2012 Orthophotography Download Help

 

Using the Download Interface

Zoom in and outThe interface is very flexible with many ways to move around and select the dataset that you are after.

To move around the map, use the + to zoom in and the - to zoom out. Pan by holding the left-click and dragging your mouse. If you have a scroll wheel or touch pad on your mouse, scroll up to zoom in and down to zoom out.

To start, EITHER:

  • Results Window for a TownSelect a Town from the drop-down list or Town drop-down
  • Click on the map.

With a town selected (colored in yellow), you can access files to download in all sorts of ways!

The Results window: Click the Town tab to download the town JPEG2000 mosaic. Click the Tile tab to download the selected GeoTIFF or MrSID tile.

The Tile List Column: Click on the word Download under the GeoTIFF column or MrSID column to (.. you guessed it), download each tile.

Result Window for a Tile Tile List

 

The Tile List Column has some other nifty functions.

- The Magnifier takes you right to the tile on the map.

- Clicking on the Town Name will zoom the map to that town and

- clicking on the X next to the town name clears out the selected tiles.

MagnifierColumn Header

 

File Formats

Images can be downloaded in three formats. All three formats

- are imagery files that include 4 bands of data (red, green, blue, near-infrared),

- have 1 foot pixel resolution,

- are in the CT State Plane NAD 83 Feet coordinate system,

- each tile (GeoTIFF or MrSID formats) covers 573.9 acres, 0.897 sq mi, 232.3 hectares, 2.3 sq km and is 97.696 Mb, and

- are delivered in a zip file that includes metadata. The file will need to be unzipped or extracted before the imagery can be accessed.

File Format

File Size

Area Covered

 

GeoTIFF Tiles

97Mb zipped to 82Mb

Each tile covers 0.9 sq mi or 2.3 sq km

The GeoTIFF tiles are the original files delivered to the State of Connecticut from Photo Science, Inc.
Tip: beware, that at nearly 100Mb each, they take a long time to draw.

MrSID TIles

3.6Mb

Each tile covers 0.9 sq mi or 2.3 sq km

The original GeoTIFF tiles were compressed to MrSID the file format. They are a much smaller file size. Read more about the MrSID format at UConn MAGIC.

JPEG2000 Town Mosaics

Range from 1Gb to 8G

Each town is a rectangle where no side is closer than 1000 feet from the town boundary. See below.

For town work, the mosaic is by far the best choice.
Tip: Because the town extents have a buffer and are a rectangle, there will be overlap when viewing multiple towns at once.

Town Mosaics

Compression: The JPEG2000 format was chosen for compression because of the ability for loss less compression (no data loss) while reducing file size as well as the ability for use in many software programs.

File Extent: the town mosaics are defined by a rectangle that is no closer than 1000 feet from the town boundary at any place. The graphic below illustrates the extent using the town of Mansfield.

Mansfield Boundaryarrow

Town Boundary (yellow)

Mansfield Envelopearrow

Rectangle extent (orange)

Mansfield Extentarrow

Rectangle extent with image

Mansfield imagearrow

Extent of town mosaic file for download.

Results: Town Mosaic ExtentThe rectangle extent was used to ensure that no part of any town would be missing. Also, image data must be a rectangular shape so instead of providing you with many black pixels that contained no information, you get a full rectangle of aerial imagery! Lucky you!

To see the extent of the town mosaic that you can download, mouse over Mosaic Extent in the Results window. The orange square outlines the rectangular extent of imagery in that town's mosaic.

 

After Download

Unzip the file. Add the image to your software of choice, such as GIS software or image processing software. If you don't know what this is or don't have it, try using the many other ways that the imagery can be accessed on CT ECO (even as a pdf) which are explained here.

Questions or comments about CT ECO and the imagery, email Emily Wilson or CLEAR at clear@uconn.edu.