GIS Projects & Layers

GIS Project

A GIS Project is a text file that contains structured specifications of the overall project, such as geographic extent extent, and layers used in the project.  Geographic projects used by CV XE GIS are named with the file extension of "gis".  GIS projects contain one or more layers, described below.

An example of a GIS project is the project US1.GIS distributed with the CV XE GIS installer.

Extent

The visible geographic extent of a GIS project is defined is defined in the start-up GIS project file.   The full geographic extent of the GIS project is the collective extended latitude-longitude represented by all layers in the project.  For CV XE GIS projects using the "OpenStreetMaps" base layer or the World by Country shapefile, the full geographic extent is the world.    

Layers and GIS Projects

A conventional two-dimensional map might be thought of a single map layer.  In geographic information system applications, many layers are often used at the same time.  A set of specific layers, and the map view that they depict, are defined by the GIS project.  CV XE uses a GIS project file to define a set of layers, the manner in which their attributes are set and the relationship among the layers.

Layers in CV XE GIS projects are often renderings of shapefiles.  Shapefiles may be thought of as point shapefiles, lines/arc shapefiles or polygon shapefiles.  The elemental unit in a shapefile is a shape or geographic object.  Points comprising the shapes represent locations on the earth surface.  Shapefiles are vector graphics as they are comprised of points and lines.

GIS projects may contain other types of layers such as tiling layers.  The OpenStreetMap layer, used widely within CV XE, is an example of a tiled layer.

 
Creating a Project

Saving a Project

Adding Layers

Deleting Layers