Resolving Data Positioning in Oasis montaj

The second major step in the Oasis montaj data processing workflow is resolving data positioning. This involves interpolating, projecting, and/or warping data to align it accurately within a geographic context.

Introduction to Coordinate Systems and Projections

A coordinate system defines how geographic locations on Earth (e.g., longitude and latitude in a specific datum) are represented on a flat map. Geographic locations—whether expressed as X/Y or Lat/Long—are either in an implied or known coordinate system..

If no coordinate system is specified, Oasis montaj assumes the data is in an unknown system.

Why Define a Map Coordinate System?

Defining coordinate systems allows you to:

  • Annotate maps with longitude and latitude locations

  • Convert data or grid locations between coordinate systems

  • Display information on a map that is in a different coordinate system

  • Define a warped coordinate system to fit data to a desired map coordinate system

Attaching Coordinate System Information

In Oasis montaj, the map coordinate system information must be attached to your data—typically via a *.GI file. Once you have attached a coordinate system to a set of coordinates, Oasis montaj can:

  • Automatically reproject data to match other datasets (of different coordinate systems)

  • Maintain dynamic links between maps and data, even across different coordinate systems

  • Use "smart projections" to project data "on the fly" during display

This enables maps to contain multiple views, each using different coordinate systems, while preserving data relationships.

Defining Projections

Map projections can be defined for:

  • Any pair of X/Y channels in a database

  • A grid coordinate system

  • A data view in a map

In most cases, you only need to define the coordinate system for the X and Y channels of the original database. This definition is then:

  • Passed to grids during gridding

  • Inherited by map views when created and posted to the map

Coordinate systems for channels, grids, and views can be viewed or modified at any time. However, modifying map coordinate systems requires precise and accurate knowledge of the coordinate system parameters.

What do you want to do?

Interpolate Data

Define and Modify Map Projections

Define the Coordinate System for Database Channels

Define the Coordinate System of a Grid

Define the Coordinate System of a Map View

Annotate Longitude and Latitude Coordinates on a Map

Display with Different Coordinate Systems on a Map

Define and Apply a Warp

Warp Data and Grids

Define a Warp File Interactively

Define a Warp File Semi-interactively

Apply a Warp to a Grid

Apply a Warp to an Image

Apply a Warp to Data

Attach a Warp to a Grid

See Also: