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
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.
March 2008 .3 Meter Resolution
2005 Half Foot Resolution
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
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
Tags: 2009AerialsFourInch Service, Aerials, Aerials2005HalfFoot map service, arcgis for autocad, Engineering, TidelandsMapbook2007 map service
June 2, 2009 at 8:54 am
These aerials look great! The comparisons to previous aerials really show the difference between 4 inch resolution and .5 foot resolution. I’ve definitely learned over the past few months how useful high resolution imagery is when conducting field work. Locating and/or adding features based on the higher resolution imagery becomes much more efficient. These new aerials will only improve our workflow.
-PG