Resolution Comparison

So I am running some test to decide on the next step strategies for upgrading the Imaging Place project. It used to be that aerial orthophotographic data was produced in the U.S. by a network of skilled aerial photographers working primarily with 9×9 inch roll film cameras through The National Aerial Photography Program (NAPP), an interagency Federal effort coordinated by the USGS. The best of the images which appear on Google Maps are still produced that way. However, with the phenomenal popularity of Google Maps commercial providers such as Digital Globe are able to finance launching increasingly sophisticated imaging satellites such as WorldView-1. Operating at an altitude of 496 kilometers, WorldView-1’s panchromatic imaging system is capable of collecting up to 750,000 square kilometers (290,000 square miles) per day at half-meter resolution imagery. Here in a 1:1 pixel detail of the data set I bought for Imaging from Digital Globe in August 2007.

Digital Globe

The resolution is very good and I expect it will be getting better. The detail of 9×9 inch aerial roll film photography is pretty tough to beat, though. As I understand it there are strict standards for altitude, tilt, roll, pitch and atmospheric clarity to qualify for the USGS image bank. I was researching this back in 2000 to see if I could commission images at elevations lower than the standard. I found a photographer/pilot at Lawrence Airport who has a business Four Star Aviation. Here is a shot of his Cessna. 

Four Star Aviation

This is a shot of the camera. 

Four Star Aviation aerial camera

Here is a full-frame scan of a 9×9 contact C-print flown, I believe at the minimum altitude allowed by the FAA over Cambridge.

Four Star Aviation 9X9′ color aerial photograph

 You can see that the detail is quite remarkable.

Four Star Aviation

Here is a comparison with the Mass GIS data set of the same area. 

Mass GIS

Here I pasted the two images to 10×10 meter scale in Second Life to approximate 512×512 file textures. You can see from this image that with the Four Star image I could put a pano node on each of the four corners of the street without crowding them. This means I could be working more or less to scale in Second Life.

Resolution Comparison

One last thing. Here is a screen shot for Google of the same street corner using Mass GIS’s 2008 data, which is not yet available to the public.  I scanned the Four Star print at 300 ppi. I will scan it a little higher to see if I can match the 2008 data. 

Google Maps via Mass GIS

The goal is to get the avatar to be able to walk across the image in avatar scale.




About John Craig Freeman

John Craig Freeman is a public artist with over twenty years of experience using emergent technologies to produce large-scale public work at sites where the forces of globalization are impacting the lives of individuals in local communities. His work seeks to expand the notion of public by exploring how digital networked technology is transforming our sense of place. Freeman is a founding member of the international artists collective Manifest.AR and he has produced work and exhibited around the world including at the Los Angeles County Museum of Art, the San Francisco Museum of Modern Art, FACT Liverpool, Kunsthallen Nikolaj Copenhagen, Triennale di Milano, the Institute of Contemporary Art Boston, and the Museum of Contemporary Art Beijing, He has had work commissioned by the ZERO1, and His work has been reviewed in The New York Times, El Pais, Liberation, Wired News, Artforum, Ten-8, Z Magazine, Afterimage, Photo Metro, New Art Examiner, Time, Harper's and Der Spiegel. Christiane Paul cites Freeman's work in her book Digital Art, as does Lucy Lippard in the Lure of the Local, and Margot Lovejoy in Digital Currents: Art in the Electronic Age. His writing has been published in Rhizomes, Leonardo, the Journal of Visual Culture, and Exposure. Freeman received a Bachelor of Art degree from the University of California, San Diego in 1986 and a Master of Fine Arts degree from the University of Colorado, Boulder in 1990. He is currently a Professor of New Media at Emerson College in Boston. Freeman writes, “If Andy Warhol set out to create a distinctly American art form in the twentieth century, I identify with those who seek to create a distinctly global art form in the twenty-first.”
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