Page 7 - Topic 1 - introduction to gis

Raster models are useful for storing and analyzing data that is continuous across an
area. Raster data includes images and grids. Images, such as an aerial photograph, a

satellite image, or a scanned map, are often used for generating GIS data.

Non-spatial data

Additional non-spatial data can also be stored along with the spatial data
represented by the coordinates of a vector geometry or the position of a raster cell.
In vector data, the additional data contains attributes of the feature. For example, a
forest inventory polygon may also have an identifier value and information about
tree species. In raster data the cell value can store attribute information, but it can
also be used as an identifier that can relate to records in another table.

Layer

A map layer defines how a GIS dataset is symbolized and labeled (i.e., portrayed) in
your map views. Each layer represents geographic data in ArcMap such as a
particular theme of data. Example map layers include streams and lakes, terrain,
roads, political boundaries, parcels, building footprints, utility lines, and orthophoto
imagery.

ArcMap offers many ways to interact with maps.

Exploring Maps let you see and interpret the spatial relationships among features.
You could use the map you have just opened to find City Hall, to identify parks
near schools, or to get the names of the streets around the library.

Analyzing You can create new information and find hidden patterns by adding
layers to a map. For example, if you added layers of geology and surface slope, you
might use the map to identify areas at risk for landslides

Presenting results ArcMap makes it easy to lay out your maps for printing,
embedding in other documents, or electronic publishing. You can quickly make
great maps of your data. When you save a map, all of your layout work, symbols,