Aligning data

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Aligning data Sabata Mcatshulwa

description

The main focus of this presentation is on coordinate systems. We describe common problems that people have, key terms , how to apply coordinate systems in 10.1 and best practices.

Transcript of Aligning data

Page 1: Aligning data

Aligning data

Sabata Mcatshulwa

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Presentation Outline

Common problems

Coordinate Systems

Geoprocessing Tools

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Presentation Outline

Common problems

Coordinate Systems

Geoprocessing Tools

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Common Problems

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Common Problems

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Common Problems

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Demonstration

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Presentation Outline

Common problems

Coordinate Systems

Geoprocessing Tools

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• A measurement of a location on the Earth’s surface

expressed in degrees of latitude and longitude

Geographic Coordinate Systems

Coordinate Systems

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• Three-dimensional spherical surface to define locations on the earth

• If two datasets are not referenced to the same geographic coordinate system, you may need to perform a geographic (datum) transformation

• It is very important to correctly use a geographic transformation if it is required.

• A GCS is often incorrectly called a datum, but a datum is only one part of a GCS. A GCS includes an angular unit of measure, a prime meridian, and a datum (based on a spheroid).

• The spheroid defines the size and shape of the earth model, while the datum connects the spheroid to the earth's surface

Geographic Coordinate Systems

Coordinate Systems

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• A method by which the curved surface of the earth is

portrayed on a flat surface

Projected Coordinate Systems

Coordinate Systems

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Projected Coordinate Systems

Coordinate Systems

• Two-dimensional surface

• locations are identified by x,y coordinates on a grid, with the origin at the center of the grid

• Unlike a GCS, a PCS has constant lengths, angles, and areas across the two dimensions

• A PCS is always based on a GCS that is based on a sphere or spheroid.

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• A frame of reference for measuring locations on the surface

of the Earth

• Cape (Port Elizabeth)

• Hartebeesthoek 1994 (Hartrao)

• WGS 1984 (Earth-centered = mass of the Earth)

Datums

Coordinate Systems

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TM

• Two degree zones (Transverse Mercator)

• LO = TM x, Cape

• WG = TM x, Hartebeesthoek

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Coordinate Systems

• South Africa or a different area

• Create a .prj file

• Update the parameters

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Demonstration

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Presentation Outline

Common problems

Coordinate Systems

Geoprocessing Tools

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Geoprocessing Tools

• Vector

• Define Projection = To assign a coordinate system

• Project = Change a coordinate system

• Raster

• Raster Properties = To assign a coordinate system

• Project Raster = Change a coordinate system

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Geoprocessing Tools

− Spatial adjustment • Projections - Shift data between coordinate systems• Transformations - Shift data in coordinate space

− Alignment tools• Bulk alignment

� Snap - snapping based on user specified rules� Integrate – will make feature coincident within a tolerance

• Interactive(New tools introduced at 10.1)� Align Edge - snap edges together to close gaps� Align to shape - adjust layers to traced shape� Replace geometry - create an entire new shape for a feature

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Demonstration

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Discussion