| Sunday, June 21, 2009 |
18:04 - The 30,000 foot view
http://www.gearthblog.com/blog/archives/2009/06/improving_google_earth_imagery.html
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Frank Taylor of Google Earth Blog has some pointed remarks about Google's recent decision to roll back some of their newer, higher-resolution satellite imagery in favor of older imagery that better indicates the topology of the land from space.
Today, I'd like to make a case that Google is going down the wrong path with their base imagery. Albeit with the best of intentions. They apparently would like to make the imagery when viewed from space look more normal (like you would see it from space). Google Earth's imagery has always looked "mottled" due to the strips of satellite imagery having many different rectangular shades of brightness (since the imagery is taken at varying times of day and year). Correcting this look is something I've also pleaded for in past blog posts. But, not the way they are doing it now.
Lately, Google has been attempting to correct the view from above by fusing different colors of shading into the imagery and using color correction on the satellite imagery. For example, this was done with Australia in December, and this weekend the US has had some of the treatment. But, the problem with this approach is that the colorization sometimes messes up the quality of the imagery (painting not only vegetation green, but also buildings, roads, and everything else (see image to the right). See the example in the screenshot here in Google Earth - turn on "Historical Imagery" option of GE 5 to see the two different shots. Not only that, but the colors are actually wrong in some places (like Arizona where they painted areas green that have no substantial green color in real life) - see the Tucson Mountains for example. However, I do approve of processing the base imagery for color saturation, brightness, and contrast consistency.
He's got some compelling examples, to be sure. But I for one think the effort is laudable. I've been miffed for a long time now that the Google Earth imagery for Oregon has been a mottled, gray patchwork, roughly the way you see it here:
—only just in Oregon, and all the way from border to border, west to east, north to south. They were apparently using a database of Oregon-only state survey imagery, judging by the copyright messages on the screen when browsing over the state—imagery that wasn't available for other states.
Thank goodness for that, too; because while I hadn't thought to take a screenshot of what it looked like (for all I knew, that's the way it would be forever), just look at that screenshot there, and bear in mind how key to the Google Earth experience I consider it to be to get a sense of the topography of the land from high above, particularly in geologically fascinating areas such as Oregon, where you would ideally get to see the Cascades clashing with the high deserts, the string of Cascade volcanoes peeking out in spots of white against dark brown sausages of evergreen-clad mountain ranges surrounding green arable lowlands, and cities only showing up as smudges of white at the confluences of rivers and estuaries. In short, it was possible to do that in California, and Nevada, and Washington, and Colorado, and all kinds of places—just not Oregon.
Well, here's what the Western states look like now, under Google's new iron-fisted regime:
Aaahhhh. Now that's more like it.
Looking at this, I don't care if some of the up-close imagery has false colors. I think it's a worthwhile tradeoff if the upside is this stark: you can now fixate on a geological feature and zoom out until it's a few pixels wide, and you can watch it blend into a tapestry of similar and starkly different features, each with its own color scheme, and you know from first-hand zoomed-in inspection just why it's that color. You can look at it from twenty miles up and know how high a bit of terrain is just by the shapes of its color ranges. And you can distinguish those lonely high-desert highways from the lowland farm-country arteries at a glance. No more do you have to zoom in to general-aviation height to tell whether what you're looking at is Crater Lake or some flooded farm field, or whether that's a lava flow coming from the summit craters or a population center, or maybe just a JPEG artifact.
Color me reassured; because I feel like I've got a friend on the inside.
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Brian Tiemann
