Posts Tagged ‘Aerials’

Introducing the 2009AerialsFourInch Service

May 29, 2009

Aerials are an integral part of any well rounded Geographic Information System. Aerials can be used as a great base to provide a context for other data, as part of a quality control effort, or as the source to create new data.

Our new 2009 aerials were flown between 11:20AM and 12:30PM on April 17th, 2009. They are 4 inch resolution meaning each pixel correlates to 4 inches by 4 inches (16 square inches) on the ground. Our new aerials are the highest quality I have ever worked with. They are on-par with the best aerials available today. Below is a table comparing some of the variables between the 3 main aerials we use here at the Port.

Aerial Service: I3_Imagery Prime_World_2D 2005AerialsHalfFoot 2009AerialsFourInch
Source: ArcGIS Online Port Port
Date Taken: 3/15/2008 in Port Area 2005 4/17/2009
Coverage: Worldwide 52.5 Sq. Miles covering Port Tidelands 48.7 Sq. Miles covering Port Tidelands
Resolution: .3 Meters (≈1 Foot) in Port Area Half Foot Four Inch
Ground Pixel Size: 12 x 12 = 144 Sq Inches 6 x 6 = 36 Sq Inches 4 x 4 = 16 Sq Inches

Below are 2 images showing measurements of one side of each pixel.

2005 Pixel Measurement

2005 Pixel Measurement

2009 Pixel Measurement

2009 Pixel Measurement

This is all great, but how does this correlate to the real world? Below are the 3 images of the Administration Building Parking lot. As you know the parking lot was recently repaved and reorganized.

2003 Parking Lot

March 2008 .3 Meter Resolution

2005 Parking Lot

2005 Half Foot Resolution

2009 Parking Lot

April 2009 Four Inch Resolution

Along with our parking lot there have been other changes on or around the Port tidelands since 2005, including the new Hilton between the Convention Center and Tenth Avenue Marine Terminal.

Left 2005 - Right 2009

Left 2005 - Right 2009

We have set up a web application where Port employees can examine the new aerial photos. You can get to this web application by clicking on the 2009 Aerials button at the PortGIS Resource Center. They are much larger images and therefore take a second or two more to render on your screen. Feel free to turn on and off layers in the “Map Contents” area. We hope to include them in the other PortGIS applications shortly.

CoolOldMap Zen