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GIS is geographic information system software technology
that lets you map and analyze geo spatial data
to see relationships patterns and trends.
The CGIS mission is to use GIS to create
tools that enhance productivity and efficacy.
Hello I’m Jeremy Monn
a GIS specialist with the center of GIS at Towson University.
I’ve been working with ArcGIS 10 for about 8 months now
and I’m discovering the ways streamlines work with geospatial data.
Today I’m going to touch on a new raster data model
introduced in ArcGIS 10 that offers several improves over past data models.
First let’s look at what was available in ArcGIS 9
The primary Raster data models were the Raster data set
and the Raster catalog.
A Raster data set is a single image that
can be stored on disk, or in a geo database in a variety of image formats.
A Raster catalog lets you simultaneously view
individual raster data sets as if they were mosaic.
In ArcGIS 10 Esri introduced a new Raster data model
called the Mosaic Data Set.
Mosaic Data Set is a data model that stores
a catalog of links to individual images.
When viewed the individual images appear as a mosaic.
So how is a Mosaic Data Set different from a Raster catalog?
Well there are several differences but we'll just focus on two.
One difference is that you have the option to create
feature classes that outline various portions of the imagery.
If you want an outline of an entire mosaic data sets perimeter
then create a boundary feature class.
If you want an outline of each individual image
that makes up the mosaic data set then create a footprint feature class.
Both of these are valuable when identifying
holes in your mosaic data set
establishing an inventory of the images that make up your mosaic data set
or identifying the cashing extents for a map service.
Another difference is that you have the option to create overviews.
Which are lower resolution versions of the mosaic data set.
The reason you should do this is so that you can
see the data at smaller scales then the source data.
There are 5 ways mosaic data sets improve your workflow.
First of all a mosaic dataset provides a single data source
you can use to access imagery for a project.
Second, creating a mosaic dataset of your imagery takes less time
then creating a raster dataset using the same imagery.
Third, if you want to share your mosaic data set
with others, but are afraid they will delete data,
you can give them a referenced mosaic dataset
This is a read only version of your source mosaic dataset.
Fourth, you can store images with different
formats in the same mosaic dataset.
This means you can display Tiff images alongside JPEG
images in the same mosaic.
And finally if you have ArcGIS server you can
you can serve the mosaic dataset as an image
service or as part of a map service.
Next time we will take a look at how you go about
actually creating a mosaic dataset.