2016 Orthophotography and Lidar Download Help

 

File Formats | Spatial Reference | Download a Small Number of Files | Download Numerous Tiles | After Download

Download a Small Number of Files

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. (Note that a download manager can be installed in your browser. If you plan on clicking and downloading a lot of files, consider using a manager to line the files up and download one at a time - it will help you manage it and help our server load)

To start, EITHER:

  • Select a Town from the drop-down list Town drop-downor
  • Click on the map.

Now that a town is selected (colored in yellow), click on a link to download the file. Find the links in the results window or the tile list. Result Window for a Tile

  • The Results window: On the Town tab click to download the town mosaic in either MrSID gen 3 or MrSID gen 4 format. Click the Tile tab to download the selected tile as a GeoTIFF, MrSID gen 3, MrSID gen 4 tile or a DEM (elevation).
  • The Tile List : Click on the file type to (.. you guessed it), download the zipped tile..
Tile List

 

The Tile List Column has some other nifty functions.

- The Magnifier zooms the map to that tile
- 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.

Magnifier

 

Town Mosaics

The town mosaics are available in MrSID gen 3 or MrSID gen 4 formats. The extent of the town mosaics are defined by a rectangle that includes the town boundary. The 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.

 

 

 

Download Numerous Tiles

Here are the steps in a nutshell. Detailed instructions follow.

  1. Install a download manager for your web browser
  2. Go the 2016 download page.
  3. Zoom in to your area of interest
  4. Check Interactive Select Mode in the top bar
  5. Draw a rectangle to highlight the tiles in area of interest
  6. In the tile column on the right, check the tiles for download. Note the top checkbox that checks them all at once. Selected tiles are highlighted in bright yellow.
  7. Below the tile list, locate the menu that says Download xx tiles as ____ and choose the format. Click Go.
  8. A boring list of the tiles opens. Use this list with your download manager.
1. Install a download manager for your web browser

Download managers are designed to help handle and manage multiple downloads at once. This is helpful for bandwidth and managing which files you actually want (and don't want) as well as additional functionality. Also, the scheduling function allows you to set a start time so you can download during the night or other quieter times. At CT ECO, we have had good luck with a download manager called DownThemAll which is an add-on to Firefox. We also here good things about FlashGot which is also an add-on to Firefox. If you would recommend other download managers (there are a lot out there!), let us know and we will add it to the page.

2. Go the 2016 download page.
3. Zoom in to your area of interest

Use the zoom tools on the left or the scroll wheel on the mouse to zoom and pan to the area.

4. Check Interactive Select Mode in the top bar

This disables the traditional zoom tools so that the mouse can draw and select tiles on the map.

5. Draw a rectangle to highlight the tiles in area of interest
6. In the tile column on the right, check the tiles for download

Then select the tiles in the list by either clicking next to each one or clicking on the top checkbox to select them all.

 

7. Below the tile list, locate the menu that says Download xx tiles as ____ and choose the format. Click Go.

Once the appropriate tiles are checked, click the format from the menu at the bottom and click GO.

8. A boring list of the tiles opens. Use this list with your download manager.

Keep reading for instructions on using the DownThemAll download manager or use your favorite one.

 

DownThemAll

1. Download and install DownThemAll from their website. You may want to browse the available features.

2. Open Firefox and navigate to the 2016 imagery page. Follow the instructions above to the place where you have a list of tiles to download in its own window.

3. In the window that contains the list of files, right-click and choose DownThemAll.

 

4. Choose the location for download and optionally the filter for Archives (zip). Click Start.

The manager runs through the files in order. Nice!

 

File Formats

Images can be downloaded in four formats. Three are imagery and one is elevation.
- are imagery files include 4 bands (red, green, blue, near-infrared)
- have 3 inch foot pixel resolution
- are delivered in a zip file that includes metadata. The file will need to be unzipped or extracted before the imagery can be accessed.
- each tile is 2500ft on a side and covers 0.224 sq miles, 0.58 sq km, 143.5 acre

File Format File Size  
MrSID Generation 3 Tiles 14.5Mb  
MrSID Generation 4 Tiles 19Mb  
GeoTIFF Tiles 381Mb Beware: at nearly 400Mb each, they take a LONG time to draw.
MrSID Generation 3 Town Mosaic   A bounding rectangle with a buffer from the town boundary.
Tip: Because the mosaic extents are a rectangle, there will be overlap when viewing multiple towns at once.
MrSID Generation 4 Town Mosaics   A bounding rectangle with a buffer from the town boundary.
Tip: Because the mosaic extents are a rectangle, there will be overlap when viewing multiple towns at once.
Digital Elevation Model (DEM) Tile