Here's another cool app for rendering satellite photos and more. this one is by NASA lets you zoom, pan and select a wide variety of map overlays. it renders the map image over landscape contours, letting you pan and bank the camera's point of view. maps include whole-earth, landsat7, topo, urban area satellite and more. the map zooms and moves fluidly between perspectives. you can zoom in, from outer space right to your house.
it's certainly a lot of fun to fly & zoom over my house and around the globe. i can see my cooler in the backyard.
like usaphotomaps, the images download from the internet and are cached locally on your drive for offline browsing. it's intuitive and easy to use. the contours and maps download automatically - but it doesn't appear to work at first, until you get enough map data to view an area properly. that threw me off at first. also, i seem to have directx glitches, maybe from missing data? bad drivers? what works really well here is that it download wide area, compress images first, so you get a good sense of where you are. then it downloads fine resolution maps. this is a nice touch.
the contour or 'vertical exaggeration' turned the portland hills into a mountain range, but once i found the proper setting, things calmed down. there are perspectives that make the terrain look really twisted, but it's commendable this feature works so easily. world wind performs what takes fair amount of work downloading contours and calibrating map images, using the 3dem software. however, it doesn't let you overlay custom map images like 3dem. fun, but it's not like i do that everyday. 3dem also lets you use much more accurate terrain contours.
it's very cool -- ok, it's not *perfect*. i still really like usaphotomaps - which has some very straightforward and very useful features (gps options, large image/map rendering). world wind uses directx to render maps, which is how it can pan so beautifully -- but i wasn't able to see the full resolution of the urban area maps. i'm assuming this is either due to compression, or the directx engine isn't accurately transforming the image. the final image was good but a little distorted (even without vertical exaggeration). this must be an artifact of inaccurate directx pov transformations? usaphotomaps shows maps with simple 1:1 pixel ratios -- there's no mistaking map resolution, the maps appear clear and perfectly orthogonal at all times. sometimes that's exactly what you need. fortunately, both are apps free, and you can use whatever you want.
follow-up: seems that downloads can occasionally hang -- deleting the file cache or the stuck image can help... this may have caused some problems initially. the image still isn't as *crisp* as usaphotomaps -- but it's pretty damn close. also, i was getting artifacts from the 'blue marble' world images while viewing the urban area ortho satellite photos -- messing things up. turning off those layers (while not viewing them) helped a lot.
world wind :
http://worldwind.arc.nasa.gov/
http://www.worldwindcentral.com/wiki/Unofficial_FAQ
usaphotomaps :
http://jdmcox.com/