display


  • a projection aspect is the orientation of a map on the page or display screen. an orientation vector controls the map projection aspect.

  • you can redefine a coordinate system and transform all points to the new coordinate system. the transformation can be useful independent of map displays.
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