From a Farmers Market to Spatial Resolution

[xpatUSA]

While looking for farmers markets near Bellville, Texas I found an address in Bastrop about a 100 miles away. Here in Texas, we call that "just down the street"

Anyway, out of curiosity, I looked it up in Google maps and, while zooming in, noticed a huge name on the ground spelled out in trees.



Apparently, NASA has used this ground feature as part of an assessment of spatial resolution in terms of ground size versus image size. Some interesting facts are to be found if you read the whole page [warning: actual numbers and formulae].

http://earth.jsc.nasa.gov/newsletter...s/default5.htm

The photo above is from Section 5.

[Donald]

I gave up after the first sentence on the linked site (maths/physics, etc were never my strong point!). But fascinating, nonetheless

[TonyW]

Being of a wonkish nature, I quite like these discussions. I am often surprised how much can be seen from google maps, including the pile of rubbish at our house which rather embarrasses me.

Fortunately, in my experiments with resolution, I have not had to resort to spherical trigonometry, being slightly closer to earth, at least in the literal sense, than the astronauts.

[FootLoose]

Being of a wonkish nature, I quite like these discussions. I am often surprised how much can be seen from google maps, including the pile of rubbish at our house which rather embarrasses me.

Fortunately, in my experiments with resolution, I have not had to resort to spherical trigonometry, being slightly closer to earth, at least in the literal sense, than the astronauts.

If you think google maps are surprising, have a look at a company called 'nearmap'. Their resolution leaves google for dead.

http://www.nearmap.com/Photomaps-sta...tures-benefits

[TonyW]

Nearmaps are good. They did a marvellous coverage of the Brisbane floods in 2011. I could be wrong but I understood that they use aerial photography rather than satellite.

[drjuice]

Hi, Tony -

I just looked at the nearmaps site and it certainly looks a WHOLE LOT better than civilian satellite imagery. I'd guess you're right about the aerial photography.

virginia

[FootLoose]

Thanks Tony, you are probably right. I hadn't looked that far into it. I was just aware of superior maps.

[mastamak]

Nearmap is based on aerial photography and standard photogrammetry. It has limited coverage. For the Queenslanders who have responded to this thread may I suggest you try Queensland Globe. It is a Google Earth add on that accesses the latest aerial photography and satellite imagery. Coverage is state wide and its free.
Grant